464 lines
10 KiB
C
464 lines
10 KiB
C
/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)mpool.c 8.5 (Berkeley) 7/26/94";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/param.h>
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#include <sys/queue.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <stdio.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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#include <db.h>
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#define __MPOOLINTERFACE_PRIVATE
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#include <mpool.h>
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static BKT *mpool_bkt __P((MPOOL *));
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static BKT *mpool_look __P((MPOOL *, pgno_t));
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static int mpool_write __P((MPOOL *, BKT *));
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/*
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* mpool_open --
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* Initialize a memory pool.
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*/
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MPOOL *
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mpool_open(key, fd, pagesize, maxcache)
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void *key;
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int fd;
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pgno_t pagesize, maxcache;
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{
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struct stat sb;
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MPOOL *mp;
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int entry;
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/*
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* Get information about the file.
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*
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* XXX
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* We don't currently handle pipes, although we should.
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*/
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if (fstat(fd, &sb))
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return (NULL);
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if (!S_ISREG(sb.st_mode)) {
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errno = ESPIPE;
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return (NULL);
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}
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/* Allocate and initialize the MPOOL cookie. */
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if ((mp = (MPOOL *)calloc(1, sizeof(MPOOL))) == NULL)
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return (NULL);
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CIRCLEQ_INIT(&mp->lqh);
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for (entry = 0; entry < HASHSIZE; ++entry)
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CIRCLEQ_INIT(&mp->hqh[entry]);
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mp->maxcache = maxcache;
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mp->npages = sb.st_size / pagesize;
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mp->pagesize = pagesize;
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mp->fd = fd;
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return (mp);
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}
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/*
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* mpool_filter --
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* Initialize input/output filters.
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*/
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void
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mpool_filter(mp, pgin, pgout, pgcookie)
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MPOOL *mp;
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void (*pgin) __P((void *, pgno_t, void *));
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void (*pgout) __P((void *, pgno_t, void *));
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void *pgcookie;
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{
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mp->pgin = pgin;
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mp->pgout = pgout;
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mp->pgcookie = pgcookie;
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}
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/*
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* mpool_new --
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* Get a new page of memory.
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*/
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void *
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mpool_new(mp, pgnoaddr)
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MPOOL *mp;
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pgno_t *pgnoaddr;
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{
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struct _hqh *head;
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BKT *bp;
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if (mp->npages == MAX_PAGE_NUMBER) {
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(void)fprintf(stderr, "mpool_new: page allocation overflow.\n");
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abort();
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}
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#ifdef STATISTICS
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++mp->pagenew;
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#endif
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/*
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* Get a BKT from the cache. Assign a new page number, attach
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* it to the head of the hash chain, the tail of the lru chain,
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* and return.
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*/
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if ((bp = mpool_bkt(mp)) == NULL)
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return (NULL);
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*pgnoaddr = bp->pgno = mp->npages++;
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bp->flags = MPOOL_PINNED;
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head = &mp->hqh[HASHKEY(bp->pgno)];
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CIRCLEQ_INSERT_HEAD(head, bp, hq);
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CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
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return (bp->page);
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}
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/*
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* mpool_get
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* Get a page.
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*/
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void *
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mpool_get(mp, pgno, flags)
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MPOOL *mp;
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pgno_t pgno;
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u_int flags; /* XXX not used? */
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{
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struct _hqh *head;
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BKT *bp;
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off_t off;
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int nr;
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/* Check for attempt to retrieve a non-existent page. */
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if (pgno >= mp->npages) {
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errno = EINVAL;
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return (NULL);
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}
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#ifdef STATISTICS
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++mp->pageget;
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#endif
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/* Check for a page that is cached. */
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if ((bp = mpool_look(mp, pgno)) != NULL) {
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#ifdef DEBUG
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if (bp->flags & MPOOL_PINNED) {
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(void)fprintf(stderr,
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"mpool_get: page %d already pinned\n", bp->pgno);
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abort();
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}
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#endif
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/*
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* Move the page to the head of the hash chain and the tail
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* of the lru chain.
