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
266
267
268
269
270
271
272
273
274
275
276
277
|
/*
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996-2009 Oracle. All rights reserved.
*
* $Id$
*/
#ifndef _DB_MUTEX_H_
#define _DB_MUTEX_H_
#ifdef HAVE_MUTEX_SUPPORT
/* The inlined trylock calls need access to the details of mutexes. */
#define LOAD_ACTUAL_MUTEX_CODE
#include "dbinc/mutex_int.h"
#ifndef HAVE_SHARED_LATCHES
#error "Shared latches are required in DB 4.8 and above"
#endif
#endif
#if defined(__cplusplus)
extern "C" {
#endif
/*
* By default, spin 50 times per processor if fail to acquire a test-and-set
* mutex, we have anecdotal evidence it's a reasonable value.
*/
#define MUTEX_SPINS_PER_PROCESSOR 50
/*
* Mutexes are represented by unsigned, 32-bit integral values. As the
* OOB value is 0, mutexes can be initialized by zero-ing out the memory
* in which they reside.
*/
#define MUTEX_INVALID 0
/*
* We track mutex allocations by ID.
*/
#define MTX_APPLICATION 1
#define MTX_ATOMIC_EMULATION 2
#define MTX_DB_HANDLE 3
#define MTX_ENV_DBLIST 4
#define MTX_ENV_HANDLE 5
#define MTX_ENV_REGION 6
#define MTX_LOCK_REGION 7
#define MTX_LOGICAL_LOCK 8
#define MTX_LOG_FILENAME 9
#define MTX_LOG_FLUSH 10
#define MTX_LOG_HANDLE 11
#define MTX_LOG_REGION 12
#define MTX_MPOOLFILE_HANDLE 13
#define MTX_MPOOL_BH 14
#define MTX_MPOOL_FH 15
#define MTX_MPOOL_FILE_BUCKET 16
#define MTX_MPOOL_HANDLE 17
#define MTX_MPOOL_HASH_BUCKET 18
#define MTX_MPOOL_REGION 19
#define MTX_MUTEX_REGION 20
#define MTX_MUTEX_TEST 21
#define MTX_REP_CHKPT 22
#define MTX_REP_DATABASE 23
#define MTX_REP_EVENT 24
#define MTX_REP_REGION 25
#define MTX_REPMGR 26
#define MTX_SEQUENCE 27
#define MTX_TWISTER 28
#define MTX_TXN_ACTIVE 29
#define MTX_TXN_CHKPT 30
#define MTX_TXN_COMMIT 31
#define MTX_TXN_MVCC 32
#define MTX_TXN_REGION 33
#define MTX_MAX_ENTRY 33
/* Redirect mutex calls to the correct functions. */
#if !defined(HAVE_MUTEX_HYBRID) && ( \
defined(HAVE_MUTEX_PTHREADS) || \
defined(HAVE_MUTEX_SOLARIS_LWP) || \
defined(HAVE_MUTEX_UI_THREADS))
#define __mutex_init(a, b, c) __db_pthread_mutex_init(a, b, c)
#define __mutex_lock(a, b) __db_pthread_mutex_lock(a, b)
#define __mutex_unlock(a, b) __db_pthread_mutex_unlock(a, b)
#define __mutex_destroy(a, b) __db_pthread_mutex_destroy(a, b)
#define __mutex_trylock(a, b) __db_pthread_mutex_trylock(a, b)
/*
* These trylock versions do not support DB_ENV_FAILCHK. Callers which loop
* checking mutexes which are held by dead processes or threads might spin.
* These have ANSI-style definitions because this file can be included by
* C++ files, and extern "C" affects linkage only, not argument typing.
