Implement timers by posting delayed tasks

Source/platform/ThreadTimers.cpp

-/*
- * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
- * Copyright (C) 2009 Google Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include "config.h"
-#include "platform/ThreadTimers.h"
-
-#include "platform/PlatformThreadData.h"
-#include "platform/SharedTimer.h"
-#include "platform/Timer.h"
-#include "platform/TraceEvent.h"
-#include "public/platform/Platform.h"
-#include "public/platform/WebScheduler.h"
-#include "wtf/AddressSanitizer.h"
-#include "wtf/CurrentTime.h"
-#include "wtf/MainThread.h"
-
-namespace blink {
-
-// Fire timers for this length of time, and then quit to let the run loop process user input events.
-// 100ms is about a perceptable delay in UI, so use a half of that as a threshold.
-// This is to prevent UI freeze when there are too many timers or machine performance is low.
-static const double maxDurationOfFiringTimers = 0.050;
-
-// Timers are created, started and fired on the same thread, and each thread has its own ThreadTimers
-// copy to keep the heap and a set of currently firing timers.
-
-static PassOwnPtr<MainThreadSharedTimer> mainThreadSharedTimer()
-{
-    return adoptPtr(new MainThreadSharedTimer);
-}
-
-ThreadTimers::ThreadTimers()
-    : m_sharedTimer(0)
-    , m_firingTimers(false)
-    , m_pendingSharedTimerFireTime(0)
-{
-    if (isMainThread())
-        setSharedTimer(mainThreadSharedTimer());
-}
-
-// A worker thread may initialize SharedTimer after some timers are created.
-// Also, SharedTimer can be replaced with 0 before all timers are destroyed.
-void ThreadTimers::setSharedTimer(PassOwnPtr<SharedTimer> sharedTimer)
-{
-    if (m_sharedTimer) {
-        m_sharedTimer->setFiredFunction(0);
-        m_sharedTimer->stop();
-        m_pendingSharedTimerFireTime = 0;
-    }
-
-    m_sharedTimer = sharedTimer;
-
-    if (m_sharedTimer) {
-        m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
-        updateSharedTimer();
-    }
-}
-
-NO_LAZY_SWEEP_SANITIZE_ADDRESS
-void ThreadTimers::updateSharedTimer()
-{
-    if (!m_sharedTimer)
-        return;
-
-    if (m_firingTimers || m_timerHeap.isEmpty()) {
-        m_pendingSharedTimerFireTime = 0;
-        m_sharedTimer->stop();
-    } else {
-        double nextFireTime = m_timerHeap.first()->m_nextFireTime;
-        double currentMonotonicTime = monotonicallyIncreasingTime();
-        if (m_pendingSharedTimerFireTime) {
-            // No need to restart the timer if both the pending fire time and the new fire time are in the past.
-            if (m_pendingSharedTimerFireTime <= currentMonotonicTime && nextFireTime <= currentMonotonicTime)
-                return;
-        }
-        m_pendingSharedTimerFireTime = nextFireTime;
-        m_sharedTimer->setFireInterval(std::max(nextFireTime - currentMonotonicTime, 0.0));
-    }
-}
-
-void ThreadTimers::sharedTimerFired()
-{
-    TRACE_EVENT_SET_SAMPLING_STATE("blink", "BlinkInternal");
-
-    // Redirect to non-static method.
-    PlatformThreadData::current().threadTimers().sharedTimerFiredInternal();
-
-    TRACE_EVENT_SET_SAMPLING_STATE("blink", "Sleeping");
-}
-
-NO_LAZY_SWEEP_SANITIZE_ADDRESS
-void ThreadTimers::sharedTimerFiredInternal()
-{
-    // Do a re-entrancy check.
-    if (m_firingTimers)
-        return;
-    m_firingTimers = true;
-    m_pendingSharedTimerFireTime = 0;
-
-    double fireTime = monotonicallyIncreasingTime();
-    double timeToQuit = fireTime + maxDurationOfFiringTimers;
-
-    while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
-        TimerBase& timer = *m_timerHeap.first();
-        timer.m_nextFireTime = 0;
-        timer.m_unalignedNextFireTime = 0;
-        timer.heapDeleteMin();
-
-        double interval = timer.repeatInterval();
-        timer.setNextFireTime(interval ? fireTime + interval : 0);
-
-        TRACE_EVENT2("blink", "ThreadTimers::sharedTimerFiredInternal",
-            "src_file", timer.location().fileName(),
-            "src_func", timer.location().functionName());
-
-        // Once the timer has been fired, it may be deleted, so do nothing else with it after this point.
-        timer.fired();
-
-        // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
-        if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime()
-            || (isMainThread() && Platform::current()->currentThread()->scheduler()->shouldYieldForHighPriorityWork()))
-            break;
-    }
-
-    m_firingTimers = false;
-
-    updateSharedTimer();
-}
-
-} // namespace blink