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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1999, 2000
* Sleepycat Software. All rights reserved.
*/
#include "db_config.h"
#ifndef lint
static const char revid[] = "$Id: mutex.c,v 11.14 2000/11/30 00:58:42 ubell Exp $";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#endif
#include "db_int.h"
/*
* __db_mutex_alloc --
* Allocate and initialize a mutex.
*
* PUBLIC: int __db_mutex_alloc __P((DB_ENV *, REGINFO *, MUTEX **));
*/
int
__db_mutex_alloc(dbenv, infop, storep)
DB_ENV *dbenv;
REGINFO *infop;
MUTEX **storep;
{
int ret;
/*
* If the architecture supports mutexes in heap memory, use that
* memory. If it doesn't, we have to allocate space in a region.
*
* XXX
* There's a nasty starvation issue here for applications running
* on systems that don't support mutexes in heap memory. If the
* normal state of the entire region is dirty (e.g., mpool), then
* we can run out of memory to allocate for mutexes when new files
* are opened in the pool. We're not trying to fix this for now,
* because the only known system where we can see this failure at
* the moment is HP-UX 10.XX.
*/
#ifdef MUTEX_NO_MALLOC_LOCKS
R_LOCK(dbenv, infop);
ret = __db_shalloc(infop->addr, sizeof(MUTEX), MUTEX_ALIGN, storep);
R_UNLOCK(dbenv, infop);
#else
COMPQUIET(dbenv, NULL);
COMPQUIET(infop, NULL);
ret = __os_calloc(dbenv, 1, sizeof(MUTEX), storep);
#endif
if (ret != 0)
__db_err(dbenv, "Unable to allocate memory for mutex");
return (ret);
}
/*
* __db_mutex_free --
* Free a mutex.
*
* PUBLIC: void __db_mutex_free __P((DB_ENV *, REGINFO *, MUTEX *));
*/
void
__db_mutex_free(dbenv, infop, mutexp)
DB_ENV *dbenv;
REGINFO *infop;
MUTEX *mutexp;
{
if (F_ISSET(mutexp, MUTEX_INITED))
__db_mutex_destroy(mutexp);
#ifdef MUTEX_NO_MALLOC_LOCKS
R_LOCK(dbenv, infop);
__db_shalloc_free(infop->addr, mutexp);
R_UNLOCK(dbenv, infop);
#else
COMPQUIET(dbenv, NULL);
COMPQUIET(infop, NULL);
__os_free(mutexp, sizeof(*mutexp));
#endif
}
#ifdef MUTEX_SYSTEM_RESOURCES
/*
* __db_shreg_locks_record --
* Record an entry in the shared locks area.
* Region lock must be held in caller.
*
* PUBLIC: int __db_shreg_locks_record __P((DB_ENV *, MUTEX *, REGINFO *,
* PUBLIC: REGMAINT *));
*/
int
__db_shreg_locks_record(dbenv, mutexp, infop, rp)
DB_ENV *dbenv;
MUTEX *mutexp;
REGINFO *infop;
REGMAINT *rp;
{
u_int i;
if (!F_ISSET(mutexp, MUTEX_INITED))
return (0);
DB_ASSERT(mutexp->reg_off == INVALID_ROFF);
rp->stat.st_records++;
i = (roff_t *)R_ADDR(infop, rp->regmutex_hint) - &rp->regmutexes[0];
if (rp->regmutexes[i] != INVALID_ROFF) {
/*
* Our hint failed, search for a open slot.
*/
rp->stat.st_hint_miss++;
for (i = 0; i < rp->reglocks; i++)
if (rp->regmutexes[i] == INVALID_ROFF)
break;
if (i == rp->reglocks) {
rp->stat.st_max_locks++;
__db_err(dbenv,
"Region mutexes: Exceeded maximum lock slots %lu",
(u_long)rp->reglocks);
return (ENOMEM);
}
} else
rp->stat.st_hint_hit++;
/*
* When we get here, i is an empty slot. Record this
* mutex, set hint to point to the next slot and we are done.
