mutex.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:9k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1999-2002
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: mutex.c,v 11.37 2002/05/31 19:37:46 bostic Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <string.h>
- #endif
- #include "db_int.h"
- #if defined(MUTEX_NO_MALLOC_LOCKS) || defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- #include "dbinc/db_shash.h"
- #include "dbinc/lock.h"
- #include "dbinc/log.h"
- #include "dbinc/mp.h"
- #include "dbinc/txn.h"
- #endif
- static int __db_mutex_alloc_int __P((DB_ENV *, REGINFO *, DB_MUTEX **));
- #ifdef HAVE_MUTEX_SYSTEM_RESOURCES
- static REGMAINT * __db_mutex_maint __P((DB_ENV *, REGINFO *));
- #endif
- /*
- * __db_mutex_setup --
- * External interface to allocate, and/or initialize, record
- * mutexes.
- *
- * PUBLIC: int __db_mutex_setup __P((DB_ENV *, REGINFO *, void *, u_int32_t));
- */
- int
- __db_mutex_setup(dbenv, infop, ptr, flags)
- DB_ENV *dbenv;
- REGINFO *infop;
- void *ptr;
- u_int32_t flags;
- {
- DB_MUTEX *mutex;
- REGMAINT *maint;
- u_int32_t iflags, offset;
- int ret;
- ret = 0;
- /*
- * If they indicated the region is not locked, then lock it.
- * This is only needed when we have unusual mutex resources.
- * (I.e. MUTEX_NO_MALLOC_LOCKS or HAVE_MUTEX_SYSTEM_RESOURCES)
- */
- #if defined(MUTEX_NO_MALLOC_LOCKS) || defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- if (!LF_ISSET(MUTEX_NO_RLOCK))
- R_LOCK(dbenv, infop);
- #endif
- /*
- * Allocate the mutex if they asked us to.
- */
- mutex = NULL;
- if (LF_ISSET(MUTEX_ALLOC)) {
- if ((ret = __db_mutex_alloc_int(dbenv, infop, ptr)) != 0)
- goto err;
- mutex = *(DB_MUTEX **)ptr;
- } else
- mutex = (DB_MUTEX *)ptr;
- /*
- * Set up to initialize the mutex.
- */
- iflags = LF_ISSET(MUTEX_THREAD | MUTEX_SELF_BLOCK);
- switch (infop->type) {
- case REGION_TYPE_LOCK:
- offset = P_TO_UINT32(mutex) + DB_FCNTL_OFF_LOCK;
- break;
- case REGION_TYPE_MPOOL:
- offset = P_TO_UINT32(mutex) + DB_FCNTL_OFF_MPOOL;
- break;
- default:
- offset = P_TO_UINT32(mutex) + DB_FCNTL_OFF_GEN;
- break;
- }
- maint = NULL;
- #ifdef HAVE_MUTEX_SYSTEM_RESOURCES
- if (!LF_ISSET(MUTEX_NO_RECORD))
- maint = (REGMAINT *)__db_mutex_maint(dbenv, infop);
- #endif
- ret = __db_mutex_init(dbenv, mutex, offset, iflags, infop, maint);
- err:
- #if defined(MUTEX_NO_MALLOC_LOCKS) || defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- if (!LF_ISSET(MUTEX_NO_RLOCK))
- R_UNLOCK(dbenv, infop);
- #endif
- /*
- * If we allocated the mutex but had an error on init'ing,
- * then we must free it before returning.
- * !!!
- * Free must be done after releasing region lock.
- */
- if (ret != 0 && LF_ISSET(MUTEX_ALLOC) && mutex != NULL) {
- __db_mutex_free(dbenv, infop, mutex);
- *(DB_MUTEX **)ptr = NULL;
- }
- return (ret);
- }
- /*
- * __db_mutex_alloc_int --
- * Allocate and initialize a mutex.
- */
- static int
- __db_mutex_alloc_int(dbenv, infop, storep)
- DB_ENV *dbenv;
- REGINFO *infop;
- DB_MUTEX **storep;
- {
- int ret;
- /*
- * If the architecture supports mutexes in heap memory, use heap memory.
- * If it doesn't, we have to allocate space in a region. If allocation
- * in the region fails, fallback to allocating from the mpool region,
- * because it's big, it almost always exists and if it's entirely dirty,
- * we can free buffers until memory is available.
