mp_trickle.c
上传用户:tsgydb
上传日期:2007-04-14
资源大小:10674k
文件大小:3k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1996, 1997, 1998, 1999, 2000
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: mp_trickle.c,v 11.12 2000/11/30 00:58:41 ubell Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <stdlib.h>
- #endif
- #ifdef HAVE_RPC
- #include "db_server.h"
- #endif
- #include "db_int.h"
- #include "db_shash.h"
- #include "mp.h"
- #ifdef HAVE_RPC
- #include "gen_client_ext.h"
- #include "rpc_client_ext.h"
- #endif
- static int __memp_trick __P((DB_ENV *, int, int, int *));
- /*
- * memp_trickle --
- * Keep a specified percentage of the buffers clean.
- */
- int
- memp_trickle(dbenv, pct, nwrotep)
- DB_ENV *dbenv;
- int pct, *nwrotep;
- {
- DB_MPOOL *dbmp;
- MPOOL *mp;
- u_int32_t i;
- int ret;
- #ifdef HAVE_RPC
- if (F_ISSET(dbenv, DB_ENV_RPCCLIENT))
- return (__dbcl_memp_trickle(dbenv, pct, nwrotep));
- #endif
- PANIC_CHECK(dbenv);
- ENV_REQUIRES_CONFIG(dbenv, dbenv->mp_handle, DB_INIT_MPOOL);
- dbmp = dbenv->mp_handle;
- mp = dbmp->reginfo[0].primary;
- if (nwrotep != NULL)
- *nwrotep = 0;
- if (pct < 1 || pct > 100)
- return (EINVAL);
- R_LOCK(dbenv, dbmp->reginfo);
- /* Loop through the caches... */
- for (ret = 0, i = 0; i < mp->nreg; ++i)
- if ((ret = __memp_trick(dbenv, i, pct, nwrotep)) != 0)
- break;
- R_UNLOCK(dbenv, dbmp->reginfo);
- return (ret);
- }
- /*
- * __memp_trick --
- * Trickle a single cache.
- */
- static int
- __memp_trick(dbenv, ncache, pct, nwrotep)
- DB_ENV *dbenv;
- int ncache, pct, *nwrotep;
- {
- BH *bhp;
- DB_MPOOL *dbmp;
- MPOOL *c_mp;
- MPOOLFILE *mfp;
- db_pgno_t pgno;
- u_long total;
- int ret, wrote;
- dbmp = dbenv->mp_handle;
- c_mp = dbmp->reginfo[ncache].primary;
- /*
- * If there are sufficient clean buffers, or no buffers or no dirty
- * buffers, we're done.
- *
- * XXX
- * Using st_page_clean and st_page_dirty is our only choice at the
- * moment, but it's not as correct as we might like in the presence
- * of pools with more than one buffer size, as a free 512-byte buffer
- * isn't the same as a free 8K buffer.
- */
- loop: total = c_mp->stat.st_page_clean + c_mp->stat.st_page_dirty;
- if (total == 0 || c_mp->stat.st_page_dirty == 0 ||
- (c_mp->stat.st_page_clean * 100) / total >= (u_long)pct)
- return (0);
- /* Loop until we write a buffer. */
- for (bhp = SH_TAILQ_FIRST(&c_mp->bhq, __bh);
- bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
- if (bhp->ref != 0 ||
- !F_ISSET(bhp, BH_DIRTY) || F_ISSET(bhp, BH_LOCKED))
- continue;
- mfp = R_ADDR(dbmp->reginfo, bhp->mf_offset);
- /*
- * We can't write to temporary files -- see the comment in
- * mp_bh.c:__memp_bhwrite().
- */
- if (F_ISSET(mfp, MP_TEMP))
- continue;
- pgno = bhp->pgno;
- if ((ret = __memp_bhwrite(dbmp, mfp, bhp, NULL, &wrote)) != 0)
- return (ret);
- /*
- * Any process syncing the shared memory buffer pool had better
- * be able to write to any underlying file. Be understanding,
- * but firm, on this point.
- */
- if (!wrote) {
- __db_err(dbenv, "%s: unable to flush page: %lu",
- __memp_fns(dbmp, mfp), (u_long)pgno);
- return (EPERM);
- }
- ++c_mp->stat.st_page_trickle;
- if (nwrotep != NULL)
- ++*nwrotep;
- goto loop;
- }
- return (0);
- }