Repository navigation
Expand file tree
/
Copy pathmutex.c
More file actions
361 lines (326 loc) · 9.61 KB
/
Copy pathmutex.c
File metadata and controls
361 lines (326 loc) · 9.61 KB
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
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
/*
** 2007 August 14
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes.
**
** This file contains code that is common across all mutex implementations.
*/
#include "sqliteInt.h"
#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
/*
** For debugging purposes, record when the mutex subsystem is initialized
** and uninitialized so that we can assert() if there is an attempt to
** allocate a mutex while the system is uninitialized.
*/
static SQLITE_WSD int mutexIsInit = 0;
#endif /* SQLITE_DEBUG && !defined(SQLITE_MUTEX_OMIT) */
#ifndef SQLITE_MUTEX_OMIT
#ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
/*
** This block (enclosed by SQLITE_ENABLE_MULTITHREADED_CHECKS) contains
** the implementation of a wrapper around the system default mutex
** implementation (sqlite3DefaultMutex()).
**
** Most calls are passed directly through to the underlying default
** mutex implementation. Except, if a mutex is configured by calling
** sqlite3MutexWarnOnContention() on it, then if contention is ever
** encountered within xMutexEnter() a warning is emitted via sqlite3_log().
**
** This type of mutex is used as the database handle mutex when testing
** apps that usually use SQLITE_CONFIG_MULTITHREAD mode.
*/
/*
** Type for all mutexes used when SQLITE_ENABLE_MULTITHREADED_CHECKS
** is defined. Variable CheckMutex.mutex is a pointer to the real mutex
** allocated by the system mutex implementation. Variable iType is usually set
** to the type of mutex requested - SQLITE_MUTEX_RECURSIVE, SQLITE_MUTEX_FAST
** or one of the static mutex identifiers. Or, if this is a recursive mutex
** that has been configured using sqlite3MutexWarnOnContention(), it is
** set to SQLITE_MUTEX_WARNONCONTENTION.
*/
typedef struct CheckMutex CheckMutex;
struct CheckMutex {
int iType;
sqlite3_mutex *mutex;
};
#define SQLITE_MUTEX_WARNONCONTENTION (-1)
/*
** Pointer to real mutex methods object used by the CheckMutex
** implementation. Set by checkMutexInit().
*/
static SQLITE_WSD const sqlite3_mutex_methods *pGlobalMutexMethods;
#ifdef SQLITE_DEBUG
static int checkMutexHeld(sqlite3_mutex *p){
return pGlobalMutexMethods->xMutexHeld(((CheckMutex*)p)->mutex);
}
static int checkMutexNotheld(sqlite3_mutex *p){
return pGlobalMutexMethods->xMutexNotheld(((CheckMutex*)p)->mutex);
}
#endif
/*
** Initialize and deinitialize the mutex subsystem.
*/
static int checkMutexInit(void){
pGlobalMutexMethods = sqlite3DefaultMutex();
return SQLITE_OK;
}
static int checkMutexEnd(void){
pGlobalMutexMethods = 0;
return SQLITE_OK;
}
/*
** Allocate a mutex.
*/
static sqlite3_mutex *checkMutexAlloc(int iType){
static CheckMutex staticMutexes[] = {
{2, 0}, {3, 0}, {4, 0}, {5, 0},
{6, 0}, {7, 0}, {8, 0}, {9, 0},
{10, 0}, {11, 0}, {12, 0}, {13, 0}
};
CheckMutex *p = 0;
assert( SQLITE_MUTEX_RECURSIVE==1 && SQLITE_MUTEX_FAST==0 );
if( iType<2 ){
p = sqlite3MallocZero(sizeof(CheckMutex));
if( p==0 ) return 0;
p->iType = iType;
}else{
#ifdef SQLITE_ENABLE_API_ARMOR
if( iType-2>=ArraySize(staticMutexes) ){
(void)SQLITE_MISUSE_BKPT;
return 0;
}
#endif
p = &staticMutexes[iType-2];
}
if( p->mutex==0 ){
p->mutex = pGlobalMutexMethods->xMutexAlloc(iType);
if( p->mutex==0 ){
if( iType<2 ){
sqlite3_free(p);
}
p = 0;
}
}
return (sqlite3_mutex*)p;
}
/*
** Free a mutex.
*/
static void checkMutexFree(sqlite3_mutex *p){
assert( SQLITE_MUTEX_RECURSIVE<2 );
assert( SQLITE_MUTEX_FAST<2 );
assert( SQLITE_MUTEX_WARNONCONTENTION<2 );
#ifdef SQLITE_ENABLE_API_ARMOR
if( ((CheckMutex*)p)->iType<2 )
#endif
{
CheckMutex *pCheck = (CheckMutex*)p;
pGlobalMutexMethods->xMutexFree(pCheck->mutex);
sqlite3_free(pCheck);
}
#ifdef SQLITE_ENABLE_API_ARMOR
else{
(void)SQLITE_MISUSE_BKPT;
}
#endif
}
/*
** Enter the mutex.
*/
static void checkMutexEnter(sqlite3_mutex *p){
CheckMutex *pCheck = (CheckMutex*)p;
if( pCheck->iType==SQLITE_MUTEX_WARNONCONTENTION ){
if( SQLITE_OK==pGlobalMutexMethods->xMutexTry(pCheck->mutex) ){
return;
}
sqlite3_log(SQLITE_MISUSE,
"illegal multi-threaded access to database connection"
);
}
pGlobalMutexMethods->xMutexEnter(pCheck->mutex);
}
/*
** Enter the mutex (do not block).
*/
static int checkMutexTry(sqlite3_mutex *p){
CheckMutex *pCheck = (CheckMutex*)p;
return pGlobalMutexMethods->xMutexTry(pCheck->mutex);
