C++ TimeStamp::IsNull方法代码示例

int ImageHost::ChooseImageIndex() const
{
  if (!GetCompositor() || mImages.IsEmpty()) {
    return -1;
  }
  TimeStamp now = GetCompositor()->GetCompositionTime();

  if (now.IsNull()) {
    // Not in a composition, so just return the last image we composited
    // (if it's one of the current images).
    for (uint32_t i = 0; i < mImages.Length(); ++i) {
      if (mImages[i].mFrameID == mLastFrameID &&
          mImages[i].mProducerID == mLastProducerID) {
        return i;
      }
    }
    return -1;
  }

  uint32_t result = 0;
  while (result + 1 < mImages.Length() &&
      GetBiasedTime(mImages[result + 1].mTimeStamp, mBias) <= now) {
    ++result;
  }
  return result;
}

TimeStamp
FPSCounter::GetLatestTimeStamp()
{
  TimeStamp timestamp = mFrameTimestamps[GetLatestReadIndex()];
  MOZ_ASSERT(!timestamp.IsNull(), "Cannot use null timestamps");
  return timestamp;
}

DOMHighResTimeStamp
nsPerformanceTiming::FetchStartHighRes()
{
  if (!mFetchStart) {
    if (!nsContentUtils::IsPerformanceTimingEnabled() || !IsInitialized()) {
      return mZeroTime;
    }
    TimeStamp stamp;
    mChannel->GetAsyncOpen(&stamp);
    MOZ_ASSERT(!stamp.IsNull(), "The fetch start time stamp should always be "
        "valid if the performance timing is enabled");
    mFetchStart = (!stamp.IsNull())
        ? TimeStampToDOMHighRes(stamp)
        : 0.0;
  }
  return mFetchStart;
}

NS_IMETHODIMP
nsAppStartup::TrackStartupCrashEnd()
{
  bool inSafeMode = false;
  nsCOMPtr<nsIXULRuntime> xr = do_GetService(XULRUNTIME_SERVICE_CONTRACTID);
  if (xr)
    xr->GetInSafeMode(&inSafeMode);

  // return if we already ended or we're restarting into safe mode
  if (mStartupCrashTrackingEnded || (mIsSafeModeNecessary && !inSafeMode))
    return NS_OK;
  mStartupCrashTrackingEnded = true;

  StartupTimeline::Record(StartupTimeline::STARTUP_CRASH_DETECTION_END);

  // Use the timestamp of XRE_main as an approximation for the lock file timestamp.
  // See MAX_STARTUP_BUFFER for the buffer time period.
  TimeStamp mainTime = StartupTimeline::Get(StartupTimeline::MAIN);
  TimeStamp now = TimeStamp::Now();
  PRTime prNow = PR_Now();
  nsresult rv;

  if (mainTime.IsNull()) {
    NS_WARNING("Could not get StartupTimeline::MAIN time.");
  } else {
    uint64_t lockFileTime = ComputeAbsoluteTimestamp(prNow, now, mainTime);

    rv = Preferences::SetInt(kPrefLastSuccess,
      (int32_t)(lockFileTime / PR_USEC_PER_SEC));

    if (NS_FAILED(rv))
      NS_WARNING("Could not set startup crash detection pref.");
  }

  if (inSafeMode && mIsSafeModeNecessary) {
    // On a successful startup in automatic safe mode, allow the user one more crash
    // in regular mode before returning to safe mode.
    int32_t maxResumedCrashes = 0;
    int32_t prefType;
    rv = Preferences::GetDefaultRootBranch()->GetPrefType(kPrefMaxResumedCrashes, &prefType);
    NS_ENSURE_SUCCESS(rv, rv);
    if (prefType == nsIPrefBranch::PREF_INT) {
      rv = Preferences::GetInt(kPrefMaxResumedCrashes, &maxResumedCrashes);
      NS_ENSURE_SUCCESS(rv, rv);
    }
    rv = Preferences::SetInt(kPrefRecentCrashes, maxResumedCrashes);
    NS_ENSURE_SUCCESS(rv, rv);
  } else if (!inSafeMode) {
    // clear the count of recent crashes after a succesful startup when not in safe mode
    rv = Preferences::ClearUser(kPrefRecentCrashes);
    if (NS_FAILED(rv)) NS_WARNING("Could not clear startup crash count.");
  }
  nsCOMPtr<nsIPrefService> prefs = Preferences::GetService();
  rv = prefs->SavePrefFile(nullptr); // flush prefs to disk since we are tracking crashes

  return rv;
}

DOMTimeMilliSec
nsDOMNavigationTiming::TimeStampToDOM(TimeStamp aStamp) const
{
  if (aStamp.IsNull()) {
    return 0;
  }

