942 lines
23 KiB
C
942 lines
23 KiB
C
/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Margo Seltzer.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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/* from: static char sccsid[] = "@(#)hash_page.c 8.2 (Berkeley) 9/6/93"; */
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static char *rcsid = "$Id: hash_page.c,v 1.5 1993/09/17 01:49:27 cgd Exp $";
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#endif /* LIBC_SCCS and not lint */
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/*
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* PACKAGE: hashing
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*
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* DESCRIPTION:
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* Page manipulation for hashing package.
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*
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* ROUTINES:
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*
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* External
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* __get_page
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* __add_ovflpage
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* Internal
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* overflow_page
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* open_temp
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#ifdef DEBUG
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#include <assert.h>
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#endif
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#include <db.h>
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#include "hash.h"
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#include "page.h"
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#include "extern.h"
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static u_long *fetch_bitmap __P((HTAB *, int));
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static u_long first_free __P((u_long));
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static int open_temp __P((HTAB *));
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static u_short overflow_page __P((HTAB *));
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static void putpair __P((char *, const DBT *, const DBT *));
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static void squeeze_key __P((u_short *, const DBT *, const DBT *));
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static int ugly_split
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__P((HTAB *, u_int, BUFHEAD *, BUFHEAD *, int, int));
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#define PAGE_INIT(P) { \
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((u_short *)(P))[0] = 0; \
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((u_short *)(P))[1] = hashp->BSIZE - 3 * sizeof(u_short); \
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((u_short *)(P))[2] = hashp->BSIZE; \
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}
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/*
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* This is called AFTER we have verified that there is room on the page for
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* the pair (PAIRFITS has returned true) so we go right ahead and start moving
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* stuff on.
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*/
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static void
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putpair(p, key, val)
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char *p;
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const DBT *key, *val;
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{
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register u_short *bp, n, off;
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bp = (u_short *)p;
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/* Enter the key first. */
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n = bp[0];
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off = OFFSET(bp) - key->size;
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memmove(p + off, key->data, key->size);
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bp[++n] = off;
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/* Now the data. */
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off -= val->size;
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memmove(p + off, val->data, val->size);
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bp[++n] = off;
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/* Adjust page info. */
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bp[0] = n;
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bp[n + 1] = off - ((n + 3) * sizeof(u_short));
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bp[n + 2] = off;
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}
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/*
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* Returns:
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* 0 OK
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* -1 error
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*/
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extern int
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__delpair(hashp, bufp, ndx)
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HTAB *hashp;
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BUFHEAD *bufp;
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register int ndx;
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{
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register u_short *bp, newoff;
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register int n;
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u_short pairlen;
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bp = (u_short *)bufp->page;
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n = bp[0];
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if (bp[ndx + 1] < REAL_KEY)
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return (__big_delete(hashp, bufp));
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if (ndx != 1)
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newoff = bp[ndx - 1];
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else
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newoff = hashp->BSIZE;
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pairlen = newoff - bp[ndx + 1];
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if (ndx != (n - 1)) {
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/* Hard Case -- need to shuffle keys */
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register int i;
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register char *src = bufp->page + (int)OFFSET(bp);
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register char *dst = src + (int)pairlen;
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memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
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/* Now adjust the pointers */
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for (i = ndx + 2; i <= n; i += 2) {
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if (bp[i + 1] == OVFLPAGE) {
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bp[i - 2] = bp[i];
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bp[i - 1] = bp[i + 1];
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} else {
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bp[i - 2] = bp[i] + pairlen;
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bp[i - 1] = bp[i + 1] + pairlen;
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}
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}
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}
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/* Finally adjust the page data */
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bp[n] = OFFSET(bp) + pairlen;
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bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_short);
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bp[0] = n - 2;
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hashp->NKEYS--;
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bufp->flags |= BUF_MOD;
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return (0);
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}
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/*
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* Returns:
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* 0 ==> OK
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* -1 ==> Error
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*/
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extern int
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__split_page(hashp, obucket, nbucket)
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HTAB *hashp;
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u_int obucket, nbucket;
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{
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register BUFHEAD *new_bufp, *old_bufp;
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register u_short *ino;
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register char *np;
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DBT key, val;
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int n, ndx, retval;
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u_short copyto, diff, off, moved;
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char *op;
