chromium/base/synchronization/lock.h

// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_SYNCHRONIZATION_LOCK_H_
#define BASE_SYNCHRONIZATION_LOCK_H_

#include "base/base_export.h"
#include "base/dcheck_is_on.h"
#include "base/synchronization/lock_impl.h"
#include "base/synchronization/lock_subtle.h"
#include "base/thread_annotations.h"
#include "build/build_config.h"

#if DCHECK_IS_ON()
#include "base/threading/platform_thread_ref.h"
#endif

namespace base {

// A convenient wrapper for an OS specific critical section.  The only real
// intelligence in this class is in debug mode for the support for the
// AssertAcquired() method.
class LOCKABLE BASE_EXPORT Lock { … };

// A helper class that acquires the given Lock while the AutoLock is in scope.
AutoLock;

// A helper class that acquires the given Lock while the MovableAutoLock is in
// scope. Unlike AutoLock, the lock can be moved out of MovableAutoLock. Unlike
// AutoLockMaybe, the passed in lock is always valid, so need to check only on
// destruction.
MovableAutoLock;

// A helper class that tries to acquire the given Lock while the AutoTryLock is
// in scope.
AutoTryLock;

// AutoUnlock is a helper that will Release() the |lock| argument in the
// constructor, and re-Acquire() it in the destructor.
AutoUnlock;

// Like AutoLock but is a no-op when the provided Lock* is null. Inspired from
// absl::MutexLockMaybe. Use this instead of std::optional<base::AutoLock> to
// get around -Wthread-safety-analysis warnings for conditional locking.
AutoLockMaybe;

// Like AutoLock but permits Release() of its mutex before destruction.
// Release() may be called at most once. Inspired from
// absl::ReleasableMutexLock. Use this instead of std::optional<base::AutoLock>
// to get around -Wthread-safety-analysis warnings for AutoLocks that are
// explicitly released early (prefer proper scoping to this).
ReleasableAutoLock;

}  // namespace base

#endif  // BASE_SYNCHRONIZATION_LOCK_H_