OLD | NEW |
| (Empty) |
1 /* | |
2 * Copyright (C) 2011 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 BlockStack_h | |
27 #define BlockStack_h | |
28 | |
29 #include <wtf/Assertions.h> | |
30 #include <wtf/FastMalloc.h> | |
31 #include <wtf/Vector.h> | |
32 | |
33 namespace WTF { | |
34 | |
35 template <typename T> class BlockStack { | |
36 public: | |
37 static const size_t blockSize = 4096; | |
38 static const size_t blockLength = blockSize / sizeof(T); | |
39 | |
40 BlockStack(); | |
41 ~BlockStack(); | |
42 | |
43 T* grow(); | |
44 void shrink(T*); | |
45 | |
46 const Vector<T*>& blocks(); | |
47 | |
48 private: | |
49 Vector<T*> m_blocks; | |
50 T* m_spareBlock; // Used to avoid thrash at block boundaries. | |
51 }; | |
52 | |
53 template <typename T> BlockStack<T>::BlockStack() | |
54 : m_spareBlock(0) | |
55 { | |
56 } | |
57 | |
58 template <typename T> BlockStack<T>::~BlockStack() | |
59 { | |
60 if (m_spareBlock) | |
61 fastFree(m_spareBlock); | |
62 for (size_t i = 0; i < m_blocks.size(); ++i) | |
63 fastFree(m_blocks[i]); | |
64 } | |
65 | |
66 template <typename T> inline const Vector<T*>& BlockStack<T>::blocks() | |
67 { | |
68 return m_blocks; | |
69 } | |
70 | |
71 template <typename T> T* BlockStack<T>::grow() | |
72 { | |
73 T* block = m_spareBlock ? m_spareBlock : static_cast<T*>(fastMalloc(blockSiz
e)); | |
74 m_spareBlock = 0; | |
75 | |
76 m_blocks.append(block); | |
77 return block; | |
78 } | |
79 | |
80 template <typename T> void BlockStack<T>::shrink(T* newEnd) | |
81 { | |
82 ASSERT(newEnd != m_blocks.last() + blockLength); | |
83 m_spareBlock = m_blocks.last(); | |
84 m_blocks.removeLast(); | |
85 | |
86 while (m_blocks.last() + blockLength != newEnd) { | |
87 fastFree(m_blocks.last()); | |
88 m_blocks.removeLast(); | |
89 } | |
90 } | |
91 | |
92 } | |
93 | |
94 using WTF::BlockStack; | |
95 | |
96 #endif | |
OLD | NEW |