1 files changed, 120 insertions, 0 deletions
diff --git a/Source/WebCore/page/scrolling/ScrollingThread.cpp b/Source/WebCore/page/scrolling/ScrollingThread.cpp
new file mode 100644
index 000000000..730c0a6bd
--- /dev/null
+++ b/Source/WebCore/page/scrolling/ScrollingThread.cpp
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+/*
+ * Copyright (C) 2012, 2015 Apple 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 INC. AND ITS CONTRIBUTORS ``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 INC. OR ITS 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 "ScrollingThread.h"
+
+#if ENABLE(ASYNC_SCROLLING)
+
+#include <mutex>
+#include <wtf/MainThread.h>
+#include <wtf/NeverDestroyed.h>
+
+namespace WebCore {
+
+ScrollingThread::ScrollingThread()
+    : m_threadIdentifier(0)
+{
+}
+
+bool ScrollingThread::isCurrentThread()
+{
+    auto threadIdentifier = ScrollingThread::singleton().m_threadIdentifier;
+    return threadIdentifier && currentThread() == threadIdentifier;
+}
+
+void ScrollingThread::dispatch(Function<void ()>&& function)
+{
+    auto& scrollingThread = ScrollingThread::singleton();
+    scrollingThread.createThreadIfNeeded();
+
+    {
+        std::lock_guard<Lock> lock(scrollingThread.m_functionsMutex);
+        scrollingThread.m_functions.append(WTFMove(function));
+    }
+
+    scrollingThread.wakeUpRunLoop();
+}
+
+void ScrollingThread::dispatchBarrier(Function<void ()>&& function)
+{
+    dispatch([function = WTFMove(function)]() mutable {
+        callOnMainThread(WTFMove(function));
+    });
+}
+
+ScrollingThread& ScrollingThread::singleton()
+{
+    static NeverDestroyed<ScrollingThread> scrollingThread;
+
+    return scrollingThread;
+}
+
+void ScrollingThread::createThreadIfNeeded()
+{
+    if (m_threadIdentifier)
+        return;
+
+    // Wait for the thread to initialize the run loop.
+    {
+        std::unique_lock<Lock> lock(m_initializeRunLoopMutex);
+
+        m_threadIdentifier = createThread(threadCallback, this, "WebCore: Scrolling");
+        
+#if PLATFORM(COCOA)
+        m_initializeRunLoopConditionVariable.wait(lock, [this]{ return m_threadRunLoop; });
+#endif
+    }
+}
+
+void ScrollingThread::threadCallback(void* scrollingThread)
+{
+    WTF::setCurrentThreadIsUserInteractive();
+    static_cast<ScrollingThread*>(scrollingThread)->threadBody();
+}
+
+void ScrollingThread::threadBody()
+{
+    initializeRunLoop();
+}
+
+void ScrollingThread::dispatchFunctionsFromScrollingThread()
+{
+    ASSERT(isCurrentThread());
+
+    Vector<Function<void ()>> functions;
+    
+    {
+        std::lock_guard<Lock> lock(m_functionsMutex);
+        functions = WTFMove(m_functions);
+    }
+
+    for (auto& function : functions)
+        function();
+}
+
+} // namespace WebCore
+
+#endif // ENABLE(ASYNC_SCROLLING)