288 lines
8.3 KiB
C
288 lines
8.3 KiB
C
/*
|
|
* CDE - Common Desktop Environment
|
|
*
|
|
* Copyright (c) 1993-2012, The Open Group. All rights reserved.
|
|
*
|
|
* These libraries and programs are free software; you can
|
|
* redistribute them and/or modify them under the terms of the GNU
|
|
* Lesser General Public License as published by the Free Software
|
|
* Foundation; either version 2 of the License, or (at your option)
|
|
* any later version.
|
|
*
|
|
* These libraries and programs are distributed in the hope that
|
|
* they will be useful, but WITHOUT ANY WARRANTY; without even the
|
|
* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
* PURPOSE. See the GNU Lesser General Public License for more
|
|
* details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with these libraries and programs; if not, write
|
|
* to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
|
|
* Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
/*%% (c) Copyright 1993, 1994 Hewlett-Packard Company */
|
|
/*%% (c) Copyright 1993, 1994 International Business Machines Corp. */
|
|
/*%% (c) Copyright 1993, 1994 Sun Microsystems, Inc. */
|
|
/*%% (c) Copyright 1993, 1994 Novell, Inc. */
|
|
/*%% $XConsortium: isbtree2.c /main/3 1995/10/23 11:36:02 rswiston $ */
|
|
|
|
/*
|
|
* Copyright (c) 1988 by Sun Microsystems, Inc.
|
|
*/
|
|
|
|
/*
|
|
* isbtree2.c
|
|
*
|
|
* Description:
|
|
* B-tree operations: INSERT
|
|
*
|
|
*/
|
|
|
|
#include "isam_impl.h"
|
|
|
|
void leftkey_up(Btree *, int);
|
|
|
|
static void insert_key(Btree *, char *, int, char *, Blkno);
|
|
static void splitblock(Btree *, char *, char *, int);
|
|
|
|
|
|
/* _isbtree_insert() - Insert entry into B-tree ----------------------------*/
|
|
|
|
void
|
|
_isbtree_insert(Btree *btree, char *key)
|
|
{
|
|
Keydesc2 *pkeydesc2 = btree->keydesc2;
|
|
int keylength = pkeydesc2->k2_len;
|
|
int nkeys; /* Number of keys in the page */
|
|
int capac = 0;
|
|
char keybuf[MAXKEYSIZE];
|
|
int i;
|
|
Blkno blkno;
|
|
char *pkp = NULL, *pkp2, *pkp3;
|
|
Bufhdr *kp2bhdr, *kp3bhdr;
|
|
Blkno blkno2, blkno3;
|
|
int level;
|
|
int halfcapac;
|
|
|
|
|
|
/*
|
|
* Set key comparison function.
|
|
*/
|
|
_iskeycmp_set(pkeydesc2, pkeydesc2->k2_nparts+1); /* +1 for recno field */
|
|
|
|
/*
|
|
* Initialize data structure before main loop.
|
|
*/
|
|
blkno = NULL_BLKNO;
|
|
memcpy( keybuf,key, keylength);
|
|
|
|
/*
|
|
* Main loop:
|
|
* Starting from the leaf, insert key after current search position.
|
|
* If necessary make block split and propage changes to upper levels.
|
|
* Root split is handled differently because we don't want to change
|
|
* root block number.
|
|
*/
|
|
|
|
for (i = btree->depth - 1; i >= 0; i--) {
|
|
|
|
/* We have to fix the block for update. */
|
|
btree->bufhdr[i] = _isdisk_refix(btree->bufhdr[i], ISFIXWRITE);
|
|
pkp = btree->bufhdr[i]->isb_buffer;
|
|
|
|
level = ldshort(pkp + BT_LEVEL_OFF);
|
|
capac = ldshort(pkp + BT_CAPAC_OFF); /* Block capacity */
|
|
nkeys = ldshort(pkp + BT_NKEYS_OFF); /* Number of keys in block */
|
|
|
|
assert(level + i + 1 == btree->depth);
|
|
assert(nkeys <= capac);
|
|
|
|
if (nkeys == capac) {
|
|
/*
|
|
* This block must be split.
|
|
* Allocate new block, move half of the entries into the new
|
|
* block, and insert the key into the appropriate
|
|
* block. If this block is not root, the loop will iterate
|
|
* to update upper levels.
|
|
*/
|
|
|
|
/* Get new page. */
|
|
kp2bhdr = _allockpage(btree->fcb, capac, level, &blkno2);
|
|
pkp2 = kp2bhdr->isb_buffer;
|
|
|
|
halfcapac = (nkeys+1) >> 1; /* Same as nkeys/2 + 1 */
|
|
|
|
splitblock(btree, pkp, pkp2, btree->curpos[i]);
|
|
|
|
if (btree->curpos[i] > halfcapac - 2) {
|
|
|
|
/* Insert entry into right block. */
|
|
insert_key(btree, pkp2, btree->curpos[i] - halfcapac, keybuf,
|
|
blkno);
|
|
}
|
|
else {
|
|
/* Insert entry into left block. */
|
|
insert_key(btree, pkp, btree->curpos[i], keybuf, blkno);
|
|
|
|
if (btree->curpos[i] == -1) /* Leftmost entry inserted - */
|
|
leftkey_up(btree, i); /* propagate to upper levels. */
|
|
}
|
|
|
|
/* Set variables for next loop iteration. */
|
|
memcpy( keybuf,pkp2 + BT_KEYS_OFF, keylength); /* Leftmost key */
|
|
blkno = blkno2;
|
|
|
|
/*
|
|
* Next loop iteration will insert entry pointing to
|
|
* new allocated page into next upper level.
