Mozilla/mozilla/xpcom/threads/TimerThread.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation. Portions created by the Initial Developer are
 * Copyright (C) 2001 the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Stuart Parmenter <pavlov@netscape.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 */


#if defined(XP_MAC) || defined (XP_MACOSX)
#include <unistd.h>  // for sleep()
#include <Power.h>
#endif

#include "nsTimerImpl.h"
#include "TimerThread.h"

#include "nsAutoLock.h"
#include "pratom.h"

#include "nsIServiceManager.h"

#if defined(XP_MAC) || defined (XP_MACOSX)

static SleepQRec  gSleepQEntry = { NULL, sleepQType, NULL, 0 };
static PRBool     gSleepQEntryInstalled = PR_FALSE;
static TimerThread* gTimerThread = NULL;

/*
  On Mac OS, we have to deal with machine sleep. If we don't readjust
  timers after sleep, the precise repeating timers think that they
  are way behind, and fire like crazy for a while after wake.
  
  We install a SleepQProc to get notified about sleep and wake.
*/

static pascal long TimerSleepQProc(long message, SleepQRecPtr sleepQ)
{
  if (!gTimerThread) return 0;
    
  /* just woke up from sleeping, so must recompute timer timeouts */
  if (message == kSleepDemand)
    gTimerThread->DoBeforeSleep();
  else if (message == kSleepWakeUp)
    gTimerThread->DoAfterSleep();

  return 0;
}

#endif  // defined(XP_MAC) || defined (XP_MACOSX)


NS_IMPL_THREADSAFE_ISUPPORTS1(TimerThread, nsIRunnable)

TimerThread::TimerThread() :
  mLock(nsnull),
  mCondVar(nsnull),
  mShutdown(PR_FALSE),
  mWaiting(PR_FALSE),
#if defined(XP_MAC) || defined (XP_MACOSX)
  mSleeping(PR_FALSE),
#endif
  mDelayLineCounter(0),
  mMinTimerPeriod(0),
  mTimeoutAdjustment(0)
{
  NS_INIT_REFCNT();
}

TimerThread::~TimerThread()
{
  if (mCondVar)
    PR_DestroyCondVar(mCondVar);
  if (mLock)
    PR_DestroyLock(mLock);

  mThread = nsnull;

  PRInt32 n = mTimers.Count();
  while (--n >= 0) {
    nsTimerImpl *timer = NS_STATIC_CAST(nsTimerImpl *, mTimers[n]);
    NS_RELEASE(timer);
  }
}

nsresult TimerThread::Init()
{
  if (mThread)
    return NS_OK;

#if defined(XP_MAC) || defined (XP_MACOSX)
  if ((gSleepQEntry.sleepQProc = NewSleepQUPP(TimerSleepQProc)) != NULL) {
    ::SleepQInstall(&gSleepQEntry);
    gSleepQEntryInstalled = PR_TRUE;
    gTimerThread = this;
  }
#endif

  mLock = PR_NewLock();
  if (!mLock)
    return NS_ERROR_OUT_OF_MEMORY;

  mCondVar = PR_NewCondVar(mLock);
  if (!mCondVar)
    return NS_ERROR_OUT_OF_MEMORY;

  nsresult rv;
  mEventQueueService = do_GetService("@mozilla.org/event-queue-service;1", &rv);
  if (NS_FAILED(rv))
    return rv;

  // We hold on to mThread to keep the thread alive.
  rv = NS_NewThread(getter_AddRefs(mThread),
                    NS_STATIC_CAST(nsIRunnable*, this),
                    0,
                    PR_JOINABLE_THREAD,
                    PR_PRIORITY_NORMAL,
                    PR_GLOBAL_THREAD);

  return rv;
}

nsresult TimerThread::Shutdown()
{
  if (!mThread)
    return NS_ERROR_NOT_INITIALIZED;

#if defined(XP_MAC) || defined (XP_MACOSX)
  // clean up the sleepQ entry
  if (gSleepQEntryInstalled)
    ::SleepQRemove(&gSleepQEntry);
  gTimerThread = NULL;
#endif

  {   // lock scope
    nsAutoLock lock(mLock);

    mShutdown = PR_TRUE;

