2 * Copyright 2013 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
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
20 #ifndef FOLLY_MALLOC_H_
21 #define FOLLY_MALLOC_H_
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)
29 #include "folly/detail/Malloc.h"
33 using std::goodMallocSize;
34 using std::jemallocMinInPlaceExpandable;
35 using std::usingJEMalloc;
36 using std::smartRealloc;
37 using std::checkedMalloc;
38 using std::checkedCalloc;
39 using std::checkedRealloc;
42 #else // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
44 #ifdef _LIBSTDCXX_FBSTRING
45 #pragma GCC system_header
48 * Declare rallocm() and allocm() as weak symbols. These will be provided by
49 * jemalloc if we are using jemalloc, or will be NULL if we are using another
50 * malloc implementation.
52 extern "C" int rallocm(void**, size_t*, size_t, size_t, int)
53 __attribute__((weak));
54 extern "C" int allocm(void**, size_t*, size_t, int)
55 __attribute__((weak));
57 #define FOLLY_HAVE_MALLOC_H 1
59 #include "folly/detail/Malloc.h"
60 #include "folly/Portability.h"
63 // for malloc_usable_size
64 // NOTE: FreeBSD 9 doesn't have malloc.h. It's defitions
65 // are found in stdlib.h.
66 #if FOLLY_HAVE_MALLOC_H
79 #include <bits/functexcept.h>
82 * Define various ALLOCM_* macros normally provided by jemalloc. We define
83 * them so that we don't have to include jemalloc.h, in case the program is
84 * built without jemalloc support.
86 #ifndef ALLOCM_SUCCESS
88 #define ALLOCM_SUCCESS 0
89 #define ALLOCM_ERR_OOM 1
90 #define ALLOCM_ERR_NOT_MOVED 2
92 #define ALLOCM_ZERO 64
93 #define ALLOCM_NO_MOVE 128
95 #define ALLOCM_LG_ALIGN(la) (la)
97 #if defined(JEMALLOC_MANGLE) && defined(JEMALLOC_EXPERIMENTAL)
98 #define rallocm je_rallocm
99 #define allocm je_allocm
102 #endif /* ALLOCM_SUCCESS */
104 #ifdef _LIBSTDCXX_FBSTRING
105 namespace std _GLIBCXX_VISIBILITY(default) {
106 _GLIBCXX_BEGIN_NAMESPACE_VERSION
113 * Determine if we are using jemalloc or not.
115 inline bool usingJEMalloc() {
116 return rallocm != NULL;
120 * For jemalloc's size classes, see
121 * http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
123 inline size_t goodMallocSize(size_t minSize) {
124 if (!usingJEMalloc()) {
125 // Not using jemalloc - no smarts
129 // Choose smallest allocation to be 64 bytes - no tripping over
130 // cache line boundaries, and small string optimization takes care
131 // of short strings anyway.
134 if (minSize <= 512) {
135 // Round up to the next multiple of 64; we don't want to trip over
136 // cache line boundaries.
137 return (minSize + 63) & ~size_t(63);
139 if (minSize <= 3840) {
140 // Round up to the next multiple of 256
141 return (minSize + 255) & ~size_t(255);
143 if (minSize <= 4072 * 1024) {
144 // Round up to the next multiple of 4KB
145 return (minSize + 4095) & ~size_t(4095);
148 // Round up to the next multiple of 4MB
149 return (minSize + 4194303) & ~size_t(4194303);
152 // We always request "good" sizes for allocation, so jemalloc can
153 // never grow in place small blocks; they're already occupied to the
154 // brim. Blocks larger than or equal to 4096 bytes can in fact be
155 // expanded in place, and this constant reflects that.
156 static const size_t jemallocMinInPlaceExpandable = 4096;
159 * Trivial wrappers around malloc, calloc, realloc that check for allocation
160 * failure and throw std::bad_alloc in that case.
162 inline void* checkedMalloc(size_t size) {
163 void* p = malloc(size);
164 if (!p) std::__throw_bad_alloc();
168 inline void* checkedCalloc(size_t n, size_t size) {
169 void* p = calloc(n, size);
170 if (!p) std::__throw_bad_alloc();
174 inline void* checkedRealloc(void* ptr, size_t size) {
175 void* p = realloc(ptr, size);
176 if (!p) std::__throw_bad_alloc();
181 * This function tries to reallocate a buffer of which only the first
182 * currentSize bytes are used. The problem with using realloc is that
183 * if currentSize is relatively small _and_ if realloc decides it
184 * needs to move the memory chunk to a new buffer, then realloc ends
185 * up copying data that is not used. It's impossible to hook into
186 * GNU's malloc to figure whether expansion will occur in-place or as
187 * a malloc-copy-free troika. (If an expand_in_place primitive would
188 * be available, smartRealloc would use it.) As things stand, this
189 * routine just tries to call realloc() (thus benefitting of potential
190 * copy-free coalescing) unless there's too much slack memory.
192 inline void* smartRealloc(void* p,
193 const size_t currentSize,
194 const size_t currentCapacity,
195 const size_t newCapacity) {
197 assert(currentSize <= currentCapacity &&
198 currentCapacity < newCapacity);
200 if (usingJEMalloc()) {
201 // using jemalloc's API. Don't forget that jemalloc can never grow
202 // in place blocks smaller than 4096 bytes.
203 if (currentCapacity >= jemallocMinInPlaceExpandable &&
204 rallocm(&p, NULL, newCapacity, 0, ALLOCM_NO_MOVE) == ALLOCM_SUCCESS) {
205 // Managed to expand in place
208 // Cannot expand; must move
209 auto const result = checkedMalloc(newCapacity);
210 std::memcpy(result, p, currentSize);
215 // No jemalloc no honey
216 auto const slack = currentCapacity - currentSize;
217 if (slack * 2 > currentSize) {
218 // Too much slack, malloc-copy-free cycle:
219 auto const result = checkedMalloc(newCapacity);
220 std::memcpy(result, p, currentSize);
224 // If there's not too much slack, we realloc in hope of coalescing
225 return checkedRealloc(p, newCapacity);
228 #ifdef _LIBSTDCXX_FBSTRING
229 _GLIBCXX_END_NAMESPACE_VERSION
234 #endif // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
236 #endif // FOLLY_MALLOC_H_