/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998
* Sleepycat Software. All rights reserved.
*/
#include "config.h"
#ifndef lint
static const char sccsid[] = "@(#)mp_region.c 10.35 (Sleepycat) 12/11/98";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#endif
#include "db_int.h"
#include "shqueue.h"
#include "db_shash.h"
#include "mp.h"
#include "common_ext.h"
/*
* __memp_reg_alloc --
* Allocate some space in the mpool region, with locking.
*
* PUBLIC: int __memp_reg_alloc __P((DB_MPOOL *, size_t, size_t *, void *));
*/
int
__memp_reg_alloc(dbmp, len, offsetp, retp)
DB_MPOOL *dbmp;
size_t len, *offsetp;
void *retp;
{
int ret;
LOCKREGION(dbmp);
ret = __memp_alloc(dbmp, len, offsetp, retp);
UNLOCKREGION(dbmp);
return (ret);
}
/*
* __memp_alloc --
* Allocate some space in the mpool region.
*
* PUBLIC: int __memp_alloc __P((DB_MPOOL *, size_t, size_t *, void *));
*/
int
__memp_alloc(dbmp, len, offsetp, retp)
DB_MPOOL *dbmp;
size_t len, *offsetp;
void *retp;
{
BH *bhp, *nbhp;
MPOOL *mp;
MPOOLFILE *mfp;
size_t fsize, total;
int nomore, restart, ret, wrote;
void *p;
mp = dbmp->mp;
nomore = 0;
alloc: if ((ret = __db_shalloc(dbmp->addr, len, MUTEX_ALIGNMENT, &p)) == 0) {
if (offsetp != NULL)
*offsetp = R_OFFSET(dbmp, p);
*(void **)retp = p;
return (0);
}
if (nomore) {
__db_err(dbmp->dbenv,
"Unable to allocate %lu bytes from mpool shared region: %s\n",
(u_long)len, strerror(ret));
return (ret);
}
/* Look for a buffer on the free list that's the right size. */
for (bhp =
SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
if (__db_shsizeof(bhp) == len) {
SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
if (offsetp != NULL)
*offsetp = R_OFFSET(dbmp, bhp);
*(void **)retp = bhp;
return (0);
}
}
/* Discard from the free list until we've freed enough memory. */
total = 0;
for (bhp =
SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
__db_shalloc_free(dbmp->addr, bhp);
--mp->stat.st_page_clean;
/*
* Retry as soon as we've freed up sufficient space. If we
* will have to coalesce memory to satisfy the request, don't
* try until it's likely (possible?) that we'll succeed.
*/
total += fsize = __db_shsizeof(bhp);
if (fsize >= len || total >= 3 * len)
goto alloc;
}
retry: /* Find a buffer we can flush; pure LRU. */
restart = total = 0;
for (bhp =
SH_TAILQ_FIRST(&mp->bhq, __bh); bhp != NULL; bhp = nbhp) {
nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
/* Ignore pinned or locked (I/O in progress) buffers. */
if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED))
continue;
/* Find the associated MPOOLFILE. */
mfp = R_ADDR(dbmp, bhp->mf_offset);
/*
* Write the page if it's dirty.
*
* If we wrote the page, fall through and free the buffer. We
* don't have to rewalk the list to acquire the buffer because
* it was never available for any other process to modify it.
* If we didn't write the page, but we discarded and reacquired
* the region lock, restart the buffer list walk. If we neither
* wrote the buffer nor discarded the region lock, continue down
* the buffer list.
*/
if (F_ISSET(bhp, BH_DIRTY)) {
++bhp->ref;
if ((ret = __memp_bhwrite(dbmp,
mfp, bhp, &restart, &wrote)) != 0)
return (ret);
--bhp->ref;
/*
* It's possible that another process wants this buffer
* and incremented the ref count while we were writing
* it.
*/
if (bhp->ref != 0)
goto retry;
if (wrote)
++mp->stat.st_rw_evict;
else {
if (restart)
goto retry;
continue;
}
} else
++mp->stat.st_ro_evict;
/*
* Check to see if the buffer is the size we're looking for.
* If it is, simply reuse it.
*/
total += fsize = __db_shsizeof(bhp);
if (fsize == len) {
__memp_bhfree(dbmp, mfp, bhp, 0);
if (offsetp != NULL)
*offsetp = R_OFFSET(dbmp, bhp);
*(void **)retp = bhp;
return (0);
}
/* Free the buffer. */
__memp_bhfree(dbmp, mfp, bhp, 1);
/*
* Retry as soon as we've freed up sufficient space. If we
* have to coalesce of memory to satisfy the request, don't
* try until it's likely (possible?) that we'll succeed.
