зеркало из https://github.com/mozilla/gecko-dev.git
522 строки
16 KiB
C++
522 строки
16 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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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 mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Stuart Parmenter <pavlov@netscape.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 of the GNU General Public License Version 2 or later (the "GPL"),
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* or 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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#include "nsTimerImpl.h"
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#include "TimerThread.h"
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#include "nsAutoLock.h"
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#include "nsThreadUtils.h"
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#include "pratom.h"
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#include "nsIObserverService.h"
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#include "nsIServiceManager.h"
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#include "nsIProxyObjectManager.h"
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#include "mozilla/Services.h"
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#include <math.h>
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NS_IMPL_THREADSAFE_ISUPPORTS2(TimerThread, nsIRunnable, nsIObserver)
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TimerThread::TimerThread() :
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mInitInProgress(0),
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mInitialized(PR_FALSE),
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mLock(nsnull),
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mCondVar(nsnull),
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mShutdown(PR_FALSE),
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mWaiting(PR_FALSE),
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mSleeping(PR_FALSE),
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mDelayLineCounter(0),
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mMinTimerPeriod(0)
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{
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}
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TimerThread::~TimerThread()
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{
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if (mCondVar)
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PR_DestroyCondVar(mCondVar);
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if (mLock)
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PR_DestroyLock(mLock);
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mThread = nsnull;
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NS_ASSERTION(mTimers.IsEmpty(), "Timers remain in TimerThread::~TimerThread");
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}
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nsresult
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TimerThread::InitLocks()
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{
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NS_ASSERTION(!mLock, "InitLocks called twice?");
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mLock = PR_NewLock();
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if (!mLock)
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return NS_ERROR_OUT_OF_MEMORY;
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mCondVar = PR_NewCondVar(mLock);
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if (!mCondVar)
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return NS_ERROR_OUT_OF_MEMORY;
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return NS_OK;
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}
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nsresult TimerThread::Init()
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{
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PR_LOG(gTimerLog, PR_LOG_DEBUG, ("TimerThread::Init [%d]\n", mInitialized));
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if (mInitialized) {
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if (!mThread)
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return NS_ERROR_FAILURE;
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return NS_OK;
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}
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if (PR_AtomicSet(&mInitInProgress, 1) == 0) {
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// We hold on to mThread to keep the thread alive.
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nsresult rv = NS_NewThread(getter_AddRefs(mThread), this);
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if (NS_FAILED(rv)) {
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mThread = nsnull;
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}
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else {
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nsCOMPtr<nsIObserverService> observerService =
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mozilla::services::GetObserverService();
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// We must not use the observer service from a background thread!
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if (observerService && !NS_IsMainThread()) {
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nsCOMPtr<nsIObserverService> result = nsnull;
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NS_GetProxyForObject(NS_PROXY_TO_MAIN_THREAD,
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NS_GET_IID(nsIObserverService),
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observerService, NS_PROXY_ASYNC,
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getter_AddRefs(result));
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observerService.swap(result);
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}
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// We'll be released at xpcom shutdown
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if (observerService) {
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observerService->AddObserver(this, "sleep_notification", PR_FALSE);
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observerService->AddObserver(this, "wake_notification", PR_FALSE);
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}
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}
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PR_Lock(mLock);
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mInitialized = PR_TRUE;
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PR_NotifyAllCondVar(mCondVar);
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PR_Unlock(mLock);
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}
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else {
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PR_Lock(mLock);
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while (!mInitialized) {
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PR_WaitCondVar(mCondVar, PR_INTERVAL_NO_TIMEOUT);
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}
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PR_Unlock(mLock);
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}
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if (!mThread)
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return NS_ERROR_FAILURE;
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return NS_OK;
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}
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nsresult TimerThread::Shutdown()
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{
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PR_LOG(gTimerLog, PR_LOG_DEBUG, ("TimerThread::Shutdown begin\n"));
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if (!mThread)
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return NS_ERROR_NOT_INITIALIZED;
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nsTArray<nsTimerImpl*> timers;
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{ // lock scope
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nsAutoLock lock(mLock);
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mShutdown = PR_TRUE;
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// notify the cond var so that Run() can return
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if (mCondVar && mWaiting)
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PR_NotifyCondVar(mCondVar);
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// Need to copy content of mTimers array to a local array
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// because call to timers' ReleaseCallback() (and release its self)
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// must not be done under the lock. Destructor of a callback
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// might potentially call some code reentering the same lock
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// that leads to unexpected behavior or deadlock.
