| Current Path : /usr/src/lib/libc/db/hash/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/lib/libc/db/hash/hash_buf.c |
/*-
* 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.
* 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 */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/lib/libc/db/hash/hash_buf.c 190493 2009-03-28 06:40:48Z delphij $");
/*
* PACKAGE: hash
*
* DESCRIPTION:
* Contains buffer management
*
* ROUTINES:
* External
* __buf_init
* __get_buf
* __buf_free
* __reclaim_buf
* Internal
* newbuf
*/
#include <sys/param.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef DEBUG
#include <assert.h>
#endif
#include <db.h>
#include "hash.h"
#include "page.h"
#include "extern.h"
static BUFHEAD *newbuf(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.
*/
BUFHEAD *
__get_buf(HTAB *hashp, u_int32_t addr,
BUFHEAD *prev_bp, /* If prev_bp set, indicates a new overflow page. */
int newpage)
{
BUFHEAD *bp;
u_int32_t is_disk_mask;
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(HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp)
{
BUFHEAD *bp; /* The buffer we're going to use */
BUFHEAD *xbp; /* Temp pointer */
BUFHEAD *next_xbp;
SEGMENT segp;
int segment_ndx;
u_int16_t oaddr, *shortp;
oaddr = 0;
bp = LRU;
/* It is bad to overwrite the page under the cursor. */
if (bp == hashp->cpage) {
BUF_REMOVE(bp);
MRU_INSERT(bp);
bp = LRU;
}
/* If prev_bp is part of bp overflow, create a new buffer. */
if (hashp->nbufs == 0 && prev_bp && bp->ovfl) {
BUFHEAD *ovfl;
for (ovfl = bp->ovfl; ovfl ; ovfl = ovfl->ovfl) {
if (ovfl == prev_bp) {
hashp->nbufs++;
break;
}
}
}
/*
* If LRU buffer is pinned, the buffer pool is too small. We need to
* allocate more buffers.
*/
if (hashp->nbufs || (bp->flags & BUF_PIN) || bp == hashp->cpage) {
/* Allocate a new one */
if ((bp = (BUFHEAD *)calloc(1, sizeof(BUFHEAD))) == NULL)
return (NULL);
if ((bp->page = (char *)calloc(1, hashp->BSIZE)) == NULL) {
free(bp);
return (NULL);
}
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 ? prev_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);
}
void
__buf_init(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;
*/
}
int
__buf_free(HTAB *hashp, int do_free, int 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) {
(void)memset(bp->page, 0, hashp->BSIZE);
free(bp->page);
}
BUF_REMOVE(bp);
free(bp);
bp = LRU;
} else
bp = bp->prev;
}
return (0);
}
void
__reclaim_buf(HTAB *hashp, BUFHEAD *bp)
{
bp->ovfl = 0;
bp->addr = 0;
bp->flags = 0;
BUF_REMOVE(bp);
LRU_INSERT(bp);
}