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27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
1 /*
2 * Copyright 2012 Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 // Functions to provide smarter use of jemalloc, if jemalloc is being used.
18 // http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
19
20 #ifndef FOLLY_MALLOC_H_
21 #define FOLLY_MALLOC_H_
22
23 // If using fbstring from libstdc++, then just define stub code
24 // here to typedef the fbstring type into the folly namespace.
25 // This provides backwards compatibility for code that explicitly
26 // includes and uses fbstring.
27 #if defined(_GLIBCXX_USE_FB) && !defined(_LIBSTDCXX_FBSTRING)
28
29 #include <string>
30 namespace folly {
31 using std::goodMallocSize;
32 using std::jemallocMinInPlaceExpandable;
33 using std::usingJEMalloc;
34 using std::smartRealloc;
21a265b3 » tudor
2012-06-05 Add #include <new> to folly/Malloc.h.
35 using std::checkedMalloc;
36 using std::checkedCalloc;
37 using std::checkedRealloc;
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
38 }
39
40 #else // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
41
42 #ifdef _LIBSTDCXX_FBSTRING
43 #pragma GCC system_header
44 #define FOLLY_HAVE_MALLOC_H 1
45 #else
46 #include "folly-config.h"
47 #endif
48
49 // for malloc_usable_size
50 // NOTE: FreeBSD 9 doesn't have malloc.h. It's defitions
51 // are found in stdlib.h.
52 #ifdef FOLLY_HAVE_MALLOC_H
53 #include <malloc.h>
54 #else
55 #include <stdlib.h>
56 #endif
57
58 #include <cassert>
59 #include <cstddef>
60 #include <cstdlib>
61 #include <cstring>
62
21a265b3 » tudor
2012-06-05 Add #include <new> to folly/Malloc.h.
63 #include <new>
64
25189ad9 » andrewjcg
2012-07-11 folly/Malloc.h: use libstdc++-safe exception wrappers
65 #include <bits/functexcept.h>
66
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
67 /**
68 * Declare rallocm() and malloc_usable_size() as weak symbols. It
69 * will be provided by jemalloc if we are using jemalloc, or it will
70 * be NULL if we are using another malloc implementation.
71 */
72 extern "C" int rallocm(void**, size_t*, size_t, size_t, int)
73 __attribute__((weak));
74
75 /**
76 * Define the ALLOCM_SUCCESS, ALLOCM_ZERO, and ALLOCM_NO_MOVE constants
77 * normally provided by jemalloc. We define them so that we don't have to
78 * include jemalloc.h, in case the program is built without jemalloc support.
79 */
80 #ifndef ALLOCM_SUCCESS
81 #define ALLOCM_SUCCESS 0
82 #define ALLOCM_ERR_OOM 1
83 #define ALLOCM_ERR_NOT_MOVED 2
84
85 #define ALLOCM_ZERO 64
86 #define ALLOCM_NO_MOVE 128
87 #endif
88
89 #ifdef _LIBSTDCXX_FBSTRING
90 namespace std _GLIBCXX_VISIBILITY(default) {
91 _GLIBCXX_BEGIN_NAMESPACE_VERSION
92 #else
93 namespace folly {
94 #endif
95
96
97 /**
98 * Determine if we are using jemalloc or not.
99 */
100 inline bool usingJEMalloc() {
101 return rallocm != NULL;
102 }
103
104 /**
105 * For jemalloc's size classes, see
106 * http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
107 */
108 inline size_t goodMallocSize(size_t minSize) {
109 if (!usingJEMalloc()) {
110 // Not using jemalloc - no smarts
111 return minSize;
112 }
113 if (minSize <= 64) {
114 // Choose smallest allocation to be 64 bytes - no tripping over
115 // cache line boundaries, and small string optimization takes care
116 // of short strings anyway.
117 return 64;
118 }
119 if (minSize <= 512) {
120 // Round up to the next multiple of 64; we don't want to trip over
121 // cache line boundaries.