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// See bug 422472.
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timers.AppendElements(mTimers);
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mTimers.Clear();
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}
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PRUint32 timersCount = timers.Length();
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for (PRUint32 i = 0; i < timersCount; i++) {
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nsTimerImpl *timer = timers[i];
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timer->ReleaseCallback();
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ReleaseTimerInternal(timer);
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}
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mThread->Shutdown(); // wait for the thread to die
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PR_LOG(gTimerLog, PR_LOG_DEBUG, ("TimerThread::Shutdown end\n"));
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return NS_OK;
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}
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// Keep track of how early (positive slack) or late (negative slack) timers
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// are running, and use the filtered slack number to adaptively estimate how
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// early timers should fire to be "on time".
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void TimerThread::UpdateFilter(PRUint32 aDelay, TimeStamp aTimeout,
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TimeStamp aNow)
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{
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TimeDuration slack = aTimeout - aNow;
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double smoothSlack = 0;
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PRUint32 i, filterLength;
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static TimeDuration kFilterFeedbackMaxTicks =
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TimeDuration::FromMilliseconds(FILTER_FEEDBACK_MAX);
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static TimeDuration kFilterFeedbackMinTicks =
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TimeDuration::FromMilliseconds(-FILTER_FEEDBACK_MAX);
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if (slack > kFilterFeedbackMaxTicks)
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slack = kFilterFeedbackMaxTicks;
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else if (slack < kFilterFeedbackMinTicks)
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slack = kFilterFeedbackMinTicks;
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mDelayLine[mDelayLineCounter & DELAY_LINE_LENGTH_MASK] =
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slack.ToMilliseconds();
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if (++mDelayLineCounter < DELAY_LINE_LENGTH) {
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// Startup mode: accumulate a full delay line before filtering.
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PR_ASSERT(mTimeoutAdjustment.ToSeconds() == 0);
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filterLength = 0;
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} else {
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// Past startup: compute number of filter taps based on mMinTimerPeriod.
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if (mMinTimerPeriod == 0) {
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mMinTimerPeriod = (aDelay != 0) ? aDelay : 1;
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} else if (aDelay != 0 && aDelay < mMinTimerPeriod) {
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mMinTimerPeriod = aDelay;
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}
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filterLength = (PRUint32) (FILTER_DURATION / mMinTimerPeriod);
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if (filterLength > DELAY_LINE_LENGTH)
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filterLength = DELAY_LINE_LENGTH;
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else if (filterLength < 4)
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filterLength = 4;
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for (i = 1; i <= filterLength; i++)
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smoothSlack += mDelayLine[(mDelayLineCounter-i) & DELAY_LINE_LENGTH_MASK];
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smoothSlack /= filterLength;
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// XXXbe do we need amplification? hacking a fudge factor, need testing...
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mTimeoutAdjustment = TimeDuration::FromMilliseconds(smoothSlack * 1.5);
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}
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#ifdef DEBUG_TIMERS
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PR_LOG(gTimerLog, PR_LOG_DEBUG,
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("UpdateFilter: smoothSlack = %g, filterLength = %u\n",
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smoothSlack, filterLength));
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#endif
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}
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/* void Run(); */
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NS_IMETHODIMP TimerThread::Run()
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{
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nsAutoLock lock(mLock);
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// We need to know how many microseconds give a positive PRIntervalTime. This
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// is platform-dependent, we calculate it at runtime now.
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// First we find a value such that PR_MicrosecondsToInterval(high) = 1
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PRInt32 low = 0, high = 1;
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while (PR_MicrosecondsToInterval(high) == 0)
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high <<= 1;
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// We now have
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// PR_MicrosecondsToInterval(low) = 0
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// PR_MicrosecondsToInterval(high) = 1
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// and we can proceed to find the critical value using binary search
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while (high-low > 1) {
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PRInt32 mid = (high+low) >> 1;
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if (PR_MicrosecondsToInterval(mid) == 0)
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low = mid;
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else
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high = mid;
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}
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// Half of the amount of microseconds needed to get positive PRIntervalTime.
