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 "HeapRootVisitor.h"
  30 #include "JSObject.h"
  31
  32 namespace JSC {
  33
  34 HandleSet::HandleSet(JSGlobalData* globalData)
  35     : m_globalData(globalData)
  36     , m_nextToFinalize(0)
  37 {
  38     grow();
  39 }
  40
  41 void HandleSet::grow()
  42 {
  43     Node* block = m_blockStack.grow();
  44     for (int i = m_blockStack.blockLength - 1; i >= 0; --i) {
  45         Node* node = &block[i];
  46         new (NotNull, node) Node(this);
  47         m_freeList.push(node);
  48     }
  49 }
  50
  51 void HandleSet::visitStrongHandles(HeapRootVisitor& heapRootVisitor)
  52 {
  53     Node* end = m_strongList.end();
  54     for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
  55 #if ENABLE(GC_VALIDATION)
  56         if (!isLiveNode(node))
  57             CRASH();
  58 #endif
  59         heapRootVisitor.visit(node->slot());
  60     }
  61 }
  62
  63 void HandleSet::writeBarrier(HandleSlot slot, const JSValue& value)
  64 {
  65     // Forbid assignment to handles during the finalization phase, since it would violate many GC invariants.
  66     // File a bug with stack trace if you hit this.
  67     if (m_nextToFinalize)
  68         CRASH();
  69
  70     if (!value == !*slot && slot->isCell() == value.isCell())
  71         return;
  72
  73     Node* node = toNode(slot);
  74 #if ENABLE(GC_VALIDATION)
  75     if (!isLiveNode(node))
  76         CRASH();
  77 #endif
  78     SentinelLinkedList<Node>::remove(node);
  79     if (!value || !value.isCell()) {
  80         m_immediateList.push(node);
  81         return;
  82     }
  83
  84     m_strongList.push(node);
  85 #if ENABLE(GC_VALIDATION)
  86     if (!isLiveNode(node))
  87         CRASH();
  88 #endif
  89 }
  90
  91 unsigned HandleSet::protectedGlobalObjectCount()
  92 {
  93     unsigned count = 0;
  94     Node* end = m_strongList.end();
  95     for (Node* node = m_strongList.begin(); node != end; node = node->next()) {
  96         JSValue value = *node->slot();
  97         if (value.isObject() && asObject(value.asCell())->isGlobalObject())
  98             count++;
  99     }
 100     return count;
 101 }
 102
 103 #if ENABLE(GC_VALIDATION) || !ASSERT_DISABLED
 104 bool HandleSet::isLiveNode(Node* node)
 105 {
 106     if (node->prev()->next() != node)
 107         return false;
 108     if (node->next()->prev() != node)
 109         return false;
 110
 111     return true;
 112 }
 113 #endif
 114
 115 } // namespace JSC