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NetBSD/lib/libc/db/hash/bigkey.c

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/*-
* Copyright (c) 1990 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[] = "@(#)bigkey.c 5.5 (Berkeley) 3/12/91";
#endif /* LIBC_SCCS and not lint */
/******************************************************************************
PACKAGE: hash
DESCRIPTION:
Big key/data handling for the hashing package.
ROUTINES:
External
__big_keydata
__big_split
__big_insert
__big_return
__big_delete
__find_last_page
Internal
collect_key
collect_data
******************************************************************************/
/* Includes */
#include <sys/param.h>
#include <assert.h>
#include <errno.h>
#include <db.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "hash.h"
#include "page.h"
/* Externals */
/* buf.c */
extern BUFHEAD *__get_buf();
/* dynahash.c */
extern u_int call_hash();
/* page.c */
extern BUFHEAD *__add_ovflpage();
/* My externals */
extern int __big_keydata();
extern int __big_split();
extern int __big_insert();
extern int __big_return();
extern int __big_delete();
extern u_short __find_last_page();
extern int __find_bigpair();
/* My internals */
static int collect_key();
static int collect_data();
#ifdef HASH_STATISTICS
extern long hash_accesses, hash_collisions, hash_expansions, hash_overflows;
#endif
/*
Big_insert
You need to do an insert and the key/data pair is too big
0 ==> OK
-1 ==> ERROR
*/
extern int
__big_insert ( bufp, key, val )
BUFHEAD *bufp;
DBT *key, *val;
{
char *cp = bufp->page; /* Character pointer of p */
register u_short *p = (u_short *)cp;
char *key_data, *val_data;
int key_size, val_size;
int n;
u_short space, move_bytes, off;
key_data = (char *)key->data;
key_size = key->size;
val_data = (char *)val->data;
val_size = val->size;
/* First move the Key */
for ( space = FREESPACE(p) - BIGOVERHEAD;
key_size;
space = FREESPACE(p) - BIGOVERHEAD ) {
move_bytes = MIN(space, key_size);
off = OFFSET(p) - move_bytes;
bcopy (key_data, cp+off, move_bytes );
key_size -= move_bytes;
key_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
FREESPACE(p) = off - PAGE_META(n);
OFFSET(p) = off;
p[n] = PARTIAL_KEY;
bufp = __add_ovflpage(bufp);
if ( !bufp ) {
return(-1);
}
n = p[0];
if ( !key_size ) {
if ( FREESPACE(p) ) {
move_bytes = MIN (FREESPACE(p), val_size);
off = OFFSET(p) - move_bytes;
p[n] = off;
bcopy ( val_data, cp + off, move_bytes );
val_data += move_bytes;
val_size -= move_bytes;
p[n-2] = FULL_KEY_DATA;
FREESPACE(p) = FREESPACE(p) - move_bytes;
OFFSET(p) = off;
}
else p[n-2] = FULL_KEY;
}
p = (u_short *)bufp->page;
cp = bufp->page;
bufp->flags |= BUF_MOD;
}
/* Now move the data */
for ( space = FREESPACE(p) - BIGOVERHEAD;
val_size;
space = FREESPACE(p) - BIGOVERHEAD ) {
move_bytes = MIN(space, val_size);
/*
Here's the hack to make sure that if the data ends
on the same page as the key ends, FREESPACE is
at least one
*/
if ( space == val_size && val_size == val->size ) {
move_bytes--;
}
off = OFFSET(p) - move_bytes;
bcopy (val_data, cp+off, move_bytes );
val_size -= move_bytes;
val_data += move_bytes;
n = p[0];
p[++n] = off;
p[0] = ++n;
FREESPACE(p) = off - PAGE_META(n);
OFFSET(p) = off;
if ( val_size ) {
p[n] = FULL_KEY;
bufp = __add_ovflpage (bufp);
if ( !bufp ) {
return(-1);
}
cp = bufp->page;
p = (u_short *)cp;
} else {
p[n] = FULL_KEY_DATA;
}
bufp->flags |= BUF_MOD;
}
return(0);
}
/*
Called when bufp's page contains a partial key (index should be 1)
All pages in the big key/data pair except bufp are freed. We cannot
free bufp because the page pointing to it is lost and we can't
get rid of its pointer.