    // notify the cond var so that Run() can return
    if (mCondVar && mWaiting)
      PR_NotifyCondVar(mCondVar);

    nsTimerImpl *timer;
    for (PRInt32 i = mTimers.Count() - 1; i >= 0; i--) {
      timer = NS_STATIC_CAST(nsTimerImpl*, mTimers[i]);
      RemoveTimerInternal(timer);
    }
  }

  mThread->Join();    // wait for the thread to die
  return NS_OK;
}

// Keep track of how early (positive slack) or late (negative slack) timers
// are running, and use the filtered slack number to adaptively estimate how
// early timers should fire to be "on time".
void TimerThread::UpdateFilter(PRUint32 aDelay, PRIntervalTime aTimeout,
                               PRIntervalTime aNow)
{
  PRInt32 slack = (PRInt32) (aTimeout - aNow);
  double smoothSlack = 0;
  PRUint32 i, filterLength;
  static PRIntervalTime kFilterFeedbackMaxTicks =
    PR_MillisecondsToInterval(FILTER_FEEDBACK_MAX);

  if (slack > 0) {
    if (slack > (PRInt32)kFilterFeedbackMaxTicks)
      slack = kFilterFeedbackMaxTicks;
  } else {
    if (slack < -(PRInt32)kFilterFeedbackMaxTicks)
      slack = -(PRInt32)kFilterFeedbackMaxTicks;
  }
  mDelayLine[mDelayLineCounter & DELAY_LINE_LENGTH_MASK] = slack;
  if (++mDelayLineCounter < DELAY_LINE_LENGTH) {
    // Startup mode: accumulate a full delay line before filtering.
    PR_ASSERT(mTimeoutAdjustment == 0);
    filterLength = 0;
  } else {
    // Past startup: compute number of filter taps based on mMinTimerPeriod.
    if (mMinTimerPeriod == 0) {
      mMinTimerPeriod = (aDelay != 0) ? aDelay : 1;
    } else if (aDelay != 0 && aDelay < mMinTimerPeriod) {
      mMinTimerPeriod = aDelay;
    }

    filterLength = (PRUint32) (FILTER_DURATION / mMinTimerPeriod);
    if (filterLength > DELAY_LINE_LENGTH)
      filterLength = DELAY_LINE_LENGTH;
    else if (filterLength < 4)
      filterLength = 4;

    for (i = 1; i <= filterLength; i++)
      smoothSlack += mDelayLine[(mDelayLineCounter-i) & DELAY_LINE_LENGTH_MASK];
    smoothSlack /= filterLength;

    // XXXbe do we need amplification?  hacking a fudge factor, need testing...
    mTimeoutAdjustment = (PRInt32) (smoothSlack * 1.5);
  }

#ifdef DEBUG_TIMERS
  if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
    PR_LOG(gTimerLog, PR_LOG_DEBUG,
           ("UpdateFilter: smoothSlack = %g, filterLength = %u\n",
            smoothSlack, filterLength));
  }
#endif
}

/* void Run(); */
NS_IMETHODIMP TimerThread::Run()
{
  nsAutoLock lock(mLock);

  while (!mShutdown) {
    
    PRIntervalTime waitFor = PR_INTERVAL_NO_TIMEOUT;
  
    PRBool suspendTimerFiring = PR_FALSE;
    
#if defined(XP_MAC) || defined (XP_MACOSX)
    if (mSleeping) {
      suspendTimerFiring = PR_TRUE;
      waitFor = PR_MillisecondsToInterval(100);   // sleep for 0.1 seconds while not firing timers
    }
#endif
    
    if (!suspendTimerFiring)
    {
      PRIntervalTime now = PR_IntervalNow();
      nsTimerImpl *timer = nsnull;
  
      if (mTimers.Count() > 0) {
        timer = NS_STATIC_CAST(nsTimerImpl*, mTimers[0]);
  
        if (!TIMER_LESS_THAN(now, timer->mTimeout + mTimeoutAdjustment)) {
    next:
          // NB: AddRef before the Release under RemoveTimerInternal to avoid
          // mRefCnt passing through zero, in case all other refs than the one
          // from mTimers have gone away (the last non-mTimers[i]-ref's Release
          // must be racing with us, blocked in gThread->RemoveTimer waiting
          // for TimerThread::mLock, under nsTimerImpl::Release.
  
          NS_ADDREF(timer);
          RemoveTimerInternal(timer);
  
          // We release mLock around the Fire call, of course, to avoid deadlock.
          lock.unlock();
  
#ifdef DEBUG_TIMERS
          if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
            PR_LOG(gTimerLog, PR_LOG_DEBUG,
                   ("Timer thread woke up %dms from when it was supposed to\n",
                    (now >= timer->mTimeout)
                    ? PR_IntervalToMilliseconds(now - timer->mTimeout)
                    : -(PRInt32)PR_IntervalToMilliseconds(timer->mTimeout - now))
                  );
          }
#endif
  
          // We are going to let the call to PostTimerEvent here handle the release of the
          // timer so that we don't end up releasing the timer on the TimerThread
          // instead of on the thread it targets.
          timer->PostTimerEvent();
          timer = nsnull;
  
          lock.lock();
          if (mShutdown)
            break;
  
          // Update now, as PostTimerEvent plus the locking may have taken a tick or two,
          // and we may goto next below.
          now = PR_IntervalNow();
        }
      }
  
      if (mTimers.Count() > 0) {
        timer = NS_STATIC_CAST(nsTimerImpl *, mTimers[0]);
  
