freebsd-skq/lib/libc/db/hash/hash_page.c
Daniel Eischen d201fe46e3 Remove _THREAD_SAFE and make libc thread-safe by default by
adding (weak definitions to) stubs for some of the pthread
functions.  If the threads library is linked in, the real
pthread functions will pulled in.

Use the following convention for system calls wrapped by the
threads library:
	__sys_foo - actual system call
	_foo - weak definition to __sys_foo
	foo - weak definition to __sys_foo

Change all libc uses of system calls wrapped by the threads
library from foo to _foo.  In order to define the prototypes
for _foo(), we introduce namespace.h and un-namespace.h
(suggested by bde).  All files that need to reference these
system calls, should include namespace.h before any standard
includes, then include un-namespace.h after the standard
includes and before any local includes.  <db.h> is an exception
and shouldn't be included in between namespace.h and
un-namespace.h  namespace.h will define foo to _foo, and
un-namespace.h will undefine foo.

Try to eliminate some of the recursive calls to MT-safe
functions in libc/stdio in preparation for adding a mutex
to FILE.  We have recursive mutexes, but would like to avoid
using them if possible.

Remove uneeded includes of <errno.h> from a few files.

Add $FreeBSD$ to a few files in order to pass commitprep.

Approved by:	-arch
2001-01-24 13:01:12 +00:00

949 lines
23 KiB
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.
* 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.
*
* $FreeBSD$
*/
#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 "namespace.h"
#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 "un-namespace.h"
#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