diff options
Diffstat (limited to 'src/backend/storage/buffer/s_lock.c')
| -rw-r--r-- | src/backend/storage/buffer/s_lock.c | 52 |
1 files changed, 39 insertions, 13 deletions
diff --git a/src/backend/storage/buffer/s_lock.c b/src/backend/storage/buffer/s_lock.c index 7f658ad26a8..932e5b0049b 100644 --- a/src/backend/storage/buffer/s_lock.c +++ b/src/backend/storage/buffer/s_lock.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.27 2000/12/11 00:49:51 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.28 2000/12/29 21:31:20 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -25,19 +25,21 @@ * number of microseconds to wait. This accomplishes pseudo random back-off. * Values are not critical but 10 milliseconds is a common platform * granularity. - * note: total time to cycle through all 16 entries might be about .07 sec. + * + * Total time to cycle through all 20 entries might be about .07 sec, + * so the given value of S_MAX_BUSY results in timeout after ~70 sec. */ #define S_NSPINCYCLE 20 #define S_MAX_BUSY 1000 * S_NSPINCYCLE int s_spincycle[S_NSPINCYCLE] = -{0, 0, 0, 0, 10000, 0, 0, 0, 10000, 0, +{ 0, 0, 0, 0, 10000, 0, 0, 0, 10000, 0, 0, 10000, 0, 0, 10000, 0, 10000, 0, 10000, 10000 }; /* - * s_lock_stuck(lock) - complain about a stuck spinlock + * s_lock_stuck() - complain about a stuck spinlock */ static void s_lock_stuck(volatile slock_t *lock, const char *file, const int line) @@ -52,13 +54,38 @@ s_lock_stuck(volatile slock_t *lock, const char *file, const int line) } +/* + * s_lock_sleep() - sleep a pseudo-random amount of time, check for timeout + * + * Normally 'microsec' is 0, specifying to use the next s_spincycle[] value. + * Some callers may pass a nonzero interval, specifying to use exactly that + * delay value rather than a pseudo-random delay. + */ void -s_lock_sleep(unsigned spin) +s_lock_sleep(unsigned spins, int microsec, + volatile slock_t *lock, + const char *file, const int line) { struct timeval delay; + unsigned max_spins; + + if (microsec > 0) + { + delay.tv_sec = 0; + delay.tv_usec = microsec; + /* two-minute timeout in this case */ + max_spins = 120000000 / microsec; + } + else + { + delay.tv_sec = 0; + delay.tv_usec = s_spincycle[spins % S_NSPINCYCLE]; + max_spins = S_MAX_BUSY; + } + + if (spins > max_spins) + s_lock_stuck(lock, file, line); - delay.tv_sec = 0; - delay.tv_usec = s_spincycle[spin % S_NSPINCYCLE]; (void) select(0, NULL, NULL, NULL, &delay); } @@ -71,14 +98,13 @@ s_lock(volatile slock_t *lock, const char *file, const int line) { unsigned spins = 0; + /* + * If you are thinking of changing this code, be careful. This same + * loop logic is used in other places that call TAS() directly. + */ while (TAS(lock)) { - s_lock_sleep(spins); - if (++spins > S_MAX_BUSY) - { - /* It's been over a minute... */ - s_lock_stuck(lock, file, line); - } + s_lock_sleep(spins++, 0, lock, file, line); } } |