2 * Copyright 2004 The WebRTC Project Authors. All rights reserved.
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.
11 #ifndef WEBRTC_BASE_SIGNALTHREAD_H_
12 #define WEBRTC_BASE_SIGNALTHREAD_H_
16 #include "webrtc/base/constructormagic.h"
17 #include "webrtc/base/sigslot.h"
18 #include "webrtc/base/thread.h"
22 ///////////////////////////////////////////////////////////////////////////////
23 // SignalThread - Base class for worker threads. The main thread should call
24 // Start() to begin work, and then follow one of these models:
25 // Normal: Wait for SignalWorkDone, and then call Release to destroy.
26 // Cancellation: Call Release(true), to abort the worker thread.
27 // Fire-and-forget: Call Release(false), which allows the thread to run to
28 // completion, and then self-destruct without further notification.
29 // Periodic tasks: Wait for SignalWorkDone, then eventually call Start()
30 // again to repeat the task. When the instance isn't needed anymore,
31 // call Release. DoWork, OnWorkStart and OnWorkStop are called again,
33 // The subclass should override DoWork() to perform the background task. By
34 // periodically calling ContinueWork(), it can check for cancellation.
35 // OnWorkStart and OnWorkDone can be overridden to do pre- or post-work
36 // tasks in the context of the main thread.
37 ///////////////////////////////////////////////////////////////////////////////
40 : public sigslot::has_slots<>,
41 protected MessageHandler {
45 // Context: Main Thread. Call before Start to change the worker's name.
46 bool SetName(const std::string& name, const void* obj);
48 // Context: Main Thread. Call before Start to change the worker's priority.
49 bool SetPriority(ThreadPriority priority);
51 // Context: Main Thread. Call to begin the worker thread.
54 // Context: Main Thread. If the worker thread is not running, deletes the
55 // object immediately. Otherwise, asks the worker thread to abort processing,
56 // and schedules the object to be deleted once the worker exits.
57 // SignalWorkDone will not be signalled. If wait is true, does not return
58 // until the thread is deleted.
59 void Destroy(bool wait);
61 // Context: Main Thread. If the worker thread is complete, deletes the
62 // object immediately. Otherwise, schedules the object to be deleted once
63 // the worker thread completes. SignalWorkDone will be signalled.
66 // Context: Main Thread. Signalled when work is complete.
67 sigslot::signal1<SignalThread *> SignalWorkDone;
69 enum { ST_MSG_WORKER_DONE, ST_MSG_FIRST_AVAILABLE };
72 virtual ~SignalThread();
74 Thread* worker() { return &worker_; }
76 // Context: Main Thread. Subclass should override to do pre-work setup.
77 virtual void OnWorkStart() { }
79 // Context: Worker Thread. Subclass should override to do work.
80 virtual void DoWork() = 0;
82 // Context: Worker Thread. Subclass should call periodically to
83 // dispatch messages and determine if the thread should terminate.
86 // Context: Worker Thread. Subclass should override when extra work is
87 // needed to abort the worker thread.
88 virtual void OnWorkStop() { }
90 // Context: Main Thread. Subclass should override to do post-work cleanup.
91 virtual void OnWorkDone() { }
93 // Context: Any Thread. If subclass overrides, be sure to call the base
94 // implementation. Do not use (message_id < ST_MSG_FIRST_AVAILABLE)
95 virtual void OnMessage(Message *msg);
99 kInit, // Initialized, but not started
100 kRunning, // Started and doing work
101 kReleasing, // Same as running, but to be deleted when work is done
102 kComplete, // Work is done
103 kStopping, // Work is being interrupted
106 class Worker : public Thread {
108 explicit Worker(SignalThread* parent) : parent_(parent) {}
109 virtual ~Worker() { Stop(); }
110 virtual void Run() { parent_->Run(); }
113 SignalThread* parent_;
115 DISALLOW_IMPLICIT_CONSTRUCTORS(Worker);
118 class SCOPED_LOCKABLE EnterExit {
120 explicit EnterExit(SignalThread* t) EXCLUSIVE_LOCK_FUNCTION(t->cs_)
123 // If refcount_ is zero then the object has already been deleted and we
124 // will be double-deleting it in ~EnterExit()! (shouldn't happen)
125 ASSERT(t_->refcount_ != 0);
128 ~EnterExit() UNLOCK_FUNCTION() {
129 bool d = (0 == --t_->refcount_);
138 DISALLOW_IMPLICIT_CONSTRUCTORS(EnterExit);
142 void OnMainThreadDestroyed();
150 DISALLOW_COPY_AND_ASSIGN(SignalThread);
153 ///////////////////////////////////////////////////////////////////////////////
157 #endif // WEBRTC_BASE_SIGNALTHREAD_H_