PostgreSQL Source Code: src/backend/port/posix_sema.c Source File (original) (raw)
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28#include <fcntl.h>
29#include <semaphore.h>
30#include <signal.h>
32#include <sys/stat.h>
33
38
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40
41#if defined(USE_NAMED_POSIX_SEMAPHORES) && defined(EXEC_BACKEND)
42#error cannot use named POSIX semaphores with EXEC_BACKEND
43#endif
44
46{
50
51
53{
56
57#define PG_SEM_REF(x) (&(x)->sem_padded.pgsem)
58
59#define IPCProtection (0600)
60
61#ifdef USE_NAMED_POSIX_SEMAPHORES
62static sem_t **mySemPointers;
63#else
65#endif
69
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73
74#ifdef USE_NAMED_POSIX_SEMAPHORES
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85static sem_t *
87{
88 int semKey;
89 char semname[64];
90 sem_t *mySem;
91
92 for (;;)
93 {
95
96 snprintf(semname, sizeof(semname), "/pgsql-%d", semKey);
97
98 mySem = sem_open(semname, O_CREAT | O_EXCL,
100
101#ifdef SEM_FAILED
102 if (mySem != (sem_t *) SEM_FAILED)
103 break;
104#else
105 if (mySem != (sem_t *) (-1))
106 break;
107#endif
108
109
110 if (errno == EEXIST || errno == EACCES || errno == EINTR)
111 continue;
112
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116 elog(FATAL, "sem_open(\"%s\") failed: %m", semname);
117 }
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123 sem_unlink(semname);
124
125 return mySem;
126}
127#else
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134static void
136{
137 if (sem_init(sem, 1, 1) < 0)
138 elog(FATAL, "sem_init failed: %m");
139}
140#endif
141
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144
145
146static void
148{
149#ifdef USE_NAMED_POSIX_SEMAPHORES
150
151 if (sem_close(sem) < 0)
152 elog(LOG, "sem_close failed: %m");
153#else
154
155 if (sem_destroy(sem) < 0)
156 elog(LOG, "sem_destroy failed: %m");
157#endif
158}
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163
166{
167#ifdef USE_NAMED_POSIX_SEMAPHORES
168
169 return 0;
170#else
171
173#endif
174}
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195void
197{
198 struct stat statbuf;
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209 errmsg("could not stat data directory \"%s\": %m",
211
212#ifdef USE_NAMED_POSIX_SEMAPHORES
213 mySemPointers = (sem_t **) malloc(maxSemas * sizeof(sem_t *));
214 if (mySemPointers == NULL)
216#else
217
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220
221
224#endif
225
229
231}
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238static void
240{
241 int i;
242
243#ifdef USE_NAMED_POSIX_SEMAPHORES
246 free(mySemPointers);
247#endif
248
249#ifdef USE_UNNAMED_POSIX_SEMAPHORES
252#endif
253}
254
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258
259
262{
264 sem_t *newsem;
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270 elog(PANIC, "too many semaphores created");
271
272#ifdef USE_NAMED_POSIX_SEMAPHORES
274
275 mySemPointers[numSems] = newsem;
277#else
281#endif
282
284
285 return sema;
286}
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293void
295{
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299
300 for (;;)
301 {
302 if (sem_trywait(PG_SEM_REF(sema)) < 0)
303 {
304 if (errno == EAGAIN || errno == EDEADLK)
305 break;
306 if (errno == EINTR)
307 continue;
308 elog(FATAL, "sem_trywait failed: %m");
309 }
310 }
311}
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318void
320{
321 int errStatus;
322
323
324 do
325 {
326 errStatus = sem_wait(PG_SEM_REF(sema));
327 } while (errStatus < 0 && errno == EINTR);
328
329 if (errStatus < 0)
330 elog(FATAL, "sem_wait failed: %m");
331}
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338void
340{
341 int errStatus;
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347
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349 do
350 {
351 errStatus = sem_post(PG_SEM_REF(sema));
352 } while (errStatus < 0 && errno == EINTR);
353
354 if (errStatus < 0)
355 elog(FATAL, "sem_post failed: %m");
356}
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363bool
365{
366 int errStatus;
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373 do
374 {
375 errStatus = sem_trywait(PG_SEM_REF(sema));
376 } while (errStatus < 0 && errno == EINTR);
377
378 if (errStatus < 0)
379 {
380 if (errno == EAGAIN || errno == EDEADLK)
381 return false;
382
383 elog(FATAL, "sem_trywait failed: %m");
384 }
385
386 return true;
387}
int errcode_for_file_access(void)
int errmsg(const char *fmt,...)
#define ereport(elevel,...)
Assert(PointerIsAligned(start, uint64))
void on_shmem_exit(pg_on_exit_callback function, Datum arg)
#define PG_CACHE_LINE_SIZE
struct PGSemaphoreData * PGSemaphore
Size PGSemaphoreShmemSize(int maxSemas)
void PGSemaphoreUnlock(PGSemaphore sema)
union SemTPadded SemTPadded
static void PosixSemaphoreKill(sem_t *sem)
struct PGSemaphoreData PGSemaphoreData
void PGReserveSemaphores(int maxSemas)
void PGSemaphoreReset(PGSemaphore sema)
void PGSemaphoreLock(PGSemaphore sema)
bool PGSemaphoreTryLock(PGSemaphore sema)
static PGSemaphore sharedSemas
PGSemaphore PGSemaphoreCreate(void)
static void ReleaseSemaphores(int status, Datum arg)
static void PosixSemaphoreCreate(sem_t *sem)
void * ShmemAllocUnlocked(Size size)
Size mul_size(Size s1, Size s2)
char pad[PG_CACHE_LINE_SIZE]