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
38namespace boost{
39namespace BOOST_REGEX_DETAIL_NS{
40
41#ifdef BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE /* lock free implementation */
42struct 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
78struct mem_block_node
79{
80 mem_block_node* next;
81};
82
83struct 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
135extern 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
146