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28 #ifndef TALK_BASE_WORKER_H_
29 #define TALK_BASE_WORKER_H_
31 #include "talk/base/constructormagic.h"
32 #include "talk/base/messagehandler.h"
38 // A worker is an object that performs some specific long-lived task in an
39 // event-driven manner.
40 // The only method that should be considered thread-safe is HaveWork(), which
41 // allows you to signal the availability of work from any thread. All other
42 // methods are thread-hostile. Specifically:
43 // StartWork()/StopWork() should not be called concurrently with themselves or
44 // each other, and it is an error to call them while the worker is running on
45 // a different thread.
46 // The destructor may not be called if the worker is currently running
47 // (regardless of the thread), but you can call StopWork() in a subclass's
49 class Worker : private MessageHandler {
53 // Destroys this Worker, but it must have already been stopped via StopWork().
56 // Attaches the worker to the current thread and begins processing work if not
59 // Stops processing work if currently doing so and detaches from the current
64 // Signal that work is available to be done. May only be called within the
65 // lifetime of a OnStart()/OnStop() pair.
68 // These must be implemented by a subclass.
69 // Called on the worker thread to start working.
70 virtual void OnStart() = 0;
71 // Called on the worker thread when work has been signalled via HaveWork().
72 virtual void OnHaveWork() = 0;
73 // Called on the worker thread to stop working. Upon return, any pending
74 // OnHaveWork() calls are cancelled.
75 virtual void OnStop() = 0;
78 // Inherited from MessageHandler.
79 virtual void OnMessage(Message *msg);
81 // The thread that is currently doing the work.
82 Thread *worker_thread_;
84 DISALLOW_COPY_AND_ASSIGN(Worker);
87 } // namespace talk_base
89 #endif // TALK_BASE_WORKER_H_