1 /* 2 * Copyright (C) 2009 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 WeakGCMap_h 27 #define WeakGCMap_h 28 29 #include "Handle.h" 30 #include "JSGlobalData.h" 31 #include <wtf/HashMap.h> 32 33 namespace JSC { 34 35 // A HashMap for GC'd values that removes entries when the associated value 36 // dies. 37 template <typename KeyType, typename MappedType> struct DefaultWeakGCMapFinalizerCallback { finalizerContextForDefaultWeakGCMapFinalizerCallback38 static void* finalizerContextFor(KeyType key) 39 { 40 return reinterpret_cast<void*>(key); 41 } 42 keyForFinalizerDefaultWeakGCMapFinalizerCallback43 static KeyType keyForFinalizer(void* context, typename HandleTypes<MappedType>::ExternalType) 44 { 45 return reinterpret_cast<KeyType>(context); 46 } 47 }; 48 49 template<typename KeyType, typename MappedType, typename FinalizerCallback = DefaultWeakGCMapFinalizerCallback<KeyType, MappedType>, typename HashArg = typename DefaultHash<KeyType>::Hash, typename KeyTraitsArg = HashTraits<KeyType> > 50 class WeakGCMap : private WeakHandleOwner { 51 WTF_MAKE_FAST_ALLOCATED; 52 WTF_MAKE_NONCOPYABLE(WeakGCMap); 53 54 typedef HashMap<KeyType, HandleSlot, HashArg, KeyTraitsArg> MapType; 55 typedef typename HandleTypes<MappedType>::ExternalType ExternalType; 56 typedef typename MapType::iterator map_iterator; 57 58 public: 59 60 struct iterator { 61 friend class WeakGCMap; iteratoriterator62 iterator(map_iterator iter) 63 : m_iterator(iter) 64 { 65 } 66 getiterator67 std::pair<KeyType, ExternalType> get() const { return std::make_pair(m_iterator->first, HandleTypes<MappedType>::getFromSlot(m_iterator->second)); } getSlotiterator68 std::pair<KeyType, HandleSlot> getSlot() const { return *m_iterator; } 69 70 iterator& operator++() { ++m_iterator; return *this; } 71 72 // postfix ++ intentionally omitted 73 74 // Comparison. 75 bool operator==(const iterator& other) const { return m_iterator == other.m_iterator; } 76 bool operator!=(const iterator& other) const { return m_iterator != other.m_iterator; } 77 78 private: 79 map_iterator m_iterator; 80 }; 81 WeakGCMap()82 WeakGCMap() 83 { 84 } 85 isEmpty()86 bool isEmpty() { return m_map.isEmpty(); } clear()87 void clear() 88 { 89 map_iterator end = m_map.end(); 90 for (map_iterator ptr = m_map.begin(); ptr != end; ++ptr) 91 HandleHeap::heapFor(ptr->second)->deallocate(ptr->second); 92 m_map.clear(); 93 } 94 contains(const KeyType & key)95 bool contains(const KeyType& key) const 96 { 97 return m_map.contains(key); 98 } 99 find(const KeyType & key)100 iterator find(const KeyType& key) 101 { 102 return m_map.find(key); 103 } 104 remove(iterator iter)105 void remove(iterator iter) 106 { 107 ASSERT(iter.m_iterator != m_map.end()); 108 HandleSlot slot = iter.m_iterator->second; 109 ASSERT(slot); 110 HandleHeap::heapFor(slot)->deallocate(slot); 111 m_map.remove(iter.m_iterator); 112 } 113 get(const KeyType & key)114 ExternalType get(const KeyType& key) const 115 { 116 return HandleTypes<MappedType>::getFromSlot(m_map.get(key)); 117 } 118 getSlot(const KeyType & key)119 HandleSlot getSlot(const KeyType& key) const 120 { 121 return m_map.get(key); 122 } 123 add(JSGlobalData & globalData,const KeyType & key,ExternalType value)124 pair<iterator, bool> add(JSGlobalData& globalData, const KeyType& key, ExternalType value) 125 { 126 pair<typename MapType::iterator, bool> iter = m_map.add(key, 0); 127 if (iter.second) { 128 HandleSlot slot = globalData.allocateGlobalHandle(); 129 iter.first->second = slot; 130 HandleHeap::heapFor(slot)->makeWeak(slot, this, FinalizerCallback::finalizerContextFor(key)); 131 HandleHeap::heapFor(slot)->writeBarrier(slot, value); 132 *slot = value; 133 } 134 return iter; 135 } 136 set(iterator iter,ExternalType value)137 void set(iterator iter, ExternalType value) 138 { 139 HandleSlot slot = iter.m_iterator->second; 140 ASSERT(slot); 141 HandleHeap::heapFor(slot)->writeBarrier(slot, value); 142 *slot = value; 143 } 144 set(JSGlobalData & globalData,const KeyType & key,ExternalType value)145 void set(JSGlobalData& globalData, const KeyType& key, ExternalType value) 146 { 147 pair<typename MapType::iterator, bool> iter = m_map.add(key, 0); 148 HandleSlot slot = iter.first->second; 149 if (iter.second) { 150 slot = globalData.allocateGlobalHandle(); 151 HandleHeap::heapFor(slot)->makeWeak(slot, this, key); 152 iter.first->second = slot; 153 } 154 HandleHeap::heapFor(slot)->writeBarrier(slot, value); 155 *slot = value; 156 } 157 take(const KeyType & key)158 ExternalType take(const KeyType& key) 159 { 160 HandleSlot slot = m_map.take(key); 161 if (!slot) 162 return HashTraits<ExternalType>::emptyValue(); 163 ExternalType result = HandleTypes<MappedType>::getFromSlot(slot); 164 HandleHeap::heapFor(slot)->deallocate(slot); 165 return result; 166 } 167 size()168 size_t size() { return m_map.size(); } 169 begin()170 iterator begin() { return iterator(m_map.begin()); } end()171 iterator end() { return iterator(m_map.end()); } 172 ~WeakGCMap()173 ~WeakGCMap() 174 { 175 clear(); 176 } 177 178 private: finalize(Handle<Unknown> handle,void * context)179 virtual void finalize(Handle<Unknown> handle, void* context) 180 { 181 HandleSlot slot = m_map.take(FinalizerCallback::keyForFinalizer(context, HandleTypes<MappedType>::getFromSlot(handle.slot()))); 182 ASSERT(slot); 183 HandleHeap::heapFor(slot)->deallocate(slot); 184 } 185 186 MapType m_map; 187 }; 188 189 } // namespace JSC 190 191 #endif // WeakGCMap_h 192