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| 1 /* |
| 2 * Copyright 2004 The WebRTC Project Authors. All rights reserved. |
| 3 * |
| 4 * Use of this source code is governed by a BSD-style license |
| 5 * that can be found in the LICENSE file in the root of the source |
| 6 * tree. An additional intellectual property rights grant can be found |
| 7 * in the file PATENTS. All contributing project authors may |
| 8 * be found in the AUTHORS file in the root of the source tree. |
| 9 */ |
| 10 |
| 11 #ifndef WEBRTC_RTC_BASE_SIGNALTHREAD_H_ |
| 12 #define WEBRTC_RTC_BASE_SIGNALTHREAD_H_ |
| 13 |
| 14 #include <string> |
| 15 |
| 16 #include "webrtc/base/checks.h" |
| 17 #include "webrtc/base/constructormagic.h" |
| 18 #include "webrtc/base/nullsocketserver.h" |
| 19 #include "webrtc/base/sigslot.h" |
| 20 #include "webrtc/base/thread.h" |
| 21 |
| 22 namespace rtc { |
| 23 |
| 24 /////////////////////////////////////////////////////////////////////////////// |
| 25 // SignalThread - Base class for worker threads. The main thread should call |
| 26 // Start() to begin work, and then follow one of these models: |
| 27 // Normal: Wait for SignalWorkDone, and then call Release to destroy. |
| 28 // Cancellation: Call Release(true), to abort the worker thread. |
| 29 // Fire-and-forget: Call Release(false), which allows the thread to run to |
| 30 // completion, and then self-destruct without further notification. |
| 31 // Periodic tasks: Wait for SignalWorkDone, then eventually call Start() |
| 32 // again to repeat the task. When the instance isn't needed anymore, |
| 33 // call Release. DoWork, OnWorkStart and OnWorkStop are called again, |
| 34 // on a new thread. |
| 35 // The subclass should override DoWork() to perform the background task. By |
| 36 // periodically calling ContinueWork(), it can check for cancellation. |
| 37 // OnWorkStart and OnWorkDone can be overridden to do pre- or post-work |
| 38 // tasks in the context of the main thread. |
| 39 /////////////////////////////////////////////////////////////////////////////// |
| 40 |
| 41 class SignalThread |
| 42 : public sigslot::has_slots<>, |
| 43 protected MessageHandler { |
| 44 public: |
| 45 explicit SignalThread(bool use_socket_server = true); |
| 46 |
| 47 // Context: Main Thread. Call before Start to change the worker's name. |
| 48 bool SetName(const std::string& name, const void* obj); |
| 49 |
| 50 // Context: Main Thread. Call to begin the worker thread. |
| 51 void Start(); |
| 52 |
| 53 // Context: Main Thread. If the worker thread is not running, deletes the |
| 54 // object immediately. Otherwise, asks the worker thread to abort processing, |
| 55 // and schedules the object to be deleted once the worker exits. |
| 56 // SignalWorkDone will not be signalled. If wait is true, does not return |
| 57 // until the thread is deleted. |
| 58 void Destroy(bool wait); |
| 59 |
| 60 // Context: Main Thread. If the worker thread is complete, deletes the |
| 61 // object immediately. Otherwise, schedules the object to be deleted once |
| 62 // the worker thread completes. SignalWorkDone will be signalled. |
| 63 void Release(); |
| 64 |
| 65 // Context: Main Thread. Signalled when work is complete. |
| 66 sigslot::signal1<SignalThread *> SignalWorkDone; |
| 67 |
| 68 enum { ST_MSG_WORKER_DONE, ST_MSG_FIRST_AVAILABLE }; |
| 69 |
| 70 protected: |
| 71 ~SignalThread() override; |
| 72 |
| 73 Thread* worker() { return &worker_; } |
| 74 |
| 75 // Context: Main Thread. Subclass should override to do pre-work setup. |
| 76 virtual void OnWorkStart() { } |
| 77 |
| 78 // Context: Worker Thread. Subclass should override to do work. |
| 79 virtual void DoWork() = 0; |
| 80 |
| 81 // Context: Worker Thread. Subclass should call periodically to |
| 82 // dispatch messages and determine if the thread should terminate. |
| 83 bool ContinueWork(); |
| 84 |
| 85 // Context: Worker Thread. Subclass should override when extra work is |
| 86 // needed to abort the worker thread. |
| 87 virtual void OnWorkStop() { } |
| 88 |
| 89 // Context: Main Thread. Subclass should override to do post-work cleanup. |
| 90 virtual void OnWorkDone() { } |
| 91 |
| 92 // Context: Any Thread. If subclass overrides, be sure to call the base |
| 93 // implementation. Do not use (message_id < ST_MSG_FIRST_AVAILABLE) |
| 94 void OnMessage(Message* msg) override; |
| 95 |
| 96 private: |
| 97 enum State { |
| 98 kInit, // Initialized, but not started |
| 99 kRunning, // Started and doing work |
| 100 kReleasing, // Same as running, but to be deleted when work is done |
| 101 kComplete, // Work is done |
| 102 kStopping, // Work is being interrupted |
| 103 }; |
| 104 |
| 105 class Worker : public Thread { |
| 106 public: |
| 107 explicit Worker(SignalThread* parent, bool use_socket_server) |
| 108 : Thread(use_socket_server |
| 109 ? SocketServer::CreateDefault() |
| 110 : std::unique_ptr<SocketServer>(new NullSocketServer())), |
| 111 parent_(parent) {} |
| 112 ~Worker() override; |
| 113 void Run() override; |
| 114 bool IsProcessingMessages() override; |
| 115 |
| 116 private: |
| 117 SignalThread* parent_; |
| 118 |
| 119 RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Worker); |
| 120 }; |
| 121 |
| 122 class SCOPED_LOCKABLE EnterExit { |
| 123 public: |
| 124 explicit EnterExit(SignalThread* t) EXCLUSIVE_LOCK_FUNCTION(t->cs_) |
| 125 : t_(t) { |
| 126 t_->cs_.Enter(); |
| 127 // If refcount_ is zero then the object has already been deleted and we |
| 128 // will be double-deleting it in ~EnterExit()! (shouldn't happen) |
| 129 RTC_DCHECK_NE(0, t_->refcount_); |
| 130 ++t_->refcount_; |
| 131 } |
| 132 ~EnterExit() UNLOCK_FUNCTION() { |
| 133 bool d = (0 == --t_->refcount_); |
| 134 t_->cs_.Leave(); |
| 135 if (d) |
| 136 delete t_; |
| 137 } |
| 138 |
| 139 private: |
| 140 SignalThread* t_; |
| 141 |
| 142 RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(EnterExit); |
| 143 }; |
| 144 |
| 145 void Run(); |
| 146 void OnMainThreadDestroyed(); |
| 147 |
| 148 Thread* main_; |
| 149 Worker worker_; |
| 150 CriticalSection cs_; |
| 151 State state_; |
| 152 int refcount_; |
| 153 |
| 154 RTC_DISALLOW_COPY_AND_ASSIGN(SignalThread); |
| 155 }; |
| 156 |
| 157 /////////////////////////////////////////////////////////////////////////////// |
| 158 |
| 159 } // namespace rtc |
| 160 |
| 161 #endif // WEBRTC_RTC_BASE_SIGNALTHREAD_H_ |
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