OpenE2K
/
glibc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
glibc/db/hash/hash_page.c

945 lines
23 KiB
C
Raw Blame History

/*-
* 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_page.c 8.7 (Berkeley) 8/16/94";
#endif /* LIBC_SCCS and not lint */
/*
* PACKAGE: hashing
*
* DESCRIPTION:
* Page manipulation for hashing package.
*
* ROUTINES:
*
* External
* __get_page
* __add_ovflpage
* Internal
* overflow_page
* open_temp
*/
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef DEBUG
#include <assert.h>
#endif
#include <db.h>
#include "hash.h"
#include "page.h"
#include "extern.h"
static u_int32_t *fetch_bitmap __P((HTAB *, int));
static u_int32_t first_free __P((u_int32_t));
static int open_temp __P((HTAB *));
static u_int16_t overflow_page __P((HTAB *));
static void putpair __P((char *, const DBT *, const DBT *));
static void squeeze_key __P((u_int16_t *, const DBT *, const DBT *));
static int ugly_split
__P((HTAB *, u_int32_t, BUFHEAD *, BUFHEAD *, int, int));
#define PAGE_INIT(P) { \
((u_int16_t *)(P))[0] = 0; \
((u_int16_t *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_int16_t); \
((u_int16_t *)(P))[2] = hashp->BSIZE; \
}
/*
* This is called AFTER we have verified that there is room on the page for
* the pair (PAIRFITS has returned true) so we go right ahead and start moving
* stuff on.
*/
static void
putpair(p, key, val)
char *p;
const DBT *key, *val;
{
register u_int16_t *bp, n, off;
bp = (u_int16_t *)p;
/* Enter the key first. */
n = bp[0];
off = OFFSET(bp) - key->size;
memmove(p + off, key->data, key->size);
bp[++n] = off;
/* Now the data. */
off -= val->size;
memmove(p + off, val->data, val->size);
bp[++n] = off;
/* Adjust page info. */
bp[0] = n;
bp[n + 1] = off - ((n + 3) * sizeof(u_int16_t));
bp[n + 2] = off;
}
/*
* Returns:
* 0 OK
* -1 error
*/
extern int
__delpair(hashp, bufp, ndx)
HTAB *hashp;
BUFHEAD *bufp;
register int ndx;
{
register u_int16_t *bp, newoff;
register int n;
u_int16_t pairlen;
bp = (u_int16_t *)bufp->page;
n = bp[0];
if (bp[ndx + 1] < REAL_KEY)
return (__big_delete(hashp, bufp));
if (ndx != 1)
newoff = bp[ndx - 1];
else
newoff = hashp->BSIZE;
pairlen = newoff - bp[ndx + 1];
if (ndx != (n - 1)) {
/* Hard Case -- need to shuffle keys */
register int i;
register char *src = bufp->page + (int)OFFSET(bp);
register char *dst = src + (int)pairlen;
memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
/* Now adjust the pointers */
for (i = ndx + 2; i <= n; i += 2) {
if (bp[i + 1] == OVFLPAGE) {
bp[i - 2] = bp[i];
bp[i - 1] = bp[i + 1];
} else {
bp[i - 2] = bp[i] + pairlen;
bp[i - 1] = bp[i + 1] + pairlen;
}
}
}
/* Finally adjust the page data */
bp[n] = OFFSET(bp) + pairlen;
bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
bp[0] = n - 2;
hashp->NKEYS--;
bufp->flags |= BUF_MOD;
return (0);
}
/*
* Returns:
* 0 ==> OK
* -1 ==> Error
*/
extern int
__split_page(hashp, obucket, nbucket)
HTAB *hashp;
u_int32_t obucket, nbucket;
{
register BUFHEAD *new_bufp, *old_bufp;
register u_int16_t *ino;
register char *np;
DBT key, val;
int n, ndx, retval;
u_int16_t copyto, diff, off, moved;
char *op;
copyto = (u_int16_t)hashp->BSIZE;
off = (u_int16_t)hashp->BSIZE;
old_bufp = __get_buf(hashp, obucket, NULL, 0);
if (old_bufp == NULL)
return (-1);
new_bufp = __get_buf(hashp, nbucket, NULL, 0);