        PRIntervalTime timeout = timer->mTimeout + mTimeoutAdjustment;
  
        // Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer is
        // due now or overdue.
        if (!TIMER_LESS_THAN(now, timeout))
          goto next;
        waitFor = timeout - now;
      }
  
#ifdef DEBUG_TIMERS
      if (PR_LOG_TEST(gTimerLog, PR_LOG_DEBUG)) {
        if (waitFor == PR_INTERVAL_NO_TIMEOUT)
          PR_LOG(gTimerLog, PR_LOG_DEBUG,
                 ("waiting for PR_INTERVAL_NO_TIMEOUT\n"));
        else
          PR_LOG(gTimerLog, PR_LOG_DEBUG,
                 ("waiting for %u\n", PR_IntervalToMilliseconds(waitFor)));
      }
#endif
    }
    
    mWaiting = PR_TRUE;
    PR_WaitCondVar(mCondVar, waitFor);
    mWaiting = PR_FALSE;
  }

  return NS_OK;
}

nsresult TimerThread::AddTimer(nsTimerImpl *aTimer)
{
  nsAutoLock lock(mLock);

  // Add the timer to our list.
  PRInt32 i = AddTimerInternal(aTimer);
  if (i < 0)
    return NS_ERROR_OUT_OF_MEMORY;

  // Awaken the timer thread.
  if (mCondVar && mWaiting && i == 0)
    PR_NotifyCondVar(mCondVar);

  return NS_OK;
}

nsresult TimerThread::TimerDelayChanged(nsTimerImpl *aTimer)
{
  nsAutoLock lock(mLock);

  // Our caller has a strong ref to aTimer, so it can't go away here under
  // ReleaseTimerInternal.
  RemoveTimerInternal(aTimer);

  PRInt32 i = AddTimerInternal(aTimer);
  if (i < 0)
    return NS_ERROR_OUT_OF_MEMORY;

  // Awaken the timer thread.
  if (mCondVar && mWaiting && i == 0)
    PR_NotifyCondVar(mCondVar);

  return NS_OK;
}

nsresult TimerThread::RemoveTimer(nsTimerImpl *aTimer)
{
  nsAutoLock lock(mLock);

  // Remove the timer from our array.  Tell callers that aTimer was not found
  // by returning NS_ERROR_NOT_AVAILABLE.  Unlike the TimerDelayChanged case
  // immediately above, our caller may be passing a (now-)weak ref in via the
  // aTimer param, specifically when nsTimerImpl::Release loses a race with
  // TimerThread::Run, must wait for the mLock auto-lock here, and during the
  // wait Run drops the only remaining ref to aTimer via RemoveTimerInternal.

  if (!RemoveTimerInternal(aTimer))
    return NS_ERROR_NOT_AVAILABLE;

  // Awaken the timer thread.
  if (mCondVar && mWaiting)
    PR_NotifyCondVar(mCondVar);

  return NS_OK;
}

// This function must be called from within a lock
PRInt32 TimerThread::AddTimerInternal(nsTimerImpl *aTimer)
{
  PRInt32 count = mTimers.Count();
  PRInt32 i = 0;
  for (; i < count; i++) {
    nsTimerImpl *timer = NS_STATIC_CAST(nsTimerImpl *, mTimers[i]);

    if (TIMER_LESS_THAN(aTimer->mTimeout, timer->mTimeout)) {
      break;
    }
  }

  if (!mTimers.InsertElementAt(aTimer, i))
    return -1;

  aTimer->mArmed = PR_TRUE;
  NS_ADDREF(aTimer);
  return i;
}

PRBool TimerThread::RemoveTimerInternal(nsTimerImpl *aTimer)
{
  if (!mTimers.RemoveElement(aTimer))
    return PR_FALSE;

  // Order is crucial here -- see nsTimerImpl::Release.
  aTimer->mArmed = PR_FALSE;
  NS_RELEASE(aTimer);
  return PR_TRUE;
}

#if defined(XP_MAC) || defined (XP_MACOSX)

void TimerThread::DoBeforeSleep()
{
  mSleeping = PR_TRUE;
}

void TimerThread::DoAfterSleep()
{
  ::sleep(1);  // this is necessary to give the OS time to update 
               // gettimeofday(), which PR_IntervalNow() uses.

  for (PRInt32 i = 0; i < mTimers.Count(); i ++)
  {
    nsTimerImpl *timer = NS_STATIC_CAST(nsTimerImpl*, mTimers[i]);
    // this does locking for me
    timer->SetDelay(timer->GetDelay());
  }
  
  // nuke the stored adjustments, so they get recalibrated
  mTimeoutAdjustment = 0;
  mDelayLineCounter = 0;
  mSleeping = PR_FALSE;
}

#endif   // defined(XP_MAC) || defined (XP_MACOSX)