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/*-
* 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);
}
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