+++ /dev/null
-/*
- * 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"
-
-#include <wtf/iphone/WebCoreThread.h>
-
-namespace WTF {
-
- // Used to allowing sharing data across classes and threads (like ThreadSafeRefCounted).
- //
- // Why not just use ThreadSafeRefCounted?
- // ThreadSafeRefCounted 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 {
- WTF_MAKE_NONCOPYABLE(CrossThreadRefCounted);
- 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, ThreadSafeRefCountedBase* 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() || ((isMainThread() || pthread_main_np()) && WebCoreWebThreadIsLockedOrDisabled());
- }
-#endif
-
- RefCountedBase m_refCounter;
- ThreadSafeRefCountedBase* 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 ThreadSafeRefCountedBase(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
projects / apple / javascriptcore.git / blobdiff