if (new_bufp == NULL)
return (-1);
old_bufp->flags |= (BUF_MOD | BUF_PIN);
new_bufp->flags |= (BUF_MOD | BUF_PIN);
ino = (u_int16_t *)(op = old_bufp->page);
np = new_bufp->page;
moved = 0;
for (n = 1, ndx = 1; n < ino[0]; n += 2) {
if (ino[n + 1] < REAL_KEY) {
retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
(int)copyto, (int)moved);
old_bufp->flags &= ~BUF_PIN;
new_bufp->flags &= ~BUF_PIN;
return (retval);
}
key.data = (u_char *)op + ino[n];
key.size = off - ino[n];
if (__call_hash(hashp, key.data, key.size) == obucket) {
/* Don't switch page */
diff = copyto - off;
if (diff) {
copyto = ino[n + 1] + diff;
memmove(op + copyto, op + ino[n + 1],
off - ino[n + 1]);
ino[ndx] = copyto + ino[n] - ino[n + 1];
ino[ndx + 1] = copyto;
} else
copyto = ino[n + 1];
ndx += 2;
} else {
/* Switch page */
val.data = (u_char *)op + ino[n + 1];
val.size = ino[n] - ino[n + 1];
putpair(np, &key, &val);
moved += 2;
}
off = ino[n + 1];
}
/* Now clean up the page */
ino[0] -= moved;
FREESPACE(ino) = copyto - sizeof(u_int16_t) * (ino[0] + 3);
OFFSET(ino) = copyto;
#ifdef DEBUG3
(void)fprintf(stderr, "split %d/%d\n",
((u_int16_t *)np)[0] / 2,
((u_int16_t *)op)[0] / 2);
#endif
/* unpin both pages */
old_bufp->flags &= ~BUF_PIN;
new_bufp->flags &= ~BUF_PIN;
return (0);
}
/*
* Called when we encounter an overflow or big key/data page during split
* handling. This is special cased since we have to begin checking whether
* the key/data pairs fit on their respective pages and because we may need
* overflow pages for both the old and new pages.
*
* The first page might be a page with regular key/data pairs in which case
* we have a regular overflow condition and just need to go on to the next
* page or it might be a big key/data pair in which case we need to fix the
* big key/data pair.
*
* Returns:
* 0 ==> success
* -1 ==> failure
*/
static int
ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved)
HTAB *hashp;
u_int32_t obucket; /* Same as __split_page. */
BUFHEAD *old_bufp, *new_bufp;
int copyto; /* First byte on page which contains key/data values. */
int moved; /* Number of pairs moved to new page. */
{
register BUFHEAD *bufp; /* Buffer header for ino */
register u_int16_t *ino; /* Page keys come off of */
register u_int16_t *np; /* New page */
register u_int16_t *op; /* Page keys go on to if they aren't moving */
BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
DBT key, val;
SPLIT_RETURN ret;
u_int16_t n, off, ov_addr, scopyto;
char *cino; /* Character value of ino */
bufp = old_bufp;
ino = (u_int16_t *)old_bufp->page;
np = (u_int16_t *)new_bufp->page;
op = (u_int16_t *)old_bufp->page;
last_bfp = NULL;
scopyto = (u_int16_t)copyto; /* ANSI */
n = ino[0] - 1;
while (n < ino[0]) {
if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
if (__big_split(hashp, old_bufp,
new_bufp, bufp, bufp->addr, obucket, &ret))
return (-1);
old_bufp = ret.oldp;
if (!old_bufp)
return (-1);
op = (u_int16_t *)old_bufp->page;
new_bufp = ret.newp;
if (!new_bufp)
return (-1);
np = (u_int16_t *)new_bufp->page;
bufp = ret.nextp;
if (!bufp)
return (0);
cino = (char *)bufp->page;
ino = (u_int16_t *)cino;
last_bfp = ret.nextp;
} else if (ino[n + 1] == OVFLPAGE) {
ov_addr = ino[n];
/*
* Fix up the old page -- the extra 2 are the fields
* which contained the overflow information.
