Heap.h   [plain text]

/*
 *  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 Heap_h
#define Heap_h

#include "HandleHeap.h"
#include "HandleStack.h"
#include "MarkedBlock.h"
#include "MarkedBlockSet.h"
#include "NewSpace.h"
#include "SlotVisitor.h"
#include <wtf/Forward.h>
#include <wtf/HashCountedSet.h>
#include <wtf/HashSet.h>

namespace JSC {

    class GCActivityCallback;
    class GlobalCodeBlock;
    class HeapRootVisitor;
    class JSCell;
    class JSGlobalData;
    class JSValue;
    class LiveObjectIterator;
    class MarkedArgumentBuffer;
    class RegisterFile;
    class UString;
    class WeakGCHandlePool;
    class SlotVisitor;

    typedef std::pair<JSValue, UString> ValueStringPair;
    typedef HashCountedSet<JSCell*> ProtectCountSet;
    typedef HashCountedSet<const char*> TypeCountSet;

    enum OperationInProgress { NoOperation, Allocation, Collection };
    
    // Heap size hint.
    enum HeapSize { SmallHeap, LargeHeap };
    
    class Heap {
        WTF_MAKE_NONCOPYABLE(Heap);
    public:
        static Heap* heap(JSValue); // 0 for immediate values
        static Heap* heap(JSCell*);

        static bool isMarked(const void*);
        static bool testAndSetMarked(const void*);
        static bool testAndClearMarked(const void*);
        static void setMarked(const void*);

        static void writeBarrier(const JSCell*, JSValue);
        static void writeBarrier(const JSCell*, JSCell*);

        Heap(JSGlobalData*, HeapSize);
        ~Heap();
        void destroy(); // JSGlobalData must call destroy() before ~Heap().

        JSGlobalData* globalData() const { return m_globalData; }
        NewSpace& markedSpace() { return m_newSpace; }
        MachineThreads& machineThreads() { return m_machineThreads; }

        GCActivityCallback* activityCallback();
        void setActivityCallback(PassOwnPtr<GCActivityCallback>);

        // true if an allocation or collection is in progress
        inline bool isBusy();

        void* allocate(size_t);
        NewSpace::SizeClass& sizeClassFor(size_t);
        void* allocate(NewSpace::SizeClass&);
        void notifyIsSafeToCollect() { m_isSafeToCollect = true; }
        void collectAllGarbage();

        void reportExtraMemoryCost(size_t cost);

        void protect(JSValue);
        bool unprotect(JSValue); // True when the protect count drops to 0.

        size_t size();
        size_t capacity();
        size_t objectCount();
        size_t globalObjectCount();
        size_t protectedObjectCount();
        size_t protectedGlobalObjectCount();
        PassOwnPtr<TypeCountSet> protectedObjectTypeCounts();
        PassOwnPtr<TypeCountSet> objectTypeCounts();

        void pushTempSortVector(Vector<ValueStringPair>*);
        void popTempSortVector(Vector<ValueStringPair>*);
    
        HashSet<MarkedArgumentBuffer*>& markListSet() { if (!m_markListSet) m_markListSet = new HashSet<MarkedArgumentBuffer*>; return *m_markListSet; }
        
        template<typename Functor> typename Functor::ReturnType forEachProtectedCell(Functor&);
        template<typename Functor> typename Functor::ReturnType forEachProtectedCell();
        template<typename Functor> typename Functor::ReturnType forEachCell(Functor&);
        template<typename Functor> typename Functor::ReturnType forEachCell();
        template<typename Functor> typename Functor::ReturnType forEachBlock(Functor&);
        template<typename Functor> typename Functor::ReturnType forEachBlock();
        
        HandleSlot allocateGlobalHandle() { return m_handleHeap.allocate(); }
        HandleSlot allocateLocalHandle() { return m_handleStack.push(); }

        HandleStack* handleStack() { return &m_handleStack; }
        void getConservativeRegisterRoots(HashSet<JSCell*>& roots);

    private:
        typedef HashSet<MarkedBlock*>::iterator BlockIterator;

        static const size_t minExtraCost = 256;
        static const size_t maxExtraCost = 1024 * 1024;
        
        enum AllocationEffort { AllocationMustSucceed, AllocationCanFail };

        bool isValidAllocation(size_t);
        void reportExtraMemoryCostSlowCase(size_t);
        void canonicalizeBlocks();
        void resetAllocator();

        MarkedBlock* allocateBlock(size_t cellSize, AllocationEffort);
        void freeBlocks(MarkedBlock*);

        void clearMarks();
        void markRoots();
        void markProtectedObjects(HeapRootVisitor&);
        void markTempSortVectors(HeapRootVisitor&);

        void* tryAllocate(NewSpace::SizeClass&);
        void* allocateSlowCase(NewSpace::SizeClass&);
        
        enum SweepToggle { DoNotSweep, DoSweep };
        void collect(SweepToggle);
        void shrink();
        void releaseFreeBlocks();
        void sweep();

        RegisterFile& registerFile();

        static void writeBarrierSlowCase(const JSCell*, JSCell*);
        
