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91e52dc714
By comparing to the total number of objects, we can better determine the hit/miss ratio of various call sites and suitable container reservation sizes based on typical inputs. PiperOrigin-RevId: 871381187 Change-Id: I88e92f028622177d1f343be3e65bcb7a3e41d234
3778 lines
148 KiB
C++
3778 lines
148 KiB
C++
// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// An open-addressing
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// hashtable with quadratic probing.
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//
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// This is a low level hashtable on top of which different interfaces can be
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// implemented, like flat_hash_set, node_hash_set, string_hash_set, etc.
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//
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// The table interface is similar to that of std::unordered_set. Notable
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// differences are that most member functions support heterogeneous keys when
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// BOTH the hash and eq functions are marked as transparent. They do so by
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// providing a typedef called `is_transparent`.
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//
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// When heterogeneous lookup is enabled, functions that take key_type act as if
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// they have an overload set like:
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//
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// iterator find(const key_type& key);
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// template <class K>
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// iterator find(const K& key);
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//
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// size_type erase(const key_type& key);
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// template <class K>
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// size_type erase(const K& key);
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//
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// std::pair<iterator, iterator> equal_range(const key_type& key);
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// template <class K>
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// std::pair<iterator, iterator> equal_range(const K& key);
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//
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// When heterogeneous lookup is disabled, only the explicit `key_type` overloads
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// exist.
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//
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// In addition the pointer to element and iterator stability guarantees are
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// weaker: all iterators and pointers are invalidated after a new element is
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// inserted.
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//
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// IMPLEMENTATION DETAILS
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//
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// # Table Layout
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//
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// A raw_hash_set's backing array consists of control bytes followed by slots
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// that may or may not contain objects.
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//
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// The layout of the backing array, for `capacity` slots, is thus, as a
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// pseudo-struct:
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//
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// struct BackingArray {
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// // Sampling handler. This field isn't present when the sampling is
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// // disabled or this allocation hasn't been selected for sampling.
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// HashtablezInfoHandle infoz_;
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// // The number of elements we can insert before growing the capacity.
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// size_t growth_left;
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// // Control bytes for the "real" slots.
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// ctrl_t ctrl[capacity];
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// // Always `ctrl_t::kSentinel`. This is used by iterators to find when to
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// // stop and serves no other purpose.
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// ctrl_t sentinel;
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// // A copy of the first `kWidth - 1` elements of `ctrl`. This is used so
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// // that if a probe sequence picks a value near the end of `ctrl`,
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// // `Group` will have valid control bytes to look at.
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// ctrl_t clones[kWidth - 1];
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// // The actual slot data.
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// slot_type slots[capacity];
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// };
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//
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// The length of this array is computed by `RawHashSetLayout::alloc_size` below.
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//
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// Control bytes (`ctrl_t`) are bytes (collected into groups of a
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// platform-specific size) that define the state of the corresponding slot in
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// the slot array. Group manipulation is tightly optimized to be as efficient
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// as possible: SSE and friends on x86, clever bit operations on other arches.
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//
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// Group 1 Group 2 Group 3
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// +---------------+---------------+---------------+
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// | | | | | | | | | | | | | | | | | | | | | | | | |
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// +---------------+---------------+---------------+
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//
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// Each control byte is either a special value for empty slots, deleted slots
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// (sometimes called *tombstones*), and a special end-of-table marker used by
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// iterators, or, if occupied, seven bits (H2) from the hash of the value in the
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// corresponding slot.
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//
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// Storing control bytes in a separate array also has beneficial cache effects,
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// since more logical slots will fit into a cache line.
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//
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// # Small Object Optimization (SOO)
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//
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// When the size/alignment of the value_type and the capacity of the table are
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// small, we enable small object optimization and store the values inline in
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// the raw_hash_set object. This optimization allows us to avoid
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// allocation/deallocation as well as cache/dTLB misses.
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//
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// # Hashing
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//
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// We compute two separate hashes, `H1` and `H2`, from the hash of an object.
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// `H1(hash(x))` is an index into `slots`, and essentially the starting point
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// for the probe sequence. `H2(hash(x))` is a 7-bit value used to filter out
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// objects that cannot possibly be the one we are looking for.
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//
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// # Table operations.
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//
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// The key operations are `insert`, `find`, and `erase`.
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//
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// Since `insert` and `erase` are implemented in terms of `find`, we describe
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// `find` first. To `find` a value `x`, we compute `hash(x)`. From
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// `H1(hash(x))` and the capacity, we construct a `probe_seq` that visits every
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// group of slots in some interesting order.
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//
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// We now walk through these indices. At each index, we select the entire group
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// starting with that index and extract potential candidates: occupied slots
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// with a control byte equal to `H2(hash(x))`. If we find an empty slot in the
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// group, we stop and return an error. Each candidate slot `y` is compared with
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// `x`; if `x == y`, we are done and return `&y`; otherwise we continue to the
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// next probe index. Tombstones effectively behave like full slots that never
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// match the value we're looking for.
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//
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// The `H2` bits ensure when we compare a slot to an object with `==`, we are
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// likely to have actually found the object. That is, the chance is low that
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// `==` is called and returns `false`. Thus, when we search for an object, we
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// are unlikely to call `==` many times. This likelyhood can be analyzed as
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// follows (assuming that H2 is a random enough hash function).
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//
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// Let's assume that there are `k` "wrong" objects that must be examined in a
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// probe sequence. For example, when doing a `find` on an object that is in the
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// table, `k` is the number of objects between the start of the probe sequence
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// and the final found object (not including the final found object). The
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// expected number of objects with an H2 match is then `k/128`. Measurements
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// and analysis indicate that even at high load factors, `k` is less than 32,
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// meaning that the number of "false positive" comparisons we must perform is
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// less than 1/8 per `find`.
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// `insert` is implemented in terms of `unchecked_insert`, which inserts a
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// value presumed to not be in the table (violating this requirement will cause
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// the table to behave erratically). Given `x` and its hash `hash(x)`, to insert
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// it, we construct a `probe_seq` once again, and use it to find the first
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// group with an unoccupied (empty *or* deleted) slot. We place `x` into the
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// first such slot in the group and mark it as full with `x`'s H2.
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//
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// To `insert`, we compose `unchecked_insert` with `find`. We compute `h(x)` and
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// perform a `find` to see if it's already present; if it is, we're done. If
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// it's not, we may decide the table is getting overcrowded (i.e. the load
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// factor is greater than 7/8 for big tables; tables smaller than one probing
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// group use a max load factor of 1); in this case, we allocate a bigger array,
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// `unchecked_insert` each element of the table into the new array (we know that
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// no insertion here will insert an already-present value), and discard the old
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// backing array. At this point, we may `unchecked_insert` the value `x`.
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//
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// Below, `unchecked_insert` is partly implemented by `prepare_insert`, which
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// presents a viable, initialized slot pointee to the caller.
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//
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// `erase` is implemented in terms of `erase_at`, which takes an index to a
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// slot. Given an offset, we simply create a tombstone and destroy its contents.
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// If we can prove that the slot would not appear in a probe sequence, we can
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// make the slot as empty, instead. We can prove this by observing that if a
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// group has any empty slots, it has never been full (assuming we never create
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// an empty slot in a group with no empties, which this heuristic guarantees we
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// never do) and find would stop at this group anyways (since it does not probe
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// beyond groups with empties).
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//
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// `erase` is `erase_at` composed with `find`: if we
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// have a value `x`, we can perform a `find`, and then `erase_at` the resulting
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// slot.
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//
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// To iterate, we simply traverse the array, skipping empty and deleted slots
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// and stopping when we hit a `kSentinel`.
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#ifndef ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
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#define ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
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#include <algorithm>
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#include <cassert>
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#include <cmath>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <functional>
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#include <initializer_list>
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#include <iterator>
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#include <limits>
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#include <memory>
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#include <tuple>
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#include <type_traits>
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#include <utility>
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#include "absl/base/attributes.h"
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#include "absl/base/casts.h"
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#include "absl/base/config.h"
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#include "absl/base/internal/endian.h"
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#include "absl/base/internal/iterator_traits.h"
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#include "absl/base/internal/raw_logging.h"
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#include "absl/base/macros.h"
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#include "absl/base/optimization.h"
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#include "absl/base/options.h"
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#include "absl/base/port.h"
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#include "absl/base/prefetch.h"
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#include "absl/container/internal/common.h" // IWYU pragma: export // for node_handle
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#include "absl/container/internal/common_policy_traits.h"
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#include "absl/container/internal/compressed_tuple.h"
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#include "absl/container/internal/container_memory.h"
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#include "absl/container/internal/hash_function_defaults.h"
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#include "absl/container/internal/hash_policy_traits.h"
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#include "absl/container/internal/hashtable_control_bytes.h"
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#include "absl/container/internal/hashtable_debug_hooks.h"
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#include "absl/container/internal/hashtablez_sampler.h"
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#include "absl/functional/function_ref.h"
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#include "absl/hash/hash.h"
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#include "absl/hash/internal/weakly_mixed_integer.h"
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#include "absl/memory/memory.h"
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#include "absl/meta/type_traits.h"
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#include "absl/numeric/bits.h"
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#include "absl/utility/utility.h"
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#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
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#include <ranges> // NOLINT(build/c++20)
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#endif
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace container_internal {
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#ifdef ABSL_SWISSTABLE_ENABLE_GENERATIONS
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#error ABSL_SWISSTABLE_ENABLE_GENERATIONS cannot be directly set
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#elif (defined(ABSL_HAVE_ADDRESS_SANITIZER) || \
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defined(ABSL_HAVE_HWADDRESS_SANITIZER) || \
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defined(ABSL_HAVE_MEMORY_SANITIZER)) && \
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!defined(NDEBUG_SANITIZER) // If defined, performance is important.
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// When compiled in sanitizer mode, we add generation integers to the backing
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// array and iterators. In the backing array, we store the generation between
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// the control bytes and the slots. When iterators are dereferenced, we assert
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// that the container has not been mutated in a way that could cause iterator
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// invalidation since the iterator was initialized.
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#define ABSL_SWISSTABLE_ENABLE_GENERATIONS
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#endif
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#ifdef ABSL_SWISSTABLE_ASSERT
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#error ABSL_SWISSTABLE_ASSERT cannot be directly set
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#else
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// We use this macro for assertions that users may see when the table is in an
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// invalid state that sanitizers may help diagnose.
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#define ABSL_SWISSTABLE_ASSERT(CONDITION) \
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assert((CONDITION) && "Try enabling sanitizers.")
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#endif
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// We use uint8_t so we don't need to worry about padding.
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using GenerationType = uint8_t;
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// A sentinel value for empty generations. Using 0 makes it easy to constexpr
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// initialize an array of this value.
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constexpr GenerationType SentinelEmptyGeneration() { return 0; }
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constexpr GenerationType NextGeneration(GenerationType generation) {
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return ++generation == SentinelEmptyGeneration() ? ++generation : generation;
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}
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#ifdef ABSL_SWISSTABLE_ENABLE_GENERATIONS
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constexpr bool SwisstableGenerationsEnabled() { return true; }
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constexpr size_t NumGenerationBytes() { return sizeof(GenerationType); }
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#else
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constexpr bool SwisstableGenerationsEnabled() { return false; }
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constexpr size_t NumGenerationBytes() { return 0; }
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#endif
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// Returns true if we should assert that the table is not accessed after it has
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// been destroyed or during the destruction of the table.
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constexpr bool SwisstableAssertAccessToDestroyedTable() {
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#ifndef NDEBUG
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return true;
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#endif
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return SwisstableGenerationsEnabled();
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}
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template <typename AllocType>
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void SwapAlloc(AllocType& lhs, AllocType& rhs,
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std::true_type /* propagate_on_container_swap */) {
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using std::swap;
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swap(lhs, rhs);
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}
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template <typename AllocType>
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void SwapAlloc([[maybe_unused]] AllocType& lhs, [[maybe_unused]] AllocType& rhs,
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std::false_type /* propagate_on_container_swap */) {
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assert(lhs == rhs &&
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"It's UB to call swap with unequal non-propagating allocators.");
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}
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template <typename AllocType>
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void CopyAlloc(AllocType& lhs, AllocType& rhs,
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std::true_type /* propagate_alloc */) {
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lhs = rhs;
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}
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template <typename AllocType>
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void CopyAlloc(AllocType&, AllocType&, std::false_type /* propagate_alloc */) {}
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// The state for a probe sequence.
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//
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// Currently, the sequence is a triangular progression of the form
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//
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// p(i) := Width * (i^2 + i)/2 + hash (mod mask + 1)
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//
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// The use of `Width` ensures that each probe step does not overlap groups;
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// the sequence effectively outputs the addresses of *groups* (although not
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// necessarily aligned to any boundary). The `Group` machinery allows us
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// to check an entire group with minimal branching.
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//
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// Wrapping around at `mask + 1` is important, but not for the obvious reason.
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// As described above, the first few entries of the control byte array
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// are mirrored at the end of the array, which `Group` will find and use
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// for selecting candidates. However, when those candidates' slots are
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// actually inspected, there are no corresponding slots for the cloned bytes,
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// so we need to make sure we've treated those offsets as "wrapping around".
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//
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// It turns out that this probe sequence visits every group exactly once if the
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// number of groups is a power of two, since (i^2+i)/2 is a bijection in
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// Z/(2^m). See https://en.wikipedia.org/wiki/Quadratic_probing
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template <size_t Width>
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class probe_seq {
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public:
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// Creates a new probe sequence using `hash` as the initial value of the
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// sequence and `mask` (usually the capacity of the table) as the mask to
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// apply to each value in the progression.
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probe_seq(size_t hash, size_t mask) {
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ABSL_SWISSTABLE_ASSERT(((mask + 1) & mask) == 0 && "not a mask");
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mask_ = mask;
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offset_ = hash & mask_;
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}
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// The offset within the table, i.e., the value `p(i)` above.
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size_t offset() const { return offset_; }
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size_t offset(size_t i) const { return (offset_ + i) & mask_; }
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void next() {
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index_ += Width;
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offset_ += index_;
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offset_ &= mask_;
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}
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// 0-based probe index, a multiple of `Width`.
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size_t index() const { return index_; }
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private:
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size_t mask_;
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size_t offset_;
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size_t index_ = 0;
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};
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template <class ContainerKey, class Hash, class Eq>
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struct RequireUsableKey {
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template <class PassedKey, class... Args>
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std::pair<
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decltype(std::declval<const Hash&>()(std::declval<const PassedKey&>())),
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decltype(std::declval<const Eq&>()(std::declval<const ContainerKey&>(),
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std::declval<const PassedKey&>()))>*
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operator()(const PassedKey&, const Args&...) const;
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};
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template <class E, class Policy, class Hash, class Eq, class... Ts>
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struct IsDecomposable : std::false_type {};
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template <class Policy, class Hash, class Eq, class... Ts>
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struct IsDecomposable<
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absl::void_t<decltype(Policy::apply(
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RequireUsableKey<typename Policy::key_type, Hash, Eq>(),
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std::declval<Ts>()...))>,
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Policy, Hash, Eq, Ts...> : std::true_type {};
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ABSL_DLL extern ctrl_t kDefaultIterControl;
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// We use these sentinel capacity values in debug mode to indicate different
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// classes of bugs.
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enum InvalidCapacity : size_t {
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kAboveMaxValidCapacity = ~size_t{} - 100,
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kReentrance,
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kDestroyed,
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// These two must be last because we use `>= kMovedFrom` to mean moved-from.
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kMovedFrom,
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kSelfMovedFrom,
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};
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// Returns a pointer to a control byte that can be used by default-constructed
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// iterators. We don't expect this pointer to be dereferenced.
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inline ctrl_t* DefaultIterControl() { return &kDefaultIterControl; }
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// For use in SOO iterators.
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// TODO(b/289225379): we could potentially get rid of this by adding an is_soo
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// bit in iterators. This would add branches but reduce cache misses.
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ABSL_DLL extern const ctrl_t kSooControl[2];
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// Returns a pointer to a full byte followed by a sentinel byte.
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inline ctrl_t* SooControl() {
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// Const must be cast away here; no uses of this function will actually write
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// to it because it is only used for SOO iterators.
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return const_cast<ctrl_t*>(kSooControl);
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}
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// Whether ctrl is from the SooControl array.
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inline bool IsSooControl(const ctrl_t* ctrl) { return ctrl == SooControl(); }
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// Returns a pointer to a generation to use for an empty hashtable.
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GenerationType* EmptyGeneration();
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// Returns whether `generation` is a generation for an empty hashtable that
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// could be returned by EmptyGeneration().
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inline bool IsEmptyGeneration(const GenerationType* generation) {
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return *generation == SentinelEmptyGeneration();
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}
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// We only allow a maximum of 1 SOO element, which makes the implementation
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// much simpler. Complications with multiple SOO elements include:
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// - Satisfying the guarantee that erasing one element doesn't invalidate
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// iterators to other elements means we would probably need actual SOO
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// control bytes.
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// - In order to prevent user code from depending on iteration order for small
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// tables, we would need to randomize the iteration order somehow.
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constexpr size_t SooCapacity() { return 1; }
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// Sentinel type to indicate SOO CommonFields construction.
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struct soo_tag_t {};
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// Sentinel type to indicate SOO CommonFields construction with full size.
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struct full_soo_tag_t {};
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// Sentinel type to indicate non-SOO CommonFields construction.
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struct non_soo_tag_t {};
|
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// Sentinel value to indicate an uninitialized value explicitly.
|
|
struct uninitialized_tag_t {};
|
|
// Sentinel value to indicate creation of an empty table without a seed.
|
|
struct no_seed_empty_tag_t {};
|
|
|
|
// Per table hash salt. This gets mixed into H1 to randomize iteration order
|
|
// per-table.
|
|
// The seed is needed to ensure non-determinism of iteration order.
|
|
class PerTableSeed {
|
|
public:
|
|
// The number of bits in the seed.
|
|
// It is big enough to ensure non-determinism of iteration order.
|
|
// We store the seed inside a uint64_t together with size and other metadata.
|
|
// Using 16 bits allows us to save one `and` instruction in H1 (we use
|
|
// zero-extended move instead of mov+and). When absl::Hash is inlined, it can
|
|
// also have lower latency knowing that the high bits of the seed are zero.
|
|
static constexpr size_t kBitCount = 16;
|
|
|
|
// Returns the seed for the table.
|
|
size_t seed() const { return seed_; }
|
|
|
|
private:
|
|
friend class HashtableSize;
|
|
explicit PerTableSeed(uint16_t seed) : seed_(seed) {}
|
|
|
|
// The most significant bit of the seed is always 1 when there is a non-zero
|
|
// seed. This way, when sign-extended the seed has non-zero high bits.
|
|
const uint16_t seed_;
|
|
};
|
|
|
|
// The size and also has additionally
|
|
// 1) one bit that stores whether we have infoz.
|
|
// 2) PerTableSeed::kBitCount bits for the seed.
|
|
class HashtableSize {
|
|
public:
|
|
static constexpr size_t kSizeBitCount = 64 - PerTableSeed::kBitCount - 1;
|
|
|
|
explicit HashtableSize(uninitialized_tag_t) {}
|
|
explicit HashtableSize(no_seed_empty_tag_t) : data_(0) {}
|
|
explicit HashtableSize(full_soo_tag_t) : data_(kSizeOneNoMetadata) {}
|
|
|
|
// Returns actual size of the table.
|
|
size_t size() const { return static_cast<size_t>(data_ >> kSizeShift); }
|
|
void increment_size() { data_ += kSizeOneNoMetadata; }
|
|
void increment_size(size_t size) {
|
|
data_ += static_cast<uint64_t>(size) * kSizeOneNoMetadata;
|
|
}
|
|
void decrement_size() { data_ -= kSizeOneNoMetadata; }
|
|
// Returns true if the table is empty.
|
|
bool empty() const { return data_ < kSizeOneNoMetadata; }
|
|
// Sets the size to zero, but keeps all the metadata bits.
|
|
void set_size_to_zero_keep_metadata() { data_ = data_ & kMetadataMask; }
|
|
|
|
PerTableSeed seed() const {
|
|
return PerTableSeed(static_cast<size_t>(data_) & kSeedMask);
|
|
}
|
|
|
|
void generate_new_seed() { set_seed(NextSeed()); }
|
|
|
|
// We need to use a constant seed when the table is sampled so that sampled
|
|
// hashes use the same seed and can e.g. identify stuck bits accurately.
|
|
void set_sampled_seed() { set_seed((std::numeric_limits<uint16_t>::max)()); }
|
|
|
|
bool is_sampled_seed() const {
|
|
return (data_ & kSeedMask) == (std::numeric_limits<uint16_t>::max)();
|
|
}
|
|
|
|
// Returns true if the table has infoz.
|
|
bool has_infoz() const {
|
|
return ABSL_PREDICT_FALSE((data_ & kHasInfozMask) != 0);
|
|
}
|
|
|
|
// Sets the has_infoz bit.
|
|
void set_has_infoz() { data_ |= kHasInfozMask; }
|
|
|
|
void set_no_seed_for_testing() { data_ &= ~kSeedMask; }
|
|
|
|
// Returns next per-table seed.
|
|
static uint16_t NextSeed();
|
|
|
|
private:
|
|
void set_seed(uint16_t seed) { data_ = (data_ & ~kSeedMask) | seed; }
|
|
static constexpr size_t kSizeShift = 64 - kSizeBitCount;
|
|
static constexpr uint64_t kSizeOneNoMetadata = uint64_t{1} << kSizeShift;
|
|
static constexpr uint64_t kMetadataMask = kSizeOneNoMetadata - 1;
|
|
static constexpr uint64_t kSeedMask =
|
|
(uint64_t{1} << PerTableSeed::kBitCount) - 1;
|
|
// The next bit after the seed.
|
|
static constexpr uint64_t kHasInfozMask = kSeedMask + 1;
|
|
uint64_t data_;
|
|
};
|
|
|
|
// H1 is just the low bits of the hash.
|
|
inline size_t H1(size_t hash) { return hash; }
|
|
|
|
// Extracts the H2 portion of a hash: the 7 most significant bits.