*/
if (fsize >= len || total >= 3 * len)
goto alloc;
/* Restart the walk if we discarded the region lock. */
if (restart)
goto retry;
}
nomore = 1;
goto alloc;
}
/*
* __memp_ropen --
* Attach to, and optionally create, the mpool region.
*
* PUBLIC: int __memp_ropen
* PUBLIC: __P((DB_MPOOL *, const char *, size_t, int, int, u_int32_t));
*/
int
__memp_ropen(dbmp, path, cachesize, mode, is_private, flags)
DB_MPOOL *dbmp;
const char *path;
size_t cachesize;
int mode, is_private;
u_int32_t flags;
{
MPOOL *mp;
size_t rlen;
int defcache, ret;
/*
* Unlike other DB subsystems, mpool can't simply grow the region
* because it returns pointers into the region to its clients. To
* "grow" the region, we'd have to allocate a new region and then
* store a region number in the structures that reference regional
* objects. It's reasonable that we fail regardless, as clients
* shouldn't have every page in the region pinned, so the only
* "failure" mode should be a performance penalty because we don't
* find a page in the cache that we'd like to have found.
*
* Up the user's cachesize by 25% to account for our overhead.
*/
defcache = 0;
if (cachesize < DB_CACHESIZE_MIN)
if (cachesize == 0) {
defcache = 1;
cachesize = DB_CACHESIZE_DEF;
} else
cachesize = DB_CACHESIZE_MIN;
rlen = cachesize + cachesize / 4;
/*
* Map in the region.
*
* If it's a private mpool, use malloc, it's a lot faster than
* instantiating a region.
*/
dbmp->reginfo.dbenv = dbmp->dbenv;
dbmp->reginfo.appname = DB_APP_NONE;
if (path == NULL)
dbmp->reginfo.path = NULL;
else
if ((ret = __os_strdup(path, &dbmp->reginfo.path)) != 0)
return (ret);
dbmp->reginfo.file = DB_DEFAULT_MPOOL_FILE;
dbmp->reginfo.mode = mode;
dbmp->reginfo.size = rlen;
dbmp->reginfo.dbflags = flags;
dbmp->reginfo.flags = 0;
if (defcache)
F_SET(&dbmp->reginfo, REGION_SIZEDEF);
/*
* If we're creating a temporary region, don't use any standard
* naming.
*/
if (is_private) {
dbmp->reginfo.appname = DB_APP_TMP;
dbmp->reginfo.file = NULL;
F_SET(&dbmp->reginfo, REGION_PRIVATE);
}
if ((ret = __db_rattach(&dbmp->reginfo)) != 0) {
if (dbmp->reginfo.path != NULL)
__os_freestr(dbmp->reginfo.path);
return (ret);
}
/*
* The MPOOL structure is first in the region, the rest of the region
* is free space.
*/
dbmp->mp = dbmp->reginfo.addr;
dbmp->addr = (u_int8_t *)dbmp->mp + sizeof(MPOOL);
/* Initialize a created region. */
if (F_ISSET(&dbmp->reginfo, REGION_CREATED)) {
mp = dbmp->mp;
SH_TAILQ_INIT(&mp->bhq);
SH_TAILQ_INIT(&mp->bhfq);
SH_TAILQ_INIT(&mp->mpfq);
__db_shalloc_init(dbmp->addr, rlen - sizeof(MPOOL));
/*
* Assume we want to keep the hash chains with under 10 pages
* on each chain. We don't know the pagesize in advance, and
* it may differ for different files. Use a pagesize of 1K for
* the calculation -- we walk these chains a lot, they should
* be short.
*/
mp->htab_buckets =
__db_tablesize((cachesize / (1 * 1024)) / 10);
/* Allocate hash table space and initialize it. */
if ((ret = __db_shalloc(dbmp->addr,
mp->htab_buckets * sizeof(DB_HASHTAB),
0, &dbmp->htab)) != 0)
goto err;
__db_hashinit(dbmp->htab, mp->htab_buckets);
mp->htab = R_OFFSET(dbmp, dbmp->htab);
ZERO_LSN(mp->lsn);
mp->lsn_cnt = 0;
memset(&mp->stat, 0, sizeof(mp->stat));
mp->stat.st_cachesize = cachesize;
mp->flags = 0;
}
/* Get the local hash table address. */
dbmp->htab = R_ADDR(dbmp, dbmp->mp->htab);
UNLOCKREGION(dbmp);
return (0);
err: UNLOCKREGION(dbmp);
(void)__db_rdetach(&dbmp->reginfo);
if (F_ISSET(&dbmp->reginfo, REGION_CREATED))
(void)memp_unlink(path, 1, dbmp->dbenv);
if (dbmp->reginfo.path != NULL)
__os_freestr(dbmp->reginfo.path);
return (ret);
}