mpool.c

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/*-
 * Copyright (c) 1990, 1993, 1994
 * The Regents of the University of California. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 * This product includes software developed by the University of
 * California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "../include/db.h"

#define __MPOOLINTERFACE_PRIVATE
#include <mpool.h>

#undef __APPLE__

#ifndef __APPLE__
#define mpool_open __mpool_open
#define mpool_filter __mpool_filter
#define mpool_new __mpool_new
#define mpool_get __mpool_get
#define mpool_put __mpool_put
#define mpool_sync __mpool_sync
#define mpool_close __mpool_close
#endif

static BKT *mpool_bkt __P((MPOOL *));
static BKT *mpool_look __P((MPOOL *, pgno_t));
static int mpool_write __P((MPOOL *, BKT *));

/*
 * mpool_open --
 * Initialize a memory pool.
 */
MPOOL *
mpool_open(key, fd, pagesize, maxcache)
 void *key;
 int fd;
 pgno_t pagesize, maxcache;
{
 struct stat sb;
 MPOOL *mp;
 int entry;

 /*
 * Get information about the file.
 *
 * XXX
 * We don't currently handle pipes, although we should.
 */
 if (fstat(fd, &sb))
 return (NULL);
 if (!S_ISREG(sb.st_mode)) {
 errno = ESPIPE;
 return (NULL);
 }

 /* Allocate and initialize the MPOOL cookie. */
 if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
 return (NULL);
 CIRCLEQ_INIT(&mp->lqh);
 for (entry = 0; entry < HASHSIZE; ++entry)
 CIRCLEQ_INIT(&mp->hqh[entry]);
 mp->maxcache = maxcache;
 mp->npages = sb.st_size / pagesize;
 mp->pagesize = pagesize;
 mp->fd = fd;
 return (mp);
}

/*
 * mpool_filter --
 * Initialize input/output filters.
 */
void
mpool_filter(mp, pgin, pgout, pgcookie)
 MPOOL *mp;
 void (*pgin) __P((void *, pgno_t, void *));
 void (*pgout) __P((void *, pgno_t, void *));
 void *pgcookie;
{
 mp->pgin = pgin;
 mp->pgout = pgout;
 mp->pgcookie = pgcookie;
}

/*
 * mpool_new --
 * Get a new page of memory.
 */
void *
mpool_new(mp, pgnoaddr)
 MPOOL *mp;
 pgno_t *pgnoaddr;
{
 struct _hqh *head;
 BKT *bp;

 if (mp->npages == MAX_PAGE_NUMBER) {
 (void)fprintf(stderr, "mpool_new: page allocation overflow.\n");
 abort();
 }
#ifdef STATISTICS
 ++mp->pagenew;
#endif
 /*
 * Get a BKT from the cache. Assign a new page number, attach
 * it to the head of the hash chain, the tail of the lru chain,
 * and return.
 */
 if ((bp = mpool_bkt(mp)) == NULL)
 return (NULL);
 *pgnoaddr = bp->pgno = mp->npages++;
 bp->flags = MPOOL_PINNED;

 head = &mp->hqh[HASHKEY(bp->pgno)];
 CIRCLEQ_INSERT_HEAD(head, bp, hq);
 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
 return (bp->page);
}

/*
 * mpool_get
 * Get a page.
 */
void *
mpool_get(mp, pgno, flags)
 MPOOL *mp;
 pgno_t pgno;
 u_int flags; /* XXX not used? */
{
 struct _hqh *head;
 BKT *bp;
 off_t off;
 int nr;

 /* Check for attempt to retrieve a non-existent page. */
 if (pgno >= mp->npages) {
 errno = EINVAL;
 return (NULL);
 }

#ifdef STATISTICS
 ++mp->pageget;
#endif

 /* Check for a page that is cached. */
 if ((bp = mpool_look(mp, pgno)) != NULL) {
#ifdef DEBUG
 if (bp->flags & MPOOL_PINNED) {
 (void)fprintf(stderr,
 "mpool_get: page %d already pinned\n", bp->pgno);
 abort();
 }
#endif
 /*
 * Move the page to the head of the hash chain and the tail
 * of the lru chain.
 */
 head = &mp->hqh[HASHKEY(bp->pgno)];
 CIRCLEQ_REMOVE(head, bp, hq);
 CIRCLEQ_INSERT_HEAD(head, bp, hq);
 CIRCLEQ_REMOVE(&mp->lqh, bp, q);
 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);