  TimeDuration duration = aStamp - mNavigationStartTimeStamp;
  return GetNavigationStart() + static_cast<int64_t>(duration.ToMilliseconds());
}

int32_t
nsSocketTransportService::Poll(uint32_t *interval,
                               TimeDuration *pollDuration)
{
    PRPollDesc *pollList;
    uint32_t pollCount;
    PRIntervalTime pollTimeout;
    *pollDuration = 0;

    // If there are pending events for this thread then
    // DoPollIteration() should service the network without blocking.
    bool pendingEvents = false;
    mRawThread->HasPendingEvents(&pendingEvents);

    if (mPollList[0].fd) {
        mPollList[0].out_flags = 0;
        pollList = mPollList;
        pollCount = mActiveCount + 1;
        pollTimeout = pendingEvents ? PR_INTERVAL_NO_WAIT : PollTimeout();
    }
    else {
        // no pollable event, so busy wait...
        pollCount = mActiveCount;
        if (pollCount)
            pollList = &mPollList[1];
        else
            pollList = nullptr;
        pollTimeout =
            pendingEvents ? PR_INTERVAL_NO_WAIT : PR_MillisecondsToInterval(25);
    }

    PRIntervalTime ts = PR_IntervalNow();

    TimeStamp pollStart;
    if (mTelemetryEnabledPref) {
        pollStart = TimeStamp::NowLoRes();
    }

    SOCKET_LOG(("    timeout = %i milliseconds\n",
         PR_IntervalToMilliseconds(pollTimeout)));
    int32_t rv = PR_Poll(pollList, pollCount, pollTimeout);

    PRIntervalTime passedInterval = PR_IntervalNow() - ts;

    if (mTelemetryEnabledPref && !pollStart.IsNull()) {
        *pollDuration = TimeStamp::NowLoRes() - pollStart;
    }

    SOCKET_LOG(("    ...returned after %i milliseconds\n",
         PR_IntervalToMilliseconds(passedInterval))); 

    *interval = PR_IntervalToSeconds(passedInterval);
    return rv;
}

static PLDHashOperator
BackdateTimeStampsEnumerator(nsISupports *aKey, TimeStamp &aTimeStamp,
                             void* aClosure)
{
  TimeStamp *minTimeStamp = static_cast<TimeStamp*>(aClosure);

  if (!aTimeStamp.IsNull() && aTimeStamp > *minTimeStamp) {
    aTimeStamp = *minTimeStamp;
  }

  return PL_DHASH_NEXT;
}

static ImageHost::Bias
UpdateBias(const TimeStamp& aCompositionTime,
           const TimeStamp& aCompositedImageTime,
           const TimeStamp& aNextImageTime, // may be null
           ImageHost::Bias aBias)
{
  if (aCompositedImageTime.IsNull()) {
    return ImageHost::BIAS_NONE;
  }
  TimeDuration threshold = TimeDuration::FromMilliseconds(1.0);
  if (aCompositionTime - aCompositedImageTime < threshold &&
      aCompositionTime - aCompositedImageTime > -threshold) {
    // The chosen frame's time is very close to the composition time (probably
    // just before the current composition time, but due to previously set
    // negative bias, it could be just after the current composition time too).
    // If the inter-frame time is almost exactly equal to (a multiple of)
    // the inter-composition time, then we're in a dangerous situation because
    // jitter might cause frames to fall one side or the other of the
    // composition times, causing many frames to be skipped or duplicated.
    // Try to prevent that by adding a negative bias to the frame times during
    // the next composite; that should ensure the next frame's time is treated
    // as falling just before a composite time.
    return ImageHost::BIAS_NEGATIVE;
  }
  if (!aNextImageTime.IsNull() &&
      aNextImageTime - aCompositionTime < threshold &&
      aNextImageTime - aCompositionTime > -threshold) {
    // The next frame's time is very close to our composition time (probably
    // just after the current composition time, but due to previously set
    // positive bias, it could be just before the current composition time too).
    // We're in a dangerous situation because jitter might cause frames to
    // fall one side or the other of the composition times, causing many frames
    // to be skipped or duplicated.
    // Try to prevent that by adding a negative bias to the frame times during
    // the next composite; that should ensure the next frame's time is treated
    // as falling just before a composite time.
    return ImageHost::BIAS_POSITIVE;
  }
  return ImageHost::BIAS_NONE;
}