*/
rp->regmutexes[i] = R_OFFSET(infop, mutexp);
mutexp->reg_off = R_OFFSET(infop, &rp->regmutexes[i]);
rp->regmutex_hint = (i < rp->reglocks - 1) ?
R_OFFSET(infop, &rp->regmutexes[i+1]) :
R_OFFSET(infop, &rp->regmutexes[0]);
return (0);
}
/*
* __db_shreg_locks_clear --
* Erase an entry in the shared locks area.
* Region lock must be held in caller.
*
* PUBLIC: void __db_shreg_locks_clear __P((MUTEX *, REGINFO *, REGMAINT *));
*/
void
__db_shreg_locks_clear(mutexp, infop, rp)
MUTEX *mutexp;
REGINFO *infop;
REGMAINT *rp;
{
if (!F_ISSET(mutexp, MUTEX_INITED))
return;
/*
* This function is generally only called on a forcible
* remove of an environment. We recorded our index in
* the mutex. Find it and clear it.
*/
DB_ASSERT(mutexp->reg_off != INVALID_ROFF);
DB_ASSERT(*(roff_t *)R_ADDR(infop, mutexp->reg_off) == \
R_OFFSET(infop, mutexp));
*(roff_t *)R_ADDR(infop, mutexp->reg_off) = 0;
rp->regmutex_hint = mutexp->reg_off;
rp->stat.st_clears++;
mutexp->reg_off = INVALID_ROFF;
__db_mutex_destroy(mutexp);
}
/*
* __db_shreg_locks_destroy --
* Destroy all mutexes in a region's range.
*
* PUBLIC: void __db_shreg_locks_destroy __P((REGINFO *, REGMAINT *));
*/
void
__db_shreg_locks_destroy(infop, rp)
REGINFO *infop;
REGMAINT *rp;
{
u_int32_t i;
/*
* Go through the list of all mutexes and destroy them.
*/
for (i = 0; i < rp->reglocks; i++)
if (rp->regmutexes[i] != 0) {
rp->stat.st_destroys++;
__db_mutex_destroy((MUTEX *)R_ADDR(infop,
rp->regmutexes[i]));
}
}
/*
* __db_shreg_mutex_init --
* Initialize a shared memory mutex.
*
* PUBLIC: int __db_shreg_mutex_init __P((DB_ENV *, MUTEX *, u_int32_t,
* PUBLIC: u_int32_t, REGINFO *, REGMAINT *));
*/
int
__db_shreg_mutex_init(dbenv, mutexp, offset, flags, infop, rp)
DB_ENV *dbenv;
MUTEX *mutexp;
u_int32_t offset;
u_int32_t flags;
REGINFO *infop;
REGMAINT *rp;
{
int ret;
if ((ret = __db_mutex_init(dbenv, mutexp, offset, flags)) != 0)
return (ret);
/*
* !!!
* Since __db_mutex_init is a macro, we may not be
* using the 'offset' as it is only used for one type
* of mutex. We COMPQUIET it here, after the call above.
*/
COMPQUIET(offset, 0);
if (!F_ISSET(mutexp, MUTEX_THREAD))
ret = __db_shreg_locks_record(dbenv, mutexp, infop, rp);
/*
* If we couldn't record it and we are returning an error,
* we need to destroy the mutex we just created.
*/
if (ret)
__db_mutex_destroy(mutexp);
return (ret);
}
/*
* __db_shreg_maintinit --
* Initialize a region's maintenance information.
*
* PUBLIC: void __db_shreg_maintinit __P((REGINFO *, void *addr, size_t));
*/
void
__db_shreg_maintinit(infop, addr, size)
REGINFO *infop;
void *addr;
size_t size;
{
REGMAINT *rp;
rp = (REGMAINT *)addr;
memset(addr, 0, sizeof(REGMAINT));
rp->reglocks = size / sizeof(roff_t);
rp->regmutex_hint = R_OFFSET(infop, &rp->regmutexes[0]);
}
#endif /* MUTEX_SYSTEM_RESOURCES */
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