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137 lines
3.0 KiB
137 lines
3.0 KiB
3 years ago
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996, 1997, 1998, 1999
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* Sleepycat Software. All rights reserved.
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*/
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#include "db_config.h"
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#ifndef lint
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static const char sccsid[] = "@(#)mp_trickle.c 11.3 (Sleepycat) 9/16/99";
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#endif /* not lint */
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#ifndef NO_SYSTEM_INCLUDES
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#include <sys/types.h>
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#include <errno.h>
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#include <stdlib.h>
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#endif
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#include "db_int.h"
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#include "db_shash.h"
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#include "mp.h"
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static int CDB___memp_trick __P((DB_ENV *, int, int, int *));
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/*
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* CDB_memp_trickle --
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* Keep a specified percentage of the buffers clean.
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*/
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int
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CDB_memp_trickle(dbenv, pct, nwrotep)
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DB_ENV *dbenv;
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int pct, *nwrotep;
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{
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DB_MPOOL *dbmp;
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MPOOL *mp;
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u_int32_t i;
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int ret;
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PANIC_CHECK(dbenv);
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ENV_REQUIRES_CONFIG(dbenv, dbenv->mp_handle, DB_INIT_MPOOL);
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dbmp = dbenv->mp_handle;
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mp = dbmp->reginfo.primary;
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if (nwrotep != NULL)
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*nwrotep = 0;
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if (pct < 1 || pct > 100)
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return (EINVAL);
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R_LOCK(dbenv, &dbmp->reginfo);
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/* Loop through the caches... */
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for (ret = 0, i = 0; i < mp->nc_reg; ++i)
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if ((ret = CDB___memp_trick(dbenv, i, pct, nwrotep)) != 0)
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break;
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R_UNLOCK(dbenv, &dbmp->reginfo);
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return (ret);
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}
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/*
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* CDB___memp_trick --
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* Trickle a single cache.
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*/
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static int
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CDB___memp_trick(dbenv, ncache, pct, nwrotep)
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DB_ENV *dbenv;
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int ncache, pct, *nwrotep;
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{
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BH *bhp;
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DB_MPOOL *dbmp;
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MCACHE *mc;
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MPOOLFILE *mfp;
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db_pgno_t pgno;
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u_long total;
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int ret, wrote;
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dbmp = dbenv->mp_handle;
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mc = dbmp->c_reginfo[ncache].primary;
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/*
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* If there are sufficient clean buffers, or no buffers or no dirty
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* buffers, we're done.
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*
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* XXX
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* Using st_page_clean and st_page_dirty is our only choice at the
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* moment, but it's not as correct as we might like in the presence
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* of pools with more than one buffer size, as a free 512-byte buffer
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* isn't the same as a free 8K buffer.
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*/
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loop: total = mc->stat.st_page_clean + mc->stat.st_page_dirty;
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if (total == 0 || mc->stat.st_page_dirty == 0 ||
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(mc->stat.st_page_clean * 100) / total >= (u_long)pct)
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return (0);
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/* Loop until we write a buffer. */
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for (bhp = SH_TAILQ_FIRST(&mc->bhq, __bh);
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bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
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if (bhp->ref != 0 ||
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!F_ISSET(bhp, BH_DIRTY) || F_ISSET(bhp, BH_LOCKED))
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continue;
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mfp = R_ADDR(&dbmp->reginfo, bhp->mf_offset);
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/*
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* We can't write to temporary files -- see the comment in
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* mp_bh.c:CDB___memp_bhwrite().
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*/
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if (F_ISSET(mfp, MP_TEMP))
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continue;
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pgno = bhp->pgno;
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if ((ret = CDB___memp_bhwrite(dbmp, mfp, bhp, NULL, &wrote)) != 0)
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return (ret);
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/*
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* Any process syncing the shared memory buffer pool had better
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* be able to write to any underlying file. Be understanding,
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* but firm, on this point.
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*/
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if (!wrote) {
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CDB___db_err(dbenv, "%s: unable to flush page: %lu",
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CDB___memp_fns(dbmp, mfp), (u_long)pgno);
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return (EPERM);
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}
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++mc->stat.st_page_trickle;
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if (nwrotep != NULL)
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++*nwrotep;
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goto loop;
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}
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return (0);
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}
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