/* | |
* 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 Collector_h | |
#define Collector_h | |
#include <stddef.h> | |
#include <string.h> | |
#include <wtf/HashCountedSet.h> | |
#include <wtf/HashSet.h> | |
#include <wtf/Noncopyable.h> | |
#include <wtf/OwnPtr.h> | |
#include <wtf/StdLibExtras.h> | |
#include <wtf/Threading.h> | |
#if ENABLE(JSC_MULTIPLE_THREADS) | |
#include <pthread.h> | |
#endif | |
#if OS(SYMBIAN) | |
#include <wtf/symbian/BlockAllocatorSymbian.h> | |
#endif | |
#define ASSERT_CLASS_FITS_IN_CELL(class) COMPILE_ASSERT(sizeof(class) <= CELL_SIZE, class_fits_in_cell) | |
namespace JSC { | |
class CollectorBlock; | |
class JSCell; | |
class JSGlobalData; | |
class JSValue; | |
class MarkedArgumentBuffer; | |
class MarkStack; | |
enum OperationInProgress { NoOperation, Allocation, Collection }; | |
class LiveObjectIterator; | |
struct CollectorHeap { | |
size_t nextBlock; | |
size_t nextCell; | |
CollectorBlock** blocks; | |
void* nextNumber; | |
size_t numBlocks; | |
size_t usedBlocks; | |
size_t extraCost; | |
bool didShrink; | |
OperationInProgress operationInProgress; | |
}; | |
class Heap : public Noncopyable { | |
public: | |
class Thread; | |
void destroy(); | |
void* allocateNumber(size_t); | |
void* allocate(size_t); | |
bool isBusy(); // true if an allocation or collection is in progress | |
void collectAllGarbage(); | |
static const size_t minExtraCost = 256; | |
static const size_t maxExtraCost = 1024 * 1024; | |
void reportExtraMemoryCost(size_t cost); | |
size_t objectCount() const; | |
struct Statistics { | |
size_t size; | |
size_t free; | |
}; | |
Statistics statistics() const; | |
void protect(JSValue); | |
void unprotect(JSValue); | |
static Heap* heap(JSValue); // 0 for immediate values | |
static Heap* heap(JSCell*); | |
size_t globalObjectCount(); | |
size_t protectedObjectCount(); | |
size_t protectedGlobalObjectCount(); | |
HashCountedSet<const char*>* protectedObjectTypeCounts(); | |
void registerThread(); // Only needs to be called by clients that can use the same heap from multiple threads. | |
static bool isCellMarked(const JSCell*); | |
static void markCell(JSCell*); | |
void markConservatively(MarkStack&, void* start, void* end); | |
HashSet<MarkedArgumentBuffer*>& markListSet() { if (!m_markListSet) m_markListSet = new HashSet<MarkedArgumentBuffer*>; return *m_markListSet; } | |
JSGlobalData* globalData() const { return m_globalData; } | |
static bool isNumber(JSCell*); | |
LiveObjectIterator primaryHeapBegin(); | |
LiveObjectIterator primaryHeapEnd(); | |
private: | |
void reset(); | |
void sweep(); | |
static CollectorBlock* cellBlock(const JSCell*); | |
static size_t cellOffset(const JSCell*); | |
friend class JSGlobalData; | |
Heap(JSGlobalData*); | |
~Heap(); | |
NEVER_INLINE CollectorBlock* allocateBlock(); | |
NEVER_INLINE void freeBlock(size_t); | |
NEVER_INLINE void freeBlockPtr(CollectorBlock*); | |
void freeBlocks(); | |
void resizeBlocks(); | |
void growBlocks(size_t neededBlocks); | |
void shrinkBlocks(size_t neededBlocks); | |
void clearMarkBits(); | |
void clearMarkBits(CollectorBlock*); | |
size_t markedCells(size_t startBlock = 0, size_t startCell = 0) const; | |
void recordExtraCost(size_t); | |
void addToStatistics(Statistics&) const; | |
void markRoots(); | |
void markProtectedObjects(MarkStack&); | |
void markCurrentThreadConservatively(MarkStack&); | |
void markCurrentThreadConservativelyInternal(MarkStack&); | |
void markOtherThreadConservatively(MarkStack&, Thread*); | |
void markStackObjectsConservatively(MarkStack&); | |
typedef HashCountedSet<JSCell*> ProtectCountSet; | |
CollectorHeap m_heap; | |
ProtectCountSet m_protectedValues; | |
HashSet<MarkedArgumentBuffer*>* m_markListSet; | |
#if ENABLE(JSC_MULTIPLE_THREADS) | |
void makeUsableFromMultipleThreads(); | |
static void unregisterThread(void*); | |
void unregisterThread(); | |
Mutex m_registeredThreadsMutex; | |
