359 lines
8.9 KiB
C
359 lines
8.9 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996, 1997
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* Sleepycat Software. All rights reserved.
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*/
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#include "config.h"
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#ifndef lint
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static const char sccsid[] = "@(#)mp_region.c 10.18 (Sleepycat) 11/29/97";
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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 <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#endif
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#include "db_int.h"
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#include "shqueue.h"
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#include "db_shash.h"
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#include "mp.h"
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#include "common_ext.h"
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/*
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* __memp_ralloc --
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* Allocate some space in the mpool region.
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*
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* PUBLIC: int __memp_ralloc __P((DB_MPOOL *, size_t, size_t *, void *));
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*/
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int
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__memp_ralloc(dbmp, len, offsetp, retp)
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DB_MPOOL *dbmp;
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size_t len, *offsetp;
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void *retp;
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{
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BH *bhp, *nbhp;
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MPOOL *mp;
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MPOOLFILE *mfp;
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size_t fsize, total;
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int nomore, restart, ret, wrote;
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void *p;
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mp = dbmp->mp;
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nomore = 0;
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alloc: if ((ret = __db_shalloc(dbmp->addr, len, MUTEX_ALIGNMENT, &p)) == 0) {
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if (offsetp != NULL)
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*offsetp = R_OFFSET(dbmp, p);
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*(void **)retp = p;
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return (0);
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}
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if (nomore) {
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__db_err(dbmp->dbenv, "%s", strerror(ret));
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return (ret);
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}
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/* Look for a buffer on the free list that's the right size. */
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for (bhp =
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SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
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nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
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if (__db_shsizeof(bhp) == len) {
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SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
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if (offsetp != NULL)
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*offsetp = R_OFFSET(dbmp, bhp);
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*(void **)retp = bhp;
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return (0);
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}
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}
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/* Discard from the free list until we've freed enough memory. */
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total = 0;
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for (bhp =
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SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
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nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
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SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
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__db_shalloc_free(dbmp->addr, bhp);
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--mp->stat.st_page_clean;
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/*
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* Retry as soon as we've freed up sufficient space. If we
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* have to coalesce of memory to satisfy the request, don't
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* try until it's likely (possible?) that we'll succeed.
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*/
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total += fsize = __db_shsizeof(bhp);
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if (fsize >= len || total >= 3 * len)
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goto alloc;
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}
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retry: /* Find a buffer we can flush; pure LRU. */
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total = 0;
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for (bhp =
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SH_TAILQ_FIRST(&mp->bhq, __bh); bhp != NULL; bhp = nbhp) {
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nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
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/* Ignore pinned or locked (I/O in progress) buffers. */
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if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED))
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continue;
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/* Find the associated MPOOLFILE. */
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mfp = R_ADDR(dbmp, bhp->mf_offset);
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/*
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* Write the page if it's dirty.
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*
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* If we wrote the page, fall through and free the buffer. We
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* don't have to rewalk the list to acquire the buffer because
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* it was never available for any other process to modify it.
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* If we didn't write the page, but we discarded and reacquired
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* the region lock, restart the buffer list walk. If we neither
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* wrote the buffer nor discarded the region lock, continue down
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* the buffer list.
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*/
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if (F_ISSET(bhp, BH_DIRTY)) {
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if ((ret = __memp_bhwrite(dbmp,
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mfp, bhp, &restart, &wrote)) != 0)
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return (ret);
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/*
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* It's possible that another process wants this buffer
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* and incremented the ref count while we were writing
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* it.
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*/
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if (bhp->ref != 0)
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goto retry;
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if (wrote)
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++mp->stat.st_rw_evict;
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else {
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if (restart)
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goto retry;
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continue;
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}
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} else
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++mp->stat.st_ro_evict;
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/*
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* Check to see if the buffer is the size we're looking for.
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* If it is, simply reuse it.
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*/
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total += fsize = __db_shsizeof(bhp);
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if (fsize == len) {
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__memp_bhfree(dbmp, mfp, bhp, 0);
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if (offsetp != NULL)
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*offsetp = R_OFFSET(dbmp, bhp);
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*(void **)retp = bhp;
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return (0);
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}
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/* Free the buffer. */
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__memp_bhfree(dbmp, mfp, bhp, 1);
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/*
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* Retry as soon as we've freed up sufficient space. If we
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* have to coalesce of memory to satisfy the request, don't
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* try until it's likely (possible?) that we'll succeed.
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*/
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if (fsize >= len || total >= 3 * len)
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goto alloc;
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/* Restart the walk if we discarded the region lock. */
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if (restart)
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goto retry;
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}
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nomore = 1;
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goto alloc;
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}
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/*
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* __memp_ropen --
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* Attach to, and optionally create, the mpool region.
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*
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* PUBLIC: int __memp_ropen
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* PUBLIC: __P((DB_MPOOL *, const char *, size_t, int, int));
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*/
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int
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__memp_ropen(dbmp, path, cachesize, mode, flags)
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DB_MPOOL *dbmp;
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const char *path;
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size_t cachesize;
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int mode, flags;
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{
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MPOOL *mp;
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size_t rlen;
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int fd, newregion, ret, retry_cnt;
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/*
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* Unlike other DB subsystems, mpool can't simply grow the region
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* because it returns pointers into the region to its clients. To
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* "grow" the region, we'd have to allocate a new region and then
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* store a region number in the structures that reference regional
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* objects. It's reasonable that we fail regardless, as clients
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* shouldn't have every page in the region pinned, so the only
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* "failure" mode should be a performance penalty because we don't
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* find a page in the cache that we'd like to have found.
