Merge WebKit at r75315: Initial merge by git.

Change-Id: I570314b346ce101c935ed22a626b48c2af266b84

1 files changed, 148 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/wtf/ThreadSafeShared.h b/Source/JavaScriptCore/wtf/ThreadSafeShared.h
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+/*
+ * Copyright (C) 2007, 2008, 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
+ *
+ * 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 implementations of InterlockedIncrement and InterlockedDecrement are based
+ * on atomic_increment and atomic_exchange_and_add from the Boost C++ Library. The license
+ * is virtually identical to the Apple license above 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.
+ */
+
+#ifndef ThreadSafeShared_h
+#define ThreadSafeShared_h
+
+#include "Platform.h"
+
+#include <wtf/Atomics.h>
+#include <wtf/Noncopyable.h>
+#include <wtf/ThreadingPrimitives.h>
+
+namespace WTF {
+
+class ThreadSafeSharedBase : public Noncopyable {
+public:
+    ThreadSafeSharedBase(int initialRefCount = 1)
+        : m_refCount(initialRefCount)
+    {
+    }
+
+    void ref()
+    {
+#if USE(LOCKFREE_THREADSAFESHARED)
+        atomicIncrement(&m_refCount);
+#else
+        MutexLocker locker(m_mutex);
+        ++m_refCount;
+#endif
+    }
+
+    bool hasOneRef()
+    {
+        return refCount() == 1;
+    }
+
+    int refCount() const
+    {
+#if !USE(LOCKFREE_THREADSAFESHARED)
+        MutexLocker locker(m_mutex);
+#endif
+        return static_cast<int const volatile &>(m_refCount);
+    }
+
+protected:
+    // Returns whether the pointer should be freed or not.
+    bool derefBase()
+    {
+#if USE(LOCKFREE_THREADSAFESHARED)
+        if (atomicDecrement(&m_refCount) <= 0)
+            return true;
+#else
+        int refCount;
+        {
+            MutexLocker locker(m_mutex);
+            --m_refCount;
+            refCount = m_refCount;
+        }
+        if (refCount <= 0)
+            return true;
+#endif
+        return false;
+    }
+
+private:
+    template<class T>
+    friend class CrossThreadRefCounted;
+
+    int m_refCount;
+#if !USE(LOCKFREE_THREADSAFESHARED)
+    mutable Mutex m_mutex;
+#endif
+};
+
+template<class T> class ThreadSafeShared : public ThreadSafeSharedBase {
+public:
+    void deref()
+    {
+        if (derefBase())
+            delete static_cast<T*>(this);
+    }
+
+protected:
+    ThreadSafeShared()
+    {
+    }
+};
+
+} // namespace WTF
+
+using WTF::ThreadSafeShared;
+
+#endif // ThreadSafeShared_h