*/
static inline int __db_pthread_mutex_trylock(ENV *env, db_mutex_t mutex)
{
int ret;
DB_MUTEX *mutexp;
if (!MUTEX_ON(env) || F_ISSET(env->dbenv, DB_ENV_NOLOCKING))
return (0);
mutexp = MUTEXP_SET(env->mutex_handle, mutex);
#ifdef HAVE_SHARED_LATCHES
if (F_ISSET(mutexp, DB_MUTEX_SHARED))
ret = pthread_rwlock_trywrlock(&mutexp->u.rwlock);
else
#endif
if ((ret = pthread_mutex_trylock(&mutexp->u.m.mutex)) == 0)
F_SET(mutexp, DB_MUTEX_LOCKED);
if (ret == EBUSY)
ret = DB_LOCK_NOTGRANTED;
#ifdef HAVE_STATISTICS
if (ret == 0)
++mutexp->mutex_set_nowait;
#endif
return (ret);
}
#ifdef HAVE_SHARED_LATCHES
#define __mutex_rdlock(a, b) __db_pthread_mutex_readlock(a, b)
#define __mutex_tryrdlock(a, b) __db_pthread_mutex_tryreadlock(a, b)
static inline int __db_pthread_mutex_tryreadlock(ENV *env, db_mutex_t mutex)
{
int ret;
DB_MUTEX *mutexp;
if (!MUTEX_ON(env) || F_ISSET(env->dbenv, DB_ENV_NOLOCKING))
return (0);
mutexp = MUTEXP_SET(env->mutex_handle, mutex);
if (F_ISSET(mutexp, DB_MUTEX_SHARED))
ret = pthread_rwlock_tryrdlock(&mutexp->u.rwlock);
else
return (EINVAL);
if (ret == EBUSY)
ret = DB_LOCK_NOTGRANTED;
#ifdef HAVE_STATISTICS
if (ret == 0)
++mutexp->mutex_set_rd_nowait;
#endif
return (ret);
}
#endif
#elif defined(HAVE_MUTEX_WIN32) || defined(HAVE_MUTEX_WIN32_GCC)
#define __mutex_init(a, b, c) __db_win32_mutex_init(a, b, c)
#define __mutex_lock(a, b) __db_win32_mutex_lock(a, b)
#define __mutex_trylock(a, b) __db_win32_mutex_trylock(a, b)
#define __mutex_unlock(a, b) __db_win32_mutex_unlock(a, b)
#define __mutex_destroy(a, b) __db_win32_mutex_destroy(a, b)
#ifdef HAVE_SHARED_LATCHES
#define __mutex_rdlock(a, b) __db_win32_mutex_readlock(a, b)
#define __mutex_tryrdlock(a, b) __db_win32_mutex_tryreadlock(a, b)
#endif
#elif defined(HAVE_MUTEX_FCNTL)
#define __mutex_init(a, b, c) __db_fcntl_mutex_init(a, b, c)
#define __mutex_lock(a, b) __db_fcntl_mutex_lock(a, b)
#define __mutex_trylock(a, b) __db_fcntl_mutex_trylock(a, b)
#define __mutex_unlock(a, b) __db_fcntl_mutex_unlock(a, b)
#define __mutex_destroy(a, b) __db_fcntl_mutex_destroy(a, b)
#else
#define __mutex_init(a, b, c) __db_tas_mutex_init(a, b, c)
#define __mutex_lock(a, b) __db_tas_mutex_lock(a, b)
#define __mutex_trylock(a, b) __db_tas_mutex_trylock(a, b)
#define __mutex_unlock(a, b) __db_tas_mutex_unlock(a, b)
#define __mutex_destroy(a, b) __db_tas_mutex_destroy(a, b)
#if defined(HAVE_SHARED_LATCHES)
#define __mutex_rdlock(a, b) __db_tas_mutex_readlock(a, b)
#define __mutex_tryrdlock(a,b) __db_tas_mutex_tryreadlock(a, b)
#endif
#endif
/*
* When there is no method to get a shared latch, fall back to
* implementing __mutex_rdlock() as getting an exclusive one.
* This occurs either when !HAVE_SHARED_LATCHES or HAVE_MUTEX_FCNTL.
*/
#ifndef __mutex_rdlock
#define __mutex_rdlock(a, b) __mutex_lock(a, b)
#endif
#ifndef __mutex_tryrdlock
#define __mutex_tryrdlock(a, b) __mutex_trylock(a, b)
#endif
/*
* Lock/unlock a mutex. If the mutex was never required, the thread of
* control can proceed without it.