|
|
//
|
|
// These are used as an occupied control byte.
|
|
inline h2_t H2(size_t hash) { return hash >> (sizeof(size_t) * 8 - 7); }
|
|
|
|
// When there is an insertion with no reserved growth, we rehash with
|
|
// probability `min(1, RehashProbabilityConstant() / capacity())`. Using a
|
|
// constant divided by capacity ensures that inserting N elements is still O(N)
|
|
// in the average case. Using the constant 16 means that we expect to rehash ~8
|
|
// times more often than when generations are disabled. We are adding expected
|
|
// rehash_probability * #insertions/capacity_growth = 16/capacity * ((7/8 -
|
|
// 7/16) * capacity)/capacity_growth = ~7 extra rehashes per capacity growth.
|
|
inline size_t RehashProbabilityConstant() { return 16; }
|
|
|
|
class CommonFieldsGenerationInfoEnabled {
|
|
// A sentinel value for reserved_growth_ indicating that we just ran out of
|
|
// reserved growth on the last insertion. When reserve is called and then
|
|
// insertions take place, reserved_growth_'s state machine is N, ..., 1,
|
|
// kReservedGrowthJustRanOut, 0.
|
|
static constexpr size_t kReservedGrowthJustRanOut =
|
|
(std::numeric_limits<size_t>::max)();
|
|
|
|
public:
|
|
CommonFieldsGenerationInfoEnabled() = default;
|
|
CommonFieldsGenerationInfoEnabled(CommonFieldsGenerationInfoEnabled&& that)
|
|
: reserved_growth_(that.reserved_growth_),
|
|
reservation_size_(that.reservation_size_),
|
|
generation_(that.generation_) {
|
|
that.reserved_growth_ = 0;
|
|
that.reservation_size_ = 0;
|
|
that.generation_ = EmptyGeneration();
|
|
}
|
|
CommonFieldsGenerationInfoEnabled& operator=(
|
|
CommonFieldsGenerationInfoEnabled&&) = default;
|
|
|
|
// Whether we should rehash on insert in order to detect bugs of using invalid
|
|
// references. We rehash on the first insertion after reserved_growth_ reaches
|
|
// 0 after a call to reserve. We also do a rehash with low probability
|
|
// whenever reserved_growth_ is zero.
|
|
bool should_rehash_for_bug_detection_on_insert(size_t capacity) const;
|
|
// Similar to above, except that we don't depend on reserved_growth_.
|
|
bool should_rehash_for_bug_detection_on_move(size_t capacity) const;
|
|
void maybe_increment_generation_on_insert() {
|
|
if (reserved_growth_ == kReservedGrowthJustRanOut) reserved_growth_ = 0;
|
|
|
|
if (reserved_growth_ > 0) {
|
|
if (--reserved_growth_ == 0) reserved_growth_ = kReservedGrowthJustRanOut;
|
|
} else {
|
|
increment_generation();
|
|
}
|
|
}
|
|
void increment_generation() { *generation_ = NextGeneration(*generation_); }
|
|
void reset_reserved_growth(size_t reservation, size_t size) {
|
|
reserved_growth_ = reservation - size;
|
|
}
|
|
size_t reserved_growth() const { return reserved_growth_; }
|
|
void set_reserved_growth(size_t r) { reserved_growth_ = r; }
|
|
size_t reservation_size() const { return reservation_size_; }
|
|
void set_reservation_size(size_t r) { reservation_size_ = r; }
|
|
GenerationType generation() const { return *generation_; }
|
|
void set_generation(GenerationType g) { *generation_ = g; }
|
|
GenerationType* generation_ptr() const { return generation_; }
|
|
void set_generation_ptr(GenerationType* g) { generation_ = g; }
|
|
|
|
private:
|
|
// The number of insertions remaining that are guaranteed to not rehash due to
|
|
// a prior call to reserve. Note: we store reserved growth in addition to
|
|
// reservation size because calls to erase() decrease size_ but don't decrease
|
|
// reserved growth.
|
|
size_t reserved_growth_ = 0;
|
|
// The maximum argument to reserve() since the container was cleared. We need
|
|
// to keep track of this, in addition to reserved growth, because we reset
|
|
// reserved growth to this when erase(begin(), end()) is called.
|
|
size_t reservation_size_ = 0;
|
|
// Pointer to the generation counter, which is used to validate iterators and
|
|
// is stored in the backing array between the control bytes and the slots.
|
|
// Note that we can't store the generation inside the container itself and
|
|
// keep a pointer to the container in the iterators because iterators must
|
|
// remain valid when the container is moved.
|
|
// Note: we could derive this pointer from the control pointer, but it makes
|
|
// the code more complicated, and there's a benefit in having the sizes of
|
|
// raw_hash_set in sanitizer mode and non-sanitizer mode a bit more different,
|
|
// which is that tests are less likely to rely on the size remaining the same.
|
|
GenerationType* generation_ = EmptyGeneration();
|
|
};
|
|
|
|
class CommonFieldsGenerationInfoDisabled {
|
|
public:
|
|
CommonFieldsGenerationInfoDisabled() = default;
|
|
CommonFieldsGenerationInfoDisabled(CommonFieldsGenerationInfoDisabled&&) =
|
|
default;
|
|
CommonFieldsGenerationInfoDisabled& operator=(
|
|
CommonFieldsGenerationInfoDisabled&&) = default;
|
|
|
|
bool should_rehash_for_bug_detection_on_insert(size_t) const { return false; }
|
|
bool should_rehash_for_bug_detection_on_move(size_t) const { return false; }
|
|
void maybe_increment_generation_on_insert() {}
|
|
void increment_generation() {}
|
|
void reset_reserved_growth(size_t, size_t) {}
|
|
size_t reserved_growth() const { return 0; }
|
|
void set_reserved_growth(size_t) {}
|
|
size_t reservation_size() const { return 0; }
|
|
void set_reservation_size(size_t) {}
|
|
GenerationType generation() const { return 0; }
|
|
void set_generation(GenerationType) {}
|
|
GenerationType* generation_ptr() const { return nullptr; }
|
|
void set_generation_ptr(GenerationType*) {}
|
|
};
|
|
|
|
class HashSetIteratorGenerationInfoEnabled {
|
|
public:
|
|
HashSetIteratorGenerationInfoEnabled() = default;
|
|
explicit HashSetIteratorGenerationInfoEnabled(
|
|
const GenerationType* generation_ptr)
|
|
: generation_ptr_(generation_ptr), generation_(*generation_ptr) {}
|
|
|
|
GenerationType generation() const { return generation_; }
|
|
void reset_generation() { generation_ = *generation_ptr_; }
|
|
const GenerationType* generation_ptr() const { return generation_ptr_; }
|
|
void set_generation_ptr(const GenerationType* ptr) { generation_ptr_ = ptr; }
|
|
|
|
private:
|
|
const GenerationType* generation_ptr_ = EmptyGeneration();
|
|
GenerationType generation_ = *generation_ptr_;
|
|
};
|
|
|
|
class HashSetIteratorGenerationInfoDisabled {
|
|
public:
|
|
HashSetIteratorGenerationInfoDisabled() = default;
|
|
explicit HashSetIteratorGenerationInfoDisabled(const GenerationType*) {}
|
|
|
|
GenerationType generation() const { return 0; }
|
|
void reset_generation() {}
|
|
const GenerationType* generation_ptr() const { return nullptr; }
|
|
void set_generation_ptr(const GenerationType*) {}
|
|
};
|
|
|
|
#ifdef ABSL_SWISSTABLE_ENABLE_GENERATIONS
|
|
using CommonFieldsGenerationInfo = CommonFieldsGenerationInfoEnabled;
|
|
using HashSetIteratorGenerationInfo = HashSetIteratorGenerationInfoEnabled;
|
|
#else
|
|
using CommonFieldsGenerationInfo = CommonFieldsGenerationInfoDisabled;
|
|
using HashSetIteratorGenerationInfo = HashSetIteratorGenerationInfoDisabled;
|
|
#endif
|
|
|
|
// Stored the information regarding number of slots we can still fill
|
|
// without needing to rehash.
|
|
//
|
|
// We want to ensure sufficient number of empty slots in the table in order
|
|
// to keep probe sequences relatively short. Empty slot in the probe group
|
|
// is required to stop probing.
|
|
//
|
|
// Tombstones (kDeleted slots) are not included in the growth capacity,
|
|
// because we'd like to rehash when the table is filled with tombstones and/or
|
|
// full slots.
|
|
//
|
|
// GrowthInfo also stores a bit that encodes whether table may have any
|
|
// deleted slots.
|
|
// Most of the tables (>95%) have no deleted slots, so some functions can
|
|
// be more efficient with this information.
|
|
//
|
|
// Callers can also force a rehash via the standard `rehash(0)`,
|
|
// which will recompute this value as a side-effect.
|
|
//
|
|
// See also `CapacityToGrowth()`.
|
|
class GrowthInfo {
|
|
public:
|
|
// Leaves data member uninitialized.
|
|
GrowthInfo() = default;
|
|
|
|
// Initializes the GrowthInfo assuming we can grow `growth_left` elements
|
|
// and there are no kDeleted slots in the table.
|
|
void InitGrowthLeftNoDeleted(size_t growth_left) {
|
|
growth_left_info_ = growth_left;
|
|
}
|
|
|
|
// Overwrites single full slot with an empty slot.
|
|
void OverwriteFullAsEmpty() { ++growth_left_info_; }
|
|
|
|
// Overwrites single empty slot with a full slot.
|
|
void OverwriteEmptyAsFull() {
|
|
ABSL_SWISSTABLE_ASSERT(GetGrowthLeft() > 0);
|
|
--growth_left_info_;
|
|
}
|
|
|
|
// Overwrites several empty slots with full slots.
|
|
void OverwriteManyEmptyAsFull(size_t count) {
|
|
ABSL_SWISSTABLE_ASSERT(GetGrowthLeft() >= count);
|
|
growth_left_info_ -= count;
|
|
}
|
|
|
|
// Overwrites specified control element with full slot.
|
|
void OverwriteControlAsFull(ctrl_t ctrl) {
|
|
ABSL_SWISSTABLE_ASSERT(GetGrowthLeft() >=
|
|
static_cast<size_t>(IsEmpty(ctrl)));
|
|
growth_left_info_ -= static_cast<size_t>(IsEmpty(ctrl));
|
|
}
|
|
|
|
// Overwrites single full slot with a deleted slot.
|
|
void OverwriteFullAsDeleted() { growth_left_info_ |= kDeletedBit; }
|
|
|
|
// Returns true if table satisfies two properties:
|
|
// 1. Guaranteed to have no kDeleted slots.
|
|
// 2. There is a place for at least one element to grow.
|
|
bool HasNoDeletedAndGrowthLeft() const {
|
|
return static_cast<std::make_signed_t<size_t>>(growth_left_info_) > 0;
|
|
}
|
|
|
|
// Returns true if the table satisfies two properties:
|
|
// 1. Guaranteed to have no kDeleted slots.
|
|
// 2. There is no growth left.
|
|
bool HasNoGrowthLeftAndNoDeleted() const { return growth_left_info_ == 0; }
|
|
|
|
// Returns true if GetGrowthLeft() == 0, but must be called only if
|
|
// HasNoDeleted() is false. It is slightly more efficient.
|
|
bool HasNoGrowthLeftAssumingMayHaveDeleted() const {
|
|
ABSL_SWISSTABLE_ASSERT(!HasNoDeleted());
|
|
return growth_left_info_ == kDeletedBit;
|
|
}
|
|
|
|
// Returns true if table guaranteed to have no kDeleted slots.
|
|
bool HasNoDeleted() const {
|
|
return static_cast<std::make_signed_t<size_t>>(growth_left_info_) >= 0;
|
|
}
|
|
|
|
// Returns the number of elements left to grow.
|
|
size_t GetGrowthLeft() const { return growth_left_info_ & kGrowthLeftMask; }
|
|
|
|
private:
|
|
static constexpr size_t kGrowthLeftMask = ((~size_t{}) >> 1);
|
|
static constexpr size_t kDeletedBit = ~kGrowthLeftMask;
|
|
// Topmost bit signal whenever there are deleted slots.
|
|
size_t growth_left_info_;
|
|
};
|
|
|
|
static_assert(sizeof(GrowthInfo) == sizeof(size_t), "");
|
|
static_assert(alignof(GrowthInfo) == alignof(size_t), "");
|
|
|
|
// Returns whether `n` is a valid capacity (i.e., number of slots).
|
|
//
|
|
// A valid capacity is a non-zero integer `2^m - 1`.
|
|
constexpr bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; }
|
|
|
|
// Whether a table is small enough that we don't need to hash any keys.
|
|
constexpr bool IsSmallCapacity(size_t capacity) { return capacity <= 1; }
|
|
|
|
// Returns the number of "cloned control bytes".
|
|
//
|
|
// This is the number of control bytes that are present both at the beginning
|
|
// of the control byte array and at the end, such that we can create a
|
|
// `Group::kWidth`-width probe window starting from any control byte.
|
|
constexpr size_t NumClonedBytes() { return Group::kWidth - 1; }
|
|
|
|
// Returns the number of control bytes including cloned.
|
|
constexpr size_t NumControlBytes(size_t capacity) {
|
|
return IsSmallCapacity(capacity) ? 0 : capacity + 1 + NumClonedBytes();
|
|
}
|
|
|
|
// Computes the offset from the start of the backing allocation of control.
|
|
// infoz and growth_info are stored at the beginning of the backing array.
|
|
constexpr size_t ControlOffset(bool has_infoz) {
|
|
return (has_infoz ? sizeof(HashtablezInfoHandle) : 0) + sizeof(GrowthInfo);
|
|
}
|
|
|
|
// Returns the offset of the next item after `offset` that is aligned to `align`
|
|
// bytes. `align` must be a power of two.
|
|
constexpr size_t AlignUpTo(size_t offset, size_t align) {
|
|
return (offset + align - 1) & (~align + 1);
|
|
}
|
|
|
|
// Helper class for computing offsets and allocation size of hash set fields.
|
|
class RawHashSetLayout {
|
|
public:
|
|
// TODO(b/413062340): maybe don't allocate growth info for capacity 1 tables.
|
|
// Doing so may require additional branches/complexity so it might not be
|
|
// worth it.
|
|
explicit RawHashSetLayout(size_t capacity, size_t slot_size,
|
|
size_t slot_align, bool has_infoz)
|
|
: control_offset_(ControlOffset(has_infoz)),
|
|
generation_offset_(control_offset_ + NumControlBytes(capacity)),
|
|
slot_offset_(
|
|
AlignUpTo(generation_offset_ + NumGenerationBytes(), slot_align)),
|
|
alloc_size_(slot_offset_ + capacity * slot_size) {
|
|
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(capacity));
|
|
ABSL_SWISSTABLE_ASSERT(
|
|
slot_size <=
|
|
((std::numeric_limits<size_t>::max)() - slot_offset_) / capacity);
|
|
}
|
|
|
|
// Returns precomputed offset from the start of the backing allocation of
|
|
// control.
|
|
size_t control_offset() const { return control_offset_; }
|
|
|
|
// Given the capacity of a table, computes the offset (from the start of the
|
|
// backing allocation) of the generation counter (if it exists).
|
|
size_t generation_offset() const { return generation_offset_; }
|
|
|
|
// Given the capacity of a table, computes the offset (from the start of the
|
|
// backing allocation) at which the slots begin.
|
|
size_t slot_offset() const { return slot_offset_; }
|
|
|
|
// Given the capacity of a table, computes the total size of the backing
|
|
// array.
|
|
size_t alloc_size() const { return alloc_size_; }
|
|
|
|
private:
|
|
size_t control_offset_;
|
|
size_t generation_offset_;
|
|
size_t slot_offset_;
|
|
size_t alloc_size_;
|
|
};
|
|
|
|
struct HashtableFreeFunctionsAccess;
|
|
|
|
// This allows us to work around an uninitialized memory warning when
|
|
// constructing begin() iterators in empty hashtables.
|
|
template <typename T>
|
|
union MaybeInitializedPtr {
|
|
T* get() const { ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(p); }
|
|
void set(T* ptr) { p = ptr; }
|
|
|
|
T* p;
|
|
};
|
|
|
|
struct HeapPtrs {
|
|
// The control bytes (and, also, a pointer near to the base of the backing
|
|
// array).
|
|
//
|
|
// This contains `capacity + 1 + NumClonedBytes()` entries.
|
|
//
|
|
// Note that growth_info is stored immediately before this pointer.
|
|
// May be uninitialized for small tables.
|
|
MaybeInitializedPtr<ctrl_t> control;
|
|
|
|
// The beginning of the slots, located at `SlotOffset()` bytes after
|
|
// `control`. May be uninitialized for empty tables.
|
|
// Note: we can't use `slots` because Qt defines "slots" as a macro.
|
|
MaybeInitializedPtr<void> slot_array;
|
|
};
|
|
|
|
// Returns the maximum size of the SOO slot.
|
|
constexpr size_t MaxSooSlotSize() { return sizeof(HeapPtrs); }
|
|
|
|
// Manages the backing array pointers or the SOO slot. When raw_hash_set::is_soo
|
|
// is true, the SOO slot is stored in `soo_data`. Otherwise, we use `heap`.
|
|
union HeapOrSoo {
|
|
MaybeInitializedPtr<ctrl_t>& control() {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(heap.control);
|
|
}
|
|
MaybeInitializedPtr<ctrl_t> control() const {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(heap.control);
|
|
}
|
|
MaybeInitializedPtr<void>& slot_array() {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(heap.slot_array);
|
|
}
|
|
MaybeInitializedPtr<void> slot_array() const {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(heap.slot_array);
|
|
}
|
|
void* get_soo_data() {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(soo_data);
|
|
}
|
|
const void* get_soo_data() const {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(soo_data);
|
|
}
|
|
|
|
HeapPtrs heap;
|
|
unsigned char soo_data[MaxSooSlotSize()];
|
|
};
|
|
|
|
// Returns a reference to the GrowthInfo object stored immediately before
|
|
// `control`.
|
|
inline GrowthInfo& GetGrowthInfoFromControl(ctrl_t* control) {
|
|
auto* gl_ptr = reinterpret_cast<GrowthInfo*>(control) - 1;
|
|
ABSL_SWISSTABLE_ASSERT(
|
|
reinterpret_cast<uintptr_t>(gl_ptr) % alignof(GrowthInfo) == 0);
|
|
return *gl_ptr;
|
|
}
|
|
|
|
// CommonFields hold the fields in raw_hash_set that do not depend
|
|
// on template parameters. This allows us to conveniently pass all
|
|
// of this state to helper functions as a single argument.
|
|
class CommonFields : public CommonFieldsGenerationInfo {
|
|
public:
|
|
explicit CommonFields(soo_tag_t)
|
|
: capacity_(SooCapacity()), size_(no_seed_empty_tag_t{}) {}
|
|
explicit CommonFields(full_soo_tag_t)
|
|
: capacity_(SooCapacity()), size_(full_soo_tag_t{}) {}
|
|
explicit CommonFields(non_soo_tag_t)
|
|
: capacity_(0), size_(no_seed_empty_tag_t{}) {}
|
|
// For use in swapping.
|
|
explicit CommonFields(uninitialized_tag_t) : size_(uninitialized_tag_t{}) {}
|
|
|
|
// Not copyable
|
|
CommonFields(const CommonFields&) = delete;
|
|
CommonFields& operator=(const CommonFields&) = delete;
|
|
|
|
// Copy with guarantee that it is not SOO.
|
|
CommonFields(non_soo_tag_t, const CommonFields& that)
|
|
: capacity_(that.capacity_),
|
|
size_(that.size_),
|
|
heap_or_soo_(that.heap_or_soo_) {
|
|
}
|
|
|
|
// Movable
|
|
CommonFields(CommonFields&& that) = default;
|
|
CommonFields& operator=(CommonFields&&) = default;
|
|
|
|
template <bool kSooEnabled>
|
|
static CommonFields CreateDefault() {
|
|
return kSooEnabled ? CommonFields{soo_tag_t{}}
|
|
: CommonFields{non_soo_tag_t{}};
|
|
}
|
|
|
|
// The inline data for SOO is written on top of control_/slots_.
|
|
const void* soo_data() const { return heap_or_soo_.get_soo_data(); }
|
|
void* soo_data() { return heap_or_soo_.get_soo_data(); }
|
|
|
|
ctrl_t* control() const {
|
|
ABSL_SWISSTABLE_ASSERT(capacity() > 0);
|
|
// Assume that the control bytes don't alias `this`.
|
|
ctrl_t* ctrl = heap_or_soo_.control().get();
|
|
[[maybe_unused]] size_t num_control_bytes = NumControlBytes(capacity());
|
|
ABSL_ASSUME(reinterpret_cast<uintptr_t>(ctrl + num_control_bytes) <=
|
|
reinterpret_cast<uintptr_t>(this) ||
|
|
reinterpret_cast<uintptr_t>(this + 1) <=
|
|
reinterpret_cast<uintptr_t>(ctrl));
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(ctrl);
|
|
}
|
|
|
|
void set_control(ctrl_t* c) { heap_or_soo_.control().set(c); }
|
|
|
|
// Note: we can't use slots() because Qt defines "slots" as a macro.
|
|
void* slot_array() const { return heap_or_soo_.slot_array().get(); }
|
|
MaybeInitializedPtr<void> slots_union() const {
|
|
return heap_or_soo_.slot_array();
|
|
}
|
|
void set_slots(void* s) { heap_or_soo_.slot_array().set(s); }
|
|
|
|
// The number of filled slots.
|
|
size_t size() const { return size_.size(); }
|
|
// Sets the size to zero, but keeps hashinfoz bit and seed.
