Source/JavaScriptCore/heap/WeakBlock.cpp

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   8  *    notice, this list of conditions and the following disclaimer.
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  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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  24  */
  25
  26 #include "config.h"
  27 #include "WeakBlock.h"
  28
  29 #include "CellContainerInlines.h"
  30 #include "Heap.h"
  31 #include "HeapRootVisitor.h"
  32 #include "JSCInlines.h"
  33 #include "JSObject.h"
  34 #include "WeakHandleOwner.h"
  35
  36 namespace JSC {
  37
  38 WeakBlock* WeakBlock::create(Heap& heap, CellContainer container)
  39 {
  40     heap.didAllocateBlock(WeakBlock::blockSize);
  41     return new (NotNull, fastMalloc(blockSize)) WeakBlock(container);
  42 }
  43
  44 void WeakBlock::destroy(Heap& heap, WeakBlock* block)
  45 {
  46     block->~WeakBlock();
  47     fastFree(block);
  48     heap.didFreeBlock(WeakBlock::blockSize);
  49 }
  50
  51 WeakBlock::WeakBlock(CellContainer container)
  52     : DoublyLinkedListNode<WeakBlock>()
  53     , m_container(container)
  54 {
  55     for (size_t i = 0; i < weakImplCount(); ++i) {
  56         WeakImpl* weakImpl = &weakImpls()[i];
  57         new (NotNull, weakImpl) WeakImpl;
  58         addToFreeList(&m_sweepResult.freeList, weakImpl);
  59     }
  60
  61     ASSERT(isEmpty());
  62 }
  63
  64 void WeakBlock::lastChanceToFinalize()
  65 {
  66     for (size_t i = 0; i < weakImplCount(); ++i) {
  67         WeakImpl* weakImpl = &weakImpls()[i];
  68         if (weakImpl->state() >= WeakImpl::Finalized)
  69             continue;
  70         weakImpl->setState(WeakImpl::Dead);
  71         finalize(weakImpl);
  72     }
  73 }
  74
  75 void WeakBlock::sweep()
  76 {
  77     // If a block is completely empty, a sweep won't have any effect.
  78     if (isEmpty())
  79         return;
  80
  81     SweepResult sweepResult;
  82     for (size_t i = 0; i < weakImplCount(); ++i) {
  83         WeakImpl* weakImpl = &weakImpls()[i];
  84         if (weakImpl->state() == WeakImpl::Dead)
  85             finalize(weakImpl);
  86         if (weakImpl->state() == WeakImpl::Deallocated)
  87             addToFreeList(&sweepResult.freeList, weakImpl);
  88         else {
  89             sweepResult.blockIsFree = false;
  90             if (weakImpl->state() == WeakImpl::Live)
  91                 sweepResult.blockIsLogicallyEmpty = false;
  92         }
  93     }
  94
  95     m_sweepResult = sweepResult;
  96     ASSERT(!m_sweepResult.isNull());
  97 }
  98
  99 template<typename ContainerType>
 100 void WeakBlock::specializedVisit(ContainerType& container, HeapRootVisitor& heapRootVisitor)
 101 {
 102     SlotVisitor& visitor = heapRootVisitor.visitor();
 103
 104     HeapVersion markingVersion = visitor.markingVersion();
 105
 106     for (size_t i = 0; i < weakImplCount(); ++i) {
 107         WeakImpl* weakImpl = &weakImpls()[i];
 108         if (weakImpl->state() != WeakImpl::Live)
 109             continue;
 110
 111         WeakHandleOwner* weakHandleOwner = weakImpl->weakHandleOwner();
 112         if (!weakHandleOwner)
 113             continue;
 114
 115         const JSValue& jsValue = weakImpl->jsValue();
 116         if (container.isMarkedConcurrently(markingVersion, jsValue.asCell()))
 117             continue;
 118
 119         if (!weakHandleOwner->isReachableFromOpaqueRoots(Handle<Unknown>::wrapSlot(&const_cast<JSValue&>(jsValue)), weakImpl->context(), visitor))
 120             continue;
 121
 122         heapRootVisitor.visit(&const_cast<JSValue&>(jsValue));
 123     }
 124 }
 125
 126 void WeakBlock::visit(HeapRootVisitor& heapRootVisitor)
 127 {
 128     // If a block is completely empty, a visit won't have any effect.
 129     if (isEmpty())
 130         return;
 131
 132     // If this WeakBlock doesn't belong to a CellContainer, we won't even be here.
 133     ASSERT(m_container);
 134
 135     if (m_container.isLargeAllocation())
 136         specializedVisit(m_container.largeAllocation(), heapRootVisitor);
 137     else
 138         specializedVisit(m_container.markedBlock(), heapRootVisitor);
 139 }
 140
 141 void WeakBlock::reap()
 142 {
 143     // If a block is completely empty, a reaping won't have any effect.
 144     if (isEmpty())
 145         return;
 146
 147     // If this WeakBlock doesn't belong to a CellContainer, we won't even be here.
 148     ASSERT(m_container);
 149
 150     HeapVersion markingVersion = m_container.heap()->objectSpace().markingVersion();
 151
 152     for (size_t i = 0; i < weakImplCount(); ++i) {
 153         WeakImpl* weakImpl = &weakImpls()[i];
 154         if (weakImpl->state() > WeakImpl::Dead)
 155             continue;
 156
 157         if (m_container.isMarked(markingVersion, weakImpl->jsValue().asCell())) {
 158             ASSERT(weakImpl->state() == WeakImpl::Live);
 159             continue;
 160         }
 161
 162         weakImpl->setState(WeakImpl::Dead);
 163     }
 164 }
 165
 166 } // namespace JSC