Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 1 | // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_ |
| 6 | #define BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_ |
| 7 | |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 8 | #include "base/atomicops.h" |
| 9 | #include "base/base_export.h" |
| 10 | #include "base/macros.h" |
| 11 | #include "base/threading/platform_thread.h" |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 12 | |
| 13 | namespace base { |
| 14 | |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 15 | // CancellationFlag allows one thread to cancel jobs executed on some worker |
| 16 | // thread. Calling Set() from one thread and IsSet() from a number of threads |
| 17 | // is thread-safe. |
| 18 | // |
| 19 | // This class IS NOT intended for synchronization between threads. |
| 20 | class BASE_EXPORT CancellationFlag { |
| 21 | public: |
| 22 | CancellationFlag() : flag_(false) { |
| 23 | #if !defined(NDEBUG) |
| 24 | set_on_ = PlatformThread::CurrentId(); |
| 25 | #endif |
| 26 | } |
| 27 | ~CancellationFlag() {} |
| 28 | |
| 29 | // Set the flag. May only be called on the thread which owns the object. |
| 30 | void Set(); |
| 31 | bool IsSet() const; // Returns true iff the flag was set. |
| 32 | |
| 33 | // For subtle reasons that may be different on different architectures, |
| 34 | // a different thread testing IsSet() may erroneously read 'true' after |
| 35 | // this method has been called. |
| 36 | void UnsafeResetForTesting(); |
| 37 | |
| 38 | private: |
| 39 | base::subtle::Atomic32 flag_; |
| 40 | #if !defined(NDEBUG) |
| 41 | PlatformThreadId set_on_; |
| 42 | #endif |
| 43 | |
| 44 | DISALLOW_COPY_AND_ASSIGN(CancellationFlag); |
| 45 | }; |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 46 | |
| 47 | } // namespace base |
| 48 | |
| 49 | #endif // BASE_SYNCHRONIZATION_CANCELLATION_FLAG_H_ |