int32_t
nsSocketTransportService::Poll(bool wait, uint32_t *interval,
                               TimeDuration *pollDuration)
{
    PRPollDesc *pollList;
    uint32_t pollCount;
    PRIntervalTime pollTimeout;
    *pollDuration = 0;

    if (mPollList[0].fd) {
        mPollList[0].out_flags = 0;
        pollList = mPollList;
        pollCount = mActiveCount + 1;
        pollTimeout = PollTimeout();
    }
    else {
        // no pollable event, so busy wait...
        pollCount = mActiveCount;
        if (pollCount)
            pollList = &mPollList[1];
        else
            pollList = nullptr;
        pollTimeout = PR_MillisecondsToInterval(25);
    }

    if (!wait)
        pollTimeout = PR_INTERVAL_NO_WAIT;

    PRIntervalTime ts = PR_IntervalNow();

    TimeStamp pollStart;
    if (mTelemetryEnabledPref) {
        pollStart = TimeStamp::NowLoRes();
    }

    SOCKET_LOG(("    timeout = %i milliseconds\n",
         PR_IntervalToMilliseconds(pollTimeout)));
    int32_t rv = PR_Poll(pollList, pollCount, pollTimeout);

    PRIntervalTime passedInterval = PR_IntervalNow() - ts;

    if (mTelemetryEnabledPref && !pollStart.IsNull()) {
        *pollDuration = TimeStamp::NowLoRes() - pollStart;
    }

    SOCKET_LOG(("    ...returned after %i milliseconds\n",
         PR_IntervalToMilliseconds(passedInterval))); 

    *interval = PR_IntervalToSeconds(passedInterval);
    return rv;
}

bool
KeyframeEffectReadOnly::CanThrottleTransformChanges(nsIFrame& aFrame) const
{
  // If we know that the animation cannot cause overflow,
  // we can just disable flushes for this animation.

  // If we don't show scrollbars, we don't care about overflow.
  if (LookAndFeel::GetInt(LookAndFeel::eIntID_ShowHideScrollbars) == 0) {
    return true;
  }

  nsPresContext* presContext = GetPresContext();
  // CanThrottleTransformChanges is only called as part of a refresh driver tick
  // in which case we expect to has a pres context.
  MOZ_ASSERT(presContext);

  TimeStamp now =
    presContext->RefreshDriver()->MostRecentRefresh();

  EffectSet* effectSet = EffectSet::GetEffectSet(mTarget->mElement,
                                                 mTarget->mPseudoType);
  MOZ_ASSERT(effectSet, "CanThrottleTransformChanges is expected to be called"
                        " on an effect in an effect set");
  MOZ_ASSERT(mAnimation, "CanThrottleTransformChanges is expected to be called"
                         " on an effect with a parent animation");
  TimeStamp animationRuleRefreshTime =
    effectSet->AnimationRuleRefreshTime(mAnimation->CascadeLevel());
  // If this animation can cause overflow, we can throttle some of the ticks.
  if (!animationRuleRefreshTime.IsNull() &&
      (now - animationRuleRefreshTime) < OverflowRegionRefreshInterval()) {
    return true;
  }

  // If the nearest scrollable ancestor has overflow:hidden,
  // we don't care about overflow.
  nsIScrollableFrame* scrollable =
    nsLayoutUtils::GetNearestScrollableFrame(&aFrame);
  if (!scrollable) {
    return true;
  }

