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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 // | 4 // |
5 // The thread pool used in the POSIX implementation of WorkerPool dynamically | 5 // The thread pool used in the POSIX implementation of WorkerPool dynamically |
6 // adds threads as necessary to handle all tasks. It keeps old threads around | 6 // adds threads as necessary to handle all tasks. It keeps old threads around |
7 // for a period of time to allow them to be reused. After this waiting period, | 7 // for a period of time to allow them to be reused. After this waiting period, |
8 // the threads exit. This thread pool uses non-joinable threads, therefore | 8 // the threads exit. This thread pool uses non-joinable threads, therefore |
9 // worker threads are not joined during process shutdown. This means that | 9 // worker threads are not joined during process shutdown. This means that |
10 // potentially long running tasks (such as DNS lookup) do not block process | 10 // potentially long running tasks (such as DNS lookup) do not block process |
11 // shutdown, but also means that process shutdown may "leak" objects. Note that | 11 // shutdown, but also means that process shutdown may "leak" objects. Note that |
12 // although PosixDynamicThreadPool spawns the worker threads and manages the | 12 // although PosixDynamicThreadPool spawns the worker threads and manages the |
13 // task queue, it does not own the worker threads. The worker threads ask the | 13 // task queue, it does not own the worker threads. The worker threads ask the |
14 // PosixDynamicThreadPool for work and eventually clean themselves up. The | 14 // PosixDynamicThreadPool for work and eventually clean themselves up. The |
15 // worker threads all maintain scoped_refptrs to the PosixDynamicThreadPool | 15 // worker threads all maintain scoped_refptrs to the PosixDynamicThreadPool |
16 // instance, which prevents PosixDynamicThreadPool from disappearing before all | 16 // instance, which prevents PosixDynamicThreadPool from disappearing before all |
17 // worker threads exit. The owner of PosixDynamicThreadPool should likewise | 17 // worker threads exit. The owner of PosixDynamicThreadPool should likewise |
18 // maintain a scoped_refptr to the PosixDynamicThreadPool instance. | 18 // maintain a scoped_refptr to the PosixDynamicThreadPool instance. |
19 // | 19 // |
20 // NOTE: The classes defined in this file are only meant for use by the POSIX | 20 // NOTE: The classes defined in this file are only meant for use by the POSIX |
21 // implementation of WorkerPool. No one else should be using these classes. | 21 // implementation of WorkerPool. No one else should be using these classes. |
22 // These symbols are exported in a header purely for testing purposes. | 22 // These symbols are exported in a header purely for testing purposes. |
23 | 23 |
24 #ifndef BASE_THREADING_WORKER_POOL_POSIX_H_ | 24 #ifndef BASE_THREADING_WORKER_POOL_POSIX_H_ |
25 #define BASE_THREADING_WORKER_POOL_POSIX_H_ | 25 #define BASE_THREADING_WORKER_POOL_POSIX_H_ |
26 | 26 |
| 27 #include <memory> |
27 #include <queue> | 28 #include <queue> |
28 #include <string> | 29 #include <string> |
29 | 30 |
30 #include "base/callback_forward.h" | 31 #include "base/callback_forward.h" |
31 #include "base/location.h" | 32 #include "base/location.h" |
32 #include "base/macros.h" | 33 #include "base/macros.h" |
33 #include "base/memory/ref_counted.h" | 34 #include "base/memory/ref_counted.h" |
34 #include "base/memory/scoped_ptr.h" | |
35 #include "base/pending_task.h" | 35 #include "base/pending_task.h" |
36 #include "base/synchronization/condition_variable.h" | 36 #include "base/synchronization/condition_variable.h" |
37 #include "base/synchronization/lock.h" | 37 #include "base/synchronization/lock.h" |
38 #include "base/threading/platform_thread.h" | 38 #include "base/threading/platform_thread.h" |
39 #include "base/tracked_objects.h" | 39 #include "base/tracked_objects.h" |
40 | 40 |
41 class Task; | 41 class Task; |
42 | 42 |
43 namespace base { | 43 namespace base { |
44 | 44 |
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81 | 81 |
82 // Signal()s worker threads to let them know more tasks are available. | 82 // Signal()s worker threads to let them know more tasks are available. |
83 // Also used for Broadcast()'ing to worker threads to let them know the pool | 83 // Also used for Broadcast()'ing to worker threads to let them know the pool |
84 // is being deleted and they can exit. | 84 // is being deleted and they can exit. |
85 ConditionVariable pending_tasks_available_cv_; | 85 ConditionVariable pending_tasks_available_cv_; |
86 int num_idle_threads_; | 86 int num_idle_threads_; |
87 TaskQueue pending_tasks_; | 87 TaskQueue pending_tasks_; |
88 bool terminated_; | 88 bool terminated_; |
89 // Only used for tests to ensure correct thread ordering. It will always be | 89 // Only used for tests to ensure correct thread ordering. It will always be |
90 // NULL in non-test code. | 90 // NULL in non-test code. |
91 scoped_ptr<ConditionVariable> num_idle_threads_cv_; | 91 std::unique_ptr<ConditionVariable> num_idle_threads_cv_; |
92 | 92 |
93 DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPool); | 93 DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPool); |
94 }; | 94 }; |
95 | 95 |
96 } // namespace base | 96 } // namespace base |
97 | 97 |
98 #endif // BASE_THREADING_WORKER_POOL_POSIX_H_ | 98 #endif // BASE_THREADING_WORKER_POOL_POSIX_H_ |
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