Returns 0 => OK
-1 => ERROR
*/
extern int
__big_delete (bufp, ndx)
BUFHEAD *bufp;
int ndx;
{
register BUFHEAD *rbufp = bufp;
register BUFHEAD *last_bfp = NULL;
char *cp;
u_short *bp = (u_short *)bufp->page;
u_short *xbp;
u_short pageno = 0;
u_short off, free_sp;
int key_done = 0;
int n;
while (!key_done || (bp[2] != FULL_KEY_DATA)) {
if ( bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA ) key_done = 1;
/*
If there is freespace left on a FULL_KEY_DATA page,
then the data is short and fits entirely on this
page, and this is the last page.
*/
if ( bp[2] == FULL_KEY_DATA && FREESPACE(bp) ) break;
pageno = bp[bp[0]-1];
rbufp->flags |= BUF_MOD;
rbufp = __get_buf ( pageno, rbufp, 0 );
if ( last_bfp ) __free_ovflpage(last_bfp);
last_bfp = rbufp;
if ( !rbufp ) return(-1); /* Error */
bp = (u_short *)rbufp->page;
}
/*
If we get here then rbufp points to the last page of
the big key/data pair. Bufp points to the first
one -- it should now be empty pointing to the next
page after this pair. Can't free it because we don't
have the page pointing to it.
*/
/* This is information from the last page of the pair */
n = bp[0];
pageno = bp[n-1];
/* Now, bp is the first page of the pair */
bp = (u_short *)bufp->page;
if ( n > 2 ) {
/* There is an overflow page */
bp[1] = pageno;
bp[2] = OVFLPAGE;
bufp->ovfl = rbufp->ovfl;
} else {
/* This is the last page */
bufp->ovfl = NULL;
}
n -= 2;
bp[0] = n;
FREESPACE(bp) = hashp->BSIZE - PAGE_META(n);
OFFSET(bp) = hashp->BSIZE - 1;
bufp->flags |= BUF_MOD;
if ( rbufp ) __free_ovflpage(rbufp);
if ( last_bfp != rbufp ) __free_ovflpage(last_bfp);
hashp->NKEYS--;
return(0);
}
/*
0 = key not found
-1 = get next overflow page
-2 means key not found and this is big key/data
-3 error
*/
extern int
__find_bigpair(bufp, ndx, key, size )
BUFHEAD *bufp;
int ndx;
char *key;
int size;
{
register u_short *bp = (u_short *)bufp->page;
register char *p = bufp->page;
int ksize = size;
char *kkey = key;
u_short bytes;
for ( bytes = hashp->BSIZE - bp[ndx];
bytes <= size && bp[ndx+1] == PARTIAL_KEY;
bytes = hashp->BSIZE - bp[ndx] ) {
if ( bcmp ( p+bp[ndx], kkey, bytes ))return(-2);
kkey += bytes;
ksize -= bytes;
bufp = __get_buf ( bp[ndx+2], bufp, 0 );
if ( !bufp ) {
return(-3);
}
p = bufp->page;
bp = (u_short *)p;
ndx = 1;
}
if ( (bytes != ksize) || bcmp ( p+bp[ndx], kkey, bytes )) {
#ifdef HASH_STATISTICS
hash_collisions++;
#endif
return(-2);
}
else return (ndx);
}
/*
Given the buffer pointer of the first overflow page of a big pair,
find the end of the big pair
This will set bpp to the buffer header of the last page of the big pair.
It will return the pageno of the overflow page following the last page of
the pair; 0 if there isn't any (i.e. big pair is the last key in the
bucket)
*/
extern u_short
__find_last_page ( bpp )
BUFHEAD **bpp;
{
int n;
u_short pageno;
BUFHEAD *bufp = *bpp;
u_short *bp = (u_short *)bufp->page;
while ( 1 ) {
n = bp[0];
/*
This is the last page if:
the tag is FULL_KEY_DATA and either
only 2 entries
OVFLPAGE marker is explicit
there is freespace on the page
*/
if ( bp[2] == FULL_KEY_DATA &&
((n == 2) || (bp[n] == OVFLPAGE) || (FREESPACE(bp)) ) ) break;
pageno = bp[n-1];
bufp = __get_buf ( pageno, bufp, 0 );
if ( !bufp ) return (0); /* Need to indicate an error! */
bp = (u_short *)bufp->page;
}
*bpp = bufp;
if ( bp[0] > 2 ) return ( bp[3] );
else return(0);
}
/*
Return the data for the key/data pair
that begins on this page at this index
(index should always be 1)
*/
extern int
__big_return ( bufp, ndx, val, set_current )
BUFHEAD *bufp;
int ndx;
DBT *val;
int set_current;
{
BUFHEAD *save_p;
u_short save_addr;
u_short *bp = (u_short *)bufp->page;
u_short off, len;
char *cp, *tp;
while ( bp[ndx+1] == PARTIAL_KEY ) {
bufp = __get_buf ( bp[bp[0]-1], bufp, 0 );
if ( !bufp ) return(-1);
bp = (u_short *)bufp->page;
ndx = 1;
}
if ( bp[ndx+1] == FULL_KEY ) {
bufp = __get_buf ( bp[bp[0]-1], bufp, 0 );
if ( !bufp ) return(-1);
bp = (u_short *)bufp->page;
save_p = bufp;
save_addr = save_p->addr;
off = bp[1];
len = 0;
} else if (!FREESPACE(bp)) {
/*
This is a hack. We can't distinguish between
FULL_KEY_DATA that contains complete data or
incomplete data, so we require that if the
data is complete, there is at least 1 byte
of free space left.
