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1 | /* |
2 | * Copyright (c) 2002 | |
3 | * John Maddock | |
4 | * | |
5 | * Use, modification and distribution are subject to the | |
6 | * Boost Software License, Version 1.0. (See accompanying file | |
7 | * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
8 | * | |
9 | */ | |
10 | ||
11 | /* | |
12 | * LOCATION: see http://www.boost.org for most recent version. | |
13 | * FILE mem_block_cache.hpp | |
14 | * VERSION see <boost/version.hpp> | |
15 | * DESCRIPTION: memory block cache used by the non-recursive matcher. | |
16 | */ | |
17 | ||
18 | #ifndef BOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP | |
19 | #define BOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP | |
20 | ||
21 | #include <new> | |
22 | #ifdef BOOST_HAS_THREADS | |
23 | #include <boost/regex/pending/static_mutex.hpp> | |
24 | #endif | |
25 | ||
26 | #ifdef BOOST_HAS_ABI_HEADERS | |
27 | # include BOOST_ABI_PREFIX | |
28 | #endif | |
29 | ||
30 | #ifndef BOOST_NO_CXX11_HDR_ATOMIC | |
31 | #include <atomic> | |
32 | #if ATOMIC_POINTER_LOCK_FREE == 2 | |
33 | #define BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE | |
34 | #define BOOST_REGEX_ATOMIC_POINTER std::atomic | |
35 | #endif | |
36 | #endif | |
37 | ||
38 | namespace boost{ | |
39 | namespace BOOST_REGEX_DETAIL_NS{ | |
40 | ||
41 | #ifdef BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE /* lock free implementation */ | |
42 | struct mem_block_cache | |
43 | { | |
44 | std::atomic<void*> cache[BOOST_REGEX_MAX_CACHE_BLOCKS]; | |
45 | ||
46 | ~mem_block_cache() | |
47 | { | |
48 | for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) { | |
49 | if (cache[i].load()) ::operator delete(cache[i].load()); | |
50 | } | |
51 | } | |
52 | void* get() | |
53 | { | |
54 | for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) { | |
55 | void* p = cache[i].load(); | |
56 | if (p != NULL) { | |
57 | if (cache[i].compare_exchange_strong(p, NULL)) return p; | |
58 | } | |
59 | } | |
60 | return ::operator new(BOOST_REGEX_BLOCKSIZE); | |
61 | } | |
62 | void put(void* ptr) | |
63 | { | |
64 | for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) { | |
65 | void* p = cache[i].load(); | |
66 | if (p == NULL) { | |
67 | if (cache[i].compare_exchange_strong(p, ptr)) return; | |
68 | } | |
69 | } | |
70 | ::operator delete(ptr); | |
71 | } | |
72 | }; | |
73 | ||
74 | ||
75 | #else /* lock-based implementation */ | |
76 | ||
77 | ||
78 | struct mem_block_node | |
79 | { | |
80 | mem_block_node* next; | |
81 | }; | |
82 | ||
83 | struct mem_block_cache | |
84 | { | |
85 | // this member has to be statically initialsed: | |
86 | mem_block_node* next; | |
87 | unsigned cached_blocks; | |
88 | #ifdef BOOST_HAS_THREADS | |
89 | boost::static_mutex mut; | |
90 | #endif | |
91 | ||
92 | ~mem_block_cache() | |
93 | { | |
94 | while(next) | |
95 | { | |
96 | mem_block_node* old = next; | |
97 | next = next->next; | |
98 | ::operator delete(old); | |
99 | } | |
100 | } | |
101 | void* get() | |
102 | { | |
103 | #ifdef BOOST_HAS_THREADS | |
104 | boost::static_mutex::scoped_lock g(mut); | |
105 | #endif | |
106 | if(next) | |
107 | { | |
108 | mem_block_node* result = next; | |
109 | next = next->next; | |
110 | --cached_blocks; | |
111 | return result; | |
112 | } | |
113 | return ::operator new(BOOST_REGEX_BLOCKSIZE); | |
114 | } | |
115 | void put(void* p) | |
116 | { | |
117 | #ifdef BOOST_HAS_THREADS | |
118 | boost::static_mutex::scoped_lock g(mut); | |
119 | #endif | |
120 | if(cached_blocks >= BOOST_REGEX_MAX_CACHE_BLOCKS) | |
121 | { | |
122 | ::operator delete(p); | |
123 | } | |
124 | else | |
125 | { | |
126 | mem_block_node* old = static_cast<mem_block_node*>(p); | |
127 | old->next = next; | |
128 | next = old; | |
129 | ++cached_blocks; | |
130 | } | |
131 | } | |
132 | }; | |
133 | #endif | |
134 | ||
135 | extern mem_block_cache block_cache; | |
136 | ||
137 | } | |
138 | } // namespace boost | |
139 | ||
140 | #ifdef BOOST_HAS_ABI_HEADERS | |
141 | # include BOOST_ABI_SUFFIX | |
142 | #endif | |
143 | ||
144 | #endif | |
145 |