diff options
Diffstat (limited to 'db2/mutex/mutex.c')
| -rw-r--r-- | db2/mutex/mutex.c | 49 |
1 files changed, 30 insertions, 19 deletions
diff --git a/db2/mutex/mutex.c b/db2/mutex/mutex.c index de0d0e23fe..acc6aa07c9 100644 --- a/db2/mutex/mutex.c +++ b/db2/mutex/mutex.c @@ -8,7 +8,7 @@ #include "config.h" #ifndef lint -static const char sccsid[] = "@(#)mutex.c 10.48 (Sleepycat) 5/23/98"; +static const char sccsid[] = "@(#)mutex.c 10.52 (Sleepycat) 11/8/98"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES @@ -37,9 +37,12 @@ static const char sccsid[] = "@(#)mutex.c 10.48 (Sleepycat) 5/23/98"; #if defined(HAVE_FUNC_MSEM) /* - * XXX - * Should we not use MSEM_IF_NOWAIT and let the system block for us? - * I've no idea if this will block all threads in the process or not. + * !!! + * Do not remove the MSEM_IF_NOWAIT flag. The problem is that if a single + * process makes two msem_lock() calls in a row, the second one returns an + * error. We depend on the fact that we can lock against ourselves in the + * locking subsystem, where we set up a mutex so that we can block ourselves. + * Tested on OSF1 v4.0. */ #define TSL_INIT(x) (msem_init(x, MSEM_UNLOCKED) == NULL) #define TSL_INIT_ERROR 1 @@ -74,6 +77,17 @@ static const char sccsid[] = "@(#)mutex.c 10.48 (Sleepycat) 5/23/98"; #define TSL_UNSET(x) _lock_clear(x) #endif +#ifdef HAVE_FUNC_VMS +#include <builtins.h> +#ifdef __ALPHA +#define TSL_SET(tsl) (!__TESTBITSSI(tsl, 0)) +#else /* __VAX */ +#define TSL_SET(tsl) (!(int)_BBSSI(0, tsl)) +#endif +#define TSL_UNSET(tsl) (*(tsl) = 0) +#define TSL_INIT(tsl) TSL_UNSET(tsl) +#endif + #ifdef HAVE_ASSEM_PARISC_GCC #include "parisc.gcc" #endif @@ -181,7 +195,7 @@ __db_mutex_lock(mp, fd) #ifdef HAVE_SPINLOCKS COMPQUIET(fd, 0); - for (usecs = MS(10);;) { + for (usecs = MS(1);;) { /* Try and acquire the uncontested resource lock for N spins. */ for (nspins = mp->spins; nspins > 0; --nspins) if (TSL_SET(&mp->tsl_resource)) { @@ -193,19 +207,17 @@ __db_mutex_lock(mp, fd) } mp->pid = getpid(); #endif - if (usecs == MS(10)) + if (usecs == MS(1)) ++mp->mutex_set_nowait; else ++mp->mutex_set_wait; return (0); } - /* Yield the processor; wait 10ms initially, up to 1 second. */ - if (__db_yield == NULL || __db_yield() != 0) { - (void)__db_sleep(0, usecs); - if ((usecs <<= 1) > SECOND) - usecs = SECOND; - } + /* Yield the processor; wait 1ms initially, up to 1 second. */ + __os_yield(usecs); + if ((usecs <<= 1) > SECOND) + usecs = SECOND; } /* NOTREACHED */ @@ -218,15 +230,14 @@ __db_mutex_lock(mp, fd) for (locked = 0, mypid = getpid();;) { /* - * Wait for the lock to become available; wait 10ms initially, + * Wait for the lock to become available; wait 1ms initially, * up to 1 second. */ - for (usecs = MS(10); mp->pid != 0;) - if (__db_yield == NULL || __db_yield() != 0) { - (void)__db_sleep(0, usecs); - if ((usecs <<= 1) > SECOND) - usecs = SECOND; - } + for (usecs = MS(1); mp->pid != 0;) { + __os_yield(usecs); + if ((usecs <<= 1) > SECOND) + usecs = SECOND; + } /* Acquire an exclusive kernel lock. */ k_lock.l_type = F_WRLCK; |