1 files changed, 234 insertions, 0 deletions
diff --git a/Source/WebKit2/Platform/win/WorkQueueWin.cpp b/Source/WebKit2/Platform/win/WorkQueueWin.cpp
new file mode 100644
index 0000000..f527432
--- /dev/null
+++ b/Source/WebKit2/Platform/win/WorkQueueWin.cpp
@@ -0,0 +1,234 @@
+/*
+ * Copyright (C) 2010 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 "WorkQueue.h"
+
+#include <wtf/Threading.h>
+#include "NotImplemented.h"
+
+inline WorkQueue::WorkItemWin::WorkItemWin(PassOwnPtr<WorkItem> item, WorkQueue* queue)
+    : m_item(item)
+    , m_queue(queue)
+{
+}
+
+PassRefPtr<WorkQueue::WorkItemWin> WorkQueue::WorkItemWin::create(PassOwnPtr<WorkItem> item, WorkQueue* queue)
+{
+    return adoptRef(new WorkItemWin(item, queue));
+}
+
+WorkQueue::WorkItemWin::~WorkItemWin()
+{
+}
+
+inline WorkQueue::HandleWorkItem::HandleWorkItem(HANDLE handle, PassOwnPtr<WorkItem> item, WorkQueue* queue)
+    : WorkItemWin(item, queue)
+    , m_handle(handle)
+    , m_waitHandle(0)
+{
+    ASSERT_ARG(handle, handle);
+}
+
+PassRefPtr<WorkQueue::HandleWorkItem> WorkQueue::HandleWorkItem::createByAdoptingHandle(HANDLE handle, PassOwnPtr<WorkItem> item, WorkQueue* queue)
+{
+    return adoptRef(new HandleWorkItem(handle, item, queue));
+}
+
+WorkQueue::HandleWorkItem::~HandleWorkItem()
+{
+    ::CloseHandle(m_handle);
+}
+
+void WorkQueue::handleCallback(void* context, BOOLEAN timerOrWaitFired)
+{
+    ASSERT_ARG(context, context);
+    ASSERT_ARG(timerOrWaitFired, !timerOrWaitFired);
+
+    WorkItemWin* item = static_cast<WorkItemWin*>(context);
+    WorkQueue* queue = item->queue();
+
+    {
+        MutexLocker lock(queue->m_workItemQueueLock);
+        queue->m_workItemQueue.append(item);
+
+        // If no other thread is performing work, we can do it on this thread.
+        if (!queue->tryRegisterAsWorkThread()) {
+            // Some other thread is performing work. Since we hold the queue lock, we can be sure
+            // that the work thread is not exiting due to an empty queue and will process the work
+            // item we just added to it. If we weren't holding the lock we'd have to signal
+            // m_performWorkEvent to make sure the work item got picked up.
+            return;
+        }
+    }
+
+    queue->performWorkOnRegisteredWorkThread();
+}
+
+void WorkQueue::registerHandle(HANDLE handle, PassOwnPtr<WorkItem> item)
+{
+    RefPtr<HandleWorkItem> handleItem = HandleWorkItem::createByAdoptingHandle(handle, item, this);
+
+    {
+        MutexLocker lock(m_handlesLock);
+        ASSERT_ARG(handle, !m_handles.contains(handle));
+        m_handles.set(handle, handleItem);
+    }
+
+    HANDLE waitHandle;
+    if (!::RegisterWaitForSingleObject(&waitHandle, handle, handleCallback, handleItem.get(), INFINITE, WT_EXECUTEDEFAULT)) {
+        DWORD error = ::GetLastError();
+        ASSERT_NOT_REACHED();
+    }
+    handleItem->setWaitHandle(waitHandle);
+}
+
+void WorkQueue::unregisterAndCloseHandle(HANDLE handle)
+{
+    RefPtr<HandleWorkItem> item;
+    {
+        MutexLocker locker(m_handlesLock);
+        ASSERT_ARG(handle, m_handles.contains(handle));
+        item = m_handles.take(handle);
+    }
+
+    unregisterWaitAndDestroyItemSoon(item.release());
+}
+
+DWORD WorkQueue::workThreadCallback(void* context)
+{
+    ASSERT_ARG(context, context);
+
+    WorkQueue* queue = static_cast<WorkQueue*>(context);
+
+    if (!queue->tryRegisterAsWorkThread())
+        return 0;
+
+    queue->performWorkOnRegisteredWorkThread();
+    return 0;
+}
+
+void WorkQueue::performWorkOnRegisteredWorkThread()
+{
+    ASSERT(m_isWorkThreadRegistered);
+
+    bool isValid = true;
+
+    m_workItemQueueLock.lock();
+
+    while (isValid && !m_workItemQueue.isEmpty()) {
+        Vector<RefPtr<WorkItemWin> > workItemQueue;
+        m_workItemQueue.swap(workItemQueue);
+
+        // Allow more work to be scheduled while we're not using the queue directly.
