Move Source/WTF/wtf to Source/wtf

Source/WTF/wtf/RefCounted.h

-/*
- * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this library; see the file COPYING.LIB.  If not, write to
- * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- *
- */
-
-#ifndef RefCounted_h
-#define RefCounted_h
-
-#include <wtf/Assertions.h>
-#include <wtf/FastAllocBase.h>
-#include <wtf/Noncopyable.h>
-#include <wtf/OwnPtr.h>
-#include <wtf/ThreadRestrictionVerifier.h>
-#include <wtf/UnusedParam.h>
-
-namespace WTF {
-
-#ifdef NDEBUG
-#define CHECK_REF_COUNTED_LIFECYCLE 0
-#else
-#define CHECK_REF_COUNTED_LIFECYCLE 1
-#endif
-
-// This base class holds the non-template methods and attributes.
-// The RefCounted class inherits from it reducing the template bloat
-// generated by the compiler (technique called template hoisting).
-class RefCountedBase {
-public:
-    void ref()
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        // Start thread verification as soon as the ref count gets to 2. This
-        // heuristic reflects the fact that items are often created on one thread
-        // and then given to another thread to be used.
-        // FIXME: Make this restriction tigher. Especially as we move to more
-        // common methods for sharing items across threads like CrossThreadCopier.h
-        // We should be able to add a "detachFromThread" method to make this explicit.
-        if (m_refCount == 1)
-            m_verifier.setShared(true);
-        // If this assert fires, it either indicates a thread safety issue or
-        // that the verification needs to change. See ThreadRestrictionVerifier for
-        // the different modes.
-        ASSERT(m_verifier.isSafeToUse());
-        ASSERT(!m_deletionHasBegun);
-        ASSERT(!m_adoptionIsRequired);
-#endif
-        ++m_refCount;
-    }
-
-    bool hasOneRef() const
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        ASSERT(m_verifier.isSafeToUse());
-        ASSERT(!m_deletionHasBegun);
-#endif
-        return m_refCount == 1;
-    }
-
-    int refCount() const
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        ASSERT(m_verifier.isSafeToUse());
-#endif
-        return m_refCount;
-    }
-
-    void setMutexForVerifier(Mutex&);
-
-#if HAVE(DISPATCH_H)
-    void setDispatchQueueForVerifier(dispatch_queue_t);
-#endif
-
-    // Turns off verification. Use of this method is discouraged (instead extend
-    // ThreadRestrictionVerifier to verify your case).
-    // NB. It is necessary to call this in the constructor of many objects in
-    // JavaScriptCore, because JavaScriptCore objects may be used from multiple
-    // threads even if the reference counting is done in a racy manner. This is
-    // because a JSC instance may be used from multiple threads so long as all
-    // accesses into that instance are protected by a per-instance lock. It would
-    // be absolutely wrong to prohibit this pattern, and it would be a disastrous
-    // regression to require that the objects within that instance use a thread-
-    // safe version of reference counting.
-    void turnOffVerifier()
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        m_verifier.turnOffVerification();
-#endif
-    }
-
-    void relaxAdoptionRequirement()
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        ASSERT(!m_deletionHasBegun);
-        ASSERT(m_adoptionIsRequired);
-        m_adoptionIsRequired = false;
-#endif
-    }
-
-    // Helper for generating JIT code. Please do not use for non-JIT purposes.
-    const int* addressOfCount() const
-    {
-        return &m_refCount;
-    }
-
-protected:
-    RefCountedBase()
-        : m_refCount(1)
-#if CHECK_REF_COUNTED_LIFECYCLE
-        , m_deletionHasBegun(false)
-        , m_adoptionIsRequired(true)
-#endif
-    {
-    }
-
-    ~RefCountedBase()
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        ASSERT(m_deletionHasBegun);
-        ASSERT(!m_adoptionIsRequired);
-#endif
-    }
-
-    // Returns whether the pointer should be freed or not.
-    bool derefBase()
-    {
-#if CHECK_REF_COUNTED_LIFECYCLE
-        ASSERT(m_verifier.isSafeToUse());
-        ASSERT(!m_deletionHasBegun);
-        ASSERT(!m_adoptionIsRequired);
-#endif
-
-        ASSERT(m_refCount > 0);
-        if (m_refCount == 1) {
-#if CHECK_REF_COUNTED_LIFECYCLE
-            m_deletionHasBegun = true;
-#endif
-            return true;
-        }
-
-        --m_refCount;
-#if CHECK_REF_COUNTED_LIFECYCLE
-        // Stop thread verification when the ref goes to 1 because it
-        // is safe to be passed to another thread at this point.
-        if (m_refCount == 1)
-            m_verifier.setShared(false);
-#endif
-        return false;
-    }
-
-#if CHECK_REF_COUNTED_LIFECYCLE
-    bool deletionHasBegun() const
-    {
-        return m_deletionHasBegun;
-    }
-#endif
-
-private:
-
-#if CHECK_REF_COUNTED_LIFECYCLE
-    friend void adopted(RefCountedBase*);
-#endif
-
-    int m_refCount;
-#if CHECK_REF_COUNTED_LIFECYCLE
-    bool m_deletionHasBegun;
-    bool m_adoptionIsRequired;
-    ThreadRestrictionVerifier m_verifier;
-#endif
-};
-
-#if CHECK_REF_COUNTED_LIFECYCLE
-inline void adopted(RefCountedBase* object)
-{
-    if (!object)
-        return;
-    ASSERT(!object->m_deletionHasBegun);
-    object->m_adoptionIsRequired = false;
-}
-#endif
-
-template<typename T> class RefCounted : public RefCountedBase {
-    WTF_MAKE_NONCOPYABLE(RefCounted); WTF_MAKE_FAST_ALLOCATED;
-public:
-    void deref()
-    {
-        if (derefBase())
-            delete static_cast<T*>(this);
-    }
-
-protected:
-    RefCounted() { }
-    ~RefCounted()
-    {
-    }
-};
-
-template<typename T> class RefCountedCustomAllocated : public RefCountedBase {
-    WTF_MAKE_NONCOPYABLE(RefCountedCustomAllocated);
-
-public:
-    void deref()
-    {
-        if (derefBase())
-            delete static_cast<T*>(this);
-    }
-
-protected:
-    ~RefCountedCustomAllocated()
-    {
-    }
-};
-
-#if CHECK_REF_COUNTED_LIFECYCLE
-inline void RefCountedBase::setMutexForVerifier(Mutex& mutex)
-{
-    m_verifier.setMutexMode(mutex);
-}
-#else
-inline void RefCountedBase::setMutexForVerifier(Mutex&) { }
-#endif
-
-#if HAVE(DISPATCH_H)
-#if CHECK_REF_COUNTED_LIFECYCLE
-inline void RefCountedBase::setDispatchQueueForVerifier(dispatch_queue_t queue)
-{
-    m_verifier.setDispatchQueueMode(queue);
-}
-#else
-inline void RefCountedBase::setDispatchQueueForVerifier(dispatch_queue_t) { }
-#endif
-#endif // HAVE(DISPATCH_H)
-
-} // namespace WTF
-
-using WTF::RefCounted;
-using WTF::RefCountedCustomAllocated;
-
-#endif // RefCounted_h