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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifndef ListableHandler_h
#define ListableHandler_h
#include <stdint.h>
#include <wtf/Locker.h>
#include <wtf/Noncopyable.h>
#include <wtf/ThreadingPrimitives.h>
#include <wtf/TCSpinLock.h>
namespace JSC {
class MarkStack;
class MarkStackThreadSharedData;
class SlotVisitor;
template<typename T>
class ListableHandler {
WTF_MAKE_NONCOPYABLE(ListableHandler);
protected:
ListableHandler()
: m_nextAndFlag(0)
{
}
virtual ~ListableHandler() { }
T* next() const
{
return reinterpret_cast<T*>(m_nextAndFlag & ~1);
}
private:
// Allow these classes to use ListableHandler::List.
friend class MarkStack;
friend class GCThreadSharedData;
friend class SlotVisitor;
class List {
WTF_MAKE_NONCOPYABLE(List);
public:
List()
: m_first(0)
{
m_lock.Init();
}
void addThreadSafe(T* handler)
{
SpinLockHolder locker(&m_lock);
addNotThreadSafe(handler);
}
bool hasNext()
{
return !!m_first;
}
T* head()
{
return m_first;
}
T* removeNext()
{
T* current = m_first;
T* next = current->next();
current->m_nextAndFlag = 0;
m_first = next;
return current;
}
void removeAll()
{
while (hasNext())
removeNext();
}
private:
void addNotThreadSafe(T* handler)
{
if (handler->m_nextAndFlag & 1)
return;
handler->m_nextAndFlag = reinterpret_cast<uintptr_t>(m_first) | 1;
m_first = handler;
}
SpinLock m_lock;
T* m_first;
};
uintptr_t m_nextAndFlag;
};
} // namespace JSC
#endif // ListableHandler_h