+        m_workItemQueueLock.unlock();
+        for (size_t i = 0; i < workItemQueue.size(); ++i) {
+            MutexLocker locker(m_isValidMutex);
+            isValid = m_isValid;
+            if (!isValid)
+                break;
+            workItemQueue[i]->item()->execute();
+        }
+        m_workItemQueueLock.lock();
+    }
+
+    // One invariant we maintain is that any work scheduled while a work thread is registered will
+    // be handled by that work thread. Unregister as the work thread while the queue lock is still
+    // held so that no work can be scheduled while we're still registered.
+    unregisterAsWorkThread();
+
+    m_workItemQueueLock.unlock();
+}
+
+void WorkQueue::platformInitialize(const char* name)
+{
+    m_isWorkThreadRegistered = 0;
+}
+
+bool WorkQueue::tryRegisterAsWorkThread()
+{
+    LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 1, 0);
+    ASSERT(!result || result == 1);
+    return !result;
+}
+
+void WorkQueue::unregisterAsWorkThread()
+{
+    LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 0, 1);
+    ASSERT_UNUSED(result, result == 1);
+}
+
+void WorkQueue::platformInvalidate()
+{
+#if !ASSERT_DISABLED
+    MutexLocker lock(m_handlesLock);
+    ASSERT(m_handles.isEmpty());
+#endif
+}
+
+void WorkQueue::scheduleWork(PassOwnPtr<WorkItem> item)
+{
+    MutexLocker locker(m_workItemQueueLock);
+
+    m_workItemQueue.append(WorkItemWin::create(item, this));
+
+    // Spawn a work thread to perform the work we just added. As an optimization, we avoid
+    // spawning the thread if a work thread is already registered. This prevents multiple work
+    // threads from being spawned in most cases. (Note that when a work thread has been spawned but
+    // hasn't registered itself yet, m_isWorkThreadRegistered will be false and we'll end up
+    // spawning a second work thread here. But work thread registration process will ensure that
+    // only one thread actually ends up performing work.)
+    if (!m_isWorkThreadRegistered)
+        ::QueueUserWorkItem(workThreadCallback, this, WT_EXECUTEDEFAULT);
+}
+
+void WorkQueue::scheduleWorkAfterDelay(PassOwnPtr<WorkItem>, double)
+{
+    notImplemented();
+}
+
+void WorkQueue::unregisterWaitAndDestroyItemSoon(PassRefPtr<HandleWorkItem> item)
+{
+    // We're going to make a blocking call to ::UnregisterWaitEx before closing the handle. (The
+    // blocking version of ::UnregisterWaitEx is much simpler than the non-blocking version.) If we
+    // do this on the current thread, we'll deadlock if we're currently in a callback function for
+    // the wait we're unregistering. So instead we do it asynchronously on some other worker thread.
+
+    ::QueueUserWorkItem(unregisterWaitAndDestroyItemCallback, item.leakRef(), WT_EXECUTEDEFAULT);
+}
+
+DWORD WINAPI WorkQueue::unregisterWaitAndDestroyItemCallback(void* context)
+{
+    ASSERT_ARG(context, context);
+    RefPtr<HandleWorkItem> item = adoptRef(static_cast<HandleWorkItem*>(context));
+
+    // Now that we know we're not in a callback function for the wait we're unregistering, we can
+    // make a blocking call to ::UnregisterWaitEx.
+    if (!::UnregisterWaitEx(item->waitHandle(), INVALID_HANDLE_VALUE)) {
+        DWORD error = ::GetLastError();
+        ASSERT_NOT_REACHED();
+    }
+
+    return 0;
+}