|
|
void set_size_to_zero() { size_.set_size_to_zero_keep_metadata(); }
|
|
void set_empty_soo() {
|
|
AssertInSooMode();
|
|
size_ = HashtableSize(no_seed_empty_tag_t{});
|
|
}
|
|
void set_full_soo() {
|
|
AssertInSooMode();
|
|
size_ = HashtableSize(full_soo_tag_t{});
|
|
}
|
|
void increment_size() {
|
|
ABSL_SWISSTABLE_ASSERT(size() < capacity());
|
|
size_.increment_size();
|
|
}
|
|
void increment_size(size_t n) {
|
|
ABSL_SWISSTABLE_ASSERT(size() + n <= capacity());
|
|
size_.increment_size(n);
|
|
}
|
|
void decrement_size() {
|
|
ABSL_SWISSTABLE_ASSERT(!empty());
|
|
size_.decrement_size();
|
|
}
|
|
bool empty() const { return size_.empty(); }
|
|
|
|
// The seed used for the hash function.
|
|
PerTableSeed seed() const { return size_.seed(); }
|
|
// Generates a new seed the hash function.
|
|
// The table will be invalidated if `!empty()` because hash is being changed.
|
|
// In such cases, we will need to rehash the table.
|
|
void generate_new_seed(bool has_infoz) {
|
|
// Note: we can't use has_infoz() here because we set has_infoz later than
|
|
// we generate the seed.
|
|
if (ABSL_PREDICT_FALSE(has_infoz)) {
|
|
size_.set_sampled_seed();
|
|
return;
|
|
}
|
|
size_.generate_new_seed();
|
|
}
|
|
void set_no_seed_for_testing() { size_.set_no_seed_for_testing(); }
|
|
|
|
// The total number of available slots.
|
|
size_t capacity() const { return capacity_; }
|
|
void set_capacity(size_t c) {
|
|
// We allow setting above the max valid capacity for debugging purposes.
|
|
ABSL_SWISSTABLE_ASSERT(c == 0 || IsValidCapacity(c) ||
|
|
c > kAboveMaxValidCapacity);
|
|
capacity_ = c;
|
|
}
|
|
bool is_small() const { return IsSmallCapacity(capacity_); }
|
|
|
|
// The number of slots we can still fill without needing to rehash.
|
|
// This is stored in the heap allocation before the control bytes.
|
|
// TODO(b/289225379): experiment with moving growth_info back inline to
|
|
// increase room for SOO.
|
|
size_t growth_left() const { return growth_info().GetGrowthLeft(); }
|
|
|
|
GrowthInfo& growth_info() {
|
|
ABSL_SWISSTABLE_ASSERT(!is_small());
|
|
return GetGrowthInfoFromControl(control());
|
|
}
|
|
GrowthInfo growth_info() const {
|
|
return const_cast<CommonFields*>(this)->growth_info();
|
|
}
|
|
|
|
bool has_infoz() const { return size_.has_infoz(); }
|
|
void set_has_infoz() {
|
|
ABSL_SWISSTABLE_ASSERT(size_.is_sampled_seed());
|
|
size_.set_has_infoz();
|
|
}
|
|
|
|
HashtablezInfoHandle* infoz_ptr() const {
|
|
// growth_info is stored before control bytes.
|
|
ABSL_SWISSTABLE_ASSERT(
|
|
reinterpret_cast<uintptr_t>(control()) % alignof(size_t) == 0);
|
|
ABSL_SWISSTABLE_ASSERT(has_infoz());
|
|
return reinterpret_cast<HashtablezInfoHandle*>(
|
|
control() - ControlOffset(/*has_infoz=*/true));
|
|
}
|
|
|
|
HashtablezInfoHandle infoz() {
|
|
return has_infoz() ? *infoz_ptr() : HashtablezInfoHandle();
|
|
}
|
|
void set_infoz(HashtablezInfoHandle infoz) {
|
|
ABSL_SWISSTABLE_ASSERT(has_infoz());
|
|
*infoz_ptr() = infoz;
|
|
}
|
|
|
|
bool should_rehash_for_bug_detection_on_insert() const {
|
|
if constexpr (!SwisstableGenerationsEnabled()) {
|
|
return false;
|
|
}
|
|
// As an optimization, we avoid calling ShouldRehashForBugDetection if we
|
|
// will end up rehashing anyways.
|
|
if (growth_left() == 0) return false;
|
|
return CommonFieldsGenerationInfo::
|
|
should_rehash_for_bug_detection_on_insert(capacity());
|
|
}
|
|
bool should_rehash_for_bug_detection_on_move() const {
|
|
return CommonFieldsGenerationInfo::should_rehash_for_bug_detection_on_move(
|
|
capacity());
|
|
}
|
|
void reset_reserved_growth(size_t reservation) {
|
|
CommonFieldsGenerationInfo::reset_reserved_growth(reservation, size());
|
|
}
|
|
|
|
// The size of the backing array allocation.
|
|
size_t alloc_size(size_t slot_size, size_t slot_align) const {
|
|
return RawHashSetLayout(capacity(), slot_size, slot_align, has_infoz())
|
|
.alloc_size();
|
|
}
|
|
|
|
// Move fields other than heap_or_soo_.
|
|
void move_non_heap_or_soo_fields(CommonFields& that) {
|
|
static_cast<CommonFieldsGenerationInfo&>(*this) =
|
|
std::move(static_cast<CommonFieldsGenerationInfo&>(that));
|
|
capacity_ = that.capacity_;
|
|
size_ = that.size_;
|
|
}
|
|
|
|
// Returns the number of control bytes set to kDeleted. For testing only.
|
|
size_t TombstonesCount() const {
|
|
return static_cast<size_t>(
|
|
std::count(control(), control() + capacity(), ctrl_t::kDeleted));
|
|
}
|
|
|
|
// Helper to enable sanitizer mode validation to protect against reentrant
|
|
// calls during element constructor/destructor.
|
|
template <typename F>
|
|
void RunWithReentrancyGuard(F f) {
|
|
#ifdef NDEBUG
|
|
f();
|
|
return;
|
|
#endif
|
|
const size_t cap = capacity();
|
|
set_capacity(InvalidCapacity::kReentrance);
|
|
f();
|
|
set_capacity(cap);
|
|
}
|
|
|
|
private:
|
|
// We store the has_infoz bit in the lowest bit of size_.
|
|
static constexpr size_t HasInfozShift() { return 1; }
|
|
static constexpr size_t HasInfozMask() {
|
|
return (size_t{1} << HasInfozShift()) - 1;
|
|
}
|
|
|
|
// We can't assert that SOO is enabled because we don't have SooEnabled(), but
|
|
// we assert what we can.
|
|
void AssertInSooMode() const {
|
|
ABSL_SWISSTABLE_ASSERT(capacity() == SooCapacity());
|
|
ABSL_SWISSTABLE_ASSERT(!has_infoz());
|
|
}
|
|
|
|
// The number of slots in the backing array. This is always 2^N-1 for an
|
|
// integer N. NOTE: we tried experimenting with compressing the capacity and
|
|
// storing it together with size_: (a) using 6 bits to store the corresponding
|
|
// power (N in 2^N-1), and (b) storing 2^N as the most significant bit of
|
|
// size_ and storing size in the low bits. Both of these experiments were
|
|
// regressions, presumably because we need capacity to do find operations.
|
|
size_t capacity_;
|
|
|
|
// TODO(b/289225379): we could put size_ into HeapOrSoo and make capacity_
|
|
// encode the size in SOO case. We would be making size()/capacity() more
|
|
// expensive in order to have more SOO space.
|
|
HashtableSize size_;
|
|
|
|
// Either the control/slots pointers or the SOO slot.
|
|
HeapOrSoo heap_or_soo_;
|
|
};
|
|
|
|
template <class Policy, class... Params>
|
|
class raw_hash_set;
|
|
|
|
// Returns the next valid capacity after `n`.
|
|
constexpr size_t NextCapacity(size_t n) {
|
|
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(n) || n == 0);
|
|
return n * 2 + 1;
|
|
}
|
|
|
|
// Returns the previous valid capacity before `n`.
|
|
constexpr size_t PreviousCapacity(size_t n) {
|
|
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(n));
|
|
return n / 2;
|
|
}
|
|
|
|
// Applies the following mapping to every byte in the control array:
|
|
// * kDeleted -> kEmpty
|
|
// * kEmpty -> kEmpty
|
|
// * _ -> kDeleted
|
|
// PRECONDITION:
|
|
// IsValidCapacity(capacity)
|
|
// ctrl[capacity] == ctrl_t::kSentinel
|
|
// ctrl[i] != ctrl_t::kSentinel for all i < capacity
|
|
void ConvertDeletedToEmptyAndFullToDeleted(ctrl_t* ctrl, size_t capacity);
|
|
|
|
// Converts `n` into the next valid capacity, per `IsValidCapacity`.
|
|
constexpr size_t NormalizeCapacity(size_t n) {
|
|
return n ? ~size_t{} >> countl_zero(n) : 1;
|
|
}
|
|
|
|
// General notes on capacity/growth methods below:
|
|
// - We use 7/8th as maximum load factor. For 16-wide groups, that gives an
|
|
// average of two empty slots per group.
|
|
// - For (capacity+1) >= Group::kWidth, growth is 7/8*capacity.
|
|
// - For (capacity+1) < Group::kWidth, growth == capacity. In this case, we
|
|
// never need to probe (the whole table fits in one group) so we don't need a
|
|
// load factor less than 1.
|
|
|
|
// Given `capacity`, applies the load factor; i.e., it returns the maximum
|
|
// number of values we should put into the table before a resizing rehash.
|
|
constexpr size_t CapacityToGrowth(size_t capacity) {
|
|
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(capacity));
|
|
// `capacity*7/8`
|
|
if (Group::kWidth == 8 && capacity == 7) {
|
|
// x-x/8 does not work when x==7.
|
|
return 6;
|
|
}
|
|
return capacity - capacity / 8;
|
|
}
|
|
|
|
// Given `size`, "unapplies" the load factor to find how large the capacity
|
|
// should be to stay within the load factor.
|
|
//
|
|
// For size == 0, returns 0.
|
|
// For other values, returns the same as `NormalizeCapacity(size*8/7)`.
|
|
constexpr size_t SizeToCapacity(size_t size) {
|
|
if (size == 0) {
|
|
return 0;
|
|
}
|
|
// The minimum possible capacity is NormalizeCapacity(size).
|
|
// Shifting right `~size_t{}` by `leading_zeros` yields
|
|
// NormalizeCapacity(size).
|
|
int leading_zeros = absl::countl_zero(size);
|
|
constexpr size_t kLast3Bits = size_t{7} << (sizeof(size_t) * 8 - 3);
|
|
// max_size_for_next_capacity = max_load_factor * next_capacity
|
|
// = (7/8) * (~size_t{} >> leading_zeros)
|
|
// = (7/8*~size_t{}) >> leading_zeros
|
|
// = kLast3Bits >> leading_zeros
|
|
size_t max_size_for_next_capacity = kLast3Bits >> leading_zeros;
|
|
// Decrease shift if size is too big for the minimum capacity.
|
|
leading_zeros -= static_cast<int>(size > max_size_for_next_capacity);
|
|
if constexpr (Group::kWidth == 8) {
|
|
// Formula doesn't work when size==7 for 8-wide groups.
|
|
leading_zeros -= (size == 7);
|
|
}
|
|
return (~size_t{}) >> leading_zeros;
|
|
}
|
|
|
|
template <class InputIter>
|
|
size_t SelectBucketCountForIterRange(InputIter first, InputIter last,
|
|
size_t bucket_count) {
|
|
if (bucket_count != 0) {
|
|
return bucket_count;
|
|
}
|
|
if (base_internal::IsAtLeastIterator<std::random_access_iterator_tag,
|
|
InputIter>()) {
|
|
return SizeToCapacity(static_cast<size_t>(std::distance(first, last)));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
constexpr bool SwisstableDebugEnabled() {
|
|
#if defined(ABSL_SWISSTABLE_ENABLE_GENERATIONS) || \
|
|
ABSL_OPTION_HARDENED == 1 || !defined(NDEBUG)
|
|
return true;
|
|
#else
|
|
return false;
|
|
#endif
|
|
}
|
|
|
|
inline void AssertIsFull(const ctrl_t* ctrl, GenerationType generation,
|
|
const GenerationType* generation_ptr,
|
|
const char* operation) {
|
|
if (!SwisstableDebugEnabled()) return;
|
|
// `SwisstableDebugEnabled()` is also true for release builds with hardening
|
|
// enabled. To minimize their impact in those builds:
|
|
// - use `ABSL_PREDICT_FALSE()` to provide a compiler hint for code layout
|
|
// - use `ABSL_RAW_LOG()` with a format string to reduce code size and improve
|
|
// the chances that the hot paths will be inlined.
|
|
if (ABSL_PREDICT_FALSE(ctrl == nullptr)) {
|
|
ABSL_RAW_LOG(FATAL, "%s called on end() iterator.", operation);
|
|
}
|
|
if (ABSL_PREDICT_FALSE(ctrl == DefaultIterControl())) {
|
|
ABSL_RAW_LOG(FATAL, "%s called on default-constructed iterator.",
|
|
operation);
|
|
}
|
|
if (SwisstableGenerationsEnabled()) {
|
|
if (ABSL_PREDICT_FALSE(generation != *generation_ptr)) {
|
|
ABSL_RAW_LOG(FATAL,
|
|
"%s called on invalid iterator. The table could have "
|
|
"rehashed or moved since this iterator was initialized.",
|
|
operation);
|
|
}
|
|
if (ABSL_PREDICT_FALSE(!IsFull(*ctrl))) {
|
|
ABSL_RAW_LOG(
|
|
FATAL,
|
|
"%s called on invalid iterator. The element was likely erased.",
|
|
operation);
|
|
}
|
|
} else {
|
|
if (ABSL_PREDICT_FALSE(!IsFull(*ctrl))) {
|
|
ABSL_RAW_LOG(
|
|
FATAL,
|
|
"%s called on invalid iterator. The element might have been erased "
|
|
"or the table might have rehashed. Consider running with "
|
|
"--config=asan to diagnose rehashing issues.",
|
|
operation);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Note that for comparisons, null/end iterators are valid.
|
|
inline void AssertIsValidForComparison(const ctrl_t* ctrl,
|
|
GenerationType generation,
|
|
const GenerationType* generation_ptr) {
|
|
if (!SwisstableDebugEnabled()) return;
|
|
const bool ctrl_is_valid_for_comparison =
|
|
ctrl == nullptr || ctrl == DefaultIterControl() || IsFull(*ctrl);
|
|
if (SwisstableGenerationsEnabled()) {
|
|
if (ABSL_PREDICT_FALSE(generation != *generation_ptr)) {
|
|
ABSL_RAW_LOG(FATAL,
|
|
"Invalid iterator comparison. The table could have rehashed "
|
|
"or moved since this iterator was initialized.");
|
|
}
|
|
if (ABSL_PREDICT_FALSE(!ctrl_is_valid_for_comparison)) {
|
|
ABSL_RAW_LOG(
|
|
FATAL, "Invalid iterator comparison. The element was likely erased.");
|
|
}
|
|
} else {
|
|
ABSL_HARDENING_ASSERT_SLOW(
|
|
ctrl_is_valid_for_comparison &&
|
|
"Invalid iterator comparison. The element might have been erased or "
|
|
"the table might have rehashed. Consider running with --config=asan to "
|
|
"diagnose rehashing issues.");
|
|
}
|
|
}
|
|
|
|
// If the two iterators come from the same container, then their pointers will
|
|
// interleave such that ctrl_a <= ctrl_b < slot_a <= slot_b or vice/versa.
|
|
// Note: we take slots by reference so that it's not UB if they're uninitialized
|
|
// as long as we don't read them (when ctrl is null).
|
|
inline bool AreItersFromSameContainer(const ctrl_t* ctrl_a,
|
|
const ctrl_t* ctrl_b,
|
|
const void* const& slot_a,
|
|
const void* const& slot_b) {
|
|
// If either control byte is null, then we can't tell.
|
|
if (ctrl_a == nullptr || ctrl_b == nullptr) return true;
|
|
const bool a_is_soo = IsSooControl(ctrl_a);
|
|
if (a_is_soo != IsSooControl(ctrl_b)) return false;
|
|
if (a_is_soo) return slot_a == slot_b;
|
|
|
|
const void* low_slot = slot_a;
|
|
const void* hi_slot = slot_b;
|
|
if (ctrl_a > ctrl_b) {
|
|
std::swap(ctrl_a, ctrl_b);
|
|
std::swap(low_slot, hi_slot);
|
|
}
|
|
return ctrl_b < low_slot && low_slot <= hi_slot;
|
|
}
|
|
|
|
// Asserts that two iterators come from the same container.
|
|
// Note: we take slots by reference so that it's not UB if they're uninitialized
|
|
// as long as we don't read them (when ctrl is null).
|
|
inline void AssertSameContainer(const ctrl_t* ctrl_a, const ctrl_t* ctrl_b,
|
|
const void* const& slot_a,
|
|
const void* const& slot_b,
|
|
const GenerationType* generation_ptr_a,
|
|
const GenerationType* generation_ptr_b) {
|
|
if (!SwisstableDebugEnabled()) return;
|
|
// `SwisstableDebugEnabled()` is also true for release builds with hardening
|
|
// enabled. To minimize their impact in those builds:
|
|
// - use `ABSL_PREDICT_FALSE()` to provide a compiler hint for code layout
|
|
// - use `ABSL_RAW_LOG()` with a format string to reduce code size and improve
|
|
// the chances that the hot paths will be inlined.
|
|
|
|
// fail_if(is_invalid, message) crashes when is_invalid is true and provides
|
|
// an error message based on `message`.
|
|
const auto fail_if = [](bool is_invalid, const char* message) {
|
|
if (ABSL_PREDICT_FALSE(is_invalid)) {
|
|
ABSL_RAW_LOG(FATAL, "Invalid iterator comparison. %s", message);
|
|
}
|
|
};
|
|
|
|
const bool a_is_default = ctrl_a == DefaultIterControl();
|
|
const bool b_is_default = ctrl_b == DefaultIterControl();
|
|
if (a_is_default && b_is_default) return;
|
|
fail_if(a_is_default != b_is_default,
|
|
"Comparing default-constructed hashtable iterator with a "
|
|
"non-default-constructed hashtable iterator.");
|
|
|
|
if (SwisstableGenerationsEnabled()) {
|
|
if (ABSL_PREDICT_TRUE(generation_ptr_a == generation_ptr_b)) return;
|
|
const bool a_is_empty = IsEmptyGeneration(generation_ptr_a);
|
|
const bool b_is_empty = IsEmptyGeneration(generation_ptr_b);
|
|
fail_if(a_is_empty != b_is_empty,
|
|
"Comparing an iterator from an empty hashtable with an iterator "
|
|
"from a non-empty hashtable.");
|
|
fail_if(a_is_empty && b_is_empty,
|
|
"Comparing iterators from different empty hashtables.");
|
|
|
|
const bool a_is_end = ctrl_a == nullptr;
|
|
const bool b_is_end = ctrl_b == nullptr;
|
|
fail_if(a_is_end || b_is_end,
|
|
"Comparing iterator with an end() iterator from a different "
|
|
"hashtable.");
|
|
fail_if(true, "Comparing non-end() iterators from different hashtables.");
|
|
} else {
|
|
ABSL_HARDENING_ASSERT_SLOW(
|
|
AreItersFromSameContainer(ctrl_a, ctrl_b, slot_a, slot_b) &&
|
|
"Invalid iterator comparison. The iterators may be from different "
|
|
"containers or the container might have rehashed or moved. Consider "
|
|
"running with --config=asan to diagnose issues.");
|
|
}
|
|
}
|
|
|
|
struct FindInfo {
|
|
size_t offset;
|
|
size_t probe_length;
|
|
};
|
|
|
|
// Whether a table fits entirely into a probing group.
|
|
// Arbitrary order of elements in such tables is correct.
|
|
constexpr bool is_single_group(size_t capacity) {
|
|
return capacity <= Group::kWidth;
|
|
}
|
|
|
|
// Begins a probing operation on `common.control`, using `hash`.
|
|
inline probe_seq<Group::kWidth> probe_h1(size_t capacity, size_t h1) {
|
|
return probe_seq<Group::kWidth>(h1, capacity);
|
|
}
|
|
inline probe_seq<Group::kWidth> probe(size_t capacity, size_t hash) {
|
|
return probe_h1(capacity, H1(hash));
|
|
}
|
|
inline probe_seq<Group::kWidth> probe(const CommonFields& common, size_t hash) {
|
|
return probe(common.capacity(), hash);
|
|
}
|
|
|
|
constexpr size_t kProbedElementIndexSentinel = ~size_t{};
|
|
|
|
// Implementation detail of transfer_unprobed_elements_to_next_capacity_fn.
|
|
// Tries to find the new index for an element whose hash corresponds to
|
|
// `h1` for growth to the next capacity.
|
|
// Returns kProbedElementIndexSentinel if full probing is required.
|
|
//
|
|
// If element is located in the first probing group in the table before growth,
|
|
// returns one of two positions: `old_index` or `old_index + old_capacity + 1`.
|
|
//
|
|
// Otherwise, we will try to insert it into the first probe group of the new
|
|
// table. We only attempt to do so if the first probe group is already
|
|
// initialized.
|
|
template <typename = void>
|
|
inline size_t TryFindNewIndexWithoutProbing(size_t h1, size_t old_index,
|
|
size_t old_capacity,
|
|
ctrl_t* new_ctrl,
|
|
size_t new_capacity) {
|
|
size_t index_diff = old_index - h1;
|
|
// The first probe group starts with h1 & capacity.
|
|
// All following groups start at (h1 + Group::kWidth * K) & capacity.
|
|
// We can find an index within the floating group as index_diff modulo
|
|
// Group::kWidth.
|
|
// Both old and new capacity are larger than Group::kWidth so we can avoid
|
|
// computing `& capacity`.
|
|
size_t in_floating_group_index = index_diff & (Group::kWidth - 1);
|
|
// By subtracting we will get the difference between the first probe group
|
|
// and the probe group corresponding to old_index.
|
|
index_diff -= in_floating_group_index;
|
|
if (ABSL_PREDICT_TRUE((index_diff & old_capacity) == 0)) {
|
|
size_t new_index = (h1 + in_floating_group_index) & new_capacity;
|
|
ABSL_ASSUME(new_index != kProbedElementIndexSentinel);
|
|
return new_index;
|
|
}
|
|
ABSL_SWISSTABLE_ASSERT(((old_index - h1) & old_capacity) >= Group::kWidth);
|
|
// Try to insert element into the first probe group.