 /* Return a pinned page. */
 bp->flags |= MPOOL_PINNED;
 return (bp->page);
 }

 /* Get a page from the cache. */
 if ((bp = mpool_bkt(mp)) == NULL)
 return (NULL);

 /* Read in the contents. */
#ifdef STATISTICS
 ++mp->pageread;
#endif
 off = mp->pagesize * pgno;
 if (lseek(mp->fd, off, SEEK_SET) != off)
 return (NULL);
 if ((u_long) (nr = read(mp->fd, bp->page, mp->pagesize))
 != mp->pagesize) {
 if (nr >= 0)
 errno = EFTYPE;
 return (NULL);
 }

 /* Set the page number, pin the page. */
 bp->pgno = pgno;
 bp->flags = MPOOL_PINNED;

 /*
 * Add the page to the head of the hash chain and the tail
 * of the lru chain.
 */
 head = &mp->hqh[HASHKEY(bp->pgno)];
 CIRCLEQ_INSERT_HEAD(head, bp, hq);
 CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);

 /* Run through the user's filter. */
 if (mp->pgin != NULL)
 (mp->pgin)(mp->pgcookie, bp->pgno, bp->page);

 return (bp->page);
}

/*
 * mpool_put
 * Return a page.
 */
int
mpool_put(mp, page, flags)
 MPOOL *mp;
 void *page;
 u_int flags;
{
 BKT *bp;

#ifdef STATISTICS
 ++mp->pageput;
#endif
 bp = (BKT *)((char *)page - sizeof(BKT));
#ifdef DEBUG
 if (!(bp->flags & MPOOL_PINNED)) {
 (void)fprintf(stderr,
 "mpool_put: page %d not pinned\n", bp->pgno);
 abort();
 }
#endif
 bp->flags &= ~MPOOL_PINNED;
 bp->flags |= flags & MPOOL_DIRTY;
 return (RET_SUCCESS);
}

/*
 * mpool_close
 * Close the buffer pool.
 */
int
mpool_close(mp)
 MPOOL *mp;
{
 BKT *bp;

 /* Free up any space allocated to the lru pages. */
 while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) {
 CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q);
 free(bp);
 }

 /* Free the MPOOL cookie. */
 free(mp);
 return (RET_SUCCESS);
}

/*
 * mpool_sync
 * Sync the pool to disk.
 */
int
mpool_sync(mp)
 MPOOL *mp;
{
 BKT *bp;

 /* Walk the lru chain, flushing any dirty pages to disk. */
 for (bp = mp->lqh.cqh_first;
 bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
 if (bp->flags & MPOOL_DIRTY &&
 mpool_write(mp, bp) == RET_ERROR)
 return (RET_ERROR);

 /* Sync the file descriptor. */
 return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
}

#define __APPLE__

#ifndef __APPLE__
#undef mpool_open
#undef mpool_filter
#undef mpool_new
#undef mpool_get
#undef mpool_put
#undef mpool_close
#undef mpool_sync

#define weak_alias(original, alias) \
 asm (".weak " #alias "\n" #alias " = " #original);
weak_alias (__mpool_open, mpool_open)
weak_alias (__mpool_filter, mpool_filter)
weak_alias (__mpool_new, mpool_new)
weak_alias (__mpool_get, mpool_get)
weak_alias (__mpool_put, mpool_put)
weak_alias (__mpool_close, mpool_close)
weak_alias (__mpool_sync, mpool_sync)
#endif

/*
 * mpool_bkt
 * Get a page from the cache (or create one).
 */
static BKT *
mpool_bkt(mp)
 MPOOL *mp;
{
 struct _hqh *head;
 BKT *bp;

 /* If under the max cached, always create a new page. */
 if (mp->curcache < mp->maxcache)
 goto new;

