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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include "webrtc/base/constructormagic.h"
#include "webrtc/base/messagehandler.h"
namespace rtc {
class Thread;
// A worker is an object that performs some specific long-lived task in an
// event-driven manner.
// The only method that should be considered thread-safe is HaveWork(), which
// allows you to signal the availability of work from any thread. All other
// methods are thread-hostile. Specifically:
// StartWork()/StopWork() should not be called concurrently with themselves or
// each other, and it is an error to call them while the worker is running on
// a different thread.
// The destructor may not be called if the worker is currently running
// (regardless of the thread), but you can call StopWork() in a subclass's
// destructor.
class Worker : private MessageHandler {
// Destroys this Worker, but it must have already been stopped via StopWork().
~Worker() override;
// Attaches the worker to the current thread and begins processing work if not
// already doing so.
bool StartWork();
// Stops processing work if currently doing so and detaches from the current
// thread.
bool StopWork();
// Signal that work is available to be done. May only be called within the
// lifetime of a OnStart()/OnStop() pair.
void HaveWork();
// These must be implemented by a subclass.
// Called on the worker thread to start working.
virtual void OnStart() = 0;
// Called on the worker thread when work has been signalled via HaveWork().
virtual void OnHaveWork() = 0;
// Called on the worker thread to stop working. Upon return, any pending
// OnHaveWork() calls are cancelled.
virtual void OnStop() = 0;
// Inherited from MessageHandler.
void OnMessage(Message* msg) override;
// The thread that is currently doing the work.
Thread *worker_thread_;
} // namespace rtc