}
/*
** Leave the mutex.
*/
static void checkMutexLeave(sqlite3_mutex *p){
CheckMutex *pCheck = (CheckMutex*)p;
pGlobalMutexMethods->xMutexLeave(pCheck->mutex);
}
sqlite3_mutex_methods const *multiThreadedCheckMutex(void){
static const sqlite3_mutex_methods sMutex = {
checkMutexInit,
checkMutexEnd,
checkMutexAlloc,
checkMutexFree,
checkMutexEnter,
checkMutexTry,
checkMutexLeave,
#ifdef SQLITE_DEBUG
checkMutexHeld,
checkMutexNotheld
#else
0,
0
#endif
};
return &sMutex;
}
/*
** Mark the SQLITE_MUTEX_RECURSIVE mutex passed as the only argument as
** one on which there should be no contention.
*/
void sqlite3MutexWarnOnContention(sqlite3_mutex *p){
if( sqlite3GlobalConfig.mutex.xMutexAlloc==checkMutexAlloc ){
CheckMutex *pCheck = (CheckMutex*)p;
assert( pCheck->iType==SQLITE_MUTEX_RECURSIVE );
pCheck->iType = SQLITE_MUTEX_WARNONCONTENTION;
}
}
#endif /* ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS */
/*
** Initialize the mutex system.
*/
int sqlite3MutexInit(void){
int rc = SQLITE_OK;
if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
/* If the xMutexAlloc method has not been set, then the user did not
** install a mutex implementation via sqlite3_config() prior to
** sqlite3_initialize() being called. This block copies pointers to
** the default implementation into the sqlite3GlobalConfig structure.
*/
sqlite3_mutex_methods const *pFrom;
sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;
if( sqlite3GlobalConfig.bCoreMutex ){
#ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
pFrom = multiThreadedCheckMutex();
#else
pFrom = sqlite3DefaultMutex();
#endif
}else{
pFrom = sqlite3NoopMutex();
}
pTo->xMutexInit = pFrom->xMutexInit;
pTo->xMutexEnd = pFrom->xMutexEnd;
pTo->xMutexFree = pFrom->xMutexFree;
pTo->xMutexEnter = pFrom->xMutexEnter;
pTo->xMutexTry = pFrom->xMutexTry;
pTo->xMutexLeave = pFrom->xMutexLeave;
pTo->xMutexHeld = pFrom->xMutexHeld;
pTo->xMutexNotheld = pFrom->xMutexNotheld;
sqlite3MemoryBarrier();
pTo->xMutexAlloc = pFrom->xMutexAlloc;
}
assert( sqlite3GlobalConfig.mutex.xMutexInit );
rc = sqlite3GlobalConfig.mutex.xMutexInit();
#ifdef SQLITE_DEBUG
GLOBAL(int, mutexIsInit) = 1;
#endif
sqlite3MemoryBarrier();
return rc;
}
/*
** Shutdown the mutex system. This call frees resources allocated by
** sqlite3MutexInit().
*/
int sqlite3MutexEnd(void){
int rc = SQLITE_OK;
if( sqlite3GlobalConfig.mutex.xMutexEnd ){
rc = sqlite3GlobalConfig.mutex.xMutexEnd();
}
#ifdef SQLITE_DEBUG
GLOBAL(int, mutexIsInit) = 0;
#endif
return rc;
}
/*
** Retrieve a pointer to a static mutex or allocate a new dynamic one.
*/
sqlite3_mutex *sqlite3_mutex_alloc(int id){
#ifndef SQLITE_OMIT_AUTOINIT
if( id<=SQLITE_MUTEX_RECURSIVE && sqlite3_initialize() ) return 0;
if( id>SQLITE_MUTEX_RECURSIVE && sqlite3MutexInit() ) return 0;
#endif
assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
}
sqlite3_mutex *sqlite3MutexAlloc(int id){
if( !sqlite3GlobalConfig.bCoreMutex ){
return 0;
}
assert( GLOBAL(int, mutexIsInit) );
assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
}
/*
** Free a dynamic mutex.
*/
void sqlite3_mutex_free(sqlite3_mutex *p){
if( p ){
assert( sqlite3GlobalConfig.mutex.xMutexFree );
sqlite3GlobalConfig.mutex.xMutexFree(p);
}
}
/*
** Obtain the mutex p. If some other thread already has the mutex, block
** until it can be obtained.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
if( p ){
assert( sqlite3GlobalConfig.mutex.xMutexEnter );
sqlite3GlobalConfig.mutex.xMutexEnter(p);
}
}
/*
** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another
** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY.
*/
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc = SQLITE_OK;
if( p ){
assert( sqlite3GlobalConfig.mutex.xMutexTry );
return sqlite3GlobalConfig.mutex.xMutexTry(p);
}
return rc;
}
/*
** The sqlite3_mutex_leave() routine exits a mutex that was previously
** entered by the same thread. The behavior is undefined if the mutex
** is not currently entered. If a NULL pointer is passed as an argument
** this function is a no-op.
*/
void sqlite3_mutex_leave(sqlite3_mutex *p){
if( p ){
assert( sqlite3GlobalConfig.mutex.xMutexLeave );
sqlite3GlobalConfig.mutex.xMutexLeave(p);
}
}
#ifndef NDEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
int sqlite3_mutex_held(sqlite3_mutex *p){
assert( p==0 || sqlite3GlobalConfig.mutex.xMutexHeld );
return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
}
int sqlite3_mutex_notheld(sqlite3_mutex *p){
assert( p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld );
return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
}
#endif
#endif /* !defined(SQLITE_MUTEX_OMIT) */