|
|
// new_ctrl is not yet fully initialized so we can't use regular search via
|
|
// find_first_non_full.
|
|
|
|
// We can search in the first probe group only if it is located in already
|
|
// initialized part of the table.
|
|
if (ABSL_PREDICT_FALSE((h1 & old_capacity) >= old_index)) {
|
|
return kProbedElementIndexSentinel;
|
|
}
|
|
size_t offset = h1 & new_capacity;
|
|
Group new_g(new_ctrl + offset);
|
|
if (auto mask = new_g.MaskNonFull(); ABSL_PREDICT_TRUE(mask)) {
|
|
size_t result = offset + mask.LowestBitSet();
|
|
ABSL_ASSUME(result != kProbedElementIndexSentinel);
|
|
return result;
|
|
}
|
|
return kProbedElementIndexSentinel;
|
|
}
|
|
|
|
// Extern template for inline function keeps possibility of inlining.
|
|
// When compiler decided to not inline, no symbols will be added to the
|
|
// corresponding translation unit.
|
|
extern template size_t TryFindNewIndexWithoutProbing(size_t h1,
|
|
size_t old_index,
|
|
size_t old_capacity,
|
|
ctrl_t* new_ctrl,
|
|
size_t new_capacity);
|
|
|
|
// growth_info (which is a size_t) is stored with the backing array.
|
|
constexpr size_t BackingArrayAlignment(size_t align_of_slot) {
|
|
return (std::max)(align_of_slot, alignof(GrowthInfo));
|
|
}
|
|
|
|
// Iterates over all full slots and calls `cb(const ctrl_t*, void*)`.
|
|
// No insertion to the table is allowed during `cb` call.
|
|
// Erasure is allowed only for the element passed to the callback.
|
|
// The table must not be in SOO mode.
|
|
void IterateOverFullSlots(const CommonFields& c, size_t slot_size,
|
|
absl::FunctionRef<void(const ctrl_t*, void*)> cb);
|
|
|
|
template <typename CharAlloc>
|
|
constexpr bool ShouldSampleHashtablezInfoForAlloc() {
|
|
// Folks with custom allocators often make unwarranted assumptions about the
|
|
// behavior of their classes vis-a-vis trivial destructability and what
|
|
// calls they will or won't make. Avoid sampling for people with custom
|
|
// allocators to get us out of this mess. This is not a hard guarantee but
|
|
// a workaround while we plan the exact guarantee we want to provide.
|
|
return std::is_same_v<CharAlloc, std::allocator<char>>;
|
|
}
|
|
|
|
// Allocates `n` bytes for a backing array.
|
|
template <size_t AlignOfBackingArray, typename Alloc>
|
|
void* AllocateBackingArray(void* alloc, size_t n) {
|
|
return Allocate<AlignOfBackingArray>(static_cast<Alloc*>(alloc), n);
|
|
}
|
|
|
|
// Note: we mark this function as ABSL_ATTRIBUTE_NOINLINE because we don't want
|
|
// it to be inlined into e.g. the destructor to save code size.
|
|
template <size_t AlignOfBackingArray, typename Alloc>
|
|
ABSL_ATTRIBUTE_NOINLINE void DeallocateBackingArray(
|
|
void* alloc, size_t capacity, ctrl_t* ctrl, size_t slot_size,
|
|
size_t slot_align, bool had_infoz) {
|
|
RawHashSetLayout layout(capacity, slot_size, slot_align, had_infoz);
|
|
void* backing_array = ctrl - layout.control_offset();
|
|
// Unpoison before returning the memory to the allocator.
|
|
SanitizerUnpoisonMemoryRegion(backing_array, layout.alloc_size());
|
|
Deallocate<AlignOfBackingArray>(static_cast<Alloc*>(alloc), backing_array,
|
|
layout.alloc_size());
|
|
}
|
|
|
|
// PolicyFunctions bundles together some information for a particular
|
|
// raw_hash_set<T, ...> instantiation. This information is passed to
|
|
// type-erased functions that want to do small amounts of type-specific
|
|
// work.
|
|
struct PolicyFunctions {
|
|
uint32_t key_size;
|
|
uint32_t value_size;
|
|
uint32_t slot_size;
|
|
uint16_t slot_align;
|
|
bool soo_enabled;
|
|
bool is_hashtablez_eligible;
|
|
|
|
// Returns the pointer to the hash function stored in the set.
|
|
void* (*hash_fn)(CommonFields& common);
|
|
|
|
// Returns the hash of the pointed-to slot.
|
|
HashSlotFn hash_slot;
|
|
|
|
// Transfers the contents of `count` slots from src_slot to dst_slot.
|
|
// We use ability to transfer several slots in single group table growth.
|
|
void (*transfer_n)(void* set, void* dst_slot, void* src_slot, size_t count);
|
|
|
|
// Returns the pointer to the CharAlloc stored in the set.
|
|
void* (*get_char_alloc)(CommonFields& common);
|
|
|
|
// Allocates n bytes for the backing store for common.
|
|
void* (*alloc)(void* alloc, size_t n);
|
|
|
|
// Deallocates the backing store from common.
|
|
void (*dealloc)(void* alloc, size_t capacity, ctrl_t* ctrl, size_t slot_size,
|
|
size_t slot_align, bool had_infoz);
|
|
|
|
// Implementation detail of GrowToNextCapacity.
|
|
// Iterates over all full slots and transfers unprobed elements.
|
|
// Initializes the new control bytes except mirrored bytes and kSentinel.
|
|
// Caller must finish the initialization.
|
|
// All slots corresponding to the full control bytes are transferred.
|
|
// Probed elements are reported by `encode_probed_element` callback.
|
|
// encode_probed_element may overwrite old_ctrl buffer till source_offset.
|
|
// Different encoding is used depending on the capacity of the table.
|
|
// See ProbedItem*Bytes classes for details.
|
|
void (*transfer_unprobed_elements_to_next_capacity)(
|
|
CommonFields& common, const ctrl_t* old_ctrl, void* old_slots,
|
|
// TODO(b/382423690): Try to use absl::FunctionRef here.
|
|
void* probed_storage,
|
|
void (*encode_probed_element)(void* probed_storage, h2_t h2,
|
|
size_t source_offset, size_t h1));
|
|
|
|
uint8_t soo_capacity() const {
|
|
return static_cast<uint8_t>(soo_enabled ? SooCapacity() : 0);
|
|
}
|
|
};
|
|
|
|
// Returns the maximum valid size for a table with 1-byte slots.
|
|
// This function is an utility shared by MaxValidSize and IsAboveValidSize.
|
|
// Template parameter is only used to enable testing.
|
|
template <size_t kSizeOfSizeT = sizeof(size_t)>
|
|
constexpr size_t MaxValidSizeFor1ByteSlot() {
|
|
if constexpr (kSizeOfSizeT == 8) {
|
|
return CapacityToGrowth(
|
|
static_cast<size_t>(uint64_t{1} << HashtableSize::kSizeBitCount) - 1);
|
|
} else {
|
|
static_assert(kSizeOfSizeT == 4);
|
|
return CapacityToGrowth((size_t{1} << (kSizeOfSizeT * 8 - 2)) - 1);
|
|
}
|
|
}
|
|
|
|
// Returns the maximum valid size for a table with provided slot size.
|
|
// Template parameter is only used to enable testing.
|
|
template <size_t kSizeOfSizeT = sizeof(size_t)>
|
|
constexpr size_t MaxValidSize(size_t slot_size) {
|
|
if constexpr (kSizeOfSizeT == 8) {
|
|
// For small slot sizes we are limited by HashtableSize::kSizeBitCount.
|
|
if (slot_size < size_t{1} << (64 - HashtableSize::kSizeBitCount)) {
|
|
return MaxValidSizeFor1ByteSlot<kSizeOfSizeT>();
|
|
}
|
|
return (size_t{1} << (kSizeOfSizeT * 8 - 2)) / slot_size;
|
|
} else {
|
|
return MaxValidSizeFor1ByteSlot<kSizeOfSizeT>() / slot_size;
|
|
}
|
|
}
|
|
|
|
// Returns true if size is larger than the maximum valid size.
|
|
// It is an optimization to avoid the division operation in the common case.
|
|
// Template parameter is only used to enable testing.
|
|
template <size_t kSizeOfSizeT = sizeof(size_t)>
|
|
constexpr bool IsAboveValidSize(size_t size, size_t slot_size) {
|
|
if constexpr (kSizeOfSizeT == 8) {
|
|
// For small slot sizes we are limited by HashtableSize::kSizeBitCount.
|
|
if (ABSL_PREDICT_TRUE(slot_size <
|
|
(size_t{1} << (64 - HashtableSize::kSizeBitCount)))) {
|
|
return size > MaxValidSizeFor1ByteSlot<kSizeOfSizeT>();
|
|
}
|
|
return size > MaxValidSize<kSizeOfSizeT>(slot_size);
|
|
} else {
|
|
return uint64_t{size} * slot_size >
|
|
MaxValidSizeFor1ByteSlot<kSizeOfSizeT>();
|
|
}
|
|
}
|
|
|
|
// Returns the index of the SOO slot when growing from SOO to non-SOO in a
|
|
// single group. See also InitializeSmallControlBytesAfterSoo(). It's important
|
|
// to use index 1 so that when resizing from capacity 1 to 3, we can still have
|
|
// random iteration order between the first two inserted elements.
|
|
// I.e. it allows inserting the second element at either index 0 or 2.
|
|
constexpr size_t SooSlotIndex() { return 1; }
|
|
|
|
// Maximum capacity for the algorithm for small table after SOO.
|
|
// Note that typical size after SOO is 3, but we allow up to 7.
|
|
// Allowing till 16 would require additional store that can be avoided.
|
|
constexpr size_t MaxSmallAfterSooCapacity() { return 7; }
|
|
|
|
// Type erased version of raw_hash_set::reserve.
|
|
// Requires: `new_size > policy.soo_capacity`.
|
|
void ReserveTableToFitNewSize(CommonFields& common,
|
|
const PolicyFunctions& policy, size_t new_size);
|
|
|
|
// Resizes empty non-allocated table to the next valid capacity after
|
|
// `bucket_count`. Requires:
|
|
// 1. `c.capacity() == policy.soo_capacity`.
|
|
// 2. `c.empty()`.
|
|
// 3. `new_size > policy.soo_capacity`.
|
|
// The table will be attempted to be sampled.
|
|
void ReserveEmptyNonAllocatedTableToFitBucketCount(
|
|
CommonFields& common, const PolicyFunctions& policy, size_t bucket_count);
|
|
|
|
// Type erased version of raw_hash_set::rehash.
|
|
void Rehash(CommonFields& common, const PolicyFunctions& policy, size_t n);
|
|
|
|
// Type erased version of copy constructor.
|
|
void Copy(CommonFields& common, const PolicyFunctions& policy,
|
|
const CommonFields& other,
|
|
absl::FunctionRef<void(void*, const void*)> copy_fn);
|
|
|
|
// Returns the optimal size for memcpy when transferring SOO slot.
|
|
// Otherwise, returns the optimal size for memcpy SOO slot transfer
|
|
// to SooSlotIndex().
|
|
// At the destination we are allowed to copy upto twice more bytes,
|
|
// because there is at least one more slot after SooSlotIndex().
|
|
// The result must not exceed MaxSooSlotSize().
|
|
// Some of the cases are merged to minimize the number of function
|
|
// instantiations.
|
|
constexpr size_t OptimalMemcpySizeForSooSlotTransfer(
|
|
size_t slot_size, size_t max_soo_slot_size = MaxSooSlotSize()) {
|
|
static_assert(MaxSooSlotSize() >= 8, "unexpectedly small SOO slot size");
|
|
if (slot_size == 1) {
|
|
return 1;
|
|
}
|
|
if (slot_size <= 3) {
|
|
return 4;
|
|
}
|
|
// We are merging 4 and 8 into one case because we expect them to be the
|
|
// hottest cases. Copying 8 bytes is as fast on common architectures.
|
|
if (slot_size <= 8) {
|
|
return 8;
|
|
}
|
|
if (max_soo_slot_size <= 16) {
|
|
return max_soo_slot_size;
|
|
}
|
|
if (slot_size <= 16) {
|
|
return 16;
|
|
}
|
|
if (max_soo_slot_size <= 24) {
|
|
return max_soo_slot_size;
|
|
}
|
|
static_assert(MaxSooSlotSize() <= 24, "unexpectedly large SOO slot size");
|
|
return 24;
|
|
}
|
|
|
|
// Resizes SOO table to the NextCapacity(SooCapacity()) and prepares insert for
|
|
// the given new_hash. Returns the offset of the new element.
|
|
// All possible template combinations are defined in cc file to improve
|
|
// compilation time.
|
|
template <size_t SooSlotMemcpySize, bool TransferUsesMemcpy>
|
|
size_t GrowSooTableToNextCapacityAndPrepareInsert(
|
|
CommonFields& common, const PolicyFunctions& policy,
|
|
absl::FunctionRef<size_t(size_t)> get_hash, bool force_sampling);
|
|
|
|
// PrepareInsert for small tables (is_small()==true).
|
|
// Returns the new control and the new slot.
|
|
// Hash is only computed if the table is sampled or grew to large size
|
|
// (is_small()==false).
|
|
std::pair<ctrl_t*, void*> PrepareInsertSmallNonSoo(
|
|
CommonFields& common, const PolicyFunctions& policy,
|
|
absl::FunctionRef<size_t(size_t)> get_hash);
|
|
|
|
// Resizes table with allocated slots and change the table seed.
|
|
// Tables with SOO enabled must have capacity > policy.soo_capacity.
|
|
// No sampling will be performed since table is already allocated.
|
|
void ResizeAllocatedTableWithSeedChange(CommonFields& common,
|
|
const PolicyFunctions& policy,
|
|
size_t new_capacity);
|
|
|
|
// ClearBackingArray clears the backing array, either modifying it in place,
|
|
// or creating a new one based on the value of "reuse".
|
|
// REQUIRES: c.capacity > 0
|
|
void ClearBackingArray(CommonFields& c, const PolicyFunctions& policy,
|
|
void* alloc, bool reuse, bool soo_enabled);
|
|
|
|
// Type-erased versions of raw_hash_set::erase_meta_only_{small,large}.
|
|
void EraseMetaOnlySmall(CommonFields& c, bool soo_enabled, size_t slot_size);
|
|
void EraseMetaOnlyLarge(CommonFields& c, const ctrl_t* ctrl, size_t slot_size);
|
|
|
|
// For trivially relocatable types we use memcpy directly. This allows us to
|
|
// share the same function body for raw_hash_set instantiations that have the
|
|
// same slot size as long as they are relocatable.
|
|
// Separate function for relocating single slot cause significant binary bloat.
|
|
template <size_t SizeOfSlot>
|
|
ABSL_ATTRIBUTE_NOINLINE void TransferNRelocatable(void*, void* dst, void* src,
|
|
size_t count) {
|
|
// TODO(b/382423690): Experiment with making specialization for power of 2 and
|
|
// non power of 2. This would require passing the size of the slot.
|
|
memcpy(dst, src, SizeOfSlot * count);
|
|
}
|
|
|
|
// Returns a pointer to `common`. This is used to implement type erased
|
|
// raw_hash_set::get_hash_ref_fn and raw_hash_set::get_alloc_ref_fn for the
|
|
// empty class cases.
|
|
void* GetRefForEmptyClass(CommonFields& common);
|
|
|
|
// Given the hash of a value not currently in the table and the first group with
|
|
// an empty slot in the probe sequence, finds a viable slot index to insert it
|
|
// at.
|
|
//
|
|
// In case there's no space left, the table can be resized or rehashed
|
|
// (for tables with deleted slots, see FindInsertPositionWithGrowthOrRehash).
|
|
//
|
|
// In the case of absence of deleted slots and positive growth_left, the element
|
|
// can be inserted in one of the empty slots in the provided `target_group`.
|
|
//
|
|
// When the table has deleted slots (according to GrowthInfo), the target
|
|
// position will be searched one more time using `find_first_non_full`.
|
|
//
|
|
// REQUIRES: `!common.is_small()`.
|
|
// REQUIRES: At least one non-full slot available.
|
|
// REQUIRES: `mask_empty` is a mask containing empty slots for the
|
|
// `target_group`.
|
|
// REQUIRES: `target_group` is a starting position for the group that has
|
|
// at least one empty slot.
|
|
size_t PrepareInsertLarge(CommonFields& common, const PolicyFunctions& policy,
|
|
size_t hash, Group::NonIterableBitMaskType mask_empty,
|
|
FindInfo target_group);
|
|
|
|
// Same as above, but with generations enabled, we may end up changing the seed,
|
|
// which means we need to be able to recompute the hash.
|
|
size_t PrepareInsertLargeGenerationsEnabled(
|
|
CommonFields& common, const PolicyFunctions& policy, size_t hash,
|
|
Group::NonIterableBitMaskType mask_empty, FindInfo target_group,
|
|
absl::FunctionRef<size_t(size_t)> recompute_hash);
|
|
|
|
template <typename Policy, typename Hash, typename Eq, typename Alloc>
|
|
struct InstantiateRawHashSet {
|
|
using type = typename ApplyWithoutDefaultSuffix<
|
|
raw_hash_set,
|
|
TypeList<void, typename Policy::DefaultHash, typename Policy::DefaultEq,
|
|
typename Policy::DefaultAlloc>,
|
|
TypeList<Policy, Hash, Eq, Alloc>>::type;
|
|
};
|
|
|
|
// A SwissTable.
|
|
//
|
|
// Policy: a policy defines how to perform different operations on
|
|
// the slots of the hashtable (see hash_policy_traits.h for the full interface
|
|
// of policy).
|
|
//
|
|
// Params...: a variadic list of parameters that allows us to omit default
|
|
// types. This reduces the mangled name of the class and the size of
|
|
// debug strings like __PRETTY_FUNCTION__. Default types do not give
|
|
// any new information.
|
|
//
|
|
// Hash: a (possibly polymorphic) functor that hashes keys of the hashtable. The
|
|
// functor should accept a key and return size_t as hash. For best performance
|
|
// it is important that the hash function provides high entropy across all bits
|
|
// of the hash.
|
|
// This is the first element in `Params...` if it exists, or Policy::DefaultHash
|
|
// otherwise.
|
|
//
|
|
// Eq: a (possibly polymorphic) functor that compares two keys for equality. It
|
|
// should accept two (of possibly different type) keys and return a bool: true
|
|
// if they are equal, false if they are not. If two keys compare equal, then
|
|
// their hash values as defined by Hash MUST be equal.
|
|
// This is the second element in `Params...` if it exists, or Policy::DefaultEq
|
|
// otherwise.
|
|
//
|
|
// Allocator: an Allocator
|
|
// [https://en.cppreference.com/w/cpp/named_req/Allocator] with which
|
|
// the storage of the hashtable will be allocated and the elements will be
|
|
// constructed and destroyed.
|
|
// This is the third element in `Params...` if it exists, or
|
|
// Policy::DefaultAlloc otherwise.
|
|
template <class Policy, class... Params>
|
|
class raw_hash_set {
|
|
using PolicyTraits = hash_policy_traits<Policy>;
|
|
using Hash = GetFromListOr<typename Policy::DefaultHash, 0, Params...>;
|
|
using Eq = GetFromListOr<typename Policy::DefaultEq, 1, Params...>;
|
|
using Alloc = GetFromListOr<typename Policy::DefaultAlloc, 2, Params...>;
|
|
using KeyArgImpl =
|
|
KeyArg<IsTransparent<Eq>::value && IsTransparent<Hash>::value>;
|
|
|
|
static_assert(
|
|
std::is_same_v<
|
|
typename InstantiateRawHashSet<Policy, Hash, Eq, Alloc>::type,
|
|
raw_hash_set>,
|
|
"Redundant template parameters were passed. Use InstantiateRawHashSet<> "
|
|
"instead");
|
|
|
|
public:
|
|
using init_type = typename PolicyTraits::init_type;
|
|
using key_type = typename PolicyTraits::key_type;
|
|
using allocator_type = Alloc;
|
|
using size_type = size_t;
|
|
using difference_type = ptrdiff_t;
|
|
using hasher = Hash;
|
|
using key_equal = Eq;
|
|
using policy_type = Policy;
|
|
using value_type = typename PolicyTraits::value_type;
|
|
using reference = value_type&;
|
|
using const_reference = const value_type&;
|
|
using pointer = typename absl::allocator_traits<
|
|
allocator_type>::template rebind_traits<value_type>::pointer;
|
|
using const_pointer = typename absl::allocator_traits<
|
|
allocator_type>::template rebind_traits<value_type>::const_pointer;
|
|
|
|
private:
|
|
// Alias used for heterogeneous lookup functions.
|
|
// `key_arg<K>` evaluates to `K` when the functors are transparent and to
|
|
// `key_type` otherwise. It permits template argument deduction on `K` for the
|
|
// transparent case.
|
|
template <class K>
|
|
using key_arg = typename KeyArgImpl::template type<K, key_type>;
|
|
|
|
using slot_type = typename PolicyTraits::slot_type;
|
|
|
|
constexpr static bool kIsDefaultHash =
|
|
std::is_same_v<hasher, absl::Hash<key_type>> ||
|
|
std::is_same_v<hasher, absl::container_internal::StringHash>;
|
|
|
|
// TODO(b/289225379): we could add extra SOO space inside raw_hash_set
|
|
// after CommonFields to allow inlining larger slot_types (e.g. std::string),
|
|
// but it's a bit complicated if we want to support incomplete mapped_type in
|
|
// flat_hash_map. We could potentially do this for flat_hash_set and for an
|
|
// allowlist of `mapped_type`s of flat_hash_map that includes e.g. arithmetic
|
|
// types, strings, cords, and pairs/tuples of allowlisted types.