*/
ino[0] -= (moved + 2);
FREESPACE(ino) =
scopyto - sizeof(u_int16_t) * (ino[0] + 3);
OFFSET(ino) = scopyto;
bufp = __get_buf(hashp, ov_addr, bufp, 0);
if (!bufp)
return (-1);
ino = (u_int16_t *)bufp->page;
n = 1;
scopyto = hashp->BSIZE;
moved = 0;
if (last_bfp)
__free_ovflpage(hashp, last_bfp);
last_bfp = bufp;
}
/* Move regular sized pairs of there are any */
off = hashp->BSIZE;
for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
cino = (char *)ino;
key.data = (u_char *)cino + ino[n];
key.size = off - ino[n];
val.data = (u_char *)cino + ino[n + 1];
val.size = ino[n] - ino[n + 1];
off = ino[n + 1];
if (__call_hash(hashp, key.data, key.size) == obucket) {
/* Keep on old page */
if (PAIRFITS(op, (&key), (&val)))
putpair((char *)op, &key, &val);
else {
old_bufp =
__add_ovflpage(hashp, old_bufp);
if (!old_bufp)
return (-1);
op = (u_int16_t *)old_bufp->page;
putpair((char *)op, &key, &val);
}
old_bufp->flags |= BUF_MOD;
} else {
/* Move to new page */
if (PAIRFITS(np, (&key), (&val)))
putpair((char *)np, &key, &val);
else {
new_bufp =
__add_ovflpage(hashp, new_bufp);
if (!new_bufp)
return (-1);
np = (u_int16_t *)new_bufp->page;
putpair((char *)np, &key, &val);
}
new_bufp->flags |= BUF_MOD;
}
}
}
if (last_bfp)
__free_ovflpage(hashp, last_bfp);
return (0);
}
/*
* Add the given pair to the page
*
* Returns:
* 0 ==> OK
* 1 ==> failure
*/
extern int
__addel(hashp, bufp, key, val)
HTAB *hashp;
BUFHEAD *bufp;
const DBT *key, *val;
{
register u_int16_t *bp, *sop;
int do_expand;
bp = (u_int16_t *)bufp->page;
do_expand = 0;
while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
/* Exception case */
if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
/* This is the last page of a big key/data pair
and we need to add another page */
break;
else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
if (!bufp)
return (-1);
bp = (u_int16_t *)bufp->page;
} else
/* Try to squeeze key on this page */
if (FREESPACE(bp) > PAIRSIZE(key, val)) {
squeeze_key(bp, key, val);
return (0);
} else {
bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
if (!bufp)
return (-1);
bp = (u_int16_t *)bufp->page;
}
if (PAIRFITS(bp, key, val))
putpair(bufp->page, key, val);
else {
do_expand = 1;
bufp = __add_ovflpage(hashp, bufp);
if (!bufp)
return (-1);
sop = (u_int16_t *)bufp->page;
if (PAIRFITS(sop, key, val))
putpair((char *)sop, key, val);
else
if (__big_insert(hashp, bufp, key, val))
return (-1);
}
bufp->flags |= BUF_MOD;
/*
* If the average number of keys per bucket exceeds the fill factor,
* expand the table.
*/
hashp->NKEYS++;
if (do_expand ||
(hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
return (__expand_table(hashp));
return (0);
}
/*
*
* Returns:
* pointer on success
* NULL on error
*/
extern BUFHEAD *
__add_ovflpage(hashp, bufp)
HTAB *hashp;
BUFHEAD *bufp;
{
register u_int16_t *sp;
u_int16_t ndx, ovfl_num;
#ifdef DEBUG1
int tmp1, tmp2;
#endif
sp = (u_int16_t *)bufp->page;
/* Check if we are dynamically determining the fill factor */
if (hashp->FFACTOR == DEF_FFACTOR) {
hashp->FFACTOR = sp[0] >> 1;
if (hashp->FFACTOR < MIN_FFACTOR)
hashp->FFACTOR = MIN_FFACTOR;
}
bufp->flags |= BUF_MOD;
ovfl_num = overflow_page(hashp);
#ifdef DEBUG1
tmp1 = bufp->addr;
tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
#endif
if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
return (NULL);
bufp->ovfl->flags |= BUF_MOD;
#ifdef DEBUG1
(void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
tmp1, tmp2, bufp->ovfl->addr);
#endif
ndx = sp[0];
/*
* Since a pair is allocated on a page only if there's room to add
* an overflow page, we know that the OVFL information will fit on
* the page.
