summaryrefslogtreecommitdiffstats
path: root/memory/replace/logalloc/LogAlloc.cpp
blob: f475db40994bba5dba61cad95ab9bcc95b5e4231 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <cstdlib>
#include <cstdio>
#include <fcntl.h>

#ifdef _WIN32
#include <windows.h>
#include <io.h>
#include <process.h>
#else
#include <unistd.h>
#include <pthread.h>
#endif

#include "replace_malloc.h"
#include "FdPrintf.h"

#include "base/lock.h"

static const malloc_table_t* sFuncs = nullptr;
static intptr_t sFd = 0;
static bool sStdoutOrStderr = false;

static Lock sLock;

static void
prefork() {
  sLock.Acquire();
}

static void
postfork() {
  sLock.Release();
}

static size_t
GetPid()
{
  return size_t(getpid());
}

static size_t
GetTid()
{
#if defined(_WIN32)
  return size_t(GetCurrentThreadId());
#else
  return size_t(pthread_self());
#endif
}

class LogAllocBridge : public ReplaceMallocBridge
{
  virtual void InitDebugFd(mozilla::DebugFdRegistry& aRegistry) override {
    if (!sStdoutOrStderr) {
      aRegistry.RegisterHandle(sFd);
    }
  }
};

void
replace_init(const malloc_table_t* aTable)
{
  sFuncs = aTable;

#ifndef _WIN32
  /* When another thread has acquired a lock before forking, the child
   * process will inherit the lock state but the thread, being nonexistent
   * in the child process, will never release it, leading to a dead-lock
   * whenever the child process gets the lock. We thus need to ensure no
   * other thread is holding the lock before forking, by acquiring it
   * ourselves, and releasing it after forking, both in the parent and child
   * processes.
   * Windows doesn't have this problem since there is no fork().
   * The real allocator, however, might be doing the same thing (jemalloc
   * does). But pthread_atfork `prepare` handlers (first argument) are
   * processed in reverse order they were established. But replace_init
   * runs before the real allocator has had any chance to initialize and
   * call pthread_atfork itself. This leads to its prefork running before
   * ours. This leads to a race condition that can lead to a deadlock like
   * the following:
   *   - thread A forks.
   *   - libc calls real allocator's prefork, so thread A holds the real
   *     allocator lock.
   *   - thread B calls malloc, which calls our replace_malloc.
   *   - consequently, thread B holds our lock.
   *   - thread B then proceeds to call the real allocator's malloc, and
   *     waits for the real allocator's lock, which thread A holds.
   *   - libc calls our prefork, so thread A waits for our lock, which
   *     thread B holds.
   * To avoid this race condition, the real allocator's prefork must be
   * called after ours, which means it needs to be registered before ours.
   * So trick the real allocator into initializing itself without more side
   * effects by calling malloc with a size it can't possibly allocate. */
  sFuncs->malloc(-1);
  pthread_atfork(prefork, postfork, postfork);
#endif

  /* Initialize output file descriptor from the MALLOC_LOG environment
   * variable. Numbers up to 9999 are considered as a preopened file
   * descriptor number. Other values are considered as a file name. */
  char* log = getenv("MALLOC_LOG");
  if (log && *log) {
    int fd = 0;
    const char *fd_num = log;
    while (*fd_num) {
      /* Reject non digits. */
      if (*fd_num < '0' || *fd_num > '9') {
        fd = -1;
        break;
      }
      fd = fd * 10 + (*fd_num - '0');
      /* Reject values >= 10000. */
      if (fd >= 10000) {
        fd = -1;
        break;
      }
      fd_num++;
    }
    if (fd == 1 || fd == 2) {
      sStdoutOrStderr = true;
    }
#ifdef _WIN32
    // See comment in FdPrintf.h as to why CreateFile is used.
    HANDLE handle;
    if (fd > 0) {
      handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
    } else {
      handle = CreateFileA(log, FILE_APPEND_DATA, FILE_SHARE_READ |
                           FILE_SHARE_WRITE, nullptr, OPEN_ALWAYS,
                           FILE_ATTRIBUTE_NORMAL, nullptr);
    }
    if (handle != INVALID_HANDLE_VALUE) {
      sFd = reinterpret_cast<intptr_t>(handle);
    }
#else
    if (fd == -1) {
      fd = open(log, O_WRONLY | O_CREAT | O_APPEND, 0644);
    }
    if (fd > 0) {
      sFd = fd;
    }
#endif
  }
}

