Move SharedTimer implementation into sky/engine

sky/engine/platform/SharedTimer.cpp

-/*
- * Copyright (C) 2006 Apple Computer, 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.
- */
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
 
 #include "sky/engine/config.h"
 #include "sky/engine/platform/SharedTimer.h"
 
-#include "sky/engine/public/platform/Platform.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "sky/engine/wtf/CurrentTime.h"
 
 namespace blink {
+namespace {
+
+class SharedTimerImpl {
+    WTF_MAKE_NONCOPYABLE(SharedTimerImpl);
+public:
+    SharedTimerImpl()
+        : m_sharedTimerFunction(nullptr)
+        , m_sharedTimerFireTime(0)
+    {
+    }
+
+    static SharedTimerImpl& instance()
+    {
+        DEFINE_STATIC_LOCAL(SharedTimerImpl, instance, ());
+        return instance;
+    }
+
+    void setSharedTimerFiredFunction(void (*function)())
+    {
+        m_sharedTimerFunction = function;
+    }
+
+    void setSharedTimerFireInterval(double intervalSeconds)
+    {
+        double now = monotonicallyIncreasingTime();
+        m_sharedTimerFireTime = intervalSeconds + now;
+
+        // By converting between double and int64 representation, we run the risk
+        // of losing precision due to rounding errors. Performing computations in
+        // microseconds reduces this risk somewhat. But there still is the potential
+        // of us computing a fire time for the timer that is shorter than what we
+        // need.
+        // As the event loop will check event deadlines prior to actually firing
+        // them, there is a risk of needlessly rescheduling events and of
+        // needlessly looping if sleep times are too short even by small amounts.
+        // This results in measurable performance degradation unless we use ceil() to
+        // always round up the sleep times.
+        int64 interval = static_cast<int64>(ceil(intervalSeconds * base::Time::kMillisecondsPerSecond)
+            * base::Time::kMicrosecondsPerMillisecond);
+
+        if (interval < 0)
+            interval = 0;
+
+        m_sharedTimer.Stop();
+        m_sharedTimer.Start(FROM_HERE,
+            base::TimeDelta::FromMicroseconds(interval), this, &SharedTimerImpl::timerFired);
+    }
+
+    void stopSharedTimer()
+    {
+          m_sharedTimer.Stop();
+    }
+
+private:
+    void timerFired()
+    {
+        if (m_sharedTimerFunction)
+            m_sharedTimerFunction();
+    }
+
+    base::OneShotTimer<SharedTimerImpl> m_sharedTimer;
+    void (*m_sharedTimerFunction)();
+    double m_sharedTimerFireTime;
+};
+
+}
 
 void setSharedTimerFiredFunction(void (*f)())
 {
-    blink::Platform::current()->setSharedTimerFiredFunction(f);
+    SharedTimerImpl::instance().setSharedTimerFiredFunction(f);
 }
 
 void setSharedTimerFireInterval(double interval)
 {
-    blink::Platform::current()->setSharedTimerFireInterval(interval);
+    SharedTimerImpl::instance().setSharedTimerFireInterval(interval);
 }
 
 void stopSharedTimer()
 {
-    blink::Platform::current()->stopSharedTimer();
+    SharedTimerImpl::instance().stopSharedTimer();
 }
 
 } // namespace blink