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89 lines
2.5 KiB
C++
89 lines
2.5 KiB
C++
// Copyright 2016 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TASK_SCHEDULER_SCHEDULER_LOCK_H
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#define BASE_TASK_SCHEDULER_SCHEDULER_LOCK_H
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#include <memory>
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#include "base/base_export.h"
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#include "base/macros.h"
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#include "base/synchronization/condition_variable.h"
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#include "base/synchronization/lock.h"
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#include "base/task_scheduler/scheduler_lock_impl.h"
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namespace base {
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namespace internal {
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// SchedulerLock should be used anywhere a lock would be used in the scheduler.
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// When DCHECK_IS_ON(), lock checking occurs. Otherwise, SchedulerLock is
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// equivalent to base::Lock.
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//
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// The shape of SchedulerLock is as follows:
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// SchedulerLock()
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// Default constructor, no predecessor lock.
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// DCHECKs
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// On Acquisition if any scheduler lock is acquired on this thread.
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//
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// SchedulerLock(const SchedulerLock* predecessor)
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// Constructor that specifies an allowed predecessor for that lock.
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// DCHECKs
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// On Construction if |predecessor| forms a predecessor lock cycle.
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// On Acquisition if the previous lock acquired on the thread is not
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// |predecessor|. Okay if there was no previous lock acquired.
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//
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// void Acquire()
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// Acquires the lock.
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//
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// void Release()
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// Releases the lock.
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//
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// void AssertAcquired().
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// DCHECKs if the lock is not acquired.
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//
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// std::unique_ptr<ConditionVariable> CreateConditionVariable()
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// Creates a condition variable using this as a lock.
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#if DCHECK_IS_ON()
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class SchedulerLock : public SchedulerLockImpl {
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public:
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SchedulerLock() = default;
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explicit SchedulerLock(const SchedulerLock* predecessor)
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: SchedulerLockImpl(predecessor) {}
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};
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#else // DCHECK_IS_ON()
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class SchedulerLock : public Lock {
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public:
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SchedulerLock() = default;
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explicit SchedulerLock(const SchedulerLock*) {}
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std::unique_ptr<ConditionVariable> CreateConditionVariable() {
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return std::unique_ptr<ConditionVariable>(new ConditionVariable(this));
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}
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};
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#endif // DCHECK_IS_ON()
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// Provides the same functionality as base::AutoLock for SchedulerLock.
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class AutoSchedulerLock {
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public:
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explicit AutoSchedulerLock(SchedulerLock& lock) : lock_(lock) {
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lock_.Acquire();
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}
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~AutoSchedulerLock() {
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lock_.AssertAcquired();
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lock_.Release();
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}
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private:
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SchedulerLock& lock_;
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DISALLOW_COPY_AND_ASSIGN(AutoSchedulerLock);
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};
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} // namespace internal
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} // namespace base
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#endif // BASE_TASK_SCHEDULER_SCHEDULER_LOCK_H
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