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#ifndef _SIGNALTHREAD_H_
#define _SIGNALTHREAD_H_
#include "talk/base/thread.h"
#include "talk/base/sigslot.h"
namespace talk_base {
///////////////////////////////////////////////////////////////////////////////
// SignalThread - Base class for worker threads. The main thread should call
// Start() to begin work, and then follow one of these models:
// Normal: Wait for SignalWorkDone, and then call Release to destroy.
// Cancellation: Call Release(true), to abort the worker thread.
// Fire-and-forget: Call Release(false), which allows the thread to run to
// completion, and then self-destruct without further notification.
// The subclass should override DoWork() to perform the background task. By
// periodically calling ContinueWork(), it can check for cancellation.
// OnWorkStart and OnWorkDone can be overridden to do pre- or post-work
// tasks in the context of the main thread.
///////////////////////////////////////////////////////////////////////////////
class SignalThread : protected MessageHandler {
public:
SignalThread();
// Context: Main Thread. Call before Start to change the worker's priority.
void SetPriority(ThreadPriority priority);
// Context: Main Thread. Call to begin the worker thread.
void Start();
// Context: Main Thread. If the worker thread is not running, deletes the
// object immediately. Otherwise, asks the worker thread to abort processing,
// and schedules the object to be deleted once the worker exits.
// SignalWorkDone will not be signalled.
void Destroy();
// Context: Main Thread. If the worker thread is complete, deletes the
// object immediately. Otherwise, schedules the object to be deleted once
// the worker thread completes. SignalWorkDone will be signalled.
void Release();
// Context: Main Thread. Signalled when work is complete.
sigslot::signal1<SignalThread *> SignalWorkDone;
enum { ST_MSG_WORKER_DONE, ST_MSG_FIRST_AVAILABLE };
protected:
virtual ~SignalThread();
// Context: Main Thread. Subclass should override to do pre-work setup.
virtual void OnWorkStart() { }
// Context: Worker Thread. Subclass should override to do work.
virtual void DoWork() = 0;
// Context: Worker Thread. Subclass should call periodically to
// dispatch messages and determine if the thread should terminate.
bool ContinueWork();
// Context: Worker Thread. Subclass should override when extra work is
// needed to abort the worker thread.
virtual void OnWorkStop() { }
// Context: Main Thread. Subclass should override to do post-work cleanup.
virtual void OnWorkDone() { }
// Context: Any Thread. If subclass overrides, be sure to call the base
// implementation. Do not use (message_id < ST_MSG_FIRST_AVAILABLE)
virtual void OnMessage(Message *msg);
private:
friend class Worker;
class Worker : public Thread {
public:
SignalThread* parent_;
virtual void Run() { parent_->Run(); }
};
void Run();
Thread* main_;
Worker worker_;
enum State { kInit, kRunning, kComplete, kStopping, kReleasing } state_;
};
///////////////////////////////////////////////////////////////////////////////
} // namespace talk_base
#endif // _SIGNALTHREAD_H_
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