122 return (minSize + 63) & ~size_t(63);
123 }
124 if (minSize <= 3840) {
125 // Round up to the next multiple of 256
126 return (minSize + 255) & ~size_t(255);
127 }
128 if (minSize <= 4072 * 1024) {
129 // Round up to the next multiple of 4KB
130 return (minSize + 4095) & ~size_t(4095);
131 }
132 // Holy Moly
133 // Round up to the next multiple of 4MB
134 return (minSize + 4194303) & ~size_t(4194303);
135 }
136
137 // We always request "good" sizes for allocation, so jemalloc can
138 // never grow in place small blocks; they're already occupied to the
139 // brim. Blocks larger than or equal to 4096 bytes can in fact be
140 // expanded in place, and this constant reflects that.
141 static const size_t jemallocMinInPlaceExpandable = 4096;
142
143 /**
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
144 * Trivial wrappers around malloc, calloc, realloc that check for allocation
145 * failure and throw std::bad_alloc in that case.
146 */
147 inline void* checkedMalloc(size_t size) {
148 void* p = malloc(size);
25189ad9 » andrewjcg
2012-07-11 folly/Malloc.h: use libstdc++-safe exception wrappers
149 if (!p) std::__throw_bad_alloc();
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
150 return p;
151 }
152
153 inline void* checkedCalloc(size_t n, size_t size) {
154 void* p = calloc(n, size);
25189ad9 » andrewjcg
2012-07-11 folly/Malloc.h: use libstdc++-safe exception wrappers
155 if (!p) std::__throw_bad_alloc();
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
156 return p;
157 }
158
159 inline void* checkedRealloc(void* ptr, size_t size) {
160 void* p = realloc(ptr, size);
25189ad9 » andrewjcg
2012-07-11 folly/Malloc.h: use libstdc++-safe exception wrappers
161 if (!p) std::__throw_bad_alloc();
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
162 return p;
163 }
164
165 /**
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
166 * This function tries to reallocate a buffer of which only the first
167 * currentSize bytes are used. The problem with using realloc is that
168 * if currentSize is relatively small _and_ if realloc decides it
169 * needs to move the memory chunk to a new buffer, then realloc ends
170 * up copying data that is not used. It's impossible to hook into
171 * GNU's malloc to figure whether expansion will occur in-place or as
172 * a malloc-copy-free troika. (If an expand_in_place primitive would
173 * be available, smartRealloc would use it.) As things stand, this
174 * routine just tries to call realloc() (thus benefitting of potential
175 * copy-free coalescing) unless there's too much slack memory.
176 */
177 inline void* smartRealloc(void* p,
178 const size_t currentSize,
179 const size_t currentCapacity,
180 const size_t newCapacity) {
181 assert(p);
182 assert(currentSize <= currentCapacity &&
183 currentCapacity < newCapacity);
184
185 if (usingJEMalloc()) {
186 // using jemalloc's API. Don't forget that jemalloc can never grow
187 // in place blocks smaller than 4096 bytes.
188 if (currentCapacity >= jemallocMinInPlaceExpandable &&
189 rallocm(&p, NULL, newCapacity, 0, ALLOCM_NO_MOVE) == ALLOCM_SUCCESS) {
190 // Managed to expand in place
191 return p;
192 }
193 // Cannot expand; must move
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
194 auto const result = checkedMalloc(newCapacity);
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
195 std::memcpy(result, p, currentSize);
196 free(p);
197 return result;
198 }
199
200 // No jemalloc no honey
201 auto const slack = currentCapacity - currentSize;
202 if (slack * 2 > currentSize) {
203 // Too much slack, malloc-copy-free cycle:
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
204 auto const result = checkedMalloc(newCapacity);
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
205 std::memcpy(result, p, currentSize);
206 free(p);
207 return result;
208 }
209 // If there's not too much slack, we realloc in hope of coalescing
050c1c3d » tudor
2012-06-04 Check the return value from malloc / realloc.
210 return checkedRealloc(p, newCapacity);
27494a20 » jdelong
2012-06-02 Pull from FB rev 63ce89e
211 }
212
213 #ifdef _LIBSTDCXX_FBSTRING
214 _GLIBCXX_END_NAMESPACE_VERSION
215 #endif
216
217 } // folly
218
219 #endif // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
220
221 #endif // FOLLY_MALLOC_H_
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