heap/WeakSet.h

   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 #ifndef WeakSet_h
  27 #define WeakSet_h
  28
  29 #include "WeakBlock.h"
  30
  31 namespace JSC {
  32
  33 class Heap;
  34 class WeakImpl;
  35
  36 class WeakSet {
  37     friend class LLIntOffsetsExtractor;
  38
  39 public:
  40     static WeakImpl* allocate(JSValue, WeakHandleOwner* = 0, void* context = 0);
  41     static void deallocate(WeakImpl*);
  42
  43     WeakSet(VM*);
  44     ~WeakSet();
  45     void lastChanceToFinalize();
  46
  47     Heap* heap() const;
  48     VM* vm() const;
  49
  50     bool isEmpty() const;
  51
  52     void visit(HeapRootVisitor&);
  53     void reap();
  54     void sweep();
  55     void shrink();
  56     void resetAllocator();
  57
  58 private:
  59     JS_EXPORT_PRIVATE WeakBlock::FreeCell* findAllocator();
  60     WeakBlock::FreeCell* tryFindAllocator();
  61     WeakBlock::FreeCell* addAllocator();
  62     void removeAllocator(WeakBlock*);
  63
  64     WeakBlock::FreeCell* m_allocator;
  65     WeakBlock* m_nextAllocator;
  66     DoublyLinkedList<WeakBlock> m_blocks;
  67     VM* m_vm;
  68 };
  69
  70 inline WeakSet::WeakSet(VM* vm)
  71     : m_allocator(0)
  72     , m_nextAllocator(0)
  73     , m_vm(vm)
  74 {
  75 }
  76
  77 inline VM* WeakSet::vm() const
  78 {
  79     return m_vm;
  80 }
  81
  82 inline bool WeakSet::isEmpty() const
  83 {
  84     for (WeakBlock* block = m_blocks.head(); block; block = block->next()) {
  85         if (!block->isEmpty())
  86             return false;
  87     }
  88
  89     return true;
  90 }
  91
  92 inline void WeakSet::deallocate(WeakImpl* weakImpl)
  93 {
  94     weakImpl->setState(WeakImpl::Deallocated);
  95 }
  96
  97 inline void WeakSet::lastChanceToFinalize()
  98 {
  99     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
 100         block->lastChanceToFinalize();
 101 }
 102
 103 inline void WeakSet::visit(HeapRootVisitor& visitor)
 104 {
 105     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
 106         block->visit(visitor);
 107 }
 108
 109 inline void WeakSet::reap()
 110 {
 111     for (WeakBlock* block = m_blocks.head(); block; block = block->next())
 112         block->reap();
 113 }
 114
 115 inline void WeakSet::shrink()
 116 {
 117     WeakBlock* next;
 118     for (WeakBlock* block = m_blocks.head(); block; block = next) {
 119         next = block->next();
 120
 121         if (block->isEmpty())
 122             removeAllocator(block);
 123     }
 124
 125     resetAllocator();
 126 }
 127
 128 inline void WeakSet::resetAllocator()
 129 {
 130     m_allocator = 0;
 131     m_nextAllocator = m_blocks.head();
 132 }
 133
 134 } // namespace JSC
 135
 136 #endif // WeakSet_h