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