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/*
* Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
* Copyright (C) 2001 Peter Kelly (pmk@post.com)
* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 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 MarkedBlock_h
#define MarkedBlock_h
#include <wtf/Bitmap.h>
#include <wtf/PageAllocationAligned.h>
#include <wtf/StdLibExtras.h>
namespace JSC {
class Heap;
class JSCell;
class JSGlobalData;
typedef uintptr_t Bits;
static const size_t KB = 1024;
class MarkedBlock {
public:
static const size_t atomSize = sizeof(double); // Ensures natural alignment for all built-in types.
static MarkedBlock* create(JSGlobalData*, size_t cellSize);
static void destroy(MarkedBlock*);
static bool isAtomAligned(const void*);
static MarkedBlock* blockFor(const void*);
static size_t firstAtom();
Heap* heap() const;
void setPrev(MarkedBlock*);
void setNext(MarkedBlock*);
MarkedBlock* prev() const;
MarkedBlock* next() const;
void* allocate();
void reset();
void sweep();
bool isEmpty();
void clearMarks();
size_t markCount();
size_t cellSize();
size_t size();
size_t capacity();
bool contains(const void*);
size_t atomNumber(const void*);
bool isMarked(const void*);
bool testAndSetMarked(const void*);
void setMarked(const void*);
template <typename Functor> void forEach(Functor&);
private:
static const size_t blockSize = 16 * KB;
static const size_t blockMask = ~(blockSize - 1); // blockSize must be a power of two.
static const size_t atomMask = ~(atomSize - 1); // atomSize must be a power of two.
static const size_t atomsPerBlock = blockSize / atomSize;
typedef char Atom[atomSize];
MarkedBlock(const PageAllocationAligned&, JSGlobalData*, size_t cellSize);
Atom* atoms();
size_t m_nextAtom;
size_t m_endAtom; // This is a fuzzy end. Always test for < m_endAtom.
size_t m_atomsPerCell;
WTF::Bitmap<blockSize / atomSize> m_marks;
PageAllocationAligned m_allocation;
Heap* m_heap;
MarkedBlock* m_prev;
MarkedBlock* m_next;
};
inline size_t MarkedBlock::firstAtom()
{
return WTF::roundUpToMultipleOf<atomSize>(sizeof(MarkedBlock)) / atomSize;
}
inline MarkedBlock::Atom* MarkedBlock::atoms()
{
return reinterpret_cast<Atom*>(this);
}
inline bool MarkedBlock::isAtomAligned(const void* p)
{
return !((intptr_t)(p) & ~atomMask);
}
inline MarkedBlock* MarkedBlock::blockFor(const void* p)
{
return reinterpret_cast<MarkedBlock*>(reinterpret_cast<uintptr_t>(p) & blockMask);
}
inline Heap* MarkedBlock::heap() const
{
return m_heap;
}
inline void MarkedBlock::setPrev(MarkedBlock* prev)
{
m_prev = prev;
}
inline void MarkedBlock::setNext(MarkedBlock* next)
{
m_next = next;
}
inline MarkedBlock* MarkedBlock::prev() const
{
return m_prev;
}
inline MarkedBlock* MarkedBlock::next() const
{
return m_next;
}
inline void MarkedBlock::reset()
{
m_nextAtom = firstAtom();
}
inline bool MarkedBlock::isEmpty()
{
return m_marks.isEmpty();
}
inline void MarkedBlock::clearMarks()
{
m_marks.clearAll();
}
inline size_t MarkedBlock::markCount()
{
return m_marks.count();
}
inline size_t MarkedBlock::cellSize()
{
return m_atomsPerCell * atomSize;
}
inline size_t MarkedBlock::size()
{
return markCount() * cellSize();
}
inline size_t MarkedBlock::capacity()
{
return m_allocation.size();
}
inline bool MarkedBlock::contains(const void* p)
{
// Since we mark the first atom of every cell when allocating and/or
// marking, any pointer to a marked atom points to the head of a valid,
// live cell. Checking the mark bit guards against reviving an object
// in a zombie state.
ASSERT(p && isAtomAligned(p));
return isMarked(p);
}
inline size_t MarkedBlock::atomNumber(const void* p)
{
return (reinterpret_cast<uintptr_t>(p) - reinterpret_cast<uintptr_t>(this)) / atomSize;
}
inline bool MarkedBlock::isMarked(const void* p)
{
return m_marks.get(atomNumber(p));
}
inline bool MarkedBlock::testAndSetMarked(const void* p)
{
return m_marks.testAndSet(atomNumber(p));
}
inline void MarkedBlock::setMarked(const void* p)
{
m_marks.set(atomNumber(p));
}
template <typename Functor> inline void MarkedBlock::forEach(Functor& functor)
{
for (size_t i = firstAtom(); i < m_endAtom; i += m_atomsPerCell) {
if (!m_marks.get(i))
continue;
functor(reinterpret_cast<JSCell*>(&atoms()[i]));
}
}
} // namespace JSC
#endif // MarkedSpace_h
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