1 /*
2 * Copyright (C) 2012,2013 Google Inc. All rights reserved.
3 * Copyright (C) 2014 Apple Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 * * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 * * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #ifndef CollectionItemsCache_h
33 #define CollectionItemsCache_h
34
35 #include "core/html/CollectionIndexCache.h"
36 #include "wtf/Vector.h"
37 #include <v8.h>
38
39 namespace blink {
40
41 template <typename Collection, typename NodeType>
42 class CollectionItemsCache : public CollectionIndexCache<Collection, NodeType> {
43 typedef CollectionIndexCache<Collection, NodeType> Base;
44
45 public:
46 CollectionItemsCache();
47 ~CollectionItemsCache();
48
49 unsigned nodeCount(const Collection&);
50 NodeType* nodeAt(const Collection&, unsigned index);
51 void invalidate();
52
53 private:
allocationSize()54 ptrdiff_t allocationSize() const { return m_cachedList.capacity() * sizeof(NodeType*); }
reportExtraMemoryCostForCollectionItemsCache(ptrdiff_t diff)55 static void reportExtraMemoryCostForCollectionItemsCache(ptrdiff_t diff)
56 {
57 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(diff);
58 }
59
60 bool m_listValid;
61 Vector<NodeType*> m_cachedList;
62 };
63
64 template <typename Collection, typename NodeType>
CollectionItemsCache()65 CollectionItemsCache<Collection, NodeType>::CollectionItemsCache()
66 : m_listValid(false)
67 {
68 }
69
70 template <typename Collection, typename NodeType>
~CollectionItemsCache()71 CollectionItemsCache<Collection, NodeType>::~CollectionItemsCache()
72 {
73 if (ptrdiff_t diff = allocationSize())
74 reportExtraMemoryCostForCollectionItemsCache(-diff);
75 }
76
77 template <typename Collection, typename NodeType>
invalidate()78 void CollectionItemsCache<Collection, NodeType>::invalidate()
79 {
80 Base::invalidate();
81 if (m_listValid) {
82 m_cachedList.shrink(0);
83 m_listValid = false;
84 }
85 }
86
87 template <class Collection, class NodeType>
nodeCount(const Collection & collection)88 unsigned CollectionItemsCache<Collection, NodeType>::nodeCount(const Collection& collection)
89 {
90 if (this->isCachedNodeCountValid())
91 return this->cachedNodeCount();
92
93 NodeType* currentNode = collection.traverseToFirst();
94 unsigned currentIndex = 0;
95 ptrdiff_t oldCapacity = allocationSize();
96 while (currentNode) {
97 m_cachedList.append(currentNode);
98 currentNode = collection.traverseForwardToOffset(currentIndex + 1, *currentNode, currentIndex);
99 }
100 if (ptrdiff_t diff = allocationSize() - oldCapacity)
101 reportExtraMemoryCostForCollectionItemsCache(diff);
102
103 this->setCachedNodeCount(m_cachedList.size());
104 m_listValid = true;
105 return this->cachedNodeCount();
106 }
107
108 template <typename Collection, typename NodeType>
nodeAt(const Collection & collection,unsigned index)109 inline NodeType* CollectionItemsCache<Collection, NodeType>::nodeAt(const Collection& collection, unsigned index)
110 {
111 if (m_listValid) {
112 ASSERT(this->isCachedNodeCountValid());
113 return index < this->cachedNodeCount() ? m_cachedList[index] : 0;
114 }
115 return Base::nodeAt(collection, index);
116 }
117
118 } // namespace blink
119
120 #endif // CollectionItemsCache_h
121