*/
off = bp[bp[0]];
len = bp[1] - off;
save_p = bufp;
save_addr = bufp->addr;
bufp = __get_buf ( bp[bp[0]-1], bufp, 0 );
if ( !bufp ) return(-1);
bp = (u_short *)bufp->page;
} else {
/* The data is all on one page */
tp = (char *)bp;
off = bp[bp[0]];
val->data = (u_char *)tp + off;
val->size = bp[1] - off;
if ( set_current ) {
if ( bp[0] == 2 ) { /* No more buckets in chain */
hashp->cpage = NULL;
hashp->cbucket++;
hashp->cndx=1;
} else {
hashp->cpage = __get_buf ( bp[bp[0]-1], bufp, 0 );
if ( !hashp->cpage )return(-1);
hashp->cndx = 1;
if ( !((u_short *)hashp->cpage->page)[0] ) {
hashp->cbucket++;
hashp->cpage = NULL;
}
}
}
return(0);
}
val->size = collect_data ( bufp, len, set_current );
if ( val->size == -1 ) {
return(-1);
}
if ( save_p->addr != save_addr ) {
/* We are pretty short on buffers */
errno = EINVAL; /* OUT OF BUFFERS */
return(-1);
}
bcopy ( (save_p->page)+off, hashp->tmp_buf, len );
val->data = (u_char *)hashp->tmp_buf;
return(0);
}
/*
Count how big the total datasize is by
recursing through the pages. Then allocate
a buffer and copy the data as you recurse up.
*/
static int
collect_data ( bufp, len, set )
BUFHEAD *bufp;
int len;
int set;
{
register char *p = bufp->page;
register u_short *bp = (u_short *)p;
u_short save_addr;
int mylen, totlen;
BUFHEAD *xbp;
mylen = hashp->BSIZE - bp[1];
save_addr = bufp->addr;
if ( bp[2] == FULL_KEY_DATA ) { /* End of Data */
totlen = len + mylen;
if ( hashp->tmp_buf ) free (hashp->tmp_buf);
hashp->tmp_buf = (char *)malloc ( totlen );
if ( !hashp->tmp_buf ) {
return(-1);
}
if ( set ) {
hashp->cndx = 1;
if ( bp[0] == 2 ) { /* No more buckets in chain */
hashp->cpage = NULL;
hashp->cbucket++;
} else {
hashp->cpage = __get_buf ( bp[bp[0]-1], bufp, 0 );
if (!hashp->cpage) {
return(-1);
} else if ( !((u_short *)hashp->cpage->page)[0] ) {
hashp->cbucket++;
hashp->cpage = NULL;
}
}
}
} else {
xbp = __get_buf ( bp[bp[0]-1], bufp, 0 );
if ( !xbp || ((totlen = collect_data ( xbp, len + mylen, set )) < 1) ) {
return(-1);
}
}
if ( bufp->addr != save_addr ) {
errno = EINVAL; /* Out of buffers */
return(-1);
}
bcopy ( (bufp->page) + bp[1], &hashp->tmp_buf[len], mylen );
return ( totlen );
}
/*
Fill in the key and data
for this big pair
*/
extern int
__big_keydata ( bufp, ndx, key, val, set )
BUFHEAD *bufp;
int ndx;
DBT *key, *val;
int set;
{
key->size = collect_key ( bufp, 0, val, set );
if ( key->size == -1 ) {
return (-1);
}
key->data = (u_char *)hashp->tmp_key;
return(0);
}
/*
Count how big the total key size is by
recursing through the pages. Then collect
the data, allocate a buffer and copy the key as
you recurse up.