*/
sp[ndx + 4] = OFFSET(sp);
sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;
sp[ndx + 1] = ovfl_num;
sp[ndx + 2] = OVFLPAGE;
sp[0] = ndx + 2;
#ifdef HASH_STATISTICS
hash_overflows++;
#endif
return (bufp->ovfl);
}
/*
* Returns:
* 0 indicates SUCCESS
* -1 indicates FAILURE
*/
extern int
__get_page(hashp, p, bucket, is_bucket, is_disk, is_bitmap)
HTAB *hashp;
char *p;
u_int32_t bucket;
int is_bucket, is_disk, is_bitmap;
{
register int fd, page, size;
int rsize;
u_int16_t *bp;
fd = hashp->fp;
size = hashp->BSIZE;
if ((fd == -1) || !is_disk) {
PAGE_INIT(p);
return (0);
}
if (is_bucket)
page = BUCKET_TO_PAGE(bucket);
else
page = OADDR_TO_PAGE(bucket);
if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
((rsize = read(fd, p, size)) == -1))
return (-1);
bp = (u_int16_t *)p;
if (!rsize)
bp[0] = 0; /* We hit the EOF, so initialize a new page */
else
if (rsize != size) {
errno = EFTYPE;
return (-1);
}
if (!is_bitmap && !bp[0]) {
PAGE_INIT(p);
} else
if (hashp->LORDER != BYTE_ORDER) {
register int i, max;
if (is_bitmap) {
max = hashp->BSIZE >> 2; /* divide by 4 */
for (i = 0; i < max; i++)
M_32_SWAP(((int *)p)[i]);
} else {
M_16_SWAP(bp[0]);
max = bp[0] + 2;
for (i = 1; i <= max; i++)
M_16_SWAP(bp[i]);
}
}
return (0);
}
/*
* Write page p to disk
*
* Returns:
* 0 ==> OK
* -1 ==>failure
*/
extern int
__put_page(hashp, p, bucket, is_bucket, is_bitmap)
HTAB *hashp;
char *p;
u_int32_t bucket;
int is_bucket, is_bitmap;
{
register int fd, page, size;
int wsize;
size = hashp->BSIZE;
if ((hashp->fp == -1) && open_temp(hashp))
return (-1);
fd = hashp->fp;
if (hashp->LORDER != BYTE_ORDER) {
register int i;
register int max;
if (is_bitmap) {
max = hashp->BSIZE >> 2; /* divide by 4 */
for (i = 0; i < max; i++)
M_32_SWAP(((int *)p)[i]);
} else {
max = ((u_int16_t *)p)[0] + 2;
for (i = 0; i <= max; i++)
M_16_SWAP(((u_int16_t *)p)[i]);
}
}
if (is_bucket)
page = BUCKET_TO_PAGE(bucket);
else
page = OADDR_TO_PAGE(bucket);
if ((lseek(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||
((wsize = write(fd, p, size)) == -1))
/* Errno is set */
return (-1);
if (wsize != size) {
errno = EFTYPE;
return (-1);
}
return (0);
}
#define BYTE_MASK ((1 << INT_BYTE_SHIFT) -1)
/*
* Initialize a new bitmap page. Bitmap pages are left in memory
* once they are read in.