|
|
constexpr static bool SooEnabled() {
|
|
return PolicyTraits::soo_enabled() &&
|
|
sizeof(slot_type) <= sizeof(HeapOrSoo) &&
|
|
alignof(slot_type) <= alignof(HeapOrSoo);
|
|
}
|
|
|
|
constexpr static size_t DefaultCapacity() {
|
|
return SooEnabled() ? SooCapacity() : 0;
|
|
}
|
|
|
|
// Whether `size` fits in the SOO capacity of this table.
|
|
bool fits_in_soo(size_t size) const {
|
|
return SooEnabled() && size <= SooCapacity();
|
|
}
|
|
// Whether this table is in SOO mode or non-SOO mode.
|
|
bool is_soo() const { return fits_in_soo(capacity()); }
|
|
bool is_full_soo() const { return is_soo() && !empty(); }
|
|
|
|
bool is_small() const { return common().is_small(); }
|
|
|
|
// Give an early error when key_type is not hashable/eq.
|
|
auto KeyTypeCanBeHashed(const Hash& h, const key_type& k) -> decltype(h(k));
|
|
auto KeyTypeCanBeEq(const Eq& eq, const key_type& k) -> decltype(eq(k, k));
|
|
|
|
// Try to be helpful when the hasher returns an unreasonable type.
|
|
using key_hash_result =
|
|
absl::remove_cvref_t<decltype(std::declval<const Hash&>()(
|
|
std::declval<const key_type&>()))>;
|
|
static_assert(sizeof(key_hash_result) >= sizeof(size_t),
|
|
"`Hash::operator()` should return a `size_t`");
|
|
|
|
using AllocTraits = absl::allocator_traits<allocator_type>;
|
|
using SlotAlloc = typename absl::allocator_traits<
|
|
allocator_type>::template rebind_alloc<slot_type>;
|
|
// People are often sloppy with the exact type of their allocator (sometimes
|
|
// it has an extra const or is missing the pair, but rebinds made it work
|
|
// anyway).
|
|
using CharAlloc =
|
|
typename absl::allocator_traits<Alloc>::template rebind_alloc<char>;
|
|
using SlotAllocTraits = typename absl::allocator_traits<
|
|
allocator_type>::template rebind_traits<slot_type>;
|
|
|
|
static_assert(std::is_lvalue_reference<reference>::value,
|
|
"Policy::element() must return a reference");
|
|
|
|
// An enabler for insert(T&&): T must be convertible to init_type or be the
|
|
// same as [cv] value_type [ref].
|
|
template <class T>
|
|
using Insertable = absl::disjunction<
|
|
std::is_same<absl::remove_cvref_t<reference>, absl::remove_cvref_t<T>>,
|
|
std::is_convertible<T, init_type>>;
|
|
template <class T>
|
|
using IsNotBitField = std::is_pointer<T*>;
|
|
|
|
// RequiresNotInit is a workaround for gcc prior to 7.1.
|
|
// See https://godbolt.org/g/Y4xsUh.
|
|
template <class T>
|
|
using RequiresNotInit =
|
|
typename std::enable_if<!std::is_same<T, init_type>::value, int>::type;
|
|
|
|
template <class... Ts>
|
|
using IsDecomposable = IsDecomposable<void, PolicyTraits, Hash, Eq, Ts...>;
|
|
|
|
template <class T>
|
|
using IsDecomposableAndInsertable =
|
|
IsDecomposable<std::enable_if_t<Insertable<T>::value, T>>;
|
|
|
|
// Evaluates to true if an assignment from the given type would require the
|
|
// source object to remain alive for the life of the element.
|
|
template <class U>
|
|
using IsLifetimeBoundAssignmentFrom = std::conditional_t<
|
|
policy_trait_element_is_owner<Policy>::value, std::false_type,
|
|
type_traits_internal::IsLifetimeBoundAssignment<init_type, U>>;
|
|
|
|
public:
|
|
static_assert(std::is_same<pointer, value_type*>::value,
|
|
"Allocators with custom pointer types are not supported");
|
|
static_assert(std::is_same<const_pointer, const value_type*>::value,
|
|
"Allocators with custom pointer types are not supported");
|
|
|
|
class iterator : private HashSetIteratorGenerationInfo {
|
|
friend class raw_hash_set;
|
|
friend struct HashtableFreeFunctionsAccess;
|
|
|
|
public:
|
|
using iterator_category = std::forward_iterator_tag;
|
|
using value_type = typename raw_hash_set::value_type;
|
|
using reference =
|
|
absl::conditional_t<PolicyTraits::constant_iterators::value,
|
|
const value_type&, value_type&>;
|
|
using pointer = absl::remove_reference_t<reference>*;
|
|
using difference_type = typename raw_hash_set::difference_type;
|
|
|
|
iterator() {}
|
|
|
|
// PRECONDITION: not an end() iterator.
|
|
reference operator*() const {
|
|
assert_is_full("operator*()");
|
|
return unchecked_deref();
|
|
}
|
|
|
|
// PRECONDITION: not an end() iterator.
|
|
pointer operator->() const {
|
|
assert_is_full("operator->");
|
|
return &operator*();
|
|
}
|
|
|
|
// PRECONDITION: not an end() iterator.
|
|
iterator& operator++() {
|
|
assert_is_full("operator++");
|
|
++ctrl_;
|
|
++slot_;
|
|
skip_empty_or_deleted();
|
|
if (ABSL_PREDICT_FALSE(*ctrl_ == ctrl_t::kSentinel)) ctrl_ = nullptr;
|
|
return *this;
|
|
}
|
|
// PRECONDITION: not an end() iterator.
|
|
iterator operator++(int) {
|
|
auto tmp = *this;
|
|
++*this;
|
|
return tmp;
|
|
}
|
|
|
|
friend bool operator==(const iterator& a, const iterator& b) {
|
|
AssertIsValidForComparison(a.ctrl_, a.generation(), a.generation_ptr());
|
|
AssertIsValidForComparison(b.ctrl_, b.generation(), b.generation_ptr());
|
|
AssertSameContainer(a.ctrl_, b.ctrl_, a.slot_, b.slot_,
|
|
a.generation_ptr(), b.generation_ptr());
|
|
return a.ctrl_ == b.ctrl_;
|
|
}
|
|
friend bool operator!=(const iterator& a, const iterator& b) {
|
|
return !(a == b);
|
|
}
|
|
|
|
private:
|
|
iterator(ctrl_t* ctrl, slot_type* slot,
|
|
const GenerationType* generation_ptr)
|
|
: HashSetIteratorGenerationInfo(generation_ptr),
|
|
ctrl_(ctrl),
|
|
slot_(slot) {
|
|
// This assumption helps the compiler know that any non-end iterator is
|
|
// not equal to any end iterator.
|
|
ABSL_ASSUME(ctrl != nullptr);
|
|
}
|
|
// This constructor is used in begin() to avoid an MSan
|
|
// use-of-uninitialized-value error. Delegating from this constructor to
|
|
// the previous one doesn't avoid the error.
|
|
iterator(ctrl_t* ctrl, MaybeInitializedPtr<void> slot,
|
|
const GenerationType* generation_ptr)
|
|
: HashSetIteratorGenerationInfo(generation_ptr),
|
|
ctrl_(ctrl),
|
|
slot_(to_slot(slot.get())) {
|
|
// This assumption helps the compiler know that any non-end iterator is
|
|
// not equal to any end iterator.
|
|
ABSL_ASSUME(ctrl != nullptr);
|
|
}
|
|
// For end() iterators.
|
|
explicit iterator(const GenerationType* generation_ptr)
|
|
: HashSetIteratorGenerationInfo(generation_ptr), ctrl_(nullptr) {}
|
|
|
|
void assert_is_full(const char* operation) const {
|
|
AssertIsFull(ctrl_, generation(), generation_ptr(), operation);
|
|
}
|
|
|
|
// Fixes up `ctrl_` to point to a full or sentinel by advancing `ctrl_` and
|
|
// `slot_` until they reach one.
|
|
void skip_empty_or_deleted() {
|
|
while (IsEmptyOrDeleted(*ctrl_)) {
|
|
++ctrl_;
|
|
++slot_;
|
|
}
|
|
}
|
|
|
|
// An equality check which skips ABSL Hardening iterator invalidation
|
|
// checks.
|
|
// Should be used when the lifetimes of the iterators are well-enough
|
|
// understood to prove that they cannot be invalid.
|
|
bool unchecked_equals(const iterator& b) const {
|
|
return ctrl_ == b.control();
|
|
}
|
|
|
|
// Dereferences the iterator without ABSL Hardening iterator invalidation
|
|
// checks.
|
|
reference unchecked_deref() const { return PolicyTraits::element(slot_); }
|
|
|
|
ctrl_t* control() const { return ctrl_; }
|
|
slot_type* slot() const { return slot_; }
|
|
|
|
// We use DefaultIterControl() for default-constructed iterators so that
|
|
// they can be distinguished from end iterators, which have nullptr ctrl_.
|
|
ctrl_t* ctrl_ = DefaultIterControl();
|
|
// To avoid uninitialized member warnings, put slot_ in an anonymous union.
|
|
// The member is not initialized on singleton and end iterators.
|
|
union {
|
|
slot_type* slot_;
|
|
};
|
|
};
|
|
|
|
class const_iterator {
|
|
friend class raw_hash_set;
|
|
template <class Container, typename Enabler>
|
|
friend struct absl::container_internal::hashtable_debug_internal::
|
|
HashtableDebugAccess;
|
|
|
|
public:
|
|
using iterator_category = typename iterator::iterator_category;
|
|
using value_type = typename raw_hash_set::value_type;
|
|
using reference = typename raw_hash_set::const_reference;
|
|
using pointer = typename raw_hash_set::const_pointer;
|
|
using difference_type = typename raw_hash_set::difference_type;
|
|
|
|
const_iterator() = default;
|
|
// Implicit construction from iterator.
|
|
const_iterator(iterator i) : inner_(std::move(i)) {} // NOLINT
|
|
|
|
reference operator*() const { return *inner_; }
|
|
pointer operator->() const { return inner_.operator->(); }
|
|
|
|
const_iterator& operator++() {
|
|
++inner_;
|
|
return *this;
|
|
}
|
|
const_iterator operator++(int) { return inner_++; }
|
|
|
|
friend bool operator==(const const_iterator& a, const const_iterator& b) {
|
|
return a.inner_ == b.inner_;
|
|
}
|
|
friend bool operator!=(const const_iterator& a, const const_iterator& b) {
|
|
return !(a == b);
|
|
}
|
|
|
|
private:
|
|
const_iterator(const ctrl_t* ctrl, const slot_type* slot,
|
|
const GenerationType* gen)
|
|
: inner_(const_cast<ctrl_t*>(ctrl), const_cast<slot_type*>(slot), gen) {
|
|
}
|
|
bool unchecked_equals(const const_iterator& b) const {
|
|
return inner_.unchecked_equals(b.inner_);
|
|
}
|
|
ctrl_t* control() const { return inner_.control(); }
|
|
slot_type* slot() const { return inner_.slot(); }
|
|
|
|
iterator inner_;
|
|
};
|
|
|
|
using node_type = node_handle<Policy, hash_policy_traits<Policy>, Alloc>;
|
|
using insert_return_type = InsertReturnType<iterator, node_type>;
|
|
|
|
// Note: can't use `= default` due to non-default noexcept (causes
|
|
// problems for some compilers). NOLINTNEXTLINE
|
|
raw_hash_set() noexcept(
|
|
std::is_nothrow_default_constructible<hasher>::value &&
|
|
std::is_nothrow_default_constructible<key_equal>::value &&
|
|
std::is_nothrow_default_constructible<allocator_type>::value) {}
|
|
|
|
explicit raw_hash_set(
|
|
size_t bucket_count, const hasher& hash = hasher(),
|
|
const key_equal& eq = key_equal(),
|
|
const allocator_type& alloc = allocator_type())
|
|
: settings_(CommonFields::CreateDefault<SooEnabled()>(), hash, eq,
|
|
alloc) {
|
|
if (bucket_count > DefaultCapacity()) {
|
|
ReserveEmptyNonAllocatedTableToFitBucketCount(
|
|
common(), GetPolicyFunctions(), bucket_count);
|
|
}
|
|
}
|
|
|
|
raw_hash_set(size_t bucket_count, const hasher& hash,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(bucket_count, hash, key_equal(), alloc) {}
|
|
|
|
raw_hash_set(size_t bucket_count, const allocator_type& alloc)
|
|
: raw_hash_set(bucket_count, hasher(), key_equal(), alloc) {}
|
|
|
|
explicit raw_hash_set(const allocator_type& alloc)
|
|
: raw_hash_set(0, hasher(), key_equal(), alloc) {}
|
|
|
|
template <class InputIter>
|
|
raw_hash_set(InputIter first, InputIter last, size_t bucket_count = 0,
|
|
const hasher& hash = hasher(), const key_equal& eq = key_equal(),
|
|
const allocator_type& alloc = allocator_type())
|
|
: raw_hash_set(SelectBucketCountForIterRange(first, last, bucket_count),
|
|
hash, eq, alloc) {
|
|
insert(first, last);
|
|
}
|
|
|
|
template <class InputIter>
|
|
raw_hash_set(InputIter first, InputIter last, size_t bucket_count,
|
|
const hasher& hash, const allocator_type& alloc)
|
|
: raw_hash_set(first, last, bucket_count, hash, key_equal(), alloc) {}
|
|
|
|
template <class InputIter>
|
|
raw_hash_set(InputIter first, InputIter last, size_t bucket_count,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(first, last, bucket_count, hasher(), key_equal(), alloc) {}
|
|
|
|
#if defined(__cpp_lib_containers_ranges) && \
|
|
__cpp_lib_containers_ranges >= 202202L
|
|
template <typename R>
|
|
raw_hash_set(std::from_range_t, R&& rg, size_type bucket_count = 0,
|
|
const hasher& hash = hasher(), const key_equal& eq = key_equal(),
|
|
const allocator_type& alloc = allocator_type())
|
|
: raw_hash_set(std::begin(rg), std::end(rg), bucket_count, hash, eq,
|
|
alloc) {}
|
|
|
|
template <typename R>
|
|
raw_hash_set(std::from_range_t, R&& rg, size_type bucket_count,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(std::from_range, std::forward<R>(rg), bucket_count,
|
|
hasher(), key_equal(), alloc) {}
|
|
|
|
template <typename R>
|
|
raw_hash_set(std::from_range_t, R&& rg, size_type bucket_count,
|
|
const hasher& hash, const allocator_type& alloc)
|
|
: raw_hash_set(std::from_range, std::forward<R>(rg), bucket_count, hash,
|
|
key_equal(), alloc) {}
|
|
#endif
|
|
|
|
template <class InputIter>
|
|
raw_hash_set(InputIter first, InputIter last, const allocator_type& alloc)
|
|
: raw_hash_set(first, last, 0, hasher(), key_equal(), alloc) {}
|
|
|
|
// Instead of accepting std::initializer_list<value_type> as the first
|
|
// argument like std::unordered_set<value_type> does, we have two overloads
|
|
// that accept std::initializer_list<T> and std::initializer_list<init_type>.
|
|
// This is advantageous for performance.
|
|
//
|
|
// // Turns {"abc", "def"} into std::initializer_list<std::string>, then
|
|
// // copies the strings into the set.
|
|
// std::unordered_set<std::string> s = {"abc", "def"};
|
|
//
|
|
// // Turns {"abc", "def"} into std::initializer_list<const char*>, then
|
|
// // copies the strings into the set.
|
|
// absl::flat_hash_set<std::string> s = {"abc", "def"};
|
|
//
|
|
// The same trick is used in insert().
|
|
//
|
|
// The enabler is necessary to prevent this constructor from triggering where
|
|
// the copy constructor is meant to be called.
|
|
//
|
|
// absl::flat_hash_set<int> a, b{a};
|
|
//
|
|
// RequiresNotInit<T> is a workaround for gcc prior to 7.1.
|
|
template <class T, RequiresNotInit<T> = 0,
|
|
std::enable_if_t<Insertable<T>::value, int> = 0>
|
|
raw_hash_set(std::initializer_list<T> init, size_t bucket_count = 0,
|
|
const hasher& hash = hasher(), const key_equal& eq = key_equal(),
|
|
const allocator_type& alloc = allocator_type())
|
|
: raw_hash_set(init.begin(), init.end(), bucket_count, hash, eq, alloc) {}
|
|
|
|
raw_hash_set(std::initializer_list<init_type> init, size_t bucket_count = 0,
|
|
const hasher& hash = hasher(), const key_equal& eq = key_equal(),
|
|
const allocator_type& alloc = allocator_type())
|
|
: raw_hash_set(init.begin(), init.end(), bucket_count, hash, eq, alloc) {}
|
|
|
|
template <class T, RequiresNotInit<T> = 0,
|
|
std::enable_if_t<Insertable<T>::value, int> = 0>
|
|
raw_hash_set(std::initializer_list<T> init, size_t bucket_count,
|
|
const hasher& hash, const allocator_type& alloc)
|
|
: raw_hash_set(init, bucket_count, hash, key_equal(), alloc) {}
|
|
|
|
raw_hash_set(std::initializer_list<init_type> init, size_t bucket_count,
|
|
const hasher& hash, const allocator_type& alloc)
|
|
: raw_hash_set(init, bucket_count, hash, key_equal(), alloc) {}
|
|
|
|
template <class T, RequiresNotInit<T> = 0,
|
|
std::enable_if_t<Insertable<T>::value, int> = 0>
|
|
raw_hash_set(std::initializer_list<T> init, size_t bucket_count,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(init, bucket_count, hasher(), key_equal(), alloc) {}
|
|
|
|
raw_hash_set(std::initializer_list<init_type> init, size_t bucket_count,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(init, bucket_count, hasher(), key_equal(), alloc) {}
|
|
|
|
template <class T, RequiresNotInit<T> = 0,
|
|
std::enable_if_t<Insertable<T>::value, int> = 0>
|
|
raw_hash_set(std::initializer_list<T> init, const allocator_type& alloc)
|
|
: raw_hash_set(init, 0, hasher(), key_equal(), alloc) {}
|
|
|
|
raw_hash_set(std::initializer_list<init_type> init,
|
|
const allocator_type& alloc)
|
|
: raw_hash_set(init, 0, hasher(), key_equal(), alloc) {}
|
|
|
|
raw_hash_set(const raw_hash_set& that)
|
|
: raw_hash_set(that, AllocTraits::select_on_container_copy_construction(
|
|
allocator_type(that.char_alloc_ref()))) {}
|
|
|
|
raw_hash_set(const raw_hash_set& that, const allocator_type& a)
|
|
: raw_hash_set(0, that.hash_ref(), that.eq_ref(), a) {
|
|
that.AssertNotDebugCapacity();
|
|
if (that.empty()) return;
|
|
Copy(common(), GetPolicyFunctions(), that.common(),
|
|
[this](void* dst, const void* src) {
|
|
// TODO(b/413598253): type erase for trivially copyable types via
|
|
// PolicyTraits.
|
|
construct(to_slot(dst),
|
|
PolicyTraits::element(
|
|
static_cast<slot_type*>(const_cast<void*>(src))));
|
|
});
|
|
}
|
|
|
|
ABSL_ATTRIBUTE_NOINLINE raw_hash_set(raw_hash_set&& that) noexcept(
|
|
std::is_nothrow_copy_constructible<hasher>::value &&
|
|
std::is_nothrow_copy_constructible<key_equal>::value &&
|
|
std::is_nothrow_copy_constructible<allocator_type>::value)
|
|
: // Hash, equality and allocator are copied instead of moved because
|
|
// `that` must be left valid. If Hash is std::function<Key>, moving it
|
|
// would create a nullptr functor that cannot be called.
|
|
// Note: we avoid using exchange for better generated code.
|
|
settings_(PolicyTraits::transfer_uses_memcpy() || !that.is_full_soo()
|
|
? std::move(that.common())
|
|
: CommonFields{full_soo_tag_t{}},
|
|
that.hash_ref(), that.eq_ref(), that.char_alloc_ref()) {
|
|
if (!PolicyTraits::transfer_uses_memcpy() && that.is_full_soo()) {
|
|
transfer(soo_slot(), that.soo_slot());
|
|
}
|
|
that.common() = CommonFields::CreateDefault<SooEnabled()>();
|
|
annotate_for_bug_detection_on_move(that);
|
|
}
|
|
|
|
raw_hash_set(raw_hash_set&& that, const allocator_type& a)
|
|
: settings_(CommonFields::CreateDefault<SooEnabled()>(), that.hash_ref(),
|
|
that.eq_ref(), a) {
|
|
if (CharAlloc(a) == that.char_alloc_ref()) {
|
|
swap_common(that);
|
|
annotate_for_bug_detection_on_move(that);
|
|
} else {
|
|
move_elements_allocs_unequal(std::move(that));
|
|
}
|
|
}
|
|
|
|
raw_hash_set& operator=(const raw_hash_set& that) {
|
|
that.AssertNotDebugCapacity();
|
|
if (ABSL_PREDICT_FALSE(this == &that)) return *this;
|
|
constexpr bool propagate_alloc =
|
|
AllocTraits::propagate_on_container_copy_assignment::value;
|
|
// TODO(ezb): maybe avoid allocating a new backing array if this->capacity()
|
|
// is an exact match for that.size(). If this->capacity() is too big, then
|
|
// it would make iteration very slow to reuse the allocation. Maybe we can
|
|
// do the same heuristic as clear() and reuse if it's small enough.
|
|
allocator_type alloc(propagate_alloc ? that.char_alloc_ref()
|
|
: char_alloc_ref());
|
|
raw_hash_set tmp(that, alloc);
|
|
// NOLINTNEXTLINE: not returning *this for performance.
|
|
return assign_impl<propagate_alloc>(std::move(tmp));
|
|
}
|
|
|
|
raw_hash_set& operator=(raw_hash_set&& that) noexcept(
|
|
AllocTraits::is_always_equal::value &&
|
|
std::is_nothrow_move_assignable<hasher>::value &&
|
|
std::is_nothrow_move_assignable<key_equal>::value) {
|
|
// TODO(sbenza): We should only use the operations from the noexcept clause
|
|
// to make sure we actually adhere to that contract.
|
|
// NOLINTNEXTLINE: not returning *this for performance.