#if ENABLE(LAZY_BLOCK_FREEING)
        void waitForRelativeTimeWhileHoldingLock(double relative);
        void waitForRelativeTime(double relative);
        void blockFreeingThreadMain();
        static void* blockFreeingThreadStartFunc(void* heap);
#endif

        const HeapSize m_heapSize;
        const size_t m_minBytesPerCycle;
        
        OperationInProgress m_operationInProgress;
        NewSpace m_newSpace;
        MarkedBlockSet m_blocks;

#if ENABLE(LAZY_BLOCK_FREEING)
        DoublyLinkedList<MarkedBlock> m_freeBlocks;
        size_t m_numberOfFreeBlocks;
        
        ThreadIdentifier m_blockFreeingThread;
        Mutex m_freeBlockLock;
        ThreadCondition m_freeBlockCondition;
        bool m_blockFreeingThreadShouldQuit;
#endif

        size_t m_extraCost;

        ProtectCountSet m_protectedValues;
        Vector<Vector<ValueStringPair>* > m_tempSortingVectors;
        HashSet<MarkedArgumentBuffer*>* m_markListSet;

        OwnPtr<GCActivityCallback> m_activityCallback;
        
        MachineThreads m_machineThreads;
        SlotVisitor m_slotVisitor;
        HandleHeap m_handleHeap;
        HandleStack m_handleStack;
        
        bool m_isSafeToCollect;

        JSGlobalData* m_globalData;
    };

    bool Heap::isBusy()
    {
        return m_operationInProgress != NoOperation;
    }

    inline Heap* Heap::heap(JSCell* cell)
    {
        return MarkedBlock::blockFor(cell)->heap();
    }

    inline Heap* Heap::heap(JSValue v)
    {
        if (!v.isCell())
            return 0;
        return heap(v.asCell());
    }

    inline bool Heap::isMarked(const void* cell)
    {
        return MarkedBlock::blockFor(cell)->isMarked(cell);
    }

    inline bool Heap::testAndSetMarked(const void* cell)
    {
        return MarkedBlock::blockFor(cell)->testAndSetMarked(cell);
    }

    inline bool Heap::testAndClearMarked(const void* cell)
    {
        return MarkedBlock::blockFor(cell)->testAndClearMarked(cell);
    }

    inline void Heap::setMarked(const void* cell)
    {
        MarkedBlock::blockFor(cell)->setMarked(cell);
    }

#if ENABLE(GGC)
    inline void Heap::writeBarrier(const JSCell* owner, JSCell* cell)
    {
        if (MarkedBlock::blockFor(owner)->inNewSpace())
            return;
        writeBarrierSlowCase(owner, cell);
    }

    inline void Heap::writeBarrier(const JSCell* owner, JSValue value)
    {
        if (!value)
            return;
        if (!value.isCell())
            return;
        writeBarrier(owner, value.asCell());
    }

#else

    inline void Heap::writeBarrier(const JSCell*, JSCell*)
    {
    }

    inline void Heap::writeBarrier(const JSCell*, JSValue)
    {
    }
#endif

    inline void Heap::reportExtraMemoryCost(size_t cost)
    {
        if (cost > minExtraCost) 
            reportExtraMemoryCostSlowCase(cost);
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachProtectedCell(Functor& functor)
    {
        canonicalizeBlocks();
        ProtectCountSet::iterator end = m_protectedValues.end();
        for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it)
            functor(it->first);
        m_handleHeap.forEachStrongHandle(functor, m_protectedValues);

        return functor.returnValue();
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachProtectedCell()
    {
        Functor functor;
        return forEachProtectedCell(functor);
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachCell(Functor& functor)
    {
        canonicalizeBlocks();
        BlockIterator end = m_blocks.set().end();
        for (BlockIterator it = m_blocks.set().begin(); it != end; ++it)
            (*it)->forEachCell(functor);
        return functor.returnValue();
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachCell()
    {
        Functor functor;
        return forEachCell(functor);
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachBlock(Functor& functor)
    {
        canonicalizeBlocks();
        BlockIterator end = m_blocks.set().end();
        for (BlockIterator it = m_blocks.set().begin(); it != end; ++it)
            functor(*it);
        return functor.returnValue();
    }

    template<typename Functor> inline typename Functor::ReturnType Heap::forEachBlock()
    {
        Functor functor;
        return forEachBlock(functor);
    }
    
    inline NewSpace::SizeClass& Heap::sizeClassFor(size_t bytes)
    {
        return m_newSpace.sizeClassFor(bytes);
    }
    
    inline void* Heap::allocate(NewSpace::SizeClass& sizeClass)
    {
        // This is a light-weight fast path to cover the most common case.
        MarkedBlock::FreeCell* firstFreeCell = sizeClass.firstFreeCell;
        if (UNLIKELY(!firstFreeCell))
            return allocateSlowCase(sizeClass);
        
        sizeClass.firstFreeCell = firstFreeCell->next;
        return firstFreeCell;
    }

    inline void* Heap::allocate(size_t bytes)
    {
        ASSERT(isValidAllocation(bytes));
        NewSpace::SizeClass& sizeClass = sizeClassFor(bytes);
        return allocate(sizeClass);
    }

} // namespace JSC

#endif // Heap_h