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