|
|
return move_assign(
|
|
std::move(that),
|
|
typename AllocTraits::propagate_on_container_move_assignment());
|
|
}
|
|
|
|
~raw_hash_set() {
|
|
destructor_impl();
|
|
if constexpr (SwisstableAssertAccessToDestroyedTable()) {
|
|
common().set_capacity(InvalidCapacity::kDestroyed);
|
|
}
|
|
}
|
|
|
|
iterator begin() ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
if (ABSL_PREDICT_FALSE(empty())) return end();
|
|
if (is_small()) return single_iterator();
|
|
iterator it = {control(), common().slots_union(),
|
|
common().generation_ptr()};
|
|
it.skip_empty_or_deleted();
|
|
ABSL_SWISSTABLE_ASSERT(IsFull(*it.control()));
|
|
return it;
|
|
}
|
|
iterator end() ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
AssertNotDebugCapacity();
|
|
return iterator(common().generation_ptr());
|
|
}
|
|
|
|
const_iterator begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return const_cast<raw_hash_set*>(this)->begin();
|
|
}
|
|
const_iterator end() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return const_cast<raw_hash_set*>(this)->end();
|
|
}
|
|
const_iterator cbegin() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return begin();
|
|
}
|
|
const_iterator cend() const ABSL_ATTRIBUTE_LIFETIME_BOUND { return end(); }
|
|
|
|
bool empty() const { return !size(); }
|
|
size_t size() const {
|
|
AssertNotDebugCapacity();
|
|
return common().size();
|
|
}
|
|
size_t capacity() const {
|
|
const size_t cap = common().capacity();
|
|
// Compiler complains when using functions in ASSUME so use local variable.
|
|
[[maybe_unused]] static constexpr size_t kDefaultCapacity =
|
|
DefaultCapacity();
|
|
ABSL_ASSUME(cap >= kDefaultCapacity);
|
|
return cap;
|
|
}
|
|
size_t max_size() const { return MaxValidSize(sizeof(slot_type)); }
|
|
|
|
ABSL_ATTRIBUTE_REINITIALIZES void clear() {
|
|
if (SwisstableGenerationsEnabled() &&
|
|
capacity() >= InvalidCapacity::kMovedFrom) {
|
|
common().set_capacity(DefaultCapacity());
|
|
}
|
|
AssertNotDebugCapacity();
|
|
// Iterating over this container is O(bucket_count()). When bucket_count()
|
|
// is much greater than size(), iteration becomes prohibitively expensive.
|
|
// For clear() it is more important to reuse the allocated array when the
|
|
// container is small because allocation takes comparatively long time
|
|
// compared to destruction of the elements of the container. So we pick the
|
|
// largest bucket_count() threshold for which iteration is still fast and
|
|
// past that we simply deallocate the array.
|
|
const size_t cap = capacity();
|
|
if (cap == 0) {
|
|
// Already guaranteed to be empty; so nothing to do.
|
|
} else if (is_small()) {
|
|
if (!empty()) {
|
|
destroy(single_slot());
|
|
decrement_small_size();
|
|
}
|
|
} else {
|
|
destroy_slots();
|
|
clear_backing_array(/*reuse=*/cap < 128);
|
|
}
|
|
common().set_reserved_growth(0);
|
|
common().set_reservation_size(0);
|
|
}
|
|
|
|
// This overload kicks in when the argument is an rvalue of insertable and
|
|
// decomposable type other than init_type.
|
|
//
|
|
// flat_hash_map<std::string, int> m;
|
|
// m.insert(std::make_pair("abc", 42));
|
|
template <class T,
|
|
int = std::enable_if_t<IsDecomposableAndInsertable<T>::value &&
|
|
IsNotBitField<T>::value &&
|
|
!IsLifetimeBoundAssignmentFrom<T>::value,
|
|
int>()>
|
|
std::pair<iterator, bool> insert(T&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return emplace(std::forward<T>(value));
|
|
}
|
|
|
|
template <class T, int&...,
|
|
std::enable_if_t<IsDecomposableAndInsertable<T>::value &&
|
|
IsNotBitField<T>::value &&
|
|
IsLifetimeBoundAssignmentFrom<T>::value,
|
|
int> = 0>
|
|
std::pair<iterator, bool> insert(
|
|
T&& value ABSL_INTERNAL_ATTRIBUTE_CAPTURED_BY(this))
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return this->template insert<T, 0>(std::forward<T>(value));
|
|
}
|
|
|
|
// This overload kicks in when the argument is a bitfield or an lvalue of
|
|
// insertable and decomposable type.
|
|
//
|
|
// union { int n : 1; };
|
|
// flat_hash_set<int> s;
|
|
// s.insert(n);
|
|
//
|
|
// flat_hash_set<std::string> s;
|
|
// const char* p = "hello";
|
|
// s.insert(p);
|
|
//
|
|
template <class T, int = std::enable_if_t<
|
|
IsDecomposableAndInsertable<const T&>::value &&
|
|
!IsLifetimeBoundAssignmentFrom<const T&>::value,
|
|
int>()>
|
|
std::pair<iterator, bool> insert(const T& value)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return emplace(value);
|
|
}
|
|
template <class T, int&...,
|
|
std::enable_if_t<IsDecomposableAndInsertable<const T&>::value &&
|
|
IsLifetimeBoundAssignmentFrom<const T&>::value,
|
|
int> = 0>
|
|
std::pair<iterator, bool> insert(
|
|
const T& value ABSL_INTERNAL_ATTRIBUTE_CAPTURED_BY(this))
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return this->template insert<T, 0>(value);
|
|
}
|
|
|
|
// This overload kicks in when the argument is an rvalue of init_type. Its
|
|
// purpose is to handle brace-init-list arguments.
|
|
//
|
|
// flat_hash_map<std::string, int> s;
|
|
// s.insert({"abc", 42});
|
|
std::pair<iterator, bool> insert(init_type&& value)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND
|
|
#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
|
|
requires(!IsLifetimeBoundAssignmentFrom<init_type>::value)
|
|
#endif
|
|
{
|
|
return emplace(std::move(value));
|
|
}
|
|
#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
|
|
std::pair<iterator, bool> insert(
|
|
init_type&& value ABSL_INTERNAL_ATTRIBUTE_CAPTURED_BY(this))
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND
|
|
requires(IsLifetimeBoundAssignmentFrom<init_type>::value)
|
|
{
|
|
return emplace(std::move(value));
|
|
}
|
|
#endif
|
|
|
|
template <class T,
|
|
int = std::enable_if_t<IsDecomposableAndInsertable<T>::value &&
|
|
IsNotBitField<T>::value &&
|
|
!IsLifetimeBoundAssignmentFrom<T>::value,
|
|
int>()>
|
|
iterator insert(const_iterator, T&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return insert(std::forward<T>(value)).first;
|
|
}
|
|
template <class T, int&...,
|
|
std::enable_if_t<IsDecomposableAndInsertable<T>::value &&
|
|
IsNotBitField<T>::value &&
|
|
IsLifetimeBoundAssignmentFrom<T>::value,
|
|
int> = 0>
|
|
iterator insert(const_iterator hint,
|
|
T&& value ABSL_INTERNAL_ATTRIBUTE_CAPTURED_BY(this))
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return this->template insert<T, 0>(hint, std::forward<T>(value));
|
|
}
|
|
|
|
template <class T, std::enable_if_t<
|
|
IsDecomposableAndInsertable<const T&>::value, int> = 0>
|
|
iterator insert(const_iterator,
|
|
const T& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return insert(value).first;
|
|
}
|
|
|
|
iterator insert(const_iterator,
|
|
init_type&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return insert(std::move(value)).first;
|
|
}
|
|
|
|
template <class InputIt>
|
|
void insert(InputIt first, InputIt last) {
|
|
insert_range(first, last);
|
|
}
|
|
|
|
template <class T, RequiresNotInit<T> = 0,
|
|
std::enable_if_t<Insertable<const T&>::value, int> = 0>
|
|
void insert(std::initializer_list<T> ilist) {
|
|
insert_range(ilist.begin(), ilist.end());
|
|
}
|
|
|
|
void insert(std::initializer_list<init_type> ilist) {
|
|
insert_range(ilist.begin(), ilist.end());
|
|
}
|
|
|
|
insert_return_type insert(node_type&& node) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
if (!node) return {end(), false, node_type()};
|
|
const auto& elem = PolicyTraits::element(CommonAccess::GetSlot(node));
|
|
auto res = PolicyTraits::apply(
|
|
InsertSlot<false>{*this, std::move(*CommonAccess::GetSlot(node))},
|
|
elem);
|
|
if (res.second) {
|
|
CommonAccess::Reset(&node);
|
|
return {res.first, true, node_type()};
|
|
} else {
|
|
return {res.first, false, std::move(node)};
|
|
}
|
|
}
|
|
|
|
iterator insert(const_iterator,
|
|
node_type&& node) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
auto res = insert(std::move(node));
|
|
node = std::move(res.node);
|
|
return res.position;
|
|
}
|
|
|
|
// This overload kicks in if we can deduce the key from args. This enables us
|
|
// to avoid constructing value_type if an entry with the same key already
|
|
// exists.
|
|
//
|
|
// For example:
|
|
//
|
|
// flat_hash_map<std::string, std::string> m = {{"abc", "def"}};
|
|
// // Creates no std::string copies and makes no heap allocations.
|
|
// m.emplace("abc", "xyz");
|
|
template <class... Args,
|
|
std::enable_if_t<IsDecomposable<Args...>::value, int> = 0>
|
|
std::pair<iterator, bool> emplace(Args&&... args)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return PolicyTraits::apply(EmplaceDecomposable{*this},
|
|
std::forward<Args>(args)...);
|
|
}
|
|
|
|
// This overload kicks in if we cannot deduce the key from args. It constructs
|
|
// value_type unconditionally and then either moves it into the table or
|
|
// destroys.
|
|
template <class... Args,
|
|
std::enable_if_t<!IsDecomposable<Args...>::value, int> = 0>
|
|
std::pair<iterator, bool> emplace(Args&&... args)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
alignas(slot_type) unsigned char raw[sizeof(slot_type)];
|
|
slot_type* slot = to_slot(&raw);
|
|
|
|
construct(slot, std::forward<Args>(args)...);
|
|
const auto& elem = PolicyTraits::element(slot);
|
|
return PolicyTraits::apply(InsertSlot<true>{*this, std::move(*slot)}, elem);
|
|
}
|
|
|
|
template <class... Args>
|
|
iterator emplace_hint(const_iterator,
|
|
Args&&... args) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return emplace(std::forward<Args>(args)...).first;
|
|
}
|
|
|
|
// Extension API: support for lazy emplace.
|
|
//
|
|
// Looks up key in the table. If found, returns the iterator to the element.
|
|
// Otherwise calls `f` with one argument of type `raw_hash_set::constructor`,
|
|
// and returns an iterator to the new element.
|
|
//
|
|
// `f` must abide by several restrictions:
|
|
// - it MUST call `raw_hash_set::constructor` with arguments as if a
|
|
// `raw_hash_set::value_type` is constructed,
|
|
// - it MUST NOT access the container before the call to
|
|
// `raw_hash_set::constructor`, and
|
|
// - it MUST NOT erase the lazily emplaced element.
|
|
// Doing any of these is undefined behavior.
|
|
//
|
|
// For example:
|
|
//
|
|
// std::unordered_set<ArenaString> s;
|
|
// // Makes ArenaStr even if "abc" is in the map.
|
|
// s.insert(ArenaString(&arena, "abc"));
|
|
//
|
|
// flat_hash_set<ArenaStr> s;
|
|
// // Makes ArenaStr only if "abc" is not in the map.
|
|
// s.lazy_emplace("abc", [&](const constructor& ctor) {
|
|
// ctor(&arena, "abc");
|
|
// });
|
|
//
|
|
// WARNING: This API is currently experimental. If there is a way to implement
|
|
// the same thing with the rest of the API, prefer that.
|
|
class constructor {
|
|
friend class raw_hash_set;
|
|
|
|
public:
|
|
template <class... Args>
|
|
void operator()(Args&&... args) const {
|
|
ABSL_SWISSTABLE_ASSERT(*slot_);
|
|
PolicyTraits::construct(alloc_, *slot_, std::forward<Args>(args)...);
|
|
*slot_ = nullptr;
|
|
}
|
|
|
|
private:
|
|
constructor(allocator_type* a, slot_type** slot) : alloc_(a), slot_(slot) {}
|
|
|
|
allocator_type* alloc_;
|
|
slot_type** slot_;
|
|
};
|
|
|
|
template <class K = key_type, class F>
|
|
iterator lazy_emplace(const key_arg<K>& key,
|
|
F&& f) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
auto res = find_or_prepare_insert(key);
|
|
if (res.second) {
|
|
slot_type* slot = res.first.slot();
|
|
allocator_type alloc(char_alloc_ref());
|
|
std::forward<F>(f)(constructor(&alloc, &slot));
|
|
ABSL_SWISSTABLE_ASSERT(!slot);
|
|
}
|
|
return res.first;
|
|
}
|
|
|
|
// Extension API: support for heterogeneous keys.
|
|
//
|
|
// std::unordered_set<std::string> s;
|
|
// // Turns "abc" into std::string.
|
|
// s.erase("abc");
|
|
//
|
|
// flat_hash_set<std::string> s;
|
|
// // Uses "abc" directly without copying it into std::string.
|
|
// s.erase("abc");
|
|
template <class K = key_type>
|
|
size_type erase(const key_arg<K>& key) {
|
|
auto it = find(key);
|
|
if (it == end()) return 0;
|
|
erase(it);
|
|
return 1;
|
|
}
|
|
|
|
// Erases the element pointed to by `it`. Unlike `std::unordered_set::erase`,
|
|
// this method returns void to reduce algorithmic complexity to O(1). The
|
|
// iterator is invalidated so any increment should be done before calling
|
|
// erase (e.g. `erase(it++)`).
|
|
void erase(const_iterator cit) { erase(cit.inner_); }
|
|
|
|
// This overload is necessary because otherwise erase<K>(const K&) would be
|
|
// a better match if non-const iterator is passed as an argument.
|
|
void erase(iterator it) {
|
|
ABSL_SWISSTABLE_ASSERT(capacity() > 0);
|
|
AssertNotDebugCapacity();
|
|
it.assert_is_full("erase()");
|
|
destroy(it.slot());
|
|
erase_meta_only(it);
|
|
}
|
|
|
|
iterator erase(const_iterator first,
|
|
const_iterator last) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
AssertNotDebugCapacity();
|
|
// We check for empty first because clear_backing_array requires that
|
|
// capacity() > 0 as a precondition.
|
|
if (empty()) return end();
|
|
if (first == last) return last.inner_;
|
|
if (is_small()) {
|
|
destroy(single_slot());
|
|
erase_meta_only_small();
|
|
return end();
|
|
}
|
|
if (first == begin() && last == end()) {
|
|
// TODO(ezb): we access control bytes in destroy_slots so it could make
|
|
// sense to combine destroy_slots and clear_backing_array to avoid cache
|
|
// misses when the table is large. Note that we also do this in clear().
|
|
destroy_slots();
|
|
clear_backing_array(/*reuse=*/true);
|
|
common().set_reserved_growth(common().reservation_size());
|
|
return end();
|
|
}
|
|
while (first != last) {
|
|
erase(first++);
|
|
}
|
|
return last.inner_;
|
|
}
|
|
|
|
// Moves elements from `src` into `this`.
|
|
// If the element already exists in `this`, it is left unmodified in `src`.
|
|
template <
|
|
typename... Params2,
|
|
typename = std::enable_if_t<std::is_same_v<
|
|
Alloc, typename raw_hash_set<Policy, Params2...>::allocator_type>>>
|
|
void merge(raw_hash_set<Policy, Params2...>& src) { // NOLINT
|
|
AssertNotDebugCapacity();
|
|
src.AssertNotDebugCapacity();
|
|
assert(this != &src);
|
|
// Returns whether insertion took place.
|
|
const auto insert_slot = [this](slot_type* src_slot) {
|
|
return PolicyTraits::apply(InsertSlot<false>{*this, std::move(*src_slot)},
|
|
PolicyTraits::element(src_slot))
|
|
.second;
|
|
};
|
|
|
|
if (src.is_small()) {
|
|
if (src.empty()) return;
|
|
if (insert_slot(src.single_slot()))
|
|
src.erase_meta_only_small();
|
|
return;
|
|
}
|
|
for (auto it = src.begin(), e = src.end(); it != e;) {
|
|
auto next = std::next(it);
|
|
if (insert_slot(it.slot())) src.erase_meta_only_large(it);
|
|
it = next;
|
|
}
|
|
}
|
|
|
|
template <
|
|
typename... Params2,
|
|
typename = std::enable_if_t<std::is_same_v<
|
|
Alloc, typename raw_hash_set<Policy, Params2...>::allocator_type>>>
|
|
void merge(raw_hash_set<Policy, Params2...>&& src) { // NOLINT
|
|
merge(src);
|
|
}
|
|
|
|
node_type extract(const_iterator position) {
|
|
AssertNotDebugCapacity();
|
|
position.inner_.assert_is_full("extract()");
|
|
allocator_type alloc(char_alloc_ref());
|
|
auto node = CommonAccess::Transfer<node_type>(alloc, position.slot());
|
|
erase_meta_only(position);
|
|
return node;
|
|
}
|
|
|
|
template <class K = key_type,
|
|
std::enable_if_t<!std::is_same<K, iterator>::value, int> = 0>
|
|
node_type extract(const key_arg<K>& key) {
|
|
auto it = find(key);
|
|
return it == end() ? node_type() : extract(const_iterator{it});
|
|
}
|
|
|
|
void swap(raw_hash_set& that) noexcept(
|
|
AllocTraits::is_always_equal::value &&
|
|
std::is_nothrow_swappable<hasher>::value &&
|
|
std::is_nothrow_swappable<key_equal>::value) {
|
|
AssertNotDebugCapacity();
|
|
that.AssertNotDebugCapacity();
|
|
using std::swap;
|
|
swap_common(that);
|
|
swap(hash_ref(), that.hash_ref());
|
|
swap(eq_ref(), that.eq_ref());
|
|
SwapAlloc(char_alloc_ref(), that.char_alloc_ref(),
|
|
typename AllocTraits::propagate_on_container_swap{});
|
|
}
|
|
|
|
void rehash(size_t n) { Rehash(common(), GetPolicyFunctions(), n); }
|
|
|
|
void reserve(size_t n) {
|
|
if (ABSL_PREDICT_TRUE(n > DefaultCapacity())) {
|
|
ReserveTableToFitNewSize(common(), GetPolicyFunctions(), n);
|
|
}
|
|
}
|
|
|
|
// Extension API: support for heterogeneous keys.
|
|
//
|
|
// std::unordered_set<std::string> s;
|
|
// // Turns "abc" into std::string.
|
|
// s.count("abc");
|
|
//
|
|
// ch_set<std::string> s;
|
|
// // Uses "abc" directly without copying it into std::string.
|
|
// s.count("abc");
|
|
template <class K = key_type>
|
|
size_t count(const key_arg<K>& key) const {
|
|
return find(key) == end() ? 0 : 1;
|
|
}
|
|
|
|
// Issues CPU prefetch instructions for the memory needed to find or insert
|
|
// a key. Like all lookup functions, this support heterogeneous keys.
|
|
//
|
|
// NOTE: This is a very low level operation and should not be used without
|
|
// specific benchmarks indicating its importance.
|
|
template <class K = key_type>
|
|
void prefetch([[maybe_unused]] const key_arg<K>& key) const {
|
|
if (capacity() == DefaultCapacity()) return;
|
|
// Avoid probing if we won't be able to prefetch the addresses received.
|
|
#ifdef ABSL_HAVE_PREFETCH
|
|
prefetch_heap_block();
|
|
if (is_small()) return;
|
|
auto seq = probe(common(), hash_of(key));
|
|
PrefetchToLocalCache(control() + seq.offset());
|
|
PrefetchToLocalCache(slot_array() + seq.offset());
|
|
#endif // ABSL_HAVE_PREFETCH
|
|
}
|
|
|
|
template <class K = key_type>
|
|
ABSL_DEPRECATE_AND_INLINE()
|
|
iterator find(const key_arg<K>& key,
|
|
size_t) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return find(key);
|
|
}
|
|
// The API of find() has one extension: the type of the key argument doesn't
|
|
// have to be key_type. This is so called heterogeneous key support.
|
|
template <class K = key_type>
|
|
iterator find(const key_arg<K>& key) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
AssertOnFind(key);
|
|
if (is_small()) return find_small(key);
|
|
prefetch_heap_block();
|
|
return find_large(key, hash_of(key));
|
|
}
|
|
|
|
template <class K = key_type>
|
|
ABSL_DEPRECATE_AND_INLINE()
|
|
const_iterator find(const key_arg<K>& key,
|
|
size_t) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return find(key);
|
|
}
|
|
template <class K = key_type>
|
|
const_iterator find(const key_arg<K>& key) const
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return const_cast<raw_hash_set*>(this)->find(key);
|
|
}
|
|
|
|
template <class K = key_type>
|
|
bool contains(const key_arg<K>& key) const {
|
|
// Here neither the iterator returned by `find()` nor `end()` can be invalid
|
|
// outside of potential thread-safety issues.
|
|
// `find()`'s return value is constructed, used, and then destructed
|
|
// all in this context.
|
|
return !find(key).unchecked_equals(end());
|
|
}
|
|
|
|
template <class K = key_type>
|
|
std::pair<iterator, iterator> equal_range(const key_arg<K>& key)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
auto it = find(key);
|
|
if (it != end()) return {it, std::next(it)};
|
|
return {it, it};
|
|
}
|
|
template <class K = key_type>
|
|
std::pair<const_iterator, const_iterator> equal_range(
|
|
const key_arg<K>& key) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
auto it = find(key);
|
|
if (it != end()) return {it, std::next(it)};
|
|
return {it, it};
|
|
}
|
|
|
|
size_t bucket_count() const { return capacity(); }
|
|
float load_factor() const {
|
|
return capacity() ? static_cast<double>(size()) / capacity() : 0.0;
|
|
}
|
|
float max_load_factor() const { return 1.0f; }
|
|
void max_load_factor(float) {
|
|
// Does nothing.