*/
static int
collect_key ( bufp, len, val, set )
BUFHEAD *bufp;
int len;
DBT *val;
int set;
{
char *p = bufp->page;
u_short *bp = (u_short *)p;
u_short save_addr;
int mylen, totlen;
BUFHEAD *xbp;
mylen = hashp->BSIZE - bp[1];
save_addr = bufp->addr;
totlen = len + mylen;
if ( bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA ) {/* End of Key */
if ( hashp->tmp_key ) free (hashp->tmp_key);
hashp->tmp_key = (char *)malloc ( totlen );
if ( !hashp->tmp_key ) {
return(-1);
}
__big_return ( bufp, 1, val, set );
} else {
xbp = __get_buf (bp[bp[0]-1], bufp, 0);
if ( !xbp || ((totlen = collect_key (xbp, totlen, val, set)) < 1 ) ) {
return(-1);
}
}
if ( bufp->addr != save_addr ) {
errno = EINVAL; /* MIS -- OUT OF BUFFERS */
return (-1);
}
bcopy ( (bufp->page) + bp[1], &hashp->tmp_key[len], mylen );
return ( totlen );
}
/*
return 0 => OK
-1 => error
*/
extern int
__big_split ( op, np, big_keyp, addr, obucket, ret )
BUFHEAD *op; /* Pointer to where to put keys that go in old bucket */
BUFHEAD *np; /* Pointer to new bucket page */
BUFHEAD *big_keyp; /* Pointer to first page containing the big key/data */
u_short addr; /* Address of big_keyp */
u_int obucket; /* Old Bucket */
SPLIT_RETURN *ret;
{
register u_short *prev_pagep;
register BUFHEAD *tmpp;
register u_short *tp;
BUFHEAD *bp = big_keyp;
u_short off, free_space;
u_short n;
DBT key, val;
u_int change;
/* Now figure out where the big key/data goes */
if (__big_keydata ( big_keyp, 1, &key, &val, 0 )) {
return(-1);
}
change = (__call_hash ( key.data, key.size ) != obucket );
if ( ret->next_addr = __find_last_page ( &big_keyp ) ) {
if (!(ret->nextp = __get_buf ( ret->next_addr, big_keyp, 0 ))) {
return(-1);;
}
} else {
ret->nextp = NULL;
}
/* Now make one of np/op point to the big key/data pair */
assert(np->ovfl == NULL);
if ( change ) tmpp = np;
else tmpp = op;
tmpp->flags |= BUF_MOD;
#ifdef DEBUG1
fprintf ( stderr, "BIG_SPLIT: %d->ovfl was %d is now %d\n", tmpp->addr,
(tmpp->ovfl?tmpp->ovfl->addr:0),
(bp?bp->addr:0) );
#endif
tmpp->ovfl = bp; /* one of op/np point to big_keyp */
tp = (u_short *)tmpp->page;
assert ( FREESPACE(tp) >= OVFLSIZE);
n = tp[0];
off = OFFSET(tp);
free_space = FREESPACE(tp);
tp[++n] = addr;
tp[++n] = OVFLPAGE;
tp[0] = n;
OFFSET(tp) = off;
FREESPACE(tp) = free_space - OVFLSIZE;
/*
Finally, set the new and old return values.
BIG_KEYP contains a pointer to the last page of the big key_data pair.
Make sure that big_keyp has no following page (2 elements) or create
an empty following page.
*/
ret->newp = np;
ret->oldp = op;
tp = (u_short *)big_keyp->page;
big_keyp->flags |= BUF_MOD;
if ( tp[0] > 2 ) {
/*
There may be either one or two offsets on this page
If there is one, then the overflow page is linked on
normally and tp[4] is OVFLPAGE. If there are two, tp[4]
contains the second offset and needs to get stuffed in
after the next overflow page is added
*/
n = tp[4];
free_space = FREESPACE(tp);
off = OFFSET(tp);
tp[0] -= 2;
FREESPACE(tp) = free_space + OVFLSIZE;
OFFSET(tp) = off;
tmpp = __add_ovflpage ( big_keyp );
if ( !tmpp ) {
return(-1);
}
tp[4] = n;
} else {
tmpp = big_keyp;
}
if ( change ) ret->newp = tmpp;
else ret->oldp = tmpp;
return(0);
}
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