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Diffstat (limited to 'db/mpool/mpool.c')
| -rw-r--r-- | db/mpool/mpool.c | 463 |
1 files changed, 463 insertions, 0 deletions
diff --git a/db/mpool/mpool.c b/db/mpool/mpool.c new file mode 100644 index 0000000000..a61041e091 --- /dev/null +++ b/db/mpool/mpool.c @@ -0,0 +1,463 @@ +/*- + * 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 <db.h> + +#define __MPOOLINTERFACE_PRIVATE +#include <mpool.h> + +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 ((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); +} + +/* + * 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 *)malloc(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 (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 |