|
|
}
|
|
|
|
hasher hash_function() const { return hash_ref(); }
|
|
key_equal key_eq() const { return eq_ref(); }
|
|
allocator_type get_allocator() const {
|
|
return allocator_type(char_alloc_ref());
|
|
}
|
|
|
|
friend bool operator==(const raw_hash_set& a, const raw_hash_set& b) {
|
|
if (a.size() != b.size()) return false;
|
|
const raw_hash_set* outer = &a;
|
|
const raw_hash_set* inner = &b;
|
|
if (outer->capacity() > inner->capacity()) std::swap(outer, inner);
|
|
for (const value_type& elem : *outer) {
|
|
auto it = PolicyTraits::apply(FindElement{*inner}, elem);
|
|
if (it == inner->end()) return false;
|
|
// Note: we used key_equal to check for key equality in FindElement, but
|
|
// we may need to do an additional comparison using
|
|
// value_type::operator==. E.g. the keys could be equal and the
|
|
// mapped_types could be unequal in a map or even in a set, key_equal
|
|
// could ignore some fields that aren't ignored by operator==.
|
|
static constexpr bool kKeyEqIsValueEq =
|
|
std::is_same<key_type, value_type>::value &&
|
|
std::is_same<key_equal, hash_default_eq<key_type>>::value;
|
|
if (!kKeyEqIsValueEq && !(*it == elem)) return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
friend bool operator!=(const raw_hash_set& a, const raw_hash_set& b) {
|
|
return !(a == b);
|
|
}
|
|
|
|
template <typename H>
|
|
friend typename std::enable_if<H::template is_hashable<value_type>::value,
|
|
H>::type
|
|
AbslHashValue(H h, const raw_hash_set& s) {
|
|
return H::combine(H::combine_unordered(std::move(h), s.begin(), s.end()),
|
|
hash_internal::WeaklyMixedInteger{s.size()});
|
|
}
|
|
|
|
friend void swap(raw_hash_set& a,
|
|
raw_hash_set& b) noexcept(noexcept(a.swap(b))) {
|
|
a.swap(b);
|
|
}
|
|
|
|
private:
|
|
template <class Container, typename Enabler>
|
|
friend struct absl::container_internal::hashtable_debug_internal::
|
|
HashtableDebugAccess;
|
|
|
|
friend struct absl::container_internal::HashtableFreeFunctionsAccess;
|
|
|
|
struct FindElement {
|
|
template <class K, class... Args>
|
|
const_iterator operator()(const K& key, Args&&...) const {
|
|
return s.find(key);
|
|
}
|
|
const raw_hash_set& s;
|
|
};
|
|
|
|
struct EmplaceDecomposable {
|
|
template <class K, class... Args>
|
|
std::pair<iterator, bool> operator()(const K& key, Args&&... args) const {
|
|
auto res = s.find_or_prepare_insert(key);
|
|
if (res.second) {
|
|
s.emplace_at(res.first, std::forward<Args>(args)...);
|
|
}
|
|
return res;
|
|
}
|
|
raw_hash_set& s;
|
|
};
|
|
|
|
template <bool do_destroy>
|
|
struct InsertSlot {
|
|
template <class K, class... Args>
|
|
std::pair<iterator, bool> operator()(const K& key, Args&&...) && {
|
|
auto res = s.find_or_prepare_insert(key);
|
|
if (res.second) {
|
|
s.transfer(res.first.slot(), &slot);
|
|
} else if (do_destroy) {
|
|
s.destroy(&slot);
|
|
}
|
|
return res;
|
|
}
|
|
raw_hash_set& s;
|
|
// Constructed slot. Either moved into place or destroyed.
|
|
slot_type&& slot;
|
|
};
|
|
|
|
template <typename... Args>
|
|
inline void construct(slot_type* slot, Args&&... args) {
|
|
common().RunWithReentrancyGuard([&] {
|
|
allocator_type alloc(char_alloc_ref());
|
|
PolicyTraits::construct(&alloc, slot, std::forward<Args>(args)...);
|
|
});
|
|
}
|
|
inline void destroy(slot_type* slot) {
|
|
common().RunWithReentrancyGuard([&] {
|
|
allocator_type alloc(char_alloc_ref());
|
|
PolicyTraits::destroy(&alloc, slot);
|
|
});
|
|
}
|
|
inline void transfer(slot_type* to, slot_type* from) {
|
|
common().RunWithReentrancyGuard([&] {
|
|
allocator_type alloc(char_alloc_ref());
|
|
PolicyTraits::transfer(&alloc, to, from);
|
|
});
|
|
}
|
|
|
|
// TODO(b/289225379): consider having a helper class that has the impls for
|
|
// SOO functionality.
|
|
template <class K = key_type>
|
|
iterator find_small(const key_arg<K>& key) {
|
|
ABSL_SWISSTABLE_ASSERT(is_small());
|
|
return empty() || !equal_to(key, single_slot()) ? end() : single_iterator();
|
|
}
|
|
|
|
template <class K = key_type>
|
|
iterator find_large(const key_arg<K>& key, size_t hash) {
|
|
ABSL_SWISSTABLE_ASSERT(!is_small());
|
|
auto seq = probe(common(), hash);
|
|
const h2_t h2 = H2(hash);
|
|
const ctrl_t* ctrl = control();
|
|
while (true) {
|
|
#ifndef ABSL_HAVE_MEMORY_SANITIZER
|
|
absl::PrefetchToLocalCache(slot_array() + seq.offset());
|
|
#endif
|
|
Group g{ctrl + seq.offset()};
|
|
for (uint32_t i : g.Match(h2)) {
|
|
if (ABSL_PREDICT_TRUE(equal_to(key, slot_array() + seq.offset(i))))
|
|
return iterator_at(seq.offset(i));
|
|
}
|
|
if (ABSL_PREDICT_TRUE(g.MaskEmpty())) return end();
|
|
seq.next();
|
|
ABSL_SWISSTABLE_ASSERT(seq.index() <= capacity() && "full table!");
|
|
}
|
|
}
|
|
|
|
// Returns true if the table needs to be sampled.
|
|
// This should be called on insertion into an empty SOO table and in copy
|
|
// construction when the size can fit in SOO capacity.
|
|
bool should_sample_soo() const {
|
|
ABSL_SWISSTABLE_ASSERT(is_soo());
|
|
if (!ShouldSampleHashtablezInfoForAlloc<CharAlloc>()) return false;
|
|
return ABSL_PREDICT_FALSE(ShouldSampleNextTable());
|
|
}
|
|
|
|
void clear_backing_array(bool reuse) {
|
|
ABSL_SWISSTABLE_ASSERT(capacity() > DefaultCapacity());
|
|
ClearBackingArray(common(), GetPolicyFunctions(), &char_alloc_ref(), reuse,
|
|
SooEnabled());
|
|
}
|
|
|
|
void destroy_slots() {
|
|
ABSL_SWISSTABLE_ASSERT(!is_small());
|
|
if (PolicyTraits::template destroy_is_trivial<Alloc>()) return;
|
|
auto destroy_slot = [&](const ctrl_t*, void* slot) {
|
|
this->destroy(static_cast<slot_type*>(slot));
|
|
};
|
|
if constexpr (SwisstableAssertAccessToDestroyedTable()) {
|
|
CommonFields common_copy(non_soo_tag_t{}, this->common());
|
|
common().set_capacity(InvalidCapacity::kDestroyed);
|
|
IterateOverFullSlots(common_copy, sizeof(slot_type), destroy_slot);
|
|
common().set_capacity(common_copy.capacity());
|
|
} else {
|
|
IterateOverFullSlots(common(), sizeof(slot_type), destroy_slot);
|
|
}
|
|
}
|
|
|
|
void dealloc() {
|
|
ABSL_SWISSTABLE_ASSERT(capacity() > DefaultCapacity());
|
|
// Unpoison before returning the memory to the allocator.
|
|
SanitizerUnpoisonMemoryRegion(slot_array(), sizeof(slot_type) * capacity());
|
|
infoz().Unregister();
|
|
DeallocateBackingArray<BackingArrayAlignment(alignof(slot_type)),
|
|
CharAlloc>(&char_alloc_ref(), capacity(), control(),
|
|
sizeof(slot_type), alignof(slot_type),
|
|
common().has_infoz());
|
|
}
|
|
|
|
void destructor_impl() {
|
|
if (SwisstableGenerationsEnabled() &&
|
|
capacity() >= InvalidCapacity::kMovedFrom) {
|
|
return;
|
|
}
|
|
if (capacity() == 0) return;
|
|
if (is_small()) {
|
|
if (!empty()) {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED(destroy(single_slot()));
|
|
}
|
|
if constexpr (SooEnabled()) return;
|
|
} else {
|
|
destroy_slots();
|
|
}
|
|
dealloc();
|
|
}
|
|
|
|
// Erases, but does not destroy, the value pointed to by `it`.
|
|
//
|
|
// This merely updates the pertinent control byte. This can be used in
|
|
// conjunction with Policy::transfer to move the object to another place.
|
|
void erase_meta_only(const_iterator it) {
|
|
if (is_small()) {
|
|
erase_meta_only_small();
|
|
return;
|
|
}
|
|
erase_meta_only_large(it);
|
|
}
|
|
void erase_meta_only_small() {
|
|
EraseMetaOnlySmall(common(), SooEnabled(), sizeof(slot_type));
|
|
}
|
|
void erase_meta_only_large(const_iterator it) {
|
|
EraseMetaOnlyLarge(common(), it.control(), sizeof(slot_type));
|
|
}
|
|
|
|
template <class K>
|
|
ABSL_ATTRIBUTE_ALWAYS_INLINE bool equal_to(const K& key,
|
|
slot_type* slot) const {
|
|
return PolicyTraits::apply(EqualElement<K, key_equal>{key, eq_ref()},
|
|
PolicyTraits::element(slot));
|
|
}
|
|
template <class K>
|
|
ABSL_ATTRIBUTE_ALWAYS_INLINE size_t hash_of(const K& key) const {
|
|
return HashElement<hasher, kIsDefaultHash>{hash_ref(),
|
|
common().seed().seed()}(key);
|
|
}
|
|
ABSL_ATTRIBUTE_ALWAYS_INLINE size_t hash_of(slot_type* slot) const {
|
|
return PolicyTraits::apply(
|
|
HashElement<hasher, kIsDefaultHash>{hash_ref(), common().seed().seed()},
|
|
PolicyTraits::element(slot));
|
|
}
|
|
|
|
// Casting directly from e.g. char* to slot_type* can cause compilation errors
|
|
// on objective-C. This function converts to void* first, avoiding the issue.
|
|
static ABSL_ATTRIBUTE_ALWAYS_INLINE slot_type* to_slot(void* buf) {
|
|
return static_cast<slot_type*>(buf);
|
|
}
|
|
|
|
// Requires that lhs does not have a full SOO slot.
|
|
static void move_common(bool rhs_is_full_soo, CharAlloc& rhs_alloc,
|
|
CommonFields& lhs, CommonFields&& rhs) {
|
|
if (PolicyTraits::transfer_uses_memcpy() || !rhs_is_full_soo) {
|
|
lhs = std::move(rhs);
|
|
} else {
|
|
lhs.move_non_heap_or_soo_fields(rhs);
|
|
rhs.RunWithReentrancyGuard([&] {
|
|
lhs.RunWithReentrancyGuard([&] {
|
|
PolicyTraits::transfer(&rhs_alloc, to_slot(lhs.soo_data()),
|
|
to_slot(rhs.soo_data()));
|
|
});
|
|
});
|
|
}
|
|
}
|
|
|
|
// Swaps common fields making sure to avoid memcpy'ing a full SOO slot if we
|
|
// aren't allowed to do so.
|
|
void swap_common(raw_hash_set& that) {
|
|
using std::swap;
|
|
if (PolicyTraits::transfer_uses_memcpy()) {
|
|
swap(common(), that.common());
|
|
return;
|
|
}
|
|
CommonFields tmp = CommonFields(uninitialized_tag_t{});
|
|
const bool that_is_full_soo = that.is_full_soo();
|
|
move_common(that_is_full_soo, that.char_alloc_ref(), tmp,
|
|
std::move(that.common()));
|
|
move_common(is_full_soo(), char_alloc_ref(), that.common(),
|
|
std::move(common()));
|
|
move_common(that_is_full_soo, that.char_alloc_ref(), common(),
|
|
std::move(tmp));
|
|
}
|
|
|
|
void annotate_for_bug_detection_on_move([[maybe_unused]] raw_hash_set& that) {
|
|
// We only enable moved-from validation when generations are enabled (rather
|
|
// than using NDEBUG) to avoid issues in which NDEBUG is enabled in some
|
|
// translation units but not in others.
|
|
if (SwisstableGenerationsEnabled()) {
|
|
that.common().set_capacity(this == &that ? InvalidCapacity::kSelfMovedFrom
|
|
: InvalidCapacity::kMovedFrom);
|
|
}
|
|
if (!SwisstableGenerationsEnabled() || capacity() == DefaultCapacity() ||
|
|
capacity() > kAboveMaxValidCapacity) {
|
|
return;
|
|
}
|
|
common().increment_generation();
|
|
if (!empty() && common().should_rehash_for_bug_detection_on_move()) {
|
|
ResizeAllocatedTableWithSeedChange(common(), GetPolicyFunctions(),
|
|
capacity());
|
|
}
|
|
}
|
|
|
|
template <bool propagate_alloc>
|
|
raw_hash_set& assign_impl(raw_hash_set&& that) {
|
|
// We don't bother checking for this/that aliasing. We just need to avoid
|
|
// breaking the invariants in that case.
|
|
destructor_impl();
|
|
move_common(that.is_full_soo(), that.char_alloc_ref(), common(),
|
|
std::move(that.common()));
|
|
hash_ref() = that.hash_ref();
|
|
eq_ref() = that.eq_ref();
|
|
CopyAlloc(char_alloc_ref(), that.char_alloc_ref(),
|
|
std::integral_constant<bool, propagate_alloc>());
|
|
that.common() = CommonFields::CreateDefault<SooEnabled()>();
|
|
annotate_for_bug_detection_on_move(that);
|
|
return *this;
|
|
}
|
|
|
|
raw_hash_set& move_elements_allocs_unequal(raw_hash_set&& that) {
|
|
const size_t size = that.size();
|
|
if (size == 0) return *this;
|
|
reserve(size);
|
|
for (iterator it = that.begin(); it != that.end(); ++it) {
|
|
insert(std::move(PolicyTraits::element(it.slot())));
|
|
that.destroy(it.slot());
|
|
}
|
|
if (!that.is_soo()) that.dealloc();
|
|
that.common() = CommonFields::CreateDefault<SooEnabled()>();
|
|
annotate_for_bug_detection_on_move(that);
|
|
return *this;
|
|
}
|
|
|
|
raw_hash_set& move_assign(raw_hash_set&& that,
|
|
std::true_type /*propagate_alloc*/) {
|
|
return assign_impl<true>(std::move(that));
|
|
}
|
|
raw_hash_set& move_assign(raw_hash_set&& that,
|
|
std::false_type /*propagate_alloc*/) {
|
|
if (char_alloc_ref() == that.char_alloc_ref()) {
|
|
return assign_impl<false>(std::move(that));
|
|
}
|
|
// Aliasing can't happen here because allocs would compare equal above.
|
|
assert(this != &that);
|
|
destructor_impl();
|
|
// We can't take over that's memory so we need to move each element.
|
|
// While moving elements, this should have that's hash/eq so copy hash/eq
|
|
// before moving elements.
|
|
hash_ref() = that.hash_ref();
|
|
eq_ref() = that.eq_ref();
|
|
return move_elements_allocs_unequal(std::move(that));
|
|
}
|
|
|
|
template <class K>
|
|
std::pair<iterator, bool> find_or_prepare_insert_soo(const K& key) {
|
|
ABSL_SWISSTABLE_ASSERT(is_soo());
|
|
bool force_sampling;
|
|
if (empty()) {
|
|
if (!should_sample_soo()) {
|
|
common().set_full_soo();
|
|
return {single_iterator(), true};
|
|
}
|
|
force_sampling = true;
|
|
} else if (equal_to(key, single_slot())) {
|
|
return {single_iterator(), false};
|
|
} else {
|
|
force_sampling = false;
|
|
}
|
|
ABSL_SWISSTABLE_ASSERT(capacity() == 1);
|
|
constexpr bool kUseMemcpy =
|
|
PolicyTraits::transfer_uses_memcpy() && SooEnabled();
|
|
size_t index = GrowSooTableToNextCapacityAndPrepareInsert<
|
|
kUseMemcpy ? OptimalMemcpySizeForSooSlotTransfer(sizeof(slot_type)) : 0,
|
|
kUseMemcpy>(common(), GetPolicyFunctions(),
|
|
HashKey<hasher, K, kIsDefaultHash>{hash_ref(), key},
|
|
force_sampling);
|
|
return {iterator_at(index), true};
|
|
}
|
|
|
|
template <class K>
|
|
std::pair<iterator, bool> find_or_prepare_insert_small(const K& key) {
|
|
ABSL_SWISSTABLE_ASSERT(is_small());
|
|
if constexpr (SooEnabled()) {
|
|
return find_or_prepare_insert_soo(key);
|
|
}
|
|
if (!empty()) {
|
|
if (equal_to(key, single_slot())) {
|
|
return {single_iterator(), false};
|
|
}
|
|
}
|
|
return {iterator_at_ptr(PrepareInsertSmallNonSoo(
|
|
common(), GetPolicyFunctions(),
|
|
HashKey<hasher, K, kIsDefaultHash>{hash_ref(), key})),
|
|
true};
|
|
}
|
|
|
|
template <class K>
|
|
std::pair<iterator, bool> find_or_prepare_insert_large(const K& key) {
|
|
ABSL_SWISSTABLE_ASSERT(!is_soo());
|
|
prefetch_heap_block();
|
|
const size_t hash = hash_of(key);
|
|
auto seq = probe(common(), hash);
|
|
const h2_t h2 = H2(hash);
|
|
const ctrl_t* ctrl = control();
|
|
size_t index;
|
|
bool inserted;
|
|
// We use a lambda function to be able to exit from the nested loop without
|
|
// duplicating generated code for the return statement (e.g. iterator_at).
|
|
[&]() ABSL_ATTRIBUTE_ALWAYS_INLINE {
|
|
while (true) {
|
|
#ifndef ABSL_HAVE_MEMORY_SANITIZER
|
|
absl::PrefetchToLocalCache(slot_array() + seq.offset());
|
|
#endif
|
|
Group g{ctrl + seq.offset()};
|
|
for (uint32_t i : g.Match(h2)) {
|
|
if (ABSL_PREDICT_TRUE(equal_to(key, slot_array() + seq.offset(i)))) {
|
|
index = seq.offset(i);
|
|
inserted = false;
|
|
return;
|
|
}
|
|
}
|
|
auto mask_empty = g.MaskEmpty();
|
|
if (ABSL_PREDICT_TRUE(mask_empty)) {
|
|
size_t target_group_offset = seq.offset();
|
|
index = SwisstableGenerationsEnabled()
|
|
? PrepareInsertLargeGenerationsEnabled(
|
|
common(), GetPolicyFunctions(), hash, mask_empty,
|
|
FindInfo{target_group_offset, seq.index()},
|
|
HashKey<hasher, K, kIsDefaultHash>{hash_ref(), key})
|
|
: PrepareInsertLarge(
|
|
common(), GetPolicyFunctions(), hash, mask_empty,
|
|
FindInfo{target_group_offset, seq.index()});
|
|
inserted = true;
|
|
return;
|
|
}
|
|
seq.next();
|
|
ABSL_SWISSTABLE_ASSERT(seq.index() <= capacity() && "full table!");
|
|
}
|
|
}();
|
|
return {iterator_at(index), inserted};
|
|
}
|
|
|
|
template <class InputIt>
|
|
void insert_range(InputIt first, InputIt last) {
|
|
for (; first != last; ++first) emplace(*first);
|
|
}
|
|
|
|
protected:
|
|
// Asserts for correctness that we run on find/find_or_prepare_insert.
|
|
template <class K>
|
|
void AssertOnFind([[maybe_unused]] const K& key) {
|
|
AssertHashEqConsistent(key);
|
|
AssertNotDebugCapacity();
|
|
}
|
|
|
|
// Asserts that the capacity is not a sentinel invalid value.
|
|
void AssertNotDebugCapacity() const {
|
|
#ifdef NDEBUG
|
|
if (!SwisstableGenerationsEnabled()) {
|
|
return;
|
|
}
|
|
#endif
|
|
if (ABSL_PREDICT_TRUE(capacity() <
|
|
InvalidCapacity::kAboveMaxValidCapacity)) {
|
|
return;
|
|
}
|
|
assert(capacity() != InvalidCapacity::kReentrance &&
|
|
"Reentrant container access during element construction/destruction "
|
|
"is not allowed.");
|
|
if constexpr (SwisstableAssertAccessToDestroyedTable()) {
|
|
if (capacity() == InvalidCapacity::kDestroyed) {
|
|
ABSL_RAW_LOG(FATAL, "Use of destroyed hash table.");
|
|
}
|
|
}
|
|
if (SwisstableGenerationsEnabled() &&
|
|
ABSL_PREDICT_FALSE(capacity() >= InvalidCapacity::kMovedFrom)) {
|
|
if (capacity() == InvalidCapacity::kSelfMovedFrom) {
|
|
// If this log triggers, then a hash table was move-assigned to itself
|
|
// and then used again later without being reinitialized.
|
|
ABSL_RAW_LOG(FATAL, "Use of self-move-assigned hash table.");
|
|
}
|
|
ABSL_RAW_LOG(FATAL, "Use of moved-from hash table.");
|
|
}
|
|
}
|
|
|
|
// Asserts that hash and equal functors provided by the user are consistent,
|
|
// meaning that `eq(k1, k2)` implies `hash(k1)==hash(k2)`.
