diff options
Diffstat (limited to 'db/hash/hash_buf.c')
| -rw-r--r-- | db/hash/hash_buf.c | 355 |
1 files changed, 355 insertions, 0 deletions
diff --git a/db/hash/hash_buf.c b/db/hash/hash_buf.c new file mode 100644 index 0000000000..92e1f933ad --- /dev/null +++ b/db/hash/hash_buf.c @@ -0,0 +1,355 @@ +/*- + * Copyright (c) 1990, 1993, 1994 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Margo Seltzer. + * + * 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[] = "@(#)hash_buf.c 8.5 (Berkeley) 7/15/94"; +#endif /* LIBC_SCCS and not lint */ + +/* + * PACKAGE: hash + * + * DESCRIPTION: + * Contains buffer management + * + * ROUTINES: + * External + * __buf_init + * __get_buf + * __buf_free + * __reclaim_buf + * Internal + * newbuf + */ + +#include <sys/param.h> + +#include <errno.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> + +#ifdef DEBUG +#include <assert.h> +#endif + +#include <db.h> +#include "hash.h" +#include "page.h" +#include "extern.h" + +static BUFHEAD *newbuf __P((HTAB *, u_int32_t, BUFHEAD *)); + +/* Unlink B from its place in the lru */ +#define BUF_REMOVE(B) { \ + (B)->prev->next = (B)->next; \ + (B)->next->prev = (B)->prev; \ +} + +/* Insert B after P */ +#define BUF_INSERT(B, P) { \ + (B)->next = (P)->next; \ + (B)->prev = (P); \ + (P)->next = (B); \ + (B)->next->prev = (B); \ +} + +#define MRU hashp->bufhead.next +#define LRU hashp->bufhead.prev + +#define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead) +#define LRU_INSERT(B) BUF_INSERT((B), LRU) + +/* + * We are looking for a buffer with address "addr". If prev_bp is NULL, then + * address is a bucket index. If prev_bp is not NULL, then it points to the + * page previous to an overflow page that we are trying to find. + * + * CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer + * be valid. Therefore, you must always verify that its address matches the + * address you are seeking. + */ +extern BUFHEAD * +__get_buf(hashp, addr, prev_bp, newpage) + HTAB *hashp; + u_int32_t addr; + BUFHEAD *prev_bp; + int newpage; /* If prev_bp set, indicates a new overflow page. */ +{ + register BUFHEAD *bp; + register u_int32_t is_disk_mask; + register int is_disk, segment_ndx; + SEGMENT segp; + + is_disk = 0; + is_disk_mask = 0; + if (prev_bp) { + bp = prev_bp->ovfl; + if (!bp || (bp->addr != addr)) + bp = NULL; + if (!newpage) + is_disk = BUF_DISK; + } else { + /* Grab buffer out of directory */ + segment_ndx = addr & (hashp->SGSIZE - 1); + + /* valid segment ensured by __call_hash() */ + segp = hashp->dir[addr >> hashp->SSHIFT]; +#ifdef DEBUG + assert(segp != NULL); +#endif + bp = PTROF(segp[segment_ndx]); + is_disk_mask = ISDISK(segp[segment_ndx]); + is_disk = is_disk_mask || !hashp->new_file; + } + + if (!bp) { + bp = newbuf(hashp, addr, prev_bp); + if (!bp || + __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0)) + return (NULL); + if (!prev_bp) + segp[segment_ndx] = + (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask); + } else { + BUF_REMOVE(bp); + MRU_INSERT(bp); + } + return (bp); +} + +/* + * We need a buffer for this page. Either allocate one, or evict a resident + * one (if we have as many buffers as we're allowed) and put this one in. + * + * If newbuf finds an error (returning NULL), it also sets errno. + */ +static BUFHEAD * +newbuf(hashp, addr, prev_bp) + HTAB *hashp; + u_int32_t addr; + BUFHEAD *prev_bp; +{ + register BUFHEAD *bp; /* The buffer we're going to use */ + register BUFHEAD *xbp; /* Temp pointer */ + register BUFHEAD *next_xbp; + SEGMENT segp; + int segment_ndx; + u_int16_t oaddr, *shortp; + + oaddr = 0; + bp = LRU; + /* + * If LRU buffer is pinned, the buffer pool is too small. We need to + * allocate more buffers. + */ + if (hashp->nbufs || (bp->flags & BUF_PIN)) { + /* Allocate a new one */ + if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL) + return (NULL); +#ifdef PURIFY + memset(bp, 