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*/
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head = &mp->hqh[HASHKEY(bp->pgno)];
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CIRCLEQ_REMOVE(head, bp, hq);
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CIRCLEQ_INSERT_HEAD(head, bp, hq);
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CIRCLEQ_REMOVE(&mp->lqh, bp, q);
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CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
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/* Return a pinned page. */
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bp->flags |= MPOOL_PINNED;
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return (bp->page);
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}
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/* Get a page from the cache. */
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if ((bp = mpool_bkt(mp)) == NULL)
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return (NULL);
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/* Read in the contents. */
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#ifdef STATISTICS
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++mp->pageread;
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#endif
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off = mp->pagesize * pgno;
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if (lseek(mp->fd, off, SEEK_SET) != off)
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return (NULL);
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if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) {
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if (nr >= 0)
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errno = EFTYPE;
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return (NULL);
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}
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/* Set the page number, pin the page. */
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bp->pgno = pgno;
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bp->flags = MPOOL_PINNED;
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/*
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* Add the page to the head of the hash chain and the tail
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* of the lru chain.
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*/
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head = &mp->hqh[HASHKEY(bp->pgno)];
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CIRCLEQ_INSERT_HEAD(head, bp, hq);
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CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
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/* Run through the user's filter. */
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if (mp->pgin != NULL)
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(mp->pgin)(mp->pgcookie, bp->pgno, bp->page);
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return (bp->page);
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}
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/*
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* mpool_put
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* Return a page.
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*/
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int
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mpool_put(mp, page, flags)
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MPOOL *mp;
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void *page;
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u_int flags;
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{
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BKT *bp;
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#ifdef STATISTICS
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++mp->pageput;
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#endif
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bp = (BKT *)((char *)page - sizeof(BKT));
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#ifdef DEBUG
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if (!(bp->flags & MPOOL_PINNED)) {
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(void)fprintf(stderr,
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"mpool_put: page %d not pinned\n", bp->pgno);
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abort();
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}
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#endif
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bp->flags &= ~MPOOL_PINNED;
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bp->flags |= flags & MPOOL_DIRTY;
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return (RET_SUCCESS);
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}
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/*
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* mpool_close
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* Close the buffer pool.
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*/
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int
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mpool_close(mp)
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MPOOL *mp;
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{
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BKT *bp;
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/* Free up any space allocated to the lru pages. */
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while ((bp = mp->lqh.cqh_first) != (void *)&mp->lqh) {
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CIRCLEQ_REMOVE(&mp->lqh, mp->lqh.cqh_first, q);
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free(bp);
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}
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/* Free the MPOOL cookie. */
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free(mp);
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return (RET_SUCCESS);
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}
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/*
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* mpool_sync
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* Sync the pool to disk.
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*/
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int
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mpool_sync(mp)
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MPOOL *mp;
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{
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BKT *bp;
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/* Walk the lru chain, flushing any dirty pages to disk. */
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for (bp = mp->lqh.cqh_first;
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bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
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if (bp->flags & MPOOL_DIRTY &&
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mpool_write(mp, bp) == RET_ERROR)
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return (RET_ERROR);
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/* Sync the file descriptor. */
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return (fsync(mp->fd) ? RET_ERROR : RET_SUCCESS);
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}
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/*
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* mpool_bkt
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* Get a page from the cache (or create one).
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*/
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static BKT *
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mpool_bkt(mp)
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MPOOL *mp;
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{
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struct _hqh *head;
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BKT *bp;
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/* If under the max cached, always create a new page. */
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if (mp->curcache < mp->maxcache)
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goto new;
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/*
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* If the cache is max'd out, walk the lru list for a buffer we
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* can flush. If we find one, write it (if necessary) and take it
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* off any lists. If we don't find anything we grow the cache anyway.
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* The cache never shrinks.