|
|
template <class K>
|
|
void AssertHashEqConsistent(const K& key) {
|
|
#ifdef NDEBUG
|
|
return;
|
|
#endif
|
|
// If the hash/eq functors are known to be consistent, then skip validation.
|
|
if (std::is_same<hasher, absl::container_internal::StringHash>::value &&
|
|
std::is_same<key_equal, absl::container_internal::StringEq>::value) {
|
|
return;
|
|
}
|
|
if (std::is_scalar<key_type>::value &&
|
|
std::is_same<hasher, absl::Hash<key_type>>::value &&
|
|
std::is_same<key_equal, std::equal_to<key_type>>::value) {
|
|
return;
|
|
}
|
|
if (empty()) return;
|
|
|
|
const size_t hash_of_arg = hash_of(key);
|
|
const auto assert_consistent = [&](const ctrl_t*, void* slot) {
|
|
const bool is_key_equal = equal_to(key, to_slot(slot));
|
|
if (!is_key_equal) return;
|
|
|
|
[[maybe_unused]] const bool is_hash_equal =
|
|
hash_of_arg == hash_of(to_slot(slot));
|
|
assert((!is_key_equal || is_hash_equal) &&
|
|
"eq(k1, k2) must imply that hash(k1) == hash(k2). "
|
|
"hash/eq functors are inconsistent.");
|
|
};
|
|
|
|
if (is_small()) {
|
|
assert_consistent(/*unused*/ nullptr, single_slot());
|
|
return;
|
|
}
|
|
// We only do validation for small tables so that it's constant time.
|
|
if (capacity() > 16) return;
|
|
IterateOverFullSlots(common(), sizeof(slot_type), assert_consistent);
|
|
}
|
|
|
|
// Attempts to find `key` in the table; if it isn't found, returns an iterator
|
|
// where the value can be inserted into, with the control byte already set to
|
|
// `key`'s H2. Returns a bool indicating whether an insertion can take place.
|
|
template <class K>
|
|
std::pair<iterator, bool> find_or_prepare_insert(const K& key) {
|
|
AssertOnFind(key);
|
|
if (is_small()) return find_or_prepare_insert_small(key);
|
|
return find_or_prepare_insert_large(key);
|
|
}
|
|
|
|
// Constructs the value in the space pointed by the iterator. This only works
|
|
// after an unsuccessful find_or_prepare_insert() and before any other
|
|
// modifications happen in the raw_hash_set.
|
|
//
|
|
// PRECONDITION: iter was returned from find_or_prepare_insert(k), where k is
|
|
// the key decomposed from `forward<Args>(args)...`, and the bool returned by
|
|
// find_or_prepare_insert(k) was true.
|
|
// POSTCONDITION: *m.iterator_at(i) == value_type(forward<Args>(args)...).
|
|
template <class... Args>
|
|
void emplace_at(iterator iter, Args&&... args) {
|
|
construct(iter.slot(), std::forward<Args>(args)...);
|
|
|
|
// When is_small, find calls find_small and if size is 0, then it will
|
|
// return an end iterator. This can happen in the raw_hash_set copy ctor.
|
|
assert((is_small() ||
|
|
PolicyTraits::apply(FindElement{*this}, *iter) == iter) &&
|
|
"constructed value does not match the lookup key");
|
|
}
|
|
|
|
iterator iterator_at(size_t i) ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return {control() + i, slot_array() + i, common().generation_ptr()};
|
|
}
|
|
const_iterator iterator_at(size_t i) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return const_cast<raw_hash_set*>(this)->iterator_at(i);
|
|
}
|
|
iterator iterator_at_ptr(std::pair<ctrl_t*, void*> ptrs)
|
|
ABSL_ATTRIBUTE_LIFETIME_BOUND {
|
|
return {ptrs.first, to_slot(ptrs.second), common().generation_ptr()};
|
|
}
|
|
|
|
reference unchecked_deref(iterator it) { return it.unchecked_deref(); }
|
|
|
|
private:
|
|
friend struct RawHashSetTestOnlyAccess;
|
|
|
|
// The number of slots we can still fill without needing to rehash.
|
|
//
|
|
// This is stored separately due to tombstones: we do not include tombstones
|
|
// in the growth capacity, because we'd like to rehash when the table is
|
|
// otherwise filled with tombstones: otherwise, probe sequences might get
|
|
// unacceptably long without triggering a rehash. Callers can also force a
|
|
// rehash via the standard `rehash(0)`, which will recompute this value as a
|
|
// side-effect.
|
|
//
|
|
// See `CapacityToGrowth()`.
|
|
size_t growth_left() const {
|
|
return common().growth_left();
|
|
}
|
|
|
|
GrowthInfo& growth_info() {
|
|
return common().growth_info();
|
|
}
|
|
GrowthInfo growth_info() const {
|
|
return common().growth_info();
|
|
}
|
|
|
|
// Prefetch the heap-allocated memory region to resolve potential TLB and
|
|
// cache misses. This is intended to overlap with execution of calculating the
|
|
// hash for a key.
|
|
void prefetch_heap_block() const {
|
|
ABSL_SWISSTABLE_ASSERT(!is_soo());
|
|
#if ABSL_HAVE_BUILTIN(__builtin_prefetch) || defined(__GNUC__)
|
|
__builtin_prefetch(control(), 0, 1);
|
|
#endif
|
|
}
|
|
|
|
CommonFields& common() { return settings_.template get<0>(); }
|
|
const CommonFields& common() const { return settings_.template get<0>(); }
|
|
|
|
ctrl_t* control() const {
|
|
ABSL_SWISSTABLE_ASSERT(!is_soo());
|
|
return common().control();
|
|
}
|
|
slot_type* slot_array() const {
|
|
ABSL_SWISSTABLE_ASSERT(!is_soo());
|
|
return static_cast<slot_type*>(common().slot_array());
|
|
}
|
|
slot_type* soo_slot() {
|
|
ABSL_SWISSTABLE_ASSERT(is_soo());
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(
|
|
static_cast<slot_type*>(common().soo_data()));
|
|
}
|
|
const slot_type* soo_slot() const {
|
|
ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(
|
|
const_cast<raw_hash_set*>(this)->soo_slot());
|
|
}
|
|
slot_type* single_slot() {
|
|
ABSL_SWISSTABLE_ASSERT(is_small());
|
|
return SooEnabled() ? soo_slot() : slot_array();
|
|
}
|
|
const slot_type* single_slot() const {
|
|
return const_cast<raw_hash_set*>(this)->single_slot();
|
|
}
|
|
void decrement_small_size() {
|
|
ABSL_SWISSTABLE_ASSERT(is_small());
|
|
SooEnabled() ? common().set_empty_soo() : common().decrement_size();
|
|
if (!SooEnabled()) {
|
|
SanitizerPoisonObject(single_slot());
|
|
}
|
|
}
|
|
iterator single_iterator() {
|
|
return {SooControl(), single_slot(), common().generation_ptr()};
|
|
}
|
|
const_iterator single_iterator() const {
|
|
return const_cast<raw_hash_set*>(this)->single_iterator();
|
|
}
|
|
HashtablezInfoHandle infoz() {
|
|
ABSL_SWISSTABLE_ASSERT(!is_soo());
|
|
return common().infoz();
|
|
}
|
|
|
|
hasher& hash_ref() { return settings_.template get<1>(); }
|
|
const hasher& hash_ref() const { return settings_.template get<1>(); }
|
|
key_equal& eq_ref() { return settings_.template get<2>(); }
|
|
const key_equal& eq_ref() const { return settings_.template get<2>(); }
|
|
CharAlloc& char_alloc_ref() { return settings_.template get<3>(); }
|
|
const CharAlloc& char_alloc_ref() const {
|
|
return settings_.template get<3>();
|
|
}
|
|
|
|
static void* get_char_alloc_ref_fn(CommonFields& common) {
|
|
auto* h = reinterpret_cast<raw_hash_set*>(&common);
|
|
return &h->char_alloc_ref();
|
|
}
|
|
static void* get_hash_ref_fn(CommonFields& common) {
|
|
auto* h = reinterpret_cast<raw_hash_set*>(&common);
|
|
// TODO(b/397453582): Remove support for const hasher.
|
|
return const_cast<std::remove_const_t<hasher>*>(&h->hash_ref());
|
|
}
|
|
static void transfer_n_slots_fn(void* set, void* dst, void* src,
|
|
size_t count) {
|
|
auto* src_slot = to_slot(src);
|
|
auto* dst_slot = to_slot(dst);
|
|
|
|
auto* h = static_cast<raw_hash_set*>(set);
|
|
for (; count > 0; --count, ++src_slot, ++dst_slot) {
|
|
h->transfer(dst_slot, src_slot);
|
|
}
|
|
}
|
|
|
|
// TODO(b/382423690): Try to type erase entire function or at least type erase
|
|
// by GetKey + Hash for memcpyable types.
|
|
// TODO(b/382423690): Try to type erase for big slots: sizeof(slot_type) > 16.
|
|
static void transfer_unprobed_elements_to_next_capacity_fn(
|
|
CommonFields& common, const ctrl_t* old_ctrl, void* old_slots,
|
|
void* probed_storage,
|
|
void (*encode_probed_element)(void* probed_storage, h2_t h2,
|
|
size_t source_offset, size_t h1)) {
|
|
const size_t new_capacity = common.capacity();
|
|
const size_t old_capacity = PreviousCapacity(new_capacity);
|
|
ABSL_ASSUME(old_capacity + 1 >= Group::kWidth);
|
|
ABSL_ASSUME((old_capacity + 1) % Group::kWidth == 0);
|
|
|
|
auto* set = reinterpret_cast<raw_hash_set*>(&common);
|
|
slot_type* old_slots_ptr = to_slot(old_slots);
|
|
ctrl_t* new_ctrl = common.control();
|
|
slot_type* new_slots = set->slot_array();
|
|
|
|
for (size_t group_index = 0; group_index < old_capacity;
|
|
group_index += Group::kWidth) {
|
|
GroupFullEmptyOrDeleted old_g(old_ctrl + group_index);
|
|
std::memset(new_ctrl + group_index, static_cast<int8_t>(ctrl_t::kEmpty),
|
|
Group::kWidth);
|
|
std::memset(new_ctrl + group_index + old_capacity + 1,
|
|
static_cast<int8_t>(ctrl_t::kEmpty), Group::kWidth);
|
|
// TODO(b/382423690): try to type erase everything outside of the loop.
|
|
// We will share a lot of code in expense of one function call per group.
|
|
for (auto in_fixed_group_index : old_g.MaskFull()) {
|
|
size_t old_index = group_index + in_fixed_group_index;
|
|
slot_type* old_slot = old_slots_ptr + old_index;
|
|
// TODO(b/382423690): try to avoid entire hash calculation since we need
|
|
// only one new bit of h1.
|
|
size_t hash = set->hash_of(old_slot);
|
|
size_t h1 = H1(hash);
|
|
h2_t h2 = H2(hash);
|
|
size_t new_index = TryFindNewIndexWithoutProbing(
|
|
h1, old_index, old_capacity, new_ctrl, new_capacity);
|
|
// Note that encode_probed_element is allowed to use old_ctrl buffer
|
|
// till and included the old_index.
|
|
if (ABSL_PREDICT_FALSE(new_index == kProbedElementIndexSentinel)) {
|
|
encode_probed_element(probed_storage, h2, old_index, h1);
|
|
continue;
|
|
}
|
|
ABSL_SWISSTABLE_ASSERT((new_index & old_capacity) <= old_index);
|
|
ABSL_SWISSTABLE_ASSERT(IsEmpty(new_ctrl[new_index]));
|
|
new_ctrl[new_index] = static_cast<ctrl_t>(h2);
|
|
auto* new_slot = new_slots + new_index;
|
|
SanitizerUnpoisonMemoryRegion(new_slot, sizeof(slot_type));
|
|
set->transfer(new_slot, old_slot);
|
|
SanitizerPoisonMemoryRegion(old_slot, sizeof(slot_type));
|
|
}
|
|
}
|
|
}
|
|
|
|
static const PolicyFunctions& GetPolicyFunctions() {
|
|
static_assert(sizeof(slot_type) <= (std::numeric_limits<uint32_t>::max)(),
|
|
"Slot size is too large. Use std::unique_ptr for value type "
|
|
"or use absl::node_hash_{map,set}.");
|
|
static_assert(alignof(slot_type) <=
|
|
size_t{(std::numeric_limits<uint16_t>::max)()});
|
|
static_assert(sizeof(key_type) <=
|
|
size_t{(std::numeric_limits<uint32_t>::max)()});
|
|
static_assert(sizeof(value_type) <=
|
|
size_t{(std::numeric_limits<uint32_t>::max)()});
|
|
static constexpr size_t kBackingArrayAlignment =
|
|
BackingArrayAlignment(alignof(slot_type));
|
|
static constexpr PolicyFunctions value = {
|
|
static_cast<uint32_t>(sizeof(key_type)),
|
|
static_cast<uint32_t>(sizeof(value_type)),
|
|
static_cast<uint32_t>(sizeof(slot_type)),
|
|
static_cast<uint16_t>(alignof(slot_type)), SooEnabled(),
|
|
ShouldSampleHashtablezInfoForAlloc<CharAlloc>(),
|
|
// TODO(b/328722020): try to type erase
|
|
// for standard layout and alignof(Hash) <= alignof(CommonFields).
|
|
std::is_empty_v<hasher> ? &GetRefForEmptyClass
|
|
: &raw_hash_set::get_hash_ref_fn,
|
|
PolicyTraits::template get_hash_slot_fn<hasher, kIsDefaultHash>(),
|
|
PolicyTraits::transfer_uses_memcpy()
|
|
? TransferNRelocatable<sizeof(slot_type)>
|
|
: &raw_hash_set::transfer_n_slots_fn,
|
|
std::is_empty_v<Alloc> ? &GetRefForEmptyClass
|
|
: &raw_hash_set::get_char_alloc_ref_fn,
|
|
&AllocateBackingArray<kBackingArrayAlignment, CharAlloc>,
|
|
&DeallocateBackingArray<kBackingArrayAlignment, CharAlloc>,
|
|
&raw_hash_set::transfer_unprobed_elements_to_next_capacity_fn};
|
|
return value;
|
|
}
|
|
|
|
// Bundle together CommonFields plus other objects which might be empty.
|
|
// CompressedTuple will ensure that sizeof is not affected by any of the empty
|
|
// fields that occur after CommonFields.
|
|
absl::container_internal::CompressedTuple<CommonFields, hasher, key_equal,
|
|
CharAlloc>
|
|
settings_{CommonFields::CreateDefault<SooEnabled()>(), hasher{},
|
|
key_equal{}, CharAlloc{}};
|
|
};
|
|
|
|
// Friend access for free functions in raw_hash_set.h.
|
|
struct HashtableFreeFunctionsAccess {
|
|
template <class Predicate, typename Set>
|
|
static typename Set::size_type EraseIf(Predicate& pred, Set* c) {
|
|
if (c->empty()) {
|
|
return 0;
|
|
}
|
|
if (c->is_small()) {
|
|
auto it = c->single_iterator();
|
|
if (!pred(*it)) {
|
|
ABSL_SWISSTABLE_ASSERT(c->size() == 1 &&
|
|
"hash table was modified unexpectedly");
|
|
return 0;
|
|
}
|
|
c->destroy(it.slot());
|
|
c->erase_meta_only_small();
|
|
return 1;
|
|
}
|
|
[[maybe_unused]] const size_t original_size_for_assert = c->size();
|
|
size_t num_deleted = 0;
|
|
using SlotType = typename Set::slot_type;
|
|
IterateOverFullSlots(
|
|
c->common(), sizeof(SlotType),
|
|
[&](const ctrl_t* ctrl, void* slot_void) {
|
|
auto* slot = static_cast<SlotType*>(slot_void);
|
|
if (pred(Set::PolicyTraits::element(slot))) {
|
|
c->destroy(slot);
|
|
EraseMetaOnlyLarge(c->common(), ctrl, sizeof(*slot));
|
|
++num_deleted;
|
|
}
|
|
});
|
|
// NOTE: IterateOverFullSlots allow removal of the current element, so we
|
|
// verify the size additionally here.
|
|
ABSL_SWISSTABLE_ASSERT(original_size_for_assert - num_deleted ==
|
|
c->size() &&
|
|
"hash table was modified unexpectedly");
|
|
return num_deleted;
|
|
}
|
|
|
|
template <class Callback, typename Set>
|
|
static void ForEach(Callback& cb, Set* c) {
|
|
if (c->empty()) {
|
|
return;
|
|
}
|
|
if (c->is_small()) {
|
|
cb(*c->single_iterator());
|
|
return;
|
|
}
|
|
using SlotType = typename Set::slot_type;
|
|
using ElementTypeWithConstness = decltype(*c->begin());
|
|
IterateOverFullSlots(
|
|
c->common(), sizeof(SlotType), [&cb](const ctrl_t*, void* slot) {
|
|
ElementTypeWithConstness& element =
|
|
Set::PolicyTraits::element(static_cast<SlotType*>(slot));
|
|
cb(element);
|
|
});
|
|
}
|
|
};
|
|
|
|
// Erases all elements that satisfy the predicate `pred` from the container `c`.
|
|
template <typename P, typename... Params, typename Predicate>
|
|
typename raw_hash_set<P, Params...>::size_type EraseIf(
|
|
Predicate& pred, raw_hash_set<P, Params...>* c) {
|
|
return HashtableFreeFunctionsAccess::EraseIf(pred, c);
|
|
}
|
|
|
|
// Calls `cb` for all elements in the container `c`.
|
|
template <typename P, typename... Params, typename Callback>
|
|
void ForEach(Callback& cb, raw_hash_set<P, Params...>* c) {
|
|
return HashtableFreeFunctionsAccess::ForEach(cb, c);
|
|
}
|
|
template <typename P, typename... Params, typename Callback>
|
|
void ForEach(Callback& cb, const raw_hash_set<P, Params...>* c) {
|
|
return HashtableFreeFunctionsAccess::ForEach(cb, c);
|
|
}
|
|
|
|
namespace hashtable_debug_internal {
|
|
template <typename Set>
|
|
struct HashtableDebugAccess<Set, absl::void_t<typename Set::raw_hash_set>> {
|
|
using Traits = typename Set::PolicyTraits;
|
|
using Slot = typename Traits::slot_type;
|
|
|
|
constexpr static bool kIsDefaultHash = Set::kIsDefaultHash;
|
|
|
|
static size_t GetNumProbes(const Set& set,
|
|
const typename Set::key_type& key) {
|
|
if (set.is_small()) return 0;
|
|
size_t num_probes = 0;
|
|
const size_t hash = set.hash_of(key);
|
|
auto seq = probe(set.common(), hash);
|
|
const h2_t h2 = H2(hash);
|
|
const ctrl_t* ctrl = set.control();
|
|
while (true) {
|
|
container_internal::Group g{ctrl + seq.offset()};
|
|
for (uint32_t i : g.Match(h2)) {
|
|
if (set.equal_to(key, set.slot_array() + seq.offset(i)))
|
|
return num_probes;
|
|
++num_probes;
|
|
}
|
|
if (g.MaskEmpty()) return num_probes;
|
|
seq.next();
|
|
++num_probes;
|
|
}
|
|
}
|
|
|
|
static size_t AllocatedByteSize(const Set& c) {
|
|
size_t capacity = c.capacity();
|
|
if (capacity == 0) return 0;
|
|
size_t m =
|
|
c.is_soo() ? 0 : c.common().alloc_size(sizeof(Slot), alignof(Slot));
|
|
|
|
size_t per_slot = Traits::space_used(static_cast<const Slot*>(nullptr));
|
|
if (per_slot != ~size_t{}) {
|
|
m += per_slot * c.size();
|
|
} else {
|
|
for (auto it = c.begin(); it != c.end(); ++it) {
|
|
m += Traits::space_used(it.slot());
|
|
}
|
|
}
|
|
return m;
|
|
}
|
|
};
|
|
|
|
} // namespace hashtable_debug_internal
|
|
|
|
// Extern template instantiations reduce binary size and linker input size.
|
|
// Function definition is in raw_hash_set.cc.
|
|
extern template size_t GrowSooTableToNextCapacityAndPrepareInsert<0, false>(
|
|
CommonFields&, const PolicyFunctions&, absl::FunctionRef<size_t(size_t)>,
|
|
bool);
|
|
extern template size_t GrowSooTableToNextCapacityAndPrepareInsert<1, true>(
|
|
CommonFields&, const PolicyFunctions&, absl::FunctionRef<size_t(size_t)>,
|
|
bool);
|
|
extern template size_t GrowSooTableToNextCapacityAndPrepareInsert<4, true>(
|
|
CommonFields&, const PolicyFunctions&, absl::FunctionRef<size_t(size_t)>,
|
|
bool);
|
|
extern template size_t GrowSooTableToNextCapacityAndPrepareInsert<8, true>(
|
|
CommonFields&, const PolicyFunctions&, absl::FunctionRef<size_t(size_t)>,
|
|
bool);
|
|
#if UINTPTR_MAX == UINT64_MAX
|
|
extern template size_t GrowSooTableToNextCapacityAndPrepareInsert<16, true>(
|
|
CommonFields&, const PolicyFunctions&, absl::FunctionRef<size_t(size_t)>,
|
|
bool);
|
|
#endif
|
|
|
|
extern template void* AllocateBackingArray<
|
|
BackingArrayAlignment(alignof(size_t)), std::allocator<char>>(void* alloc,
|
|
size_t n);
|
|
extern template void DeallocateBackingArray<
|
|
BackingArrayAlignment(alignof(size_t)), std::allocator<char>>(
|
|
void* alloc, size_t capacity, ctrl_t* ctrl, size_t slot_size,
|
|
size_t slot_align, bool had_infoz);
|
|
|
|
} // namespace container_internal
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#undef ABSL_SWISSTABLE_ENABLE_GENERATIONS
|
|
#undef ABSL_SWISSTABLE_IGNORE_UNINITIALIZED
|
|
#undef ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN
|
|
#undef ABSL_SWISSTABLE_ASSERT
|
|
|
|
#endif // ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
|