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// We use this to decide how to round our wait times later
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PRInt32 halfMicrosecondsIntervalResolution = high >> 1;
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while (!mShutdown) {
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// Have to use PRIntervalTime here, since PR_WaitCondVar takes it
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PRIntervalTime waitFor;
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if (mSleeping) {
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// Sleep for 0.1 seconds while not firing timers.
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waitFor = PR_MillisecondsToInterval(100);
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} else {
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waitFor = PR_INTERVAL_NO_TIMEOUT;
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TimeStamp now = TimeStamp::Now();
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nsTimerImpl *timer = nsnull;
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if (!mTimers.IsEmpty()) {
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timer = mTimers[0];
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if (now >= timer->mTimeout + mTimeoutAdjustment) {
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next:
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// NB: AddRef before the Release under RemoveTimerInternal to avoid
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// mRefCnt passing through zero, in case all other refs than the one
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// from mTimers have gone away (the last non-mTimers[i]-ref's Release
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// must be racing with us, blocked in gThread->RemoveTimer waiting
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// for TimerThread::mLock, under nsTimerImpl::Release.
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NS_ADDREF(timer);
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RemoveTimerInternal(timer);
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// We release mLock around the Fire call to avoid deadlock.
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lock.unlock();
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#ifdef DEBUG_TIMERS
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if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
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PR_LOG(gTimerLog, PR_LOG_DEBUG,
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("Timer thread woke up %fms from when it was supposed to\n",
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fabs((now - timer->mTimeout).ToMilliseconds())));
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}
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#endif
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// We are going to let the call to PostTimerEvent here handle the
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// release of the timer so that we don't end up releasing the timer
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// on the TimerThread instead of on the thread it targets.
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if (NS_FAILED(timer->PostTimerEvent())) {
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nsrefcnt rc;
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NS_RELEASE2(timer, rc);
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// The nsITimer interface requires that its users keep a reference
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// to the timers they use while those timers are initialized but
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// have not yet fired. If this ever happens, it is a bug in the
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// code that created and used the timer.
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//
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// Further, note that this should never happen even with a
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// misbehaving user, because nsTimerImpl::Release checks for a
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// refcount of 1 with an armed timer (a timer whose only reference
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// is from the timer thread) and when it hits this will remove the
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// timer from the timer thread and thus destroy the last reference,
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// preventing this situation from occurring.
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NS_ASSERTION(rc != 0, "destroyed timer off its target thread!");
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}
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timer = nsnull;
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lock.lock();
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if (mShutdown)
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break;
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// Update now, as PostTimerEvent plus the locking may have taken a
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// tick or two, and we may goto next below.
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now = TimeStamp::Now();
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}
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}
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if (!mTimers.IsEmpty()) {
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timer = mTimers[0];
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TimeStamp timeout = timer->mTimeout + mTimeoutAdjustment;
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// Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer
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// is due now or overdue.
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//
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// Note that we can only sleep for integer values of a certain
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// resolution. We use halfMicrosecondsIntervalResolution, calculated
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// before, to do the optimal rounding (i.e., of how to decide what
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// interval is so small we should not wait at all).
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double microseconds = (timeout - now).ToMilliseconds()*1000;
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if (microseconds < halfMicrosecondsIntervalResolution)
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goto next; // round down; execute event now
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waitFor = PR_MicrosecondsToInterval(microseconds);
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if (waitFor == 0)
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waitFor = 1; // round up, wait the minimum time we can wait
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}
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#ifdef DEBUG_TIMERS
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if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
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if (waitFor == PR_INTERVAL_NO_TIMEOUT)
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PR_LOG(gTimerLog, PR_LOG_DEBUG,
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("waiting for PR_INTERVAL_NO_TIMEOUT\n"));
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else
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PR_LOG(gTimerLog, PR_LOG_DEBUG,
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("waiting for %u\n", PR_IntervalToMilliseconds(waitFor)));
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}
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#endif
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}
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mWaiting = PR_TRUE;
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PR_WaitCondVar(mCondVar, waitFor);
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mWaiting = PR_FALSE;
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}
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return NS_OK;
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}
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nsresult TimerThread::AddTimer(nsTimerImpl *aTimer)
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{
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nsAutoLock lock(mLock);
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// Add the timer to our list.
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PRInt32 i = AddTimerInternal(aTimer);
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if (i < 0)
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return NS_ERROR_OUT_OF_MEMORY;
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// Awaken the timer thread.