  ScrollbarStyles ss = scrollable->GetScrollbarStyles();
  if (ss.mVertical == NS_STYLE_OVERFLOW_HIDDEN &&
      ss.mHorizontal == NS_STYLE_OVERFLOW_HIDDEN &&
      scrollable->GetLogicalScrollPosition() == nsPoint(0, 0)) {
    return true;
  }

  return false;
}

// aID is a sub-identifier (in particular a specific MediaStramTrack)
void AsyncLatencyLogger::WriteLog(LatencyLogIndex aIndex, uint64_t aID, int64_t aValue,
                                  TimeStamp aTimeStamp)
{
  if (aTimeStamp.IsNull()) {
    MOZ_LOG(GetLatencyLog(), LogLevel::Debug,
      ("Latency: %s,%" PRIu64 ",%" PRId64 ",%" PRId64,
       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue));
  } else {
    MOZ_LOG(GetLatencyLog(), LogLevel::Debug,
      ("Latency: %s,%" PRIu64 ",%" PRId64 ",%" PRId64 ",%" PRId64,
       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue,
       static_cast<int64_t>((aTimeStamp - gAsyncLogger->mStart).ToMilliseconds())));
  }
}

// aID is a sub-identifier (in particular a specific MediaStramTrack)
void AsyncLatencyLogger::WriteLog(LatencyLogIndex aIndex, uint64_t aID, int64_t aValue,
                                  TimeStamp aTimeStamp)
{
  if (aTimeStamp.IsNull()) {
    PR_LOG(GetLatencyLog(), PR_LOG_DEBUG,
      ("Latency: %s,%llu,%lld,%lld",
       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue));
  } else {
    PR_LOG(GetLatencyLog(), PR_LOG_DEBUG,
      ("Latency: %s,%llu,%lld,%lld,%lld",
       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue,
       static_cast<int64_t>((aTimeStamp - gAsyncLogger->mStart).ToMilliseconds())));
  }
}

Nullable<TimeDuration> DocumentTimeline::ToTimelineTime(
    const TimeStamp& aTimeStamp) const {
  Nullable<TimeDuration> result;  // Initializes to null
  if (aTimeStamp.IsNull()) {
    return result;
  }

  nsDOMNavigationTiming* timing = mDocument->GetNavigationTiming();
  if (MOZ_UNLIKELY(!timing)) {
    return result;
  }

  result.SetValue(aTimeStamp - timing->GetNavigationStartTimeStamp() -
                  mOriginTime);
  return result;
}

void mozilla_sampler_responsiveness(const TimeStamp& aTime)
{
  if (!sLastTracerEvent.IsNull()) {
    if (sResponsivenessLoc == 100) {
      for(size_t i = 0; i < 100-1; i++) {
        sResponsivenessTimes[i] = sResponsivenessTimes[i+1];
      }
      sResponsivenessLoc--;
    }
    TimeDuration delta = aTime - sLastTracerEvent;
    sResponsivenessTimes[sResponsivenessLoc++] = delta.ToMilliseconds();
  }
  sCurrentEventGeneration++;

  sLastTracerEvent = aTime;
}

void
LayerManagerComposite::EndTransaction(const TimeStamp& aTimeStamp,
                                      EndTransactionFlags aFlags)
{
  NS_ASSERTION(mInTransaction, "Didn't call BeginTransaction?");
  NS_ASSERTION(!(aFlags & END_NO_COMPOSITE),
               "Shouldn't get END_NO_COMPOSITE here");
  mInTransaction = false;
  mRenderStartTime = TimeStamp::Now();

  if (!mIsCompositorReady) {
    return;
  }
  mIsCompositorReady = false;

#ifdef MOZ_LAYERS_HAVE_LOG
  MOZ_LAYERS_LOG(("  ----- (beginning paint)"));
  Log();
#endif

  if (mDestroyed) {
    NS_WARNING("Call on destroyed layer manager");
    return;
  }

  // Set composition timestamp here because we need it in
  // ComputeEffectiveTransforms (so the correct video frame size is picked) and
  // also to compute invalid regions properly.
  mCompositor->SetCompositionTime(aTimeStamp);

  if (mRoot && !(aFlags & END_NO_IMMEDIATE_REDRAW)) {
    MOZ_ASSERT(!aTimeStamp.IsNull());
    UpdateAndRender();
    mCompositor->FlushPendingNotifyNotUsed();
  } else {
    // Modified the layer tree.
    mGeometryChanged = true;
  }

  mCompositor->ClearTargetContext();
  mTarget = nullptr;

#ifdef MOZ_LAYERS_HAVE_LOG
  Log();
  MOZ_LAYERS_LOG(("]----- EndTransaction"));
#endif
}