0xff, sizeof(BUFHEAD)); +#endif + if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) { + free(bp); + return (NULL); + } +#ifdef PURIFY + memset(bp->page, 0xff, hashp->BSIZE); +#endif + if (hashp->nbufs) + hashp->nbufs--; + } else { + /* Kick someone out */ + BUF_REMOVE(bp); + /* + * If this is an overflow page with addr 0, it's already been + * flushed back in an overflow chain and initialized. + */ + if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) { + /* + * Set oaddr before __put_page so that you get it + * before bytes are swapped. + */ + shortp = (u_int16_t *)bp->page; + if (shortp[0]) + oaddr = shortp[shortp[0] - 1]; + if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page, + bp->addr, (int)IS_BUCKET(bp->flags), 0)) + return (NULL); + /* + * Update the pointer to this page (i.e. invalidate it). + * + * If this is a new file (i.e. we created it at open + * time), make sure that we mark pages which have been + * written to disk so we retrieve them from disk later, + * rather than allocating new pages. + */ + if (IS_BUCKET(bp->flags)) { + segment_ndx = bp->addr & (hashp->SGSIZE - 1); + segp = hashp->dir[bp->addr >> hashp->SSHIFT]; +#ifdef DEBUG + assert(segp != NULL); +#endif + + if (hashp->new_file && + ((bp->flags & BUF_MOD) || + ISDISK(segp[segment_ndx]))) + segp[segment_ndx] = (BUFHEAD *)BUF_DISK; + else + segp[segment_ndx] = NULL; + } + /* + * Since overflow pages can only be access by means of + * their bucket, free overflow pages associated with + * this bucket. + */ + for (xbp = bp; xbp->ovfl;) { + next_xbp = xbp->ovfl; + xbp->ovfl = 0; + xbp = next_xbp; + + /* Check that ovfl pointer is up date. */ + if (IS_BUCKET(xbp->flags) || + (oaddr != xbp->addr)) + break; + + shortp = (u_int16_t *)xbp->page; + if (shortp[0]) + /* set before __put_page */ + oaddr = shortp[shortp[0] - 1]; + if ((xbp->flags & BUF_MOD) && __put_page(hashp, + xbp->page, xbp->addr, 0, 0)) + return (NULL); + xbp->addr = 0; + xbp->flags = 0; + BUF_REMOVE(xbp); + LRU_INSERT(xbp); + } + } + } + + /* Now assign this buffer */ + bp->addr = addr; +#ifdef DEBUG1 + (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n", + bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0); +#endif + bp->ovfl = NULL; + if (prev_bp) { + /* + * If prev_bp is set, this is an overflow page, hook it in to + * the buffer overflow links. + */ +#ifdef DEBUG1 + (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n", + prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0), + (bp ? bp->addr : 0)); +#endif + prev_bp->ovfl = bp; + bp->flags = 0; + } else + bp->flags = BUF_BUCKET; + MRU_INSERT(bp); + return (bp); +} + +extern void +__buf_init(hashp, nbytes) + HTAB *hashp; + int nbytes; +{ + BUFHEAD *bfp; + int npages; + + bfp = &(hashp->bufhead); + npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT; + npages = MAX(npages, MIN_BUFFERS); + + hashp->nbufs = npages; + bfp->next = bfp; + bfp->prev = bfp; + /* + * This space is calloc'd so these are already null. + * + * bfp->ovfl = NULL; + * bfp->flags = 0; + * bfp->page = NULL; + * bfp->addr = 0; + */ +} + +extern int +__buf_free(hashp, do_free, to_disk) + HTAB *hashp; + int do_free, to_disk; +{ + BUFHEAD *bp; + + /* Need to make sure that buffer manager has been initialized */ + if (!LRU) + return (0); + for (bp = LRU; bp != &hashp->bufhead;) { + /* Check that the buffer is valid */ + if (bp->addr || IS_BUCKET(bp->flags)) { + if (to_disk && (bp->flags & BUF_MOD) && + __put_page(hashp, bp->page, + bp->addr, IS_BUCKET(bp->flags), 0)) + return (-1); + } + /* Check if we are freeing stuff */ + if (do_free) { + if (bp->page) + free(bp->page); + BUF_REMOVE(bp); + free(bp); + bp = LRU; + } else + bp = bp->prev; + } + return (0); +} + +extern void +__reclaim_buf(hashp, bp) + HTAB *hashp; + BUFHEAD *bp; +{ + bp->ovfl = 0; + bp->addr = 0; + bp->flags = 0; + BUF_REMOVE(bp); + LRU_INSERT(bp); +} |