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*/
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for (bp = mp->lqh.cqh_first;
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bp != (void *)&mp->lqh; bp = bp->q.cqe_next)
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if (!(bp->flags & MPOOL_PINNED)) {
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/* Flush if dirty. */
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if (bp->flags & MPOOL_DIRTY &&
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mpool_write(mp, bp) == RET_ERROR)
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return (NULL);
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#ifdef STATISTICS
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++mp->pageflush;
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#endif
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/* Remove from the hash and lru queues. */
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head = &mp->hqh[HASHKEY(bp->pgno)];
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CIRCLEQ_REMOVE(head, bp, hq);
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CIRCLEQ_REMOVE(&mp->lqh, bp, q);
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#ifdef DEBUG
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{ void *spage;
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spage = bp->page;
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memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
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bp->page = spage;
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}
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#endif
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return (bp);
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}
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new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL)
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return (NULL);
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#ifdef STATISTICS
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++mp->pagealloc;
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#endif
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#if defined(DEBUG) || defined(PURIFY)
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memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
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#endif
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bp->page = (char *)bp + sizeof(BKT);
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++mp->curcache;
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return (bp);
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}
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/*
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* mpool_write
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* Write a page to disk.
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*/
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static int
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mpool_write(mp, bp)
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MPOOL *mp;
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BKT *bp;
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{
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off_t off;
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#ifdef STATISTICS
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++mp->pagewrite;
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#endif
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/* Run through the user's filter. */
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if (mp->pgout)
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(mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
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off = mp->pagesize * bp->pgno;
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if (lseek(mp->fd, off, SEEK_SET) != off)
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return (RET_ERROR);
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if (write(mp->fd, bp->page, mp->pagesize) != mp->pagesize)
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return (RET_ERROR);
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bp->flags &= ~MPOOL_DIRTY;
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return (RET_SUCCESS);
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}
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/*
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* mpool_look
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* Lookup a page in the cache.
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*/
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static BKT *
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mpool_look(mp, pgno)
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MPOOL *mp;
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pgno_t pgno;
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{
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struct _hqh *head;
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BKT *bp;
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head = &mp->hqh[HASHKEY(pgno)];
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for (bp = head->cqh_first; bp != (void *)head; bp = bp->hq.cqe_next)
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if (bp->pgno == pgno) {
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#ifdef STATISTICS
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++mp->cachehit;
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#endif
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return (bp);
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}
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#ifdef STATISTICS
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++mp->cachemiss;
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#endif
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return (NULL);
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}
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#ifdef STATISTICS
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/*
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* mpool_stat
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* Print out cache statistics.
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*/
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void
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mpool_stat(mp)
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MPOOL *mp;
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{
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BKT *bp;
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int cnt;
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char *sep;
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(void)fprintf(stderr, "%lu pages in the file\n", mp->npages);
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(void)fprintf(stderr,
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"page size %lu, cacheing %lu pages of %lu page max cache\n",
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mp->pagesize, mp->curcache, mp->maxcache);
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(void)fprintf(stderr, "%lu page puts, %lu page gets, %lu page new\n",
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mp->pageput, mp->pageget, mp->pagenew);
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(void)fprintf(stderr, "%lu page allocs, %lu page flushes\n",
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mp->pagealloc, mp->pageflush);
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if (mp->cachehit + mp->cachemiss)
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(void)fprintf(stderr,
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"%.0f%% cache hit rate (%lu hits, %lu misses)\n",
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((double)mp->cachehit / (mp->cachehit + mp->cachemiss))
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* 100, mp->cachehit, mp->cachemiss);
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(void)fprintf(stderr, "%lu page reads, %lu page writes\n",
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mp->pageread, mp->pagewrite);
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sep = "";
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cnt = 0;
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for (bp = mp->lqh.cqh_first;
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bp != (void *)&mp->lqh; bp = bp->q.cqe_next) {
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(void)fprintf(stderr, "%s%d", sep, bp->pgno);
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if (bp->flags & MPOOL_DIRTY)
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(void)fprintf(stderr, "d");
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if (bp->flags & MPOOL_PINNED)
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(void)fprintf(stderr, "P");
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if (++cnt == 10) {
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sep = "\n";
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cnt = 0;
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} else
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sep = ", ";
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}
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(void)fprintf(stderr, "\n");
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}
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#endif
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