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Print lock tracing to stderr.

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Decrement granted read lock when releasing a read lock if there are no
pending write locks.  This still allows fair queuing between read and
write locks but does not block on aquiring a new read relock if we are
below quota of active locks and there are no pending writes.
This commit is contained in:
Mark Andrews 1999-12-23 05:05:04 +00:00
parent 3ddd814a97
commit 202e42a230
1 changed files with 9 additions and 11 deletions
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20
lib/isc/rwlock.c
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@ -32,14 +32,12 @@
#ifdef ISC_RWLOCK_TRACE #ifdef ISC_RWLOCK_TRACE
static void static void
print_lock(char *operation, isc_rwlock_t *rwl, isc_rwlocktype_t type) { print_lock(char *operation, isc_rwlock_t *rwl, isc_rwlocktype_t type) {
printf("%s(%s): ", operation, fprintf(stderr,
(type == isc_rwlocktype_read ? "read" : "write")); "%s(%s): %s, %u active, %u granted, %u rwaiting, %u wwaiting\n",
printf("%s, %u active, %u granted", operation, (type == isc_rwlocktype_read ? "read" : "write"),
(rwl->type == isc_rwlocktype_read ? "reading" : "writing"), (rwl->type == isc_rwlocktype_read ? "reading" : "writing"),
rwl->active, rwl->granted); rwl->active, rwl->granted, rwl->readers_waiting,
printf(", %u rwaiting, %u wwaiting\n", rwl->writers_waiting);
rwl->readers_waiting,
rwl->writers_waiting);
} }
#endif #endif
@ -196,11 +194,11 @@ isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
} }
} else { } else {
if (rwl->type == isc_rwlocktype_read && if (rwl->type == isc_rwlocktype_read &&
rwl->writers_waiting == 0 && rwl->writers_waiting == 0) {
rwl->readers_waiting > 0) {
INSIST(rwl->granted > 0); INSIST(rwl->granted > 0);
rwl->granted--; rwl->granted--;
SIGNAL(&rwl->readable); if (rwl->readers_waiting > 0)
SIGNAL(&rwl->readable);
} }
} }