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copyto = (u_short)hashp->BSIZE;
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off = (u_short)hashp->BSIZE;
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old_bufp = __get_buf(hashp, obucket, NULL, 0);
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if (old_bufp == NULL)
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return (-1);
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new_bufp = __get_buf(hashp, nbucket, NULL, 0);
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if (new_bufp == NULL)
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return (-1);
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old_bufp->flags |= (BUF_MOD | BUF_PIN);
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new_bufp->flags |= (BUF_MOD | BUF_PIN);
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ino = (u_short *)(op = old_bufp->page);
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np = new_bufp->page;
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moved = 0;
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for (n = 1, ndx = 1; n < ino[0]; n += 2) {
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if (ino[n + 1] < REAL_KEY) {
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retval = ugly_split(hashp, obucket, old_bufp, new_bufp,
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(int)copyto, (int)moved);
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old_bufp->flags &= ~BUF_PIN;
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new_bufp->flags &= ~BUF_PIN;
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return (retval);
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}
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key.data = (u_char *)op + ino[n];
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key.size = off - ino[n];
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if (__call_hash(hashp, key.data, key.size) == obucket) {
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/* Don't switch page */
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diff = copyto - off;
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if (diff) {
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copyto = ino[n + 1] + diff;
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memmove(op + copyto, op + ino[n + 1],
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off - ino[n + 1]);
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ino[ndx] = copyto + ino[n] - ino[n + 1];
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ino[ndx + 1] = copyto;
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} else
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copyto = ino[n + 1];
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ndx += 2;
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} else {
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/* Switch page */
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val.data = (u_char *)op + ino[n + 1];
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val.size = ino[n] - ino[n + 1];
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putpair(np, &key, &val);
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moved += 2;
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}
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off = ino[n + 1];
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}
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/* Now clean up the page */
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ino[0] -= moved;
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FREESPACE(ino) = copyto - sizeof(u_short) * (ino[0] + 3);
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OFFSET(ino) = copyto;
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#ifdef DEBUG3
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(void)fprintf(stderr, "split %d/%d\n",
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((u_short *)np)[0] / 2,
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((u_short *)op)[0] / 2);
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#endif
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/* unpin both pages */
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old_bufp->flags &= ~BUF_PIN;
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new_bufp->flags &= ~BUF_PIN;
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return (0);
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}
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/*
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* Called when we encounter an overflow or big key/data page during split
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* handling. This is special cased since we have to begin checking whether
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* the key/data pairs fit on their respective pages and because we may need
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* overflow pages for both the old and new pages.
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*
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* The first page might be a page with regular key/data pairs in which case
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* we have a regular overflow condition and just need to go on to the next
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* page or it might be a big key/data pair in which case we need to fix the
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* big key/data pair.
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*
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* Returns:
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* 0 ==> success
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* -1 ==> failure
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*/
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static int
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ugly_split(hashp, obucket, old_bufp, new_bufp, copyto, moved)
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HTAB *hashp;
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u_int obucket; /* Same as __split_page. */
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BUFHEAD *old_bufp, *new_bufp;
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int copyto; /* First byte on page which contains key/data values. */
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int moved; /* Number of pairs moved to new page. */
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{
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register BUFHEAD *bufp; /* Buffer header for ino */
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register u_short *ino; /* Page keys come off of */
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register u_short *np; /* New page */
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register u_short *op; /* Page keys go on to if they aren't moving */
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BUFHEAD *last_bfp; /* Last buf header OVFL needing to be freed */
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DBT key, val;
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SPLIT_RETURN ret;
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u_short n, off, ov_addr, scopyto;
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char *cino; /* Character value of ino */
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bufp = old_bufp;
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ino = (u_short *)old_bufp->page;
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np = (u_short *)new_bufp->page;
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op = (u_short *)old_bufp->page;
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last_bfp = NULL;
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scopyto = (u_short)copyto; /* ANSI */
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n = ino[0] - 1;
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while (n < ino[0]) {
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if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {
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if (__big_split(hashp, old_bufp,
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new_bufp, bufp, bufp->addr, obucket, &ret))
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return (-1);
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old_bufp = ret.oldp;
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if (!old_bufp)
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return (-1);
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op = (u_short *)old_bufp->page;
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new_bufp = ret.newp;
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if (!new_bufp)
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return (-1);
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np = (u_short *)new_bufp->page;
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bufp = ret.nextp;
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if (!bufp)
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return (0);
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cino = (char *)bufp->page;
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ino = (u_short *)cino;
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last_bfp = ret.nextp;
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} else if (ino[n + 1] == OVFLPAGE) {
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ov_addr = ino[n];
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/*
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* Fix up the old page -- the extra 2 are the fields
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* which contained the overflow information.
