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Split logic for resizing empty and allocated tables.

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In the follow up changes these functions would have even more difference in the implementation.

PiperOrigin-RevId: 924857072
Change-Id: I637e532b1e6ed1e7fe5d700686d9775cc0e8ec11
This commit is contained in:
Vitaly Goldshteyn
2026-06-01 12:42:00 -07:00
committed by Copybara-Service
parent a30bcb2c51
commit 19937ca3e5
1 changed files with 52 additions and 61 deletions
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113
absl/container/internal/raw_hash_set.cc
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@@ -681,11 +681,6 @@ void ClearBackingArray(CommonFields& c,
namespace {
enum class ResizeNonSooMode {
kGuaranteedEmpty,
kGuaranteedAllocated,
};
// Iterates over full slots in old table, finds new positions for them and
// transfers the slots.
// This function is used for reserving or rehashing non-empty tables.
@@ -795,23 +790,22 @@ BackingArrayPtrs AllocBackingArray(CommonFields& common,
mem + layout.slot_offset()};
}
template <ResizeNonSooMode kMode>
void ResizeNonSooImpl(CommonFields& common,
const PolicyFunctions& __restrict policy,
size_t new_capacity, HashtablezInfoHandle infoz) {
void ResizeEmptyNonAllocatedTableImpl(CommonFields& common,
const PolicyFunctions& __restrict policy,
size_t new_capacity, bool force_infoz) {
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(new_capacity));
ABSL_SWISSTABLE_ASSERT(new_capacity > policy.soo_capacity());
[[maybe_unused]] const size_t old_capacity = common.capacity();
[[maybe_unused]] ctrl_t* old_ctrl;
[[maybe_unused]] void* old_slots;
if constexpr (kMode == ResizeNonSooMode::kGuaranteedAllocated) {
old_ctrl = common.control();
old_slots = common.slot_array();
}
ABSL_SWISSTABLE_ASSERT(!force_infoz || policy.soo_enabled);
ABSL_SWISSTABLE_ASSERT(common.capacity() == policy.soo_capacity());
ABSL_SWISSTABLE_ASSERT(common.empty());
const size_t slot_size = policy.slot_size;
[[maybe_unused]] const size_t slot_align = policy.slot_align;
HashtablezInfoHandle infoz;
const bool should_sample =
policy.is_hashtablez_eligible && (force_infoz || ShouldSampleNextTable());
if (ABSL_PREDICT_FALSE(should_sample)) {
infoz = ForcedTrySample(slot_size, policy.key_size, policy.value_size,
policy.soo_capacity());
}
const bool has_infoz = infoz.IsSampled();
void* alloc = policy.get_char_alloc(common);
@@ -822,53 +816,17 @@ void ResizeNonSooImpl(CommonFields& common,
common.set_slots(new_slots);
common.generate_new_seed(has_infoz);
size_t total_probe_length = 0;
ResetCtrl(common, slot_size);
ABSL_SWISSTABLE_ASSERT(kMode != ResizeNonSooMode::kGuaranteedEmpty ||
old_capacity == policy.soo_capacity());
ABSL_SWISSTABLE_ASSERT(kMode != ResizeNonSooMode::kGuaranteedAllocated ||
old_capacity > 0);
if constexpr (kMode == ResizeNonSooMode::kGuaranteedAllocated) {
total_probe_length = FindNewPositionsAndTransferSlots(
common, policy, old_ctrl, old_slots, old_capacity);
(*policy.dealloc)(alloc, old_capacity, old_ctrl, slot_size, slot_align,
has_infoz);
if (HasGrowthInfoForCapacity(new_capacity)) {
ResetGrowthLeft(GetGrowthInfoFromControl(new_ctrl), new_capacity,
common.size());
}
} else {
if (HasGrowthInfoForCapacity(new_capacity)) {
GetGrowthInfoFromControl(new_ctrl).InitGrowthLeftNoDeleted(
CapacityToGrowth(new_capacity));
}
if (HasGrowthInfoForCapacity(new_capacity)) {
GetGrowthInfoFromControl(new_ctrl).InitGrowthLeftNoDeleted(
CapacityToGrowth(new_capacity));
}
if (ABSL_PREDICT_FALSE(has_infoz)) {
ReportResizeToInfoz(common, infoz, total_probe_length);
ReportResizeToInfoz(common, infoz, 0);
}
}
void ResizeEmptyNonAllocatedTableImpl(CommonFields& common,
const PolicyFunctions& __restrict policy,
size_t new_capacity, bool force_infoz) {
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(new_capacity));
ABSL_SWISSTABLE_ASSERT(new_capacity > policy.soo_capacity());
ABSL_SWISSTABLE_ASSERT(!force_infoz || policy.soo_enabled);
ABSL_SWISSTABLE_ASSERT(common.capacity() <= policy.soo_capacity());
ABSL_SWISSTABLE_ASSERT(common.empty());
const size_t slot_size = policy.slot_size;
HashtablezInfoHandle infoz;
const bool should_sample =
policy.is_hashtablez_eligible && (force_infoz || ShouldSampleNextTable());
if (ABSL_PREDICT_FALSE(should_sample)) {
infoz = ForcedTrySample(slot_size, policy.key_size, policy.value_size,
policy.soo_capacity());
}
ResizeNonSooImpl<ResizeNonSooMode::kGuaranteedEmpty>(common, policy,
new_capacity, infoz);
}
// If the table was SOO, initializes new control bytes and transfers slot.
// After transferring the slot, sets control and slots in CommonFields.
// It is rare to resize an SOO table with one element to a large size.
@@ -1760,8 +1718,41 @@ void* GetRefForEmptyClass(CommonFields& common) {
void ResizeAllocatedTableWithSeedChange(
CommonFields& common, const PolicyFunctions& __restrict policy,
size_t new_capacity) {
ResizeNonSooImpl<ResizeNonSooMode::kGuaranteedAllocated>(
common, policy, new_capacity, common.infoz());
ABSL_SWISSTABLE_ASSERT(IsValidCapacity(new_capacity));
ABSL_SWISSTABLE_ASSERT(new_capacity > policy.soo_capacity());
const size_t old_capacity = common.capacity();
ctrl_t* const old_ctrl = common.control();
void* const old_slots = common.slot_array();
const size_t slot_size = policy.slot_size;
const size_t slot_align = policy.slot_align;
HashtablezInfoHandle infoz = common.infoz();
const bool has_infoz = infoz.IsSampled();
void* alloc = policy.get_char_alloc(common);
common.set_capacity(new_capacity);
const auto [new_ctrl, new_slots] =
AllocBackingArray(common, policy, new_capacity, has_infoz, alloc);
common.set_control(new_ctrl);
common.set_slots(new_slots);
common.generate_new_seed(has_infoz);
size_t total_probe_length = 0;
ResetCtrl(common, slot_size);
ABSL_SWISSTABLE_ASSERT(old_capacity > 0);
total_probe_length = FindNewPositionsAndTransferSlots(
common, policy, old_ctrl, old_slots, old_capacity);
(*policy.dealloc)(alloc, old_capacity, old_ctrl, slot_size, slot_align,
has_infoz);
if (HasGrowthInfoForCapacity(new_capacity)) {
ResetGrowthLeft(GetGrowthInfoFromControl(new_ctrl), new_capacity,
common.size());
}
if (ABSL_PREDICT_FALSE(has_infoz)) {
ReportResizeToInfoz(common, infoz, total_probe_length);
}
}
void ReserveEmptyNonAllocatedTableToFitBucketCount(