| Index: components/scheduler/child/pollable_thread_safe_flag.h
|
| diff --git a/components/scheduler/child/pollable_thread_safe_flag.h b/components/scheduler/child/pollable_thread_safe_flag.h
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..cf0564120607fe5388996cea17e1b9e1b6e17102
|
| --- /dev/null
|
| +++ b/components/scheduler/child/pollable_thread_safe_flag.h
|
| @@ -0,0 +1,35 @@
|
| +// Copyright 2015 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 COMPONENTS_SCHEDULER_CHILD_POLLABLE_THREAD_SAFE_FLAG_H_
|
| +#define COMPONENTS_SCHEDULER_CHILD_POLLABLE_THREAD_SAFE_FLAG_H_
|
| +
|
| +#include "base/atomicops.h"
|
| +#include "base/synchronization/lock.h"
|
| +
|
| +// A PollableThreadSafeFlag can be polled without requiring a lock, but can only
|
| +// be updated if a lock is held. This enables lock-free checking as to whether a
|
| +// condition has changed, while protecting operations which update the condition
|
| +// with a lock. You must ensure that the flag is only updated within the same
|
| +// lock-protected critical section as any other variables on which the condition
|
| +// depends.
|
| +class PollableThreadSafeFlag {
|
| + public:
|
| + explicit PollableThreadSafeFlag(base::Lock* write_lock);
|
| + ~PollableThreadSafeFlag();
|
| +
|
| + // Set the flag. May only be called if |write_lock| is held.
|
| + void SetWhileLocked(bool value);
|
| +
|
| + // Returns true iff the flag is set to true.
|
| + bool IsSet() const;
|
| +
|
| + private:
|
| + base::subtle::Atomic32 flag_;
|
| + base::Lock* write_lock_; // Not owned.
|
| +
|
| + DISALLOW_COPY_AND_ASSIGN(PollableThreadSafeFlag);
|
| +};
|
| +
|
| +#endif // COMPONENTS_SCHEDULER_CHILD_POLLABLE_THREAD_SAFE_FLAG_H_
|
|
|