diff -r 000000000000 -r 4f2f89ce4247 WebCore/platform/ThreadTimers.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/platform/ThreadTimers.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,132 @@
+/*
+ * 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 "ThreadTimers.h"
+
+#include "SharedTimer.h"
+#include "ThreadGlobalData.h"
+#include "Timer.h"
+#include <wtf/CurrentTime.h>
+
+namespace WebCore {
+
+// 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 MainThreadSharedTimer* mainThreadSharedTimer()
+{
+    static MainThreadSharedTimer* timer = new MainThreadSharedTimer;
+    return timer;
+}
+
+ThreadTimers::ThreadTimers()
+    : m_sharedTimer(0)
+    , m_firingTimers(false)
+{
+    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(SharedTimer* sharedTimer)
+{
+    if (m_sharedTimer) {
+        m_sharedTimer->setFiredFunction(0);
+        m_sharedTimer->stop();
+    }
+    
+    m_sharedTimer = sharedTimer;
+    
+    if (sharedTimer) {
+        m_sharedTimer->setFiredFunction(ThreadTimers::sharedTimerFired);
+        updateSharedTimer();
+    }
+}
+
+void ThreadTimers::updateSharedTimer()
+{
+    if (!m_sharedTimer)
+        return;
+        
+    if (m_firingTimers || m_timerHeap.isEmpty())
+        m_sharedTimer->stop();
+    else
+        m_sharedTimer->setFireTime(m_timerHeap.first()->m_nextFireTime);
+}
+
+void ThreadTimers::sharedTimerFired()
+{
+    // Redirect to non-static method.
+    threadGlobalData().threadTimers().sharedTimerFiredInternal();
+}
+
+void ThreadTimers::sharedTimerFiredInternal()
+{
+    // Do a re-entrancy check.
+    if (m_firingTimers)
+        return;
+    m_firingTimers = true;
+
+    double fireTime = currentTime();
+    double timeToQuit = fireTime + maxDurationOfFiringTimers;
+
+    while (!m_timerHeap.isEmpty() && m_timerHeap.first()->m_nextFireTime <= fireTime) {
+        TimerBase* timer = m_timerHeap.first();
+        timer->m_nextFireTime = 0;
+        timer->heapDeleteMin();
+
+        double interval = timer->repeatInterval();
+        timer->setNextFireTime(interval ? fireTime + interval : 0);
+
+        // 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 < currentTime())
+            break;
+    }
+
+    m_firingTimers = false;
+
+    updateSharedTimer();
+}
+
+void ThreadTimers::fireTimersInNestedEventLoop()
+{
+    // Reset the reentrancy guard so the timers can fire again.
+    m_firingTimers = false;
+    updateSharedTimer();
+}
+
+} // namespace WebCore
+