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if (mCondVar && mWaiting && i == 0)
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PR_NotifyCondVar(mCondVar);
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return NS_OK;
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}
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nsresult TimerThread::TimerDelayChanged(nsTimerImpl *aTimer)
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{
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nsAutoLock lock(mLock);
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// Our caller has a strong ref to aTimer, so it can't go away here under
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// ReleaseTimerInternal.
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RemoveTimerInternal(aTimer);
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PRInt32 i = AddTimerInternal(aTimer);
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if (i < 0)
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return NS_ERROR_OUT_OF_MEMORY;
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// Awaken the timer thread.
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if (mCondVar && mWaiting && i == 0)
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PR_NotifyCondVar(mCondVar);
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return NS_OK;
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}
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nsresult TimerThread::RemoveTimer(nsTimerImpl *aTimer)
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{
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nsAutoLock lock(mLock);
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// Remove the timer from our array. Tell callers that aTimer was not found
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// by returning NS_ERROR_NOT_AVAILABLE. Unlike the TimerDelayChanged case
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// immediately above, our caller may be passing a (now-)weak ref in via the
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// aTimer param, specifically when nsTimerImpl::Release loses a race with
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// TimerThread::Run, must wait for the mLock auto-lock here, and during the
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// wait Run drops the only remaining ref to aTimer via RemoveTimerInternal.
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if (!RemoveTimerInternal(aTimer))
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return NS_ERROR_NOT_AVAILABLE;
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// Awaken the timer thread.
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if (mCondVar && mWaiting)
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PR_NotifyCondVar(mCondVar);
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return NS_OK;
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}
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// This function must be called from within a lock
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PRInt32 TimerThread::AddTimerInternal(nsTimerImpl *aTimer)
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{
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if (mShutdown)
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return -1;
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TimeStamp now = TimeStamp::Now();
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PRUint32 count = mTimers.Length();
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PRUint32 i = 0;
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for (; i < count; i++) {
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nsTimerImpl *timer = mTimers[i];
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// Don't break till we have skipped any overdue timers.
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// XXXbz why? Given our definition of overdue in terms of
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// mTimeoutAdjustment, aTimer might be overdue already! Why not
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// just fire timers in order?
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// XXX does this hold for TYPE_REPEATING_PRECISE? /be
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if (now < timer->mTimeout + mTimeoutAdjustment &&
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aTimer->mTimeout < timer->mTimeout) {
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break;
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}
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}
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if (!mTimers.InsertElementAt(i, aTimer))
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return -1;
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aTimer->mArmed = PR_TRUE;
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NS_ADDREF(aTimer);
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return i;
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}
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PRBool TimerThread::RemoveTimerInternal(nsTimerImpl *aTimer)
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{
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if (!mTimers.RemoveElement(aTimer))
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return PR_FALSE;
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ReleaseTimerInternal(aTimer);
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return PR_TRUE;
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}
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void TimerThread::ReleaseTimerInternal(nsTimerImpl *aTimer)
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{
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// Order is crucial here -- see nsTimerImpl::Release.
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aTimer->mArmed = PR_FALSE;
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NS_RELEASE(aTimer);
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}
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void TimerThread::DoBeforeSleep()
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{
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mSleeping = PR_TRUE;
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}
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void TimerThread::DoAfterSleep()
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{
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mSleeping = PR_TRUE; // wake may be notified without preceding sleep notification
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for (PRUint32 i = 0; i < mTimers.Length(); i ++) {
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nsTimerImpl *timer = mTimers[i];
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// get and set the delay to cause its timeout to be recomputed
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PRUint32 delay;
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timer->GetDelay(&delay);
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timer->SetDelay(delay);
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}
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// nuke the stored adjustments, so they get recalibrated
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mTimeoutAdjustment = TimeDuration(0);
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mDelayLineCounter = 0;
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mSleeping = PR_FALSE;
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}
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/* void observe (in nsISupports aSubject, in string aTopic, in wstring aData); */
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NS_IMETHODIMP
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TimerThread::Observe(nsISupports* /* aSubject */, const char *aTopic, const PRUnichar* /* aData */)
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{
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if (strcmp(aTopic, "sleep_notification") == 0)
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DoBeforeSleep();
|
|
else if (strcmp(aTopic, "wake_notification") == 0)
|
|
DoAfterSleep();
|
|
|
|
return NS_OK;
|
|
}
|