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*/
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ino[0] -= (moved + 2);
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FREESPACE(ino) =
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scopyto - sizeof(u_short) * (ino[0] + 3);
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OFFSET(ino) = scopyto;
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bufp = __get_buf(hashp, ov_addr, bufp, 0);
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if (!bufp)
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return (-1);
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ino = (u_short *)bufp->page;
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n = 1;
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scopyto = hashp->BSIZE;
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moved = 0;
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if (last_bfp)
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__free_ovflpage(hashp, last_bfp);
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last_bfp = bufp;
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}
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/* Move regular sized pairs of there are any */
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off = hashp->BSIZE;
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for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {
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cino = (char *)ino;
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key.data = (u_char *)cino + ino[n];
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key.size = off - ino[n];
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val.data = (u_char *)cino + ino[n + 1];
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val.size = ino[n] - ino[n + 1];
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off = ino[n + 1];
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if (__call_hash(hashp, key.data, key.size) == obucket) {
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/* Keep on old page */
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if (PAIRFITS(op, (&key), (&val)))
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putpair((char *)op, &key, &val);
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else {
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old_bufp =
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__add_ovflpage(hashp, old_bufp);
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if (!old_bufp)
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return (-1);
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op = (u_short *)old_bufp->page;
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putpair((char *)op, &key, &val);
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}
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old_bufp->flags |= BUF_MOD;
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} else {
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/* Move to new page */
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if (PAIRFITS(np, (&key), (&val)))
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putpair((char *)np, &key, &val);
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else {
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new_bufp =
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__add_ovflpage(hashp, new_bufp);
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if (!new_bufp)
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return (-1);
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np = (u_short *)new_bufp->page;
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putpair((char *)np, &key, &val);
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}
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new_bufp->flags |= BUF_MOD;
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}
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}
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}
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if (last_bfp)
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__free_ovflpage(hashp, last_bfp);
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return (0);
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}
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/*
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* Add the given pair to the page
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*
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* Returns:
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* 0 ==> OK
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* 1 ==> failure
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*/
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extern int
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__addel(hashp, bufp, key, val)
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HTAB *hashp;
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BUFHEAD *bufp;
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const DBT *key, *val;
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{
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register u_short *bp, *sop;
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int do_expand;
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bp = (u_short *)bufp->page;
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do_expand = 0;
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while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))
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/* Exception case */
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if (bp[2] == FULL_KEY_DATA && bp[0] == 2)
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/* This is the last page of a big key/data pair
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and we need to add another page */
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break;
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else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {
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bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
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if (!bufp)
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return (-1);
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bp = (u_short *)bufp->page;
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} else
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/* Try to squeeze key on this page */
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if (FREESPACE(bp) > PAIRSIZE(key, val)) {
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squeeze_key(bp, key, val);
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return (0);
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} else {
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bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);
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if (!bufp)
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return (-1);
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bp = (u_short *)bufp->page;
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}
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if (PAIRFITS(bp, key, val))
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putpair(bufp->page, key, val);
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else {
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do_expand = 1;
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bufp = __add_ovflpage(hashp, bufp);
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if (!bufp)
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return (-1);
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sop = (u_short *)bufp->page;
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if (PAIRFITS(sop, key, val))
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putpair((char *)sop, key, val);
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else
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if (__big_insert(hashp, bufp, key, val))
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return (-1);
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}
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bufp->flags |= BUF_MOD;
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/*
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* If the average number of keys per bucket exceeds the fill factor,
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* expand the table.