*
* We never fail to acquire or release a mutex without panicing. Simplify
* the macros to always return a panic value rather than saving the actual
* return value of the mutex routine.
*/
#ifdef HAVE_MUTEX_SUPPORT
#define MUTEX_LOCK(env, mutex) do { \
if ((mutex) != MUTEX_INVALID && \
__mutex_lock(env, mutex) != 0) \
return (DB_RUNRECOVERY); \
} while (0)
/*
* Always check the return value of MUTEX_TRYLOCK()! Expect 0 on success,
* or DB_LOCK_NOTGRANTED, or possibly DB_RUNRECOVERY for failchk.
*/
#define MUTEX_TRYLOCK(env, mutex) \
(((mutex) == MUTEX_INVALID) ? 0 : __mutex_trylock(env, mutex))
/*
* Acquire a DB_MUTEX_SHARED "mutex" in shared mode.
*/
#define MUTEX_READLOCK(env, mutex) do { \
if ((mutex) != MUTEX_INVALID && \
__mutex_rdlock(env, mutex) != 0) \
return (DB_RUNRECOVERY); \
} while (0)
#define MUTEX_TRY_READLOCK(env, mutex) \
((mutex) != MUTEX_INVALID ? __mutex_tryrdlock(env, mutex) : 0)
#define MUTEX_UNLOCK(env, mutex) do { \
if ((mutex) != MUTEX_INVALID && \
__mutex_unlock(env, mutex) != 0) \
return (DB_RUNRECOVERY); \
} while (0)
#else
/*
* There are calls to lock/unlock mutexes outside of #ifdef's -- replace
* the call with something the compiler can discard, but which will make
* if-then-else blocks work correctly.
*/
#define MUTEX_LOCK(env, mutex) (mutex) = (mutex)
#define MUTEX_TRYLOCK(env, mutex) (mutex) = (mutex)
#define MUTEX_READLOCK(env, mutex) (mutex) = (mutex)
#define MUTEX_TRY_READLOCK(env, mutex) (mutex) = (mutex)
#define MUTEX_UNLOCK(env, mutex) (mutex) = (mutex)
#define MUTEX_REQUIRED(env, mutex) (mutex) = (mutex)
#define MUTEX_REQUIRED_READ(env, mutex) (mutex) = (mutex)
#endif
/*
* Berkeley DB ports may require single-threading at places in the code.
*/
#ifdef HAVE_MUTEX_VXWORKS
#include "taskLib.h"
/*
* Use the taskLock() mutex to eliminate a race where two tasks are
* trying to initialize the global lock at the same time.
*/
#define DB_BEGIN_SINGLE_THREAD do { \
if (DB_GLOBAL(db_global_init)) \
(void)semTake(DB_GLOBAL(db_global_lock), WAIT_FOREVER); \
else { \
taskLock(); \
if (DB_GLOBAL(db_global_init)) { \
taskUnlock(); \
(void)semTake(DB_GLOBAL(db_global_lock), \
WAIT_FOREVER); \
continue; \
} \
DB_GLOBAL(db_global_lock) = \
semBCreate(SEM_Q_FIFO, SEM_EMPTY); \
if (DB_GLOBAL(db_global_lock) != NULL) \
DB_GLOBAL(db_global_init) = 1; \
taskUnlock(); \
} \
} while (DB_GLOBAL(db_global_init) == 0)
#define DB_END_SINGLE_THREAD (void)semGive(DB_GLOBAL(db_global_lock))
#endif
/*
* Single-threading defaults to a no-op.
*/
#ifndef DB_BEGIN_SINGLE_THREAD
#define DB_BEGIN_SINGLE_THREAD
#endif
#ifndef DB_END_SINGLE_THREAD
#define DB_END_SINGLE_THREAD
#endif
#if defined(__cplusplus)
}
#endif
#include "dbinc_auto/mutex_ext.h"
#endif /* !_DB_MUTEX_H_ */
|