ReplaceMallocBridge*
replace_get_bridge()
{
  static LogAllocBridge bridge;
  return &bridge;
}

/* Do a simple, text-form, log of all calls to replace-malloc functions.
 * Use locking to guarantee that an allocation that did happen is logged
 * before any other allocation/free happens.
 * TODO: Add a thread id to the log: different allocators, or even different
 * configurations of jemalloc behave differently when allocations are coming
 * from different threads. Reproducing those multi-threaded workloads would be
 * useful to test those differences.
 */

void*
replace_malloc(size_t aSize)
{
  AutoLock lock(sLock);
  void* ptr = sFuncs->malloc(aSize);
  if (ptr) {
    FdPrintf(sFd, "%zu %zu malloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr);
  }
  return ptr;
}

int
replace_posix_memalign(void** aPtr, size_t aAlignment, size_t aSize)
{
  AutoLock lock(sLock);
  int ret = sFuncs->posix_memalign(aPtr, aAlignment, aSize);
  if (ret == 0) {
    FdPrintf(sFd, "%zu %zu posix_memalign(%zu,%zu)=%p\n", GetPid(), GetTid(),
             aAlignment, aSize, *aPtr);
  }
  return ret;
}

void*
replace_aligned_alloc(size_t aAlignment, size_t aSize)
{
  AutoLock lock(sLock);
  void* ptr = sFuncs->aligned_alloc(aAlignment, aSize);
  if (ptr) {
    FdPrintf(sFd, "%zu %zu aligned_alloc(%zu,%zu)=%p\n", GetPid(), GetTid(),
             aAlignment, aSize, ptr);
  }
  return ptr;
}

void*
replace_calloc(size_t aNum, size_t aSize)
{
  AutoLock lock(sLock);
  void* ptr = sFuncs->calloc(aNum, aSize);
  if (ptr) {
    FdPrintf(sFd, "%zu %zu calloc(%zu,%zu)=%p\n", GetPid(), GetTid(), aNum,
             aSize, ptr);
  }
  return ptr;
}

void*
replace_realloc(void* aPtr, size_t aSize)
{
  AutoLock lock(sLock);
  void* new_ptr = sFuncs->realloc(aPtr, aSize);
  if (new_ptr || !aSize) {
    FdPrintf(sFd, "%zu %zu realloc(%p,%zu)=%p\n", GetPid(), GetTid(), aPtr,
             aSize, new_ptr);
  }
  return new_ptr;
}

void
replace_free(void* aPtr)
{
  AutoLock lock(sLock);
  if (aPtr) {
    FdPrintf(sFd, "%zu %zu free(%p)\n", GetPid(), GetTid(), aPtr);
  }
  sFuncs->free(aPtr);
}

void*
replace_memalign(size_t aAlignment, size_t aSize)
{
  AutoLock lock(sLock);
  void* ptr = sFuncs->memalign(aAlignment, aSize);
  if (ptr) {
    FdPrintf(sFd, "%zu %zu memalign(%zu,%zu)=%p\n", GetPid(), GetTid(),
             aAlignment, aSize, ptr);
  }
  return ptr;
}

void*
replace_valloc(size_t aSize)
{
  AutoLock lock(sLock);
  void* ptr = sFuncs->valloc(aSize);
  if (ptr) {
    FdPrintf(sFd, "%zu %zu valloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr);
  }
  return ptr;
}

void
replace_jemalloc_stats(jemalloc_stats_t* aStats)
{
  AutoLock lock(sLock);
  sFuncs->jemalloc_stats(aStats);
  FdPrintf(sFd, "%zu %zu jemalloc_stats()\n", GetPid(), GetTid());
}