tommi@webrtc.org 0c3e12b7bf Revamp the ProcessThreadImpl implementation.
* Add a new WakeUp method that gives a module a chance to be called back right away on the worker thread.
* Wrote unit tests for the class.
* Significantly reduce the amount of locking.
  - ProcessThreadImpl itself does a lot less locking.
  - Reimplemented the way we keep track of when to make calls to Process.
    This reduces the amount of calls to TimeUntilNextProcess and since most implementations of that function grab a lock, this means less locking.
* Renamed ProcessThread::CreateProcessThread to ProcessThread::Create.
* Added thread checks for Start/Stop.  Threading model of other functions is now documented.
* We now log an error if an implementation of TimeUntilNextProcess returns a negative value (some implementations do, but the method should only return a positive nr of ms).
* Removed the DestroyProcessThread method and instead force callers to use scoped_ptr<> to maintain object lifetime.

BUG=2822
R=henrika@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/35999004

Cr-Commit-Position: refs/heads/master@{#8261}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8261 4adac7df-926f-26a2-2b94-8c16560cd09d
2015-02-06 09:44:45 +00:00

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/*
* Copyright (c) 2012 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.
*/
#ifndef MODULES_INTERFACE_MODULE_H_
#define MODULES_INTERFACE_MODULE_H_
#include "webrtc/typedefs.h"
namespace webrtc {
class Module {
public:
// Returns the number of milliseconds until the module wants a worker
// thread to call Process.
// This method is called on the same worker thread as Process will
// be called on.
// TODO(tommi): Almost all implementations of this function, need to know
// the current tick count. Consider passing it as an argument. It could
// also improve the accuracy of when the next callback occurs since the
// thread that calls Process() will also have it's tick count reference
// which might not match with what the implementations use.
virtual int64_t TimeUntilNextProcess() = 0;
// Process any pending tasks such as timeouts.
// Called on a worker thread.
virtual int32_t Process() = 0;
protected:
virtual ~Module() {}
};
// Reference counted version of the Module interface.
class RefCountedModule : public Module {
public:
// Increase the reference count by one.
// Returns the incremented reference count.
virtual int32_t AddRef() = 0;
// Decrease the reference count by one.
// Returns the decreased reference count.
// Returns 0 if the last reference was just released.
// When the reference count reaches 0 the object will self-destruct.
virtual int32_t Release() = 0;
protected:
virtual ~RefCountedModule() {}
};
} // namespace webrtc
#endif // MODULES_INTERFACE_MODULE_H_