- */
- #if defined(MUTEX_NO_MALLOC_LOCKS) || defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- ret = __db_shalloc(infop->addr, sizeof(DB_MUTEX), MUTEX_ALIGN, storep);
- if (ret == ENOMEM && MPOOL_ON(dbenv)) {
- DB_MPOOL *dbmp;
- dbmp = dbenv->mp_handle;
- if ((ret = __memp_alloc(dbmp,
- dbmp->reginfo, NULL, sizeof(DB_MUTEX), NULL, storep)) == 0)
- (*storep)->flags = MUTEX_MPOOL;
- } else
- (*storep)->flags = 0;
- #else
- COMPQUIET(dbenv, NULL);
- COMPQUIET(infop, NULL);
- ret = __os_calloc(dbenv, 1, sizeof(DB_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 *, DB_MUTEX *));
- */
- void
- __db_mutex_free(dbenv, infop, mutexp)
- DB_ENV *dbenv;
- REGINFO *infop;
- DB_MUTEX *mutexp;
- {
- #if defined(MUTEX_NO_MALLOC_LOCKS) || defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- R_LOCK(dbenv, infop);
- #if defined(HAVE_MUTEX_SYSTEM_RESOURCES)
- if (F_ISSET(mutexp, MUTEX_INITED))
- __db_shlocks_clear(mutexp, infop, NULL);
- #endif
- if (F_ISSET(mutexp, MUTEX_MPOOL)) {
- DB_MPOOL *dbmp;
- dbmp = dbenv->mp_handle;
- R_LOCK(dbenv, dbmp->reginfo);
- __db_shalloc_free(dbmp->reginfo[0].addr, mutexp);
- R_UNLOCK(dbenv, dbmp->reginfo);
- } else
- __db_shalloc_free(infop->addr, mutexp);
- R_UNLOCK(dbenv, infop);
- #else
- COMPQUIET(dbenv, NULL);
- COMPQUIET(infop, NULL);
- __os_free(dbenv, mutexp);
- #endif
- }
- #ifdef HAVE_MUTEX_SYSTEM_RESOURCES
- /*
- * __db_shreg_locks_record --
- * Record an entry in the shared locks area.
- * Region lock must be held in caller.
- */
- static int
- __db_shreg_locks_record(dbenv, mutexp, infop, rp)
- DB_ENV *dbenv;
- DB_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 an 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.
- *
- * PUBLIC: void __db_shreg_locks_clear __P((DB_MUTEX *, REGINFO *, REGMAINT *));
- */
- void
- __db_shreg_locks_clear(mutexp, infop, rp)
- DB_MUTEX *mutexp;
- REGINFO *infop;
- REGMAINT *rp;
- {
- /*
- * !!!
- * Assumes the caller's region lock is held.
- */
- 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 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;
- if (rp != NULL) {
- 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((DB_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 *, DB_MUTEX *, u_int32_t,
- * PUBLIC: u_int32_t, REGINFO *, REGMAINT *));
- */
- int
- __db_shreg_mutex_init(dbenv, mutexp, offset, flags, infop, rp)
- DB_ENV *dbenv;
- DB_MUTEX *mutexp;
- u_int32_t offset;
- u_int32_t flags;
- REGINFO *infop;
- REGMAINT *rp;
- {
- int ret;
- if ((ret = __db_mutex_init_int(dbenv, mutexp, offset, flags)) != 0)
- return (ret);
- /*
- * Some mutexes cannot be recorded, but we want one interface.
- * So, if we have no REGMAINT, then just return.
- */
- if (rp == NULL)
- return (ret);
- /*
- * !!!
- * Since __db_mutex_init_int 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);
- 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;
- u_int32_t i;
- rp = (REGMAINT *)addr;
- memset(addr, 0, sizeof(REGMAINT));
- rp->reglocks = size / sizeof(roff_t);
- rp->regmutex_hint = R_OFFSET(infop, &rp->regmutexes[0]);
- for (i = 0; i < rp->reglocks; i++)
- rp->regmutexes[i] = INVALID_ROFF;
- }
- static REGMAINT *
- __db_mutex_maint(dbenv, infop)
- DB_ENV *dbenv;
- REGINFO *infop;
- {
- roff_t moff;
- switch (infop->type) {
- case REGION_TYPE_LOCK:
- moff = ((DB_LOCKREGION *)R_ADDR(infop,
- infop->rp->primary))->maint_off;
- break;
- case REGION_TYPE_LOG:
- moff = ((LOG *)R_ADDR(infop, infop->rp->primary))->maint_off;
- break;
- case REGION_TYPE_MPOOL:
- moff = ((MPOOL *)R_ADDR(infop, infop->rp->primary))->maint_off;
- break;
- case REGION_TYPE_TXN:
- moff = ((DB_TXNREGION *)R_ADDR(infop,
- infop->rp->primary))->maint_off;
- break;
- default:
- __db_err(dbenv,
- "Attempting to record mutex in a region not set up to do so");
- return (NULL);
- }
- return ((REGMAINT *)R_ADDR(infop, moff));
- }
- #endif /* HAVE_MUTEX_SYSTEM_RESOURCES */