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*/
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hashp->NKEYS++;
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if (do_expand ||
|
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(hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))
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return (__expand_table(hashp));
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return (0);
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}
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/*
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*
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* Returns:
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* pointer on success
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* NULL on error
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*/
|
|
extern BUFHEAD *
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__add_ovflpage(hashp, bufp)
|
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HTAB *hashp;
|
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BUFHEAD *bufp;
|
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{
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register u_short *sp;
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u_short ndx, ovfl_num;
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#ifdef DEBUG1
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int tmp1, tmp2;
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#endif
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sp = (u_short *)bufp->page;
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/* Check if we are dynamically determining the fill factor */
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if (hashp->FFACTOR == DEF_FFACTOR) {
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hashp->FFACTOR = sp[0] >> 1;
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if (hashp->FFACTOR < MIN_FFACTOR)
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hashp->FFACTOR = MIN_FFACTOR;
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}
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bufp->flags |= BUF_MOD;
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ovfl_num = overflow_page(hashp);
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#ifdef DEBUG1
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tmp1 = bufp->addr;
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tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;
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#endif
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if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))
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return (NULL);
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bufp->ovfl->flags |= BUF_MOD;
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#ifdef DEBUG1
|
|
(void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",
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tmp1, tmp2, bufp->ovfl->addr);
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#endif
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ndx = sp[0];
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/*
|
|
* 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_int bucket;
|
|
int is_bucket, is_disk, is_bitmap;
|
|
{
|
|
register int fd, page, size;
|
|
int rsize;
|
|
u_short *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_short *)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++)
|
|
BLSWAP(((long *)p)[i]);
|
|
} else {
|
|
BSSWAP(bp[0]);
|
|
max = bp[0] + 2;
|
|
for (i = 1; i <= max; i++)
|
|
BSSWAP(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_int 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++)
|
|
BLSWAP(((long *)p)[i]);
|
|
} else {
|
|
max = ((u_short *)p)[0] + 2;
|
|
for (i = 0; i <= max; i++)
|
|
BSSWAP(((u_short *)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
|
|
__init_bitmap(hashp, pnum, nbits, ndx)
|
|
HTAB *hashp;
|
|
int pnum, nbits, ndx;
|
|
{
|
|
u_long *ip;
|
|
int clearbytes, clearints;
|
|
|
|
if (!(ip = malloc(hashp->BSIZE)))
|
|
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_short)pnum;
|
|
hashp->mapp[ndx] = ip;
|
|
return (0);
|
|
}
|
|
|
|
static u_long
|
|
first_free(map)
|
|
u_long map;
|
|
{
|
|
register u_long i, mask;
|
|
|
|
mask = 0x1;
|
|
for (i = 0; i < BITS_PER_MAP; i++) {
|
|
if (!(mask & map))
|
|
return (i);
|
|
mask = mask << 1;
|
|
}
|
|
return (i);
|
|
}
|
|
|
|
static u_short
|
|
overflow_page(hashp)
|
|
HTAB *hashp;
|
|
{
|
|
register u_long *freep;
|
|
register int max_free, offset, splitnum;
|
|
u_short 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_long *)hashp->mapp[i]) &&
|
|
!(freep = fetch_bitmap(hashp, i)))
|
|
return (NULL);
|
|
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 (NULL);
|
|
}
|
|
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 (NULL);
|
|
}
|
|
/*
|
|
* 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 (__init_bitmap(hashp, (int)OADDR_OF(splitnum, offset),
|
|
1, free_page))
|
|
return (NULL);
|
|
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 (NULL);
|
|
}
|
|
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 (NULL); /* 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_short addr;
|
|
u_long *freep;
|
|
int bit_address, free_page, free_bit;
|
|
u_short ndx;
|
|
|
|
addr = obufp->addr;
|
|
#ifdef DEBUG1
|
|
(void)fprintf(stderr, "Freeing %d\n", addr);
|
|
#endif
|
|
ndx = (((u_short)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_short *sp;
|
|
const DBT *key, *val;
|
|
{
|
|
register char *p;
|
|
u_short 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_long *
|
|
fetch_bitmap(hashp, ndx)
|
|
HTAB *hashp;
|
|
int ndx;
|
|
{
|
|
if (ndx >= hashp->nmaps ||
|
|
!(hashp->mapp[ndx] = malloc(hashp->BSIZE)) ||
|
|
__get_page(hashp, (char *)hashp->mapp[ndx],
|
|
hashp->BITMAPS[ndx], 0, 1, 1))
|
|
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
|