1 /* 2 * libjingle 3 * Copyright 2004--2009, Google Inc. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright notice, 9 * this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #ifndef TALK_BASE_SIGNALTHREAD_H_ 29 #define TALK_BASE_SIGNALTHREAD_H_ 30 31 #include <string> 32 33 #include "talk/base/thread.h" 34 #include "talk/base/sigslot.h" 35 36 namespace talk_base { 37 38 /////////////////////////////////////////////////////////////////////////////// 39 // SignalThread - Base class for worker threads. The main thread should call 40 // Start() to begin work, and then follow one of these models: 41 // Normal: Wait for SignalWorkDone, and then call Release to destroy. 42 // Cancellation: Call Release(true), to abort the worker thread. 43 // Fire-and-forget: Call Release(false), which allows the thread to run to 44 // completion, and then self-destruct without further notification. 45 // Periodic tasks: Wait for SignalWorkDone, then eventually call Start() 46 // again to repeat the task. When the instance isn't needed anymore, 47 // call Release. DoWork, OnWorkStart and OnWorkStop are called again, 48 // on a new thread. 49 // The subclass should override DoWork() to perform the background task. By 50 // periodically calling ContinueWork(), it can check for cancellation. 51 // OnWorkStart and OnWorkDone can be overridden to do pre- or post-work 52 // tasks in the context of the main thread. 53 /////////////////////////////////////////////////////////////////////////////// 54 55 class SignalThread : public sigslot::has_slots<>, protected MessageHandler { 56 public: 57 SignalThread(); 58 59 // Context: Main Thread. Call before Start to change the worker's name. 60 bool SetName(const std::string& name, const void* obj); 61 62 // Context: Main Thread. Call before Start to change the worker's priority. 63 bool SetPriority(ThreadPriority priority); 64 65 // Context: Main Thread. Call to begin the worker thread. 66 void Start(); 67 68 // Context: Main Thread. If the worker thread is not running, deletes the 69 // object immediately. Otherwise, asks the worker thread to abort processing, 70 // and schedules the object to be deleted once the worker exits. 71 // SignalWorkDone will not be signalled. If wait is true, does not return 72 // until the thread is deleted. 73 void Destroy(bool wait); 74 75 // Context: Main Thread. If the worker thread is complete, deletes the 76 // object immediately. Otherwise, schedules the object to be deleted once 77 // the worker thread completes. SignalWorkDone will be signalled. 78 void Release(); 79 80 // Context: Main Thread. Signalled when work is complete. 81 sigslot::signal1<SignalThread *> SignalWorkDone; 82 83 enum { ST_MSG_WORKER_DONE, ST_MSG_FIRST_AVAILABLE }; 84 85 protected: 86 virtual ~SignalThread(); 87 88 Thread* worker() { return &worker_; } 89 90 // Context: Main Thread. Subclass should override to do pre-work setup. 91 virtual void OnWorkStart() { } 92 93 // Context: Worker Thread. Subclass should override to do work. 94 virtual void DoWork() = 0; 95 96 // Context: Worker Thread. Subclass should call periodically to 97 // dispatch messages and determine if the thread should terminate. 98 bool ContinueWork(); 99 100 // Context: Worker Thread. Subclass should override when extra work is 101 // needed to abort the worker thread. 102 virtual void OnWorkStop() { } 103 104 // Context: Main Thread. Subclass should override to do post-work cleanup. 105 virtual void OnWorkDone() { } 106 107 // Context: Any Thread. If subclass overrides, be sure to call the base 108 // implementation. Do not use (message_id < ST_MSG_FIRST_AVAILABLE) 109 virtual void OnMessage(Message *msg); 110 111 private: 112 enum State { 113 kInit, // Initialized, but not started 114 kRunning, // Started and doing work 115 kReleasing, // Same as running, but to be deleted when work is done 116 kComplete, // Work is done 117 kStopping, // Work is being interrupted 118 }; 119 120 friend class Worker; 121 class Worker : public Thread { 122 public: 123 SignalThread* parent_; 124 virtual void Run() { parent_->Run(); } 125 }; 126 127 friend class EnterExit; 128 class EnterExit { 129 public: 130 explicit EnterExit(SignalThread* t) : t_(t) { 131 t_->cs_.Enter(); 132 t_->refcount_ += 1; 133 } 134 ~EnterExit() { 135 bool d = (0 == (--(t_->refcount_))); 136 t_->cs_.Leave(); 137 if (d) 138 delete t_; 139 } 140 private: 141 SignalThread* t_; 142 }; 143 144 void Run(); 145 void OnMainThreadDestroyed(); 146 147 Thread* main_; 148 Worker worker_; 149 CriticalSection cs_; 150 State state_; 151 int refcount_; 152 }; 153 154 /////////////////////////////////////////////////////////////////////////////// 155 156 } // namespace talk_base 157 158 #endif // TALK_BASE_SIGNALTHREAD_H_ 159
