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/*
* 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 "Assertions.h"
#include "FastAllocBase.h"
#include "ThreadRestrictionVerifier.h"
#include "Noncopyable.h"
#include "OwnPtr.h"
#include "UnusedParam.h"
namespace WTF {
// 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()
{
#ifndef NDEBUG
// 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);
#endif
// 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);
++m_refCount;
}
bool hasOneRef() const
{
ASSERT(m_verifier.isSafeToUse());
ASSERT(!m_deletionHasBegun);
return m_refCount == 1;
}
int refCount() const
{
ASSERT(m_verifier.isSafeToUse());
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).
// FIXME: remove this method.
void deprecatedTurnOffVerifier()
{
#ifndef NDEBUG
m_verifier.turnOffVerification();
#endif
}
void relaxAdoptionRequirement()
{
#ifndef NDEBUG
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)
#ifndef NDEBUG
, m_deletionHasBegun(false)
, m_adoptionIsRequired(true)
#endif
{
}
~RefCountedBase()
{
ASSERT(m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
}
// Returns whether the pointer should be freed or not.
bool derefBase()
{
ASSERT(m_verifier.isSafeToUse());
ASSERT(!m_deletionHasBegun);
ASSERT(!m_adoptionIsRequired);
ASSERT(m_refCount > 0);
if (m_refCount == 1) {
#ifndef NDEBUG
m_deletionHasBegun = true;
#endif
return true;
}
--m_refCount;
#ifndef NDEBUG
// 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;
}
#ifndef NDEBUG
bool deletionHasBegun() const
{
return m_deletionHasBegun;
}
#endif
private:
#ifndef NDEBUG
friend void adopted(RefCountedBase*);
#endif
int m_refCount;
#ifndef NDEBUG
bool m_deletionHasBegun;
bool m_adoptionIsRequired;
ThreadRestrictionVerifier m_verifier;
#endif
};
#ifndef NDEBUG
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()
{
}
};
#ifdef NDEBUG
inline void RefCountedBase::setMutexForVerifier(Mutex&) { }
#else
inline void RefCountedBase::setMutexForVerifier(Mutex& mutex)
{
m_verifier.setMutexMode(mutex);
}
#endif
#if HAVE(DISPATCH_H)
#ifdef NDEBUG
inline void RefCountedBase::setDispatchQueueForVerifier(dispatch_queue_t) { }
#else
inline void RefCountedBase::setDispatchQueueForVerifier(dispatch_queue_t queue)
{
m_verifier.setDispatchQueueMode(queue);
}
#endif // NDEBUG
#endif // HAVE(DISPATCH_H)
} // namespace WTF
using WTF::RefCounted;
using WTF::RefCountedCustomAllocated;
#endif // RefCounted_h
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