hash_page.c

asterisk 一个模拟IPPBX的源代码

/*-
 * 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 "../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