diff options
Diffstat (limited to 'JavaScriptCore/wtf/CrossThreadRefCounted.h')
| -rw-r--r-- | JavaScriptCore/wtf/CrossThreadRefCounted.h | 174 |
1 files changed, 0 insertions, 174 deletions
diff --git a/JavaScriptCore/wtf/CrossThreadRefCounted.h b/JavaScriptCore/wtf/CrossThreadRefCounted.h deleted file mode 100644 index 0c0e997..0000000 --- a/JavaScriptCore/wtf/CrossThreadRefCounted.h +++ /dev/null @@ -1,174 +0,0 @@ -/* - * Copyright (C) 2009 Google Inc. All rights reserved. - * 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: - * - * * Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * * 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. - * * Neither the name of Google Inc. 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT - * OWNER 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. - */ - -#ifndef CrossThreadRefCounted_h -#define CrossThreadRefCounted_h - -#include "PassRefPtr.h" -#include "RefCounted.h" -#include "Threading.h" - -namespace WTF { - - // Used to allowing sharing data across classes and threads (like ThreadedSafeShared). - // - // Why not just use ThreadSafeShared? - // ThreadSafeShared can have a significant perf impact when used in low level classes - // (like UString) that get ref/deref'ed a lot. This class has the benefit of doing fast ref - // counts like RefPtr whenever possible, but it has the downside that you need to copy it - // to use it on another thread. - // - // Is this class threadsafe? - // While each instance of the class is not threadsafe, the copied instance is threadsafe - // with respect to the original and any other copies. The underlying m_data is jointly - // owned by the original instance and all copies. - template<class T> - class CrossThreadRefCounted : public Noncopyable { - public: - static PassRefPtr<CrossThreadRefCounted<T> > create(T* data) - { - return adoptRef(new CrossThreadRefCounted<T>(data, 0)); - } - - // Used to make an instance that can be used on another thread. - PassRefPtr<CrossThreadRefCounted<T> > crossThreadCopy(); - - void ref(); - void deref(); - T* release(); - - bool isShared() const - { - return !m_refCounter.hasOneRef() || (m_threadSafeRefCounter && !m_threadSafeRefCounter->hasOneRef()); - } - - private: - CrossThreadRefCounted(T* data, ThreadSafeSharedBase* threadedCounter) - : m_threadSafeRefCounter(threadedCounter) - , m_data(data) -#ifndef NDEBUG - , m_threadId(0) -#endif - { - // We use RefCountedBase in an unusual way here, so get rid of the requirement - // that adoptRef be called on it. - m_refCounter.relaxAdoptionRequirement(); - } - - ~CrossThreadRefCounted() - { - if (!m_threadSafeRefCounter) - delete m_data; - } - - void threadSafeDeref(); - -#ifndef NDEBUG - bool isOwnedByCurrentThread() const { return !m_threadId || m_threadId == currentThread(); } -#endif - - RefCountedBase m_refCounter; - ThreadSafeSharedBase* m_threadSafeRefCounter; - T* m_data; -#ifndef NDEBUG - ThreadIdentifier m_threadId; -#endif - }; - - template<class T> - void CrossThreadRefCounted<T>::ref() - { - ASSERT(isOwnedByCurrentThread()); - m_refCounter.ref(); -#ifndef NDEBUG - // Store the threadId as soon as the ref count gets to 2. - // The class gets created with a ref count of 1 and then passed - // to another thread where to ref count get increased. This - // is a heuristic but it seems to always work and has helped - // find some bugs. - if (!m_threadId && m_refCounter.refCount() == 2) - m_threadId = currentThread(); -#endif - } - - template<class T> - void CrossThreadRefCounted<T>::deref() - { - ASSERT(isOwnedByCurrentThread()); - if (m_refCounter.derefBase()) { - threadSafeDeref(); - delete this; - } else { -#ifndef NDEBUG - // Clear the threadId when the ref goes to 1 because it - // is safe to be passed to another thread at this point. - if (m_threadId && m_refCounter.refCount() == 1) - m_threadId = 0; -#endif - } - } - - template<class T> - T* CrossThreadRefCounted<T>::release() - { - ASSERT(!isShared()); - - T* data = m_data; - m_data = 0; - return data; - } - - template<class T> - PassRefPtr<CrossThreadRefCounted<T> > CrossThreadRefCounted<T>::crossThreadCopy() - { - ASSERT(isOwnedByCurrentThread()); - if (m_threadSafeRefCounter) - m_threadSafeRefCounter->ref(); - else - m_threadSafeRefCounter = new ThreadSafeSharedBase(2); - - return adoptRef(new CrossThreadRefCounted<T>(m_data, m_threadSafeRefCounter)); - } - - - template<class T> - void CrossThreadRefCounted<T>::threadSafeDeref() - { - if (m_threadSafeRefCounter && m_threadSafeRefCounter->derefBase()) { - delete m_threadSafeRefCounter; - m_threadSafeRefCounter = 0; - } - } -} // namespace WTF - -using WTF::CrossThreadRefCounted; - -#endif // CrossThreadRefCounted_h |