*/
extern int
__ibitmap(hashp, pnum, nbits, ndx)
HTAB *hashp;
int pnum, nbits, ndx;
{
u_int32_t *ip;
int clearbytes, clearints;
if ((ip = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
return (1);
hashp->nmaps++;
clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;
clearbytes = clearints << INT_TO_BYTE;
(void)memset((char *)ip, 0, clearbytes);
(void)memset(((char *)ip) + clearbytes, 0xFF,
hashp->BSIZE - clearbytes);
ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);
SETBIT(ip, 0);
hashp->BITMAPS[ndx] = (u_int16_t)pnum;
hashp->mapp[ndx] = ip;
return (0);
}
static u_int32_t
first_free(map)
u_int32_t map;
{
register u_int32_t i, mask;
mask = 0x1;
for (i = 0; i < BITS_PER_MAP; i++) {
if (!(mask & map))
return (i);
mask = mask << 1;
}
return (i);
}
static u_int16_t
overflow_page(hashp)
HTAB *hashp;
{
register u_int32_t *freep;
register int max_free, offset, splitnum;
u_int16_t addr;
int bit, first_page, free_bit, free_page, i, in_use_bits, j;
#ifdef DEBUG2
int tmp1, tmp2;
#endif
splitnum = hashp->OVFL_POINT;
max_free = hashp->SPARES[splitnum];
free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);
free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);
/* Look through all the free maps to find the first free block */
first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);
for ( i = first_page; i <= free_page; i++ ) {
if (!(freep = (u_int32_t *)hashp->mapp[i]) &&
!(freep = fetch_bitmap(hashp, i)))
return (0);
if (i == free_page)
in_use_bits = free_bit;
else
in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;
if (i == first_page) {
bit = hashp->LAST_FREED &
((hashp->BSIZE << BYTE_SHIFT) - 1);
j = bit / BITS_PER_MAP;
bit = bit & ~(BITS_PER_MAP - 1);
} else {
bit = 0;
j = 0;
}
for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
if (freep[j] != ALL_SET)
goto found;
}
/* No Free Page Found */
hashp->LAST_FREED = hashp->SPARES[splitnum];
hashp->SPARES[splitnum]++;
offset = hashp->SPARES[splitnum] -
(splitnum ? hashp->SPARES[splitnum - 1] : 0);
#define OVMSG "HASH: Out of overflow pages. Increase page size\n"
if (offset > SPLITMASK) {
if (++splitnum >= NCACHED) {
(void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
return (0);
}
hashp->OVFL_POINT = splitnum;
hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
hashp->SPARES[splitnum-1]--;
offset = 1;
}
/* Check if we need to allocate a new bitmap page */
if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {
free_page++;
if (free_page >= NCACHED) {
(void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);
return (0);
}
/*
* This is tricky. The 1 indicates that you want the new page
* allocated with 1 clear bit. Actually, you are going to
* allocate 2 pages from this map. The first is going to be
* the map page, the second is the overflow page we were
* looking for. The init_bitmap routine automatically, sets
* the first bit of itself to indicate that the bitmap itself
* is in use. We would explicitly set the second bit, but
* don't have to if we tell init_bitmap not to leave it clear
* in the first place.
*/
if (__ibitmap(hashp,
(int)OADDR_OF(splitnum, offset), 1, free_page))
return (0);
hashp->SPARES[splitnum]++;
#ifdef DEBUG2
free_bit = 2;
#endif
offset++;
if (offset > SPLITMASK) {
if (++splitnum >= NCACHED) {
(void)write(STDERR_FILENO, OVMSG,
sizeof(OVMSG) - 1);
return (0);
}
hashp->OVFL_POINT = splitnum;
hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];
hashp->SPARES[splitnum-1]--;
offset = 0;
}
} else {
/*
* Free_bit addresses the last used bit. Bump it to address
* the first available bit.
*/
free_bit++;
SETBIT(freep, free_bit);
}
/* Calculate address of the new overflow page */
addr = OADDR_OF(splitnum, offset);
#ifdef DEBUG2
(void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
addr, free_bit, free_page);
#endif
return (addr);
found:
bit = bit + first_free(freep[j]);
SETBIT(freep, bit);
#ifdef DEBUG2
tmp1 = bit;
tmp2 = i;
#endif
/*
* Bits are addressed starting with 0, but overflow pages are addressed
* beginning at 1. Bit is a bit addressnumber, so we need to increment
* it to convert it to a page number.