 /*
 * If the cache is max'd out, walk the lru list for a buffer we
 * can flush. If we find one, write it (if necessary) and take it
 * off any lists. If we don't find anything we grow the cache anyway.
 * The cache never shrinks.
 */
 for (bp = mp->lqh.cqh_first;
 bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
 if (!(bp->flags & MPOOL_PINNED)) {
 /* Flush if dirty. */
 if (bp->flags & MPOOL_DIRTY &&
 mpool_write(mp, bp) == RET_ERROR)
 return (NULL);
#ifdef STATISTICS
 ++mp->pageflush;
#endif
 /* Remove from the hash and lru queues. */
 head = &mp->hqh[HASHKEY(bp->pgno)];
 CIRCLEQ_REMOVE(head, bp, hq);
 CIRCLEQ_REMOVE(&mp->lqh, bp, q);
#ifdef DEBUG
 { void *spage;
 spage = bp->page;
 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 bp->page = spage;
 }
#endif
 return (bp);
 }

new: if ((bp = (BKT *) calloc(1, sizeof(BKT) + mp->pagesize)) == NULL)
 return (NULL);
#ifdef STATISTICS
 ++mp->pagealloc;
#endif
#if defined(DEBUG) || defined(PURIFY)
 memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
#endif
 bp->page = (char *)bp + sizeof(BKT);
 ++mp->curcache;
 return (bp);
}

/*
 * mpool_write
 * Write a page to disk.
 */
static int
mpool_write(mp, bp)
 MPOOL *mp;
 BKT *bp;
{
 off_t off;

#ifdef STATISTICS
 ++mp->pagewrite;
#endif

 /* Run through the user's filter. */
 if (mp->pgout)
 (mp->pgout)(mp->pgcookie, bp->pgno, bp->page);

 off = mp->pagesize * bp->pgno;
 if (lseek(mp->fd, off, SEEK_SET) != off)
 return (RET_ERROR);
 if ((u_long) write(mp->fd, bp->page, mp->pagesize) != mp->pagesize)
 return (RET_ERROR);

 bp->flags &= ~MPOOL_DIRTY;
 return (RET_SUCCESS);
}

/*
 * mpool_look
 * Lookup a page in the cache.
 */
static BKT *
mpool_look(mp, pgno)
 MPOOL *mp;
 pgno_t pgno;
{
 struct _hqh *head;
 BKT *bp;

 head = &mp->hqh[HASHKEY(pgno)];
 for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next)
 if (bp->pgno == pgno) {
#ifdef STATISTICS
 ++mp->cachehit;
#endif
 return (bp);
 }
#ifdef STATISTICS
 ++mp->cachemiss;
#endif
 return (NULL);
}

#ifdef STATISTICS
/*
 * mpool_stat
 * Print out cache statistics.
 */
void
mpool_stat(mp)
 MPOOL *mp;
{
 BKT *bp;
 int cnt;
 char *sep;

 (void)fprintf(stderr, "%lu pages in the file\n", mp->npages);
 (void)fprintf(stderr,
 "page size %lu, cacheing %lu pages of %lu page max cache\n",
 mp->pagesize, mp->curcache, mp->maxcache);
 (void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
 mp->pageput, mp->pageget, mp->pagenew);
 (void)fprintf(stderr, "%lu page allocs, %lu page flushes\n",
 mp->pagealloc, mp->pageflush);
 if (mp->cachehit + mp->cachemiss)
 (void)fprintf(stderr,
 "%.0f%% cache hit rate (%lu hits, %lu misses)\n",
 ((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
 * 100, mp->cachehit, mp->cachemiss);
 (void)fprintf(stderr, "%lu page reads, %lu page writes\n",
 mp->pageread, mp->pagewrite);

 sep = "";
 cnt = 0;
 for (bp = mp->lqh.cqh_first;
 bp != (void *)&mp->lqh; bp = bp->q.cqe_next) {
 (void)fprintf(stderr, "%s%d", sep, bp->pgno);
 if (bp->flags & MPOOL_DIRTY)
 (void)fprintf(stderr, "d");
 if (bp->flags & MPOOL_PINNED)
 (void)fprintf(stderr, "P");
 if (++cnt == 10) {
 sep = "\n";
 cnt = 0;
 } else
 sep = ", ";

 }
 (void)fprintf(stderr, "\n");
}
#endif