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*
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* Up the user's cachesize by 25% to account for our overhead.
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*/
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if (cachesize < DB_CACHESIZE_MIN)
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if (cachesize == 0)
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cachesize = DB_CACHESIZE_DEF;
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else
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cachesize = DB_CACHESIZE_MIN;
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rlen = cachesize + cachesize / 4;
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/* Map in the region. */
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retry_cnt = newregion = 0;
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retry: if (LF_ISSET(DB_CREATE)) {
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/*
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* If it's a private mpool, use malloc, it's a lot faster than
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* instantiating a region.
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*
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* XXX
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* If we're doing locking and don't have spinlocks for this
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* architecture, we'd have to instantiate the file, we need
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* the file descriptor for locking. However, it should not
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* be possible for DB_THREAD to be set if HAVE_SPINLOCKS aren't
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* defined.
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*
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* XXX
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* HP-UX won't permit mutexes to live in anything but shared
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* memory. So, instantiate the shared mpool region file on
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* that architecture, regardless. If this turns out to be a
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* performance problem, we could use anonymous memory instead.
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*/
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#if !defined(__hppa)
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if (F_ISSET(dbmp, MP_ISPRIVATE))
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if ((dbmp->maddr = __db_malloc(rlen)) == NULL)
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ret = ENOMEM;
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else {
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F_SET(dbmp, MP_MALLOC);
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ret = __db_rinit(dbmp->dbenv,
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dbmp->maddr, 0, rlen, 0);
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}
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else
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#endif
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ret = __db_rcreate(dbmp->dbenv, DB_APP_NONE, path,
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DB_DEFAULT_MPOOL_FILE, mode, rlen,
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F_ISSET(dbmp, MP_ISPRIVATE) ? DB_TEMPORARY : 0,
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&fd, &dbmp->maddr);
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if (ret == 0) {
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/* Put the MPOOL structure first in the region. */
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mp = dbmp->maddr;
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SH_TAILQ_INIT(&mp->bhq);
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SH_TAILQ_INIT(&mp->bhfq);
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SH_TAILQ_INIT(&mp->mpfq);
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/* Initialize the rest of the region as free space. */
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dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL);
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__db_shalloc_init(dbmp->addr, rlen - sizeof(MPOOL));
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/*
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*
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* Pretend that the cache will be broken up into 4K
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* pages, and that we want to keep it under, say, 10
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* pages on each chain. This means a 256MB cache will
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* allocate ~6500 offset pairs.
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*/
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mp->htab_buckets =
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__db_tablesize((cachesize / (4 * 1024)) / 10);
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/* Allocate hash table space and initialize it. */
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if ((ret = __db_shalloc(dbmp->addr,
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mp->htab_buckets * sizeof(DB_HASHTAB),
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0, &dbmp->htab)) != 0)
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goto err;
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__db_hashinit(dbmp->htab, mp->htab_buckets);
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mp->htab = R_OFFSET(dbmp, dbmp->htab);
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ZERO_LSN(mp->lsn);
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mp->lsn_cnt = 0;
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memset(&mp->stat, 0, sizeof(mp->stat));
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mp->stat.st_cachesize = cachesize;
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mp->flags = 0;
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newregion = 1;
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} else if (ret != EEXIST)
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return (ret);
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}
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/* If we didn't or couldn't create the region, try and join it. */
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if (!newregion &&
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(ret = __db_ropen(dbmp->dbenv, DB_APP_NONE,
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path, DB_DEFAULT_MPOOL_FILE, 0, &fd, &dbmp->maddr)) != 0) {
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/*
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* If we failed because the file wasn't available, wait a
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* second and try again.
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*/
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if (ret == EAGAIN && ++retry_cnt < 3) {
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(void)__db_sleep(1, 0);
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goto retry;
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}
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return (ret);
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}
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/* Set up the common pointers. */
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dbmp->mp = dbmp->maddr;
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dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL);
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/*
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* If not already locked, lock the region -- if it's a new region,
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* then either __db_rcreate() locked it for us or we malloc'd it
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* instead of creating a region, neither of which requires locking
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* here.
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*/
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if (!newregion)
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LOCKREGION(dbmp);
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/*
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* Get the hash table address; it's on the shared page, so we have
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* to lock first.
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*/
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dbmp->htab = R_ADDR(dbmp, dbmp->mp->htab);
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dbmp->fd = fd;
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/* If we locked the region, release it now. */
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if (!F_ISSET(dbmp, MP_MALLOC))
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UNLOCKREGION(dbmp);
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return (0);
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err: if (fd != -1) {
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dbmp->fd = fd;
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(void)__memp_rclose(dbmp);
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}
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if (newregion)
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(void)memp_unlink(path, 1, dbmp->dbenv);
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return (ret);
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}
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/*
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* __memp_rclose --
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* Close the mpool region.
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*
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* PUBLIC: int __memp_rclose __P((DB_MPOOL *));
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*/
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int
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__memp_rclose(dbmp)
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DB_MPOOL *dbmp;
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{
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if (F_ISSET(dbmp, MP_MALLOC)) {
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__db_free(dbmp->maddr);
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return (0);
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}
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return (__db_rclose(dbmp->dbenv, dbmp->fd, dbmp->maddr));
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}
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