*/
bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));
if (bit >= hashp->LAST_FREED)
hashp->LAST_FREED = bit - 1;
/* Calculate the split number for this page */
for (i = 0; (i < splitnum) && (bit > hashp->SPARES[i]); i++);
offset = (i ? bit - hashp->SPARES[i - 1] : bit);
if (offset >= SPLITMASK)
return (0); /* Out of overflow pages */
addr = OADDR_OF(i, offset);
#ifdef DEBUG2
(void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",
addr, tmp1, tmp2);
#endif
/* Allocate and return the overflow page */
return (addr);
}
/*
* Mark this overflow page as free.
*/
extern void
__free_ovflpage(hashp, obufp)
HTAB *hashp;
BUFHEAD *obufp;
{
register u_int16_t addr;
u_int32_t *freep;
int bit_address, free_page, free_bit;
u_int16_t ndx;
addr = obufp->addr;
#ifdef DEBUG1
(void)fprintf(stderr, "Freeing %d\n", addr);
#endif
ndx = (((u_int16_t)addr) >> SPLITSHIFT);
bit_address =
(ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;
if (bit_address < hashp->LAST_FREED)
hashp->LAST_FREED = bit_address;
free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));
free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);
if (!(freep = hashp->mapp[free_page]))
freep = fetch_bitmap(hashp, free_page);
#ifdef DEBUG
/*
* This had better never happen. It means we tried to read a bitmap
* that has already had overflow pages allocated off it, and we
* failed to read it from the file.
*/
if (!freep)
assert(0);
#endif
CLRBIT(freep, free_bit);
#ifdef DEBUG2
(void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",
obufp->addr, free_bit, free_page);
#endif
__reclaim_buf(hashp, obufp);
}
/*
* Returns:
* 0 success
* -1 failure
*/
static int
open_temp(hashp)
HTAB *hashp;
{
sigset_t set, oset;
static char namestr[] = "_hashXXXXXX";
/* Block signals; make sure file goes away at process exit. */
(void)sigfillset(&set);
(void)sigprocmask(SIG_BLOCK, &set, &oset);
if ((hashp->fp = mkstemp(namestr)) != -1) {
(void)unlink(namestr);
(void)fcntl(hashp->fp, F_SETFD, 1);
}
(void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);
return (hashp->fp != -1 ? 0 : -1);
}
/*
* We have to know that the key will fit, but the last entry on the page is
* an overflow pair, so we need to shift things.
*/
static void
squeeze_key(sp, key, val)
u_int16_t *sp;
const DBT *key, *val;
{
register char *p;
u_int16_t free_space, n, off, pageno;
p = (char *)sp;
n = sp[0];
free_space = FREESPACE(sp);
off = OFFSET(sp);
pageno = sp[n - 1];
off -= key->size;
sp[n - 1] = off;
memmove(p + off, key->data, key->size);
off -= val->size;
sp[n] = off;
memmove(p + off, val->data, val->size);
sp[0] = n + 2;
sp[n + 1] = pageno;
sp[n + 2] = OVFLPAGE;
FREESPACE(sp) = free_space - PAIRSIZE(key, val);
OFFSET(sp) = off;
}
static u_int32_t *
fetch_bitmap(hashp, ndx)
HTAB *hashp;
int ndx;
{
if (ndx >= hashp->nmaps)
return (NULL);
if ((hashp->mapp[ndx] = (u_int32_t *)malloc(hashp->BSIZE)) == NULL)
return (NULL);
if (__get_page(hashp,
(char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {
free(hashp->mapp[ndx]);
return (NULL);
}
return (hashp->mapp[ndx]);
}
#ifdef DEBUG4
int
print_chain(addr)
int addr;
{
BUFHEAD *bufp;
short *bp, oaddr;
(void)fprintf(stderr, "%d ", addr);
bufp = __get_buf(hashp, addr, NULL, 0);
bp = (short *)bufp->page;
while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||
((bp[0] > 2) && bp[2] < REAL_KEY))) {
oaddr = bp[bp[0] - 1];
(void)fprintf(stderr, "%d ", (int)oaddr);
bufp = __get_buf(hashp, (int)oaddr, bufp, 0);
bp = (short *)bufp->page;
}
(void)fprintf(stderr, "\n");
}
#endif
Reference in New Issue View Git Blame Copy Permalink