heap/HandleSet.cpp

   1 /*
   2  * Copyright (C) 2011 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  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''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "HandleSet.h"
  28
  29 #include "HandleBlock.h"
  30 #include "HandleBlockInlines.h"
  31 #include "HeapRootVisitor.h"
  32 #include "JSObject.h"
  33 #include "Operations.h"
  34 #include <wtf/DataLog.h>
  35
  36 namespace JSC {
  37
  38 HandleSet::HandleSet(VM* vm)
  39     : m_vm(vm)
  40     , m_nextToFinalize(0)
  41 {
  42     grow();
  43 }
  44
  45 HandleSet::~HandleSet()
  46 {
  47     while (!m_blockList.isEmpty())
  48         m_vm->heap.blockAllocator().deallocate(HandleBlock::destroy(m_blockList.removeHead()));
  49 }
  50
  51 void HandleSet::grow()
  52 {
  53     HandleBlock* newBlock = HandleBlock::create(m_vm->heap.blockAllocator().allocate<HandleBlock>(), this);
  54     m_blockList.append(newBlock);
  55
  56     for (int i = newBlock->nodeCapacity() - 1; i >= 0; --i) {
  57         Node* node = newBlock->nodeAtIndex(i);
  58         new (NotNull, node) Node;
  59         m_freeList.push(node);
  60     }
  61 }
  62
  63 void HandleSet::visitStrongHandles(HeapRootVisitor& heapRootVisitor)
  64 {
  65     Node* end = m_strongList.end();
  66     for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
  67 #if ENABLE(GC_VALIDATION)
  68         RELEASE_ASSERT(isLiveNode(node));
  69 #endif
  70         heapRootVisitor.visit(node->slot());
  71     }
  72 }
  73
  74 void HandleSet::writeBarrier(HandleSlot slot, const JSValue& value)
  75 {
  76     // Forbid assignment to handles during the finalization phase, since it would violate many GC invariants.
  77     // File a bug with stack trace if you hit this.
  78     RELEASE_ASSERT(!m_nextToFinalize);
  79
  80     if (!value == !*slot && slot->isCell() == value.isCell())
  81         return;
  82
  83     Node* node = toNode(slot);
  84 #if ENABLE(GC_VALIDATION)
  85     RELEASE_ASSERT(isLiveNode(node));
  86 #endif
  87     SentinelLinkedList<Node>::remove(node);
  88     if (!value || !value.isCell()) {
  89         m_immediateList.push(node);
  90         return;
  91     }
  92
  93     m_strongList.push(node);
  94 #if ENABLE(GC_VALIDATION)
  95     RELEASE_ASSERT(isLiveNode(node));
  96 #endif
  97 }
  98
  99 unsigned HandleSet::protectedGlobalObjectCount()
 100 {
 101     unsigned count = 0;
 102     Node* end = m_strongList.end();
 103     for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
 104         JSValue value = *node->slot();
 105         if (value.isObject() && asObject(value.asCell())->isGlobalObject())
 106             count++;
 107     }
 108     return count;
 109 }
 110
 111 #if ENABLE(GC_VALIDATION) || !ASSERT_DISABLED
 112 bool HandleSet::isLiveNode(Node* node)
 113 {
 114     if (node->prev()->next() != node)
 115         return false;
 116     if (node->next()->prev() != node)
 117         return false;
 118
 119     return true;
 120 }
 121 #endif
 122
 123 } // namespace JSC