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