Thread* m_registeredThreads; | |
pthread_key_t m_currentThreadRegistrar; | |
#endif | |
#if OS(SYMBIAN) | |
// Allocates collector blocks with correct alignment | |
WTF::AlignedBlockAllocator m_blockallocator; | |
#endif | |
JSGlobalData* m_globalData; | |
}; | |
// tunable parameters | |
template<size_t bytesPerWord> struct CellSize; | |
// cell size needs to be a power of two for certain optimizations in collector.cpp | |
#if USE(JSVALUE32) | |
template<> struct CellSize<sizeof(uint32_t)> { static const size_t m_value = 32; }; | |
#else | |
template<> struct CellSize<sizeof(uint32_t)> { static const size_t m_value = 64; }; | |
#endif | |
template<> struct CellSize<sizeof(uint64_t)> { static const size_t m_value = 64; }; | |
#if OS(WINCE) || OS(SYMBIAN) | |
const size_t BLOCK_SIZE = 64 * 1024; // 64k | |
#else | |
const size_t BLOCK_SIZE = 64 * 4096; // 256k | |
#endif | |
// derived constants | |
const size_t BLOCK_OFFSET_MASK = BLOCK_SIZE - 1; | |
const size_t BLOCK_MASK = ~BLOCK_OFFSET_MASK; | |
const size_t MINIMUM_CELL_SIZE = CellSize<sizeof(void*)>::m_value; | |
const size_t CELL_ARRAY_LENGTH = (MINIMUM_CELL_SIZE / sizeof(double)) + (MINIMUM_CELL_SIZE % sizeof(double) != 0 ? sizeof(double) : 0); | |
const size_t CELL_SIZE = CELL_ARRAY_LENGTH * sizeof(double); | |
const size_t SMALL_CELL_SIZE = CELL_SIZE / 2; | |
const size_t CELL_MASK = CELL_SIZE - 1; | |
const size_t CELL_ALIGN_MASK = ~CELL_MASK; | |
const size_t CELLS_PER_BLOCK = (BLOCK_SIZE - sizeof(Heap*)) * 8 * CELL_SIZE / (8 * CELL_SIZE + 1) / CELL_SIZE; // one bitmap byte can represent 8 cells. | |
const size_t BITMAP_SIZE = (CELLS_PER_BLOCK + 7) / 8; | |
const size_t BITMAP_WORDS = (BITMAP_SIZE + 3) / sizeof(uint32_t); | |
struct CollectorBitmap { | |
uint32_t bits[BITMAP_WORDS]; | |
bool get(size_t n) const { return !!(bits[n >> 5] & (1 << (n & 0x1F))); } | |
void set(size_t n) { bits[n >> 5] |= (1 << (n & 0x1F)); } | |
void clear(size_t n) { bits[n >> 5] &= ~(1 << (n & 0x1F)); } | |
void clearAll() { memset(bits, 0, sizeof(bits)); } | |
size_t count(size_t startCell = 0) | |
{ | |
size_t result = 0; | |
for ( ; (startCell & 0x1F) != 0; ++startCell) { | |
if (get(startCell)) | |
++result; | |
} | |
for (size_t i = startCell >> 5; i < BITMAP_WORDS; ++i) | |
result += WTF::bitCount(bits[i]); | |
return result; | |
} | |
size_t isEmpty() // Much more efficient than testing count() == 0. | |
{ | |
for (size_t i = 0; i < BITMAP_WORDS; ++i) | |
if (bits[i] != 0) | |
return false; | |
return true; | |
} | |
}; | |
struct CollectorCell { | |
double memory[CELL_ARRAY_LENGTH]; | |
}; | |
class CollectorBlock { | |
public: | |
CollectorCell cells[CELLS_PER_BLOCK]; | |
CollectorBitmap marked; | |
Heap* heap; | |
}; | |
struct HeapConstants { | |
static const size_t cellSize = CELL_SIZE; | |
static const size_t cellsPerBlock = CELLS_PER_BLOCK; | |
typedef CollectorCell Cell; | |
typedef CollectorBlock Block; | |
}; | |
inline CollectorBlock* Heap::cellBlock(const JSCell* cell) | |
{ | |
return reinterpret_cast<CollectorBlock*>(reinterpret_cast<uintptr_t>(cell) & BLOCK_MASK); | |
} | |
inline size_t Heap::cellOffset(const JSCell* cell) | |
{ | |
return (reinterpret_cast<uintptr_t>(cell) & BLOCK_OFFSET_MASK) / CELL_SIZE; | |
} | |
inline bool Heap::isCellMarked(const JSCell* cell) | |
{ | |
return cellBlock(cell)->marked.get(cellOffset(cell)); | |
} | |
inline void Heap::markCell(JSCell* cell) | |
{ | |
cellBlock(cell)->marked.set(cellOffset(cell)); | |
} | |
inline void Heap::reportExtraMemoryCost(size_t cost) | |
{ | |
if (cost > minExtraCost) | |
recordExtraCost(cost); | |
} | |
inline void* Heap::allocateNumber(size_t s) | |
{ | |
if (void* result = m_heap.nextNumber) { | |
m_heap.nextNumber = 0; | |
return result; | |
} | |
void* result = allocate(s); | |
m_heap.nextNumber = static_cast<char*>(result) + (CELL_SIZE / 2); | |
return result; | |
} | |
} // namespace JSC | |
#endif /* Collector_h */ |