/*-
* 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 8.7 (Berkeley) 11/2/95";
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "db-int.h"
#include "mpool.h"
static BKT *mpool_bkt __P((MPOOL *));
static BKT *mpool_look __P((MPOOL *, db_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;
db_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 *, db_pgno_t, void *));
void (*pgout) __P((void *, db_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, flags)
MPOOL *mp;
db_pgno_t *pgnoaddr;
u_int flags;
{
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);
if (flags == MPOOL_PAGE_REQUEST) {
mp->npages++;
bp->pgno = *pgnoaddr;
} else
bp->pgno = *pgnoaddr = mp->npages++;
bp->flags = MPOOL_PINNED | MPOOL_INUSE;
head = &mp->hqh[HASHKEY(bp->pgno)];
CIRCLEQ_INSERT_HEAD(head, bp, hq);
CIRCLEQ_INSERT_TAIL(&mp->lqh, bp, q);
return (bp->page);
}
int
mpool_delete(mp, page)
MPOOL *mp;
void *page;
{
struct _hqh *head;
BKT *bp;
bp = (BKT *)((char *)page - sizeof(BKT));
#ifdef DEBUG
if (!(bp->flags & MPOOL_PINNED)) {
(void)fprintf(stderr,
"mpool_delete: page %d not pinned\n", bp->pgno);
abort();
}
#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);
free(bp);
return (RET_SUCCESS);
}
/*
* mpool_get
* Get a page.
*/
void *
mpool_get(mp, pgno, flags)
MPOOL *mp;
db_pgno_t pgno;
u_int flags; /* XXX not used? */
{
struct _hqh *head;
BKT *bp;
off_t off;
int nr;
#ifdef STATISTICS
++mp->pageget;
#endif
/* Check for a page that is cached. */
if ((bp = mpool_look(mp, pgno)) != NULL) {
#ifdef DEBUG
if (!(flags & MPOOL_IGNOREPIN) && 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 (off / mp->pagesize != pgno) {
/* Run past the end of the file, or at least the part we
can address without large-file support? */
errno = E2BIG;
return NULL;
}
if (lseek(mp->fd, off, SEEK_SET) != off)
return (NULL);
if ((nr = read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) {
if (nr > 0) {
/* A partial read is definitely bad. */
errno = EINVAL;
return (NULL);
} else {
/*
* A zero-length reads, means you need to create a
* new page.
*/
memset(bp->page, 0, mp->pagesize);
}
}
/* Set the page number, pin the page. */
bp->pgno = pgno;
if (!(flags & MPOOL_IGNOREPIN))
bp->flags = MPOOL_PINNED;
bp->flags |= MPOOL_INUSE;
/*
* 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;
if (flags & MPOOL_DIRTY)
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);
}
/*
* 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
bp->flags = 0;
return (bp);
}
new: if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL)
return (NULL);
#ifdef STATISTICS
++mp->pagealloc;
#endif
#if defined(DEBUG) || defined(PURIFY) || 1
memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
#endif
bp->page = (char *)bp + sizeof(BKT);
bp->flags = 0;
++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 (off / mp->pagesize != bp->pgno) {
/* Run past the end of the file, or at least the part we
can address without large-file support? */
errno = E2BIG;
return RET_ERROR;
}
if (lseek(mp->fd, off, SEEK_SET) != off)
return (RET_ERROR);
if (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;
db_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) && (bp->flags & MPOOL_INUSE)) {
#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