heap/WeakSet.cpp

   1 /*
   2  * Copyright (C) 2012 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 "WeakSet.h"
  28
  29 #include "Heap.h"
  30
  31 namespace JSC {
  32
  33 WeakSet::~WeakSet()
  34 {
  35     WeakBlock* next = 0;
  36     for (WeakBlock* block = m_blocks.head(); block; block = next) {
  37         next = block->next();
  38         WeakBlock::destroy(block);
  39     }
  40     m_blocks.clear();
  41 }
  42
  43 void WeakSet::finalizeAll()
  44 {
  45     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
  46         block->finalizeAll();
  47 }
  48
  49 void WeakSet::visitLiveWeakImpls(HeapRootVisitor& visitor)
  50 {
  51     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
  52         block->visitLiveWeakImpls(visitor);
  53 }
  54
  55 void WeakSet::visitDeadWeakImpls(HeapRootVisitor& visitor)
  56 {
  57     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
  58         block->visitDeadWeakImpls(visitor);
  59 }
  60
  61 void WeakSet::sweep()
  62 {
  63     WeakBlock* next;
  64     for (WeakBlock* block = m_blocks.head(); block; block = next) {
  65         next = block->next();
  66
  67         // If a block is completely empty, a new sweep won't have any effect.
  68         if (!block->sweepResult().isNull() && block->sweepResult().blockIsFree)
  69             continue;
  70
  71         block->takeSweepResult(); // Force a new sweep by discarding the last sweep.
  72         block->sweep();
  73     }
  74 }
  75
  76 void WeakSet::shrink()
  77 {
  78     WeakBlock* next;
  79     for (WeakBlock* block = m_blocks.head(); block; block = next) {
  80         next = block->next();
  81
  82         if (!block->sweepResult().isNull() && block->sweepResult().blockIsFree)
  83             removeAllocator(block);
  84     }
  85 }
  86
  87 void WeakSet::resetAllocator()
  88 {
  89     m_allocator = 0;
  90     m_nextAllocator = m_blocks.head();
  91 }
  92
  93 WeakBlock::FreeCell* WeakSet::findAllocator()
  94 {
  95     if (WeakBlock::FreeCell* allocator = tryFindAllocator())
  96         return allocator;
  97
  98     return addAllocator();
  99 }
 100
 101 WeakBlock::FreeCell* WeakSet::tryFindAllocator()
 102 {
 103     while (m_nextAllocator) {
 104         WeakBlock* block = m_nextAllocator;
 105         m_nextAllocator = m_nextAllocator->next();
 106
 107         block->sweep();
 108         WeakBlock::SweepResult sweepResult = block->takeSweepResult();
 109         if (sweepResult.freeList)
 110             return sweepResult.freeList;
 111     }
 112
 113     return 0;
 114 }
 115
 116 WeakBlock::FreeCell* WeakSet::addAllocator()
 117 {
 118     WeakBlock* block = WeakBlock::create();
 119     m_heap->didAllocate(WeakBlock::blockSize);
 120     m_blocks.append(block);
 121     WeakBlock::SweepResult sweepResult = block->takeSweepResult();
 122     ASSERT(!sweepResult.isNull() && sweepResult.freeList);
 123     return sweepResult.freeList;
 124 }
 125
 126 void WeakSet::removeAllocator(WeakBlock* block)
 127 {
 128     m_blocks.remove(block);
 129     WeakBlock::destroy(block);
 130 }
 131
 132 } // namespace JSC