зеркало из https://github.com/mozilla/pjs.git
246 строки
7.3 KiB
C++
246 строки
7.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=2 et sw=2 tw=80: */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Indexed Database.
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*
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* The Initial Developer of the Original Code is
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* The Mozilla Foundation.
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* Portions created by the Initial Developer are Copyright (C) 2010
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Ben Turner <bent.mozilla@gmail.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef mozilla_lazyidlethread_h__
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#define mozilla_lazyidlethread_h__
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#ifndef MOZILLA_INTERNAL_API
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#error "This header is only usable from within libxul (MOZILLA_INTERNAL_API)."
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#endif
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#include "nsIObserver.h"
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#include "nsIThreadInternal.h"
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#include "nsITimer.h"
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#include "mozilla/Mutex.h"
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#include "nsCOMPtr.h"
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#include "nsTArray.h"
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#define IDLE_THREAD_TOPIC "thread-shutting-down"
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namespace mozilla {
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/**
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* This class provides a basic event target that creates its thread lazily and
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* destroys its thread after a period of inactivity. It may be created on any
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* thread but it may only be used from the thread on which it is created. If it
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* is created on the main thread then it will automatically join its thread on
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* XPCOM shutdown using the Observer Service.
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*/
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class LazyIdleThread : public nsIThread,
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public nsITimerCallback,
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public nsIThreadObserver,
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public nsIObserver
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{
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public:
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NS_DECL_ISUPPORTS
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NS_DECL_NSIEVENTTARGET
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NS_DECL_NSITHREAD
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NS_DECL_NSITIMERCALLBACK
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NS_DECL_NSITHREADOBSERVER
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NS_DECL_NSIOBSERVER
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enum ShutdownMethod {
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AutomaticShutdown = 0,
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ManualShutdown
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};
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/**
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* Create a new LazyIdleThread that will destroy its thread after the given
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* number of milliseconds.
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*/
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LazyIdleThread(PRUint32 aIdleTimeoutMS,
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ShutdownMethod aShutdownMethod = AutomaticShutdown,
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nsIObserver* aIdleObserver = nsnull);
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/**
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* Add an observer that will be notified when the thread is idle and about to
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* be shut down. The aSubject argument can be QueryInterface'd to an nsIThread
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* that can be used to post cleanup events. The aTopic argument will be
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* IDLE_THREAD_TOPIC, and aData will be null. The LazyIdleThread does not add
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* a reference to the observer to avoid circular references as it is assumed
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* to be the owner. It is the caller's responsibility to clear this observer
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* if the pointer becomes invalid.
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*/
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void SetWeakIdleObserver(nsIObserver* aObserver);
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/**
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* Disable the idle timeout for this thread. No effect if the timeout is
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* already disabled.
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*/
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void DisableIdleTimeout();
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/**
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* Enable the idle timeout. No effect if the timeout is already enabled.
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*/
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void EnableIdleTimeout();
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private:
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/**
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* Calls Shutdown().
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*/
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~LazyIdleThread();
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/**
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* Called just before dispatching to mThread.
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*/
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void PreDispatch();
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/**
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* Makes sure a valid thread lives in mThread.
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*/
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nsresult EnsureThread();
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/**
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* Called on mThread to set up the thread observer.
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*/
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void InitThread();
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/**
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* Called on mThread to clean up the thread observer.
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*/
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void CleanupThread();
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/**
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* Called on the main thread when mThread believes itself to be idle. Sets up
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* the idle timer.
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*/
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void ScheduleTimer();
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/**
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* Called when we are shutting down mThread.
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*/
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nsresult ShutdownThread();
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/**
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* Deletes this object. Used to delay calling mThread->Shutdown() during the
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* final release (during a GC, for instance).
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*/
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void SelfDestruct();
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/**
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* Returns true if events should be queued rather than immediately dispatched
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* to mThread. Currently only happens when the thread is shutting down.
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*/
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bool UseRunnableQueue() {
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return !!mQueuedRunnables;
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}
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/**
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* Protects data that is accessed on both threads.
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*/
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mozilla::Mutex mMutex;
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/**
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* Touched on both threads but set before mThread is created. Used to direct
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* timer events to the owning thread.
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*/
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nsCOMPtr<nsIThread> mOwningThread;
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/**
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* Only accessed on the owning thread. Set by EnsureThread().
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*/
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nsCOMPtr<nsIThread> mThread;
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/**
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* Protected by mMutex. Created when mThread has no pending events and fired
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* at mOwningThread. Any thread that dispatches to mThread will take ownership
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* of the timer and fire a separate cancel event to the owning thread.
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*/
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nsCOMPtr<nsITimer> mIdleTimer;
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/**
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* Idle observer. Called when the thread is about to be shut down. Released
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* only when Shutdown() is called.
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*/
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nsIObserver* mIdleObserver;
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/**
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* Temporary storage for events that happen to be dispatched while we're in
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* the process of shutting down our real thread.
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*/
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nsTArray<nsCOMPtr<nsIRunnable> >* mQueuedRunnables;
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/**
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* The number of milliseconds a thread should be idle before dying.
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*/
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const PRUint32 mIdleTimeoutMS;
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/**
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* The number of events that are pending on mThread. A nonzero value means
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* that the thread cannot be cleaned up.
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*/
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PRUint32 mPendingEventCount;
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/**
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* The number of times that mThread has dispatched an idle notification. Any
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* timer that fires while this count is nonzero can safely be ignored as
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* another timer will be on the way.
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*/
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PRUint32 mIdleNotificationCount;
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/**
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* Whether or not the thread should automatically shutdown. If the owner
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* specified ManualShutdown at construction time then the owner should take
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* care to call Shutdown() manually when appropriate.
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*/
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ShutdownMethod mShutdownMethod;
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/**
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* Only accessed on the owning thread. Set to true when Shutdown() has been
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* called and prevents EnsureThread() from recreating mThread.
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*/
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bool mShutdown;
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/**
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* Set from CleanupThread and lasting until the thread has shut down. Prevents
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* further idle notifications during the shutdown process.
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*/
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bool mThreadIsShuttingDown;
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/**
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* Whether or not the idle timeout is enabled.
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*/
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bool mIdleTimeoutEnabled;
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};
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} // namespace mozilla
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#endif // mozilla_lazyidlethread_h__
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