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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_lazyidlethread_h__
#define mozilla_lazyidlethread_h__
#ifndef MOZILLA_INTERNAL_API
# error "This header is only usable from within libxul (MOZILLA_INTERNAL_API)."
#endif
#include "mozilla/TaskQueue.h"
#include "nsIObserver.h"
#include "nsThreadPool.h"
namespace mozilla {
/**
* This class provides a basic event target that creates its thread lazily and
* destroys its thread after a period of inactivity. It may be created and used
* on any thread but it may only be shut down from the thread on which it is
* created.
*/
class LazyIdleThread final : public nsISerialEventTarget, public nsIObserver {
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIEVENTTARGET_FULL
NS_DECL_NSIOBSERVER
/**
* If AutomaticShutdown is specified, and the LazyIdleThread is created on the
* main thread, Shutdown() will automatically be called during
* xpcom-shutdown-threads.
*/
enum ShutdownMethod { AutomaticShutdown = 0, ManualShutdown };
/**
* Create a new LazyIdleThread that will destroy its thread after the given
* number of milliseconds.
*/
LazyIdleThread(uint32_t aIdleTimeoutMS, const char* aName,
ShutdownMethod aShutdownMethod = AutomaticShutdown);
/**
* Shuts down the LazyIdleThread, waiting for any pending work to complete.
* Must be called from mOwningEventTarget.
*/
void Shutdown();
/**
* Register a nsIThreadPoolListener on the underlying threadpool to track the
* thread as it is created/destroyed.
*/
nsresult SetListener(nsIThreadPoolListener* aListener);
private:
/**
* Asynchronously shuts down the LazyIdleThread on mOwningEventTarget.
*/
~LazyIdleThread();
/**
* The thread which created this LazyIdleThread and is responsible for
* shutting it down.
*/
const nsCOMPtr<nsISerialEventTarget> mOwningEventTarget;
/**
* The single-thread backing threadpool which provides the actual threads used
* by LazyIdleThread, and implements the timeout.
*/
const RefPtr<nsThreadPool> mThreadPool;
/**
* The serial event target providing a `nsISerialEventTarget` implementation
* when on the LazyIdleThread.
*/
const RefPtr<TaskQueue> mTaskQueue;
/**
* Only safe to access on the owning thread or in the destructor (as no other
* threads have access then). If `true`, means the LazyIdleThread has already
* been shut down, so it does not need to be shut down asynchronously from the
* destructor.
*/
bool mShutdown = false;
};
} // namespace mozilla
#endif // mozilla_lazyidlethread_h__
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