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+/*
+ * Copyright (C) 2007 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.
+ * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ * its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE 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 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.
+ *
+ * =============================================================================
+ * Note: The implementation of condition variables under the Windows
+ * plaform was based on that of the excellent BOOST C++ library. It
+ * has been rewritten to fit in with the WebKit architecture and to
+ * use its coding conventions.
+ * =============================================================================
+ *
+ * The Boost license is virtually identical to the Apple variation at the
+ * top of this file, but is included here for completeness:
+ *
+ * Boost Software License - Version 1.0 - August 17th, 2003
+ *
+ * Permission is hereby granted, free of charge, to any person or organization
+ * obtaining a copy of the software and accompanying documentation covered by
+ * this license (the "Software") to use, reproduce, display, distribute,
+ * execute, and transmit the Software, and to prepare derivative works of the
+ * Software, and to permit third-parties to whom the Software is furnished to
+ * do so, all subject to the following:
+ *
+ * The copyright notices in the Software and this entire statement, including
+ * the above license grant, this restriction and the following disclaimer,
+ * must be included in all copies of the Software, in whole or in part, and
+ * all derivative works of the Software, unless such copies or derivative
+ * works are solely in the form of machine-executable object code generated by
+ * a source language processor.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+ * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+ * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+#include "Logging.h"
+#include "Threading.h"
+#include <limits>
+#include <errno.h>
+
+namespace WebCore {
+
+static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1);
+
+ThreadCondition::ThreadCondition()
+{
+ m_condition.m_timedOut = 0;
+ m_condition.m_blocked = 0;
+ m_condition.m_waitingForRemoval = 0;
+ m_condition.m_gate = ::CreateSemaphore(0, 1, 1, 0);
+ m_condition.m_queue = ::CreateSemaphore(0, 0, MaxSemaphoreCount, 0);
+ m_condition.m_mutex = ::CreateMutex(0, 0, 0);
+
+ if (!m_condition.m_gate || !m_condition.m_queue || !m_condition.m_mutex) {
+ if (m_condition.m_gate)
+ ::CloseHandle(m_condition.m_gate);
+ if (m_condition.m_queue)
+ ::CloseHandle(m_condition.m_queue);
+ if (m_condition.m_mutex)
+ ::CloseHandle(m_condition.m_mutex);
+ }
+}
+
+ThreadCondition::~ThreadCondition()
+{
+ ::CloseHandle(m_condition.m_gate);
+ ::CloseHandle(m_condition.m_queue);
+ ::CloseHandle(m_condition.m_mutex);
+}
+
+void ThreadCondition::wait(Mutex& mutex)
+{
+ PlatformMutex& cs = mutex.impl();
+
+ // Enter the wait state.
+ DWORD res = ::WaitForSingleObject(m_condition.m_gate, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ ++m_condition.m_blocked;
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0);
+ ASSERT(res);
+
+ ::LeaveCriticalSection(&cs.m_internalMutex);
+
+ res = ::WaitForSingleObject(m_condition.m_queue, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+
+ res = ::WaitForSingleObject(m_condition.m_mutex, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ size_t wasWaiting = m_condition.m_waitingForRemoval;
+ size_t wasTimedOut = m_condition.m_timedOut;
+ if (wasWaiting != 0) {
+ if (--m_condition.m_waitingForRemoval == 0) {
+ if (m_condition.m_blocked != 0) {
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0); // open m_gate
+ ASSERT(res);
+ wasWaiting = 0;
+ }
+ else if (m_condition.m_timedOut != 0)
+ m_condition.m_timedOut = 0;
+ }
+ } else if (++m_condition.m_timedOut == ((std::numeric_limits<unsigned>::max)() / 2)) {
+ // timeout occured, normalize the m_condition.m_timedOut count
+ // this may occur if many calls to wait with a timeout are made and
+ // no call to notify_* is made
+ res = ::WaitForSingleObject(m_condition.m_gate, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ m_condition.m_blocked -= m_condition.m_timedOut;
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0);
+ ASSERT(res);
+ m_condition.m_timedOut = 0;
+ }
+ res = ::ReleaseMutex(m_condition.m_mutex);
+ ASSERT(res);
+
+ if (wasWaiting == 1) {
+ for (/**/ ; wasTimedOut; --wasTimedOut) {
+ // better now than spurious later
+ res = ::WaitForSingleObject(m_condition.m_queue, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ }
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0);
+ ASSERT(res);
+ }
+
+ ::EnterCriticalSection (&cs.m_internalMutex);
+}
+
+void ThreadCondition::signal()
+{
+ unsigned signals = 0;
+
+ DWORD res = ::WaitForSingleObject(m_condition.m_mutex, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+
+ if (m_condition.m_waitingForRemoval != 0) { // the m_gate is already closed
+ if (m_condition.m_blocked == 0) {
+ res = ::ReleaseMutex(m_condition.m_mutex);
+ ASSERT(res);
+ return;
+ }
+
+ ++m_condition.m_waitingForRemoval;
+ --m_condition.m_blocked;
+
+ signals = 1;
+ } else {
+ res = ::WaitForSingleObject(m_condition.m_gate, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ if (m_condition.m_blocked > m_condition.m_timedOut) {
+ if (m_condition.m_timedOut != 0) {
+ m_condition.m_blocked -= m_condition.m_timedOut;
+ m_condition.m_timedOut = 0;
+ }
+ signals = m_condition.m_waitingForRemoval = 1;
+ --m_condition.m_blocked;
+ } else {
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0);
+ ASSERT(res);
+ }
+ }
+
+ res =::ReleaseMutex(m_condition.m_mutex);
+ ASSERT(res);
+
+ if (signals) {
+ res = ::ReleaseSemaphore(m_condition.m_queue, signals, 0);
+ ASSERT(res);
+ }
+}
+
+void ThreadCondition::broadcast()
+{
+ unsigned signals = 0;
+
+ WORD res = ::WaitForSingleObject(m_condition.m_mutex, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+
+ if (m_condition.m_waitingForRemoval != 0) { // the m_gate is already closed
+ if (m_condition.m_blocked == 0) {
+ res = ::ReleaseMutex(m_condition.m_mutex);
+ ASSERT(res);
+ return;
+ }
+
+ m_condition.m_waitingForRemoval += (signals = m_condition.m_blocked);
+ m_condition.m_blocked = 0;
+ } else {
+ res = ::WaitForSingleObject(m_condition.m_gate, INFINITE);
+ ASSERT(res == WAIT_OBJECT_0);
+ if (m_condition.m_blocked > m_condition.m_timedOut) {
+ if (m_condition.m_timedOut != 0) {
+ m_condition.m_blocked -= m_condition.m_timedOut;
+ m_condition.m_timedOut = 0;
+ }
+ signals = m_condition.m_waitingForRemoval = m_condition.m_blocked;
+ m_condition.m_blocked = 0;
+ } else {
+ res = ::ReleaseSemaphore(m_condition.m_gate, 1, 0);
+ ASSERT(res);
+ }
+ }
+
+ res = ::ReleaseMutex(m_condition.m_mutex);
+ ASSERT(res);
+
+ if (signals) {
+ res = ::ReleaseSemaphore(m_condition.m_queue, signals, 0);
+ ASSERT(res);
+ }
+}
+
+} // namespace WebCore