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94 lines
3.0 KiB
C++
94 lines
3.0 KiB
C++
// Copyright 2026 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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// -----------------------------------------------------------------------------
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// File: clock_interface.h
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// -----------------------------------------------------------------------------
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#ifndef ABSL_TIME_CLOCK_INTERFACE_H_
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#define ABSL_TIME_CLOCK_INTERFACE_H_
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#include "absl/base/config.h"
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#include "absl/base/macros.h"
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#include "absl/base/nullability.h"
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#include "absl/synchronization/mutex.h"
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#include "absl/time/time.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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// An abstract interface representing a Clock, which is an object that can
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// tell you the current time, sleep, and wait for a condition variable.
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//
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// This interface allows decoupling code that uses time from the code that
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// creates a point in time. You can use this to your advantage by injecting
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// Clocks into interfaces rather than having implementations call absl::Now()
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// directly.
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//
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// Implementations of this interface must be thread-safe.
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//
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// The Clock::GetRealClock() function returns a reference to the global realtime
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// clock.
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//
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// Example:
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//
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// bool IsWeekend(Clock& clock) {
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// absl::Time now = clock.TimeNow();
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// // ... code to check if 'now' is a weekend.
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// }
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//
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// // Production code.
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// IsWeekend(Clock::GetRealClock());
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//
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// // Test code:
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// MyTestClock test_clock(SATURDAY);
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// IsWeekend(test_clock);
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//
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class Clock {
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public:
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// Returns a reference to the global realtime clock.
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// The returned clock is thread-safe.
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static Clock& GetRealClock();
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virtual ~Clock();
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// Returns the current time.
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virtual absl::Time TimeNow() = 0;
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// Sleeps for the specified duration.
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virtual void Sleep(absl::Duration d) = 0;
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// Sleeps until the specified time.
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virtual void SleepUntil(absl::Time wakeup_time) = 0;
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// Returns when cond is true or the deadline has passed. Returns true iff
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// cond holds when returning.
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//
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// Requires *mu to be held at least in shared mode. It will be held when
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// evaluating cond, and upon return, but it may be released and reacquired
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// in the meantime.
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//
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// This method is similar to mu->AwaitWithDeadline() except that the
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// latter only works with real-time deadlines. This call works properly
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// with simulated time if invoked on a simulated clock.
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virtual bool AwaitWithDeadline(absl::Mutex* absl_nonnull mu,
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const absl::Condition& cond,
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absl::Time deadline) = 0;
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};
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_TIME_CLOCK_INTERFACE_H_
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