|
|
*/
|
|
}
|
|
else {
|
|
/*
|
|
* Block split is not necessary. Simply insert key into
|
|
* the block. If the inserted key becomes the leftmost entry
|
|
* in the block, update upper levels.
|
|
*/
|
|
|
|
insert_key(btree, pkp, btree->curpos[i], keybuf, blkno);
|
|
|
|
if (btree->curpos[i] == -1 && i > 0)
|
|
leftkey_up(btree, i);
|
|
|
|
break; /* from main loop */
|
|
}
|
|
|
|
}
|
|
|
|
if (i < 0) {
|
|
|
|
/*
|
|
* Root was split.
|
|
* Allocate new page. However, to keep root block the same,
|
|
* the new page is used for the left son of root.
|
|
*
|
|
* pkp is the new root, pkp3 is the left son,
|
|
* and pkp3 is the right of the root.
|
|
*/
|
|
|
|
kp3bhdr = _allockpage(btree->fcb, capac, 1, &blkno3);
|
|
pkp3 = kp3bhdr->isb_buffer;
|
|
|
|
memcpy( pkp3,pkp, ISPAGESIZE);
|
|
|
|
stshort((short) getkeyspernode(keylength), pkp + BT_CAPAC_OFF);
|
|
stshort((short) 0, pkp + BT_NKEYS_OFF);
|
|
stshort((short)btree->depth, pkp + BT_LEVEL_OFF);
|
|
|
|
insert_key(btree, pkp, -1, pkp3 + BT_KEYS_OFF, blkno3);
|
|
insert_key(btree, pkp, 0 , keybuf, blkno);
|
|
}
|
|
}
|
|
|
|
/*--------- insert supporting local functions -------------------------------*/
|
|
|
|
/* leftkey_up() - Update upper levels with new leftmost entry -----------*/
|
|
void
|
|
leftkey_up(Btree *btree, int level)
|
|
{
|
|
int keylength = btree->keydesc2->k2_len;
|
|
char *pkp;
|
|
char *key;
|
|
|
|
pkp = btree->bufhdr[level]->isb_buffer;
|
|
key = pkp + BT_KEYS_OFF; /* Leftmost key */
|
|
|
|
while (--level >= 0) {
|
|
|
|
btree->bufhdr[level] = _isdisk_refix(btree->bufhdr[level], ISFIXWRITE);
|
|
pkp = btree->bufhdr[level]->isb_buffer;
|
|
|
|
memcpy( pkp + BT_KEYS_OFF + (btree->curpos[level] * keylength),key,
|
|
keylength);
|
|
|
|
if (btree->curpos[level] > 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* insert_key - Insert key into block ------------------------*/
|
|
static void
|
|
insert_key(Btree *btree, char *pkp, int pos, char *key, Blkno blkno)
|
|
{
|
|
int keylength = btree->keydesc2->k2_len;
|
|
int nkeys = ldshort(pkp + BT_NKEYS_OFF);
|
|
int capac = ldshort(pkp + BT_CAPAC_OFF);
|
|
int level = ldshort(pkp + BT_LEVEL_OFF);
|
|
|
|
assert(nkeys < capac);
|
|
|
|
/* Shift nkeys - pos - 1 entries to the right. */
|
|
/* memmove() handle overlaps correctly */
|
|
|
|
memmove(pkp + BT_KEYS_OFF + (pos + 2) * keylength,
|
|
pkp + BT_KEYS_OFF + (pos + 1) * keylength,
|
|
(nkeys - pos - 1) * keylength);
|
|
|
|
/* Copy new key entry into the block. */
|
|
memcpy( pkp + BT_KEYS_OFF + (pos + 1) * keylength,key, keylength);
|
|
|
|
/* For non-leaf nodes, insert block number into table of down pointers. */
|
|
if (level > 0) {
|
|
|
|
memcpy(pkp + ISPAGESIZE - (nkeys + 1) * BLKNOSIZE,
|
|
pkp + ISPAGESIZE - nkeys * BLKNOSIZE,
|
|
(nkeys - pos - 1) * BLKNOSIZE);
|
|
|
|
stblkno(blkno, pkp + ISPAGESIZE - (pos + 2) * BLKNOSIZE);
|
|
}
|
|
|
|
stshort((short) (nkeys + 1), pkp + BT_NKEYS_OFF);
|
|
}
|
|
|
|
/* splitblock() - Split block into two -----------------------------*/
|
|
static void
|
|
splitblock(Btree *btree, char *fullpage, char *newpage, int pos)
|
|
{
|
|
int keylength = btree->keydesc2->k2_len;
|
|
int nkeys, capac, level;
|
|
int halfcapac;
|
|
int newpage_nkeys;
|
|
int fullpage_nkeys;
|
|
|
|
nkeys = ldshort(fullpage + BT_NKEYS_OFF);
|
|
capac = ldshort(fullpage + BT_NKEYS_OFF);
|
|
level = ldshort(fullpage + BT_LEVEL_OFF);
|
|
|
|
assert(nkeys == capac);
|
|
|
|
halfcapac = (capac + 1) >> 1; /* same as capac/2 + 1 */
|
|
|
|
if (pos > halfcapac - 2) {
|
|
|
|
/* New entry will go into right page(fullpage). */
|
|
fullpage_nkeys = halfcapac;
|
|
newpage_nkeys = halfcapac - 1;
|
|
}
|
|
else {
|
|
|
|
/* New entry will go into left page (newpage). */
|
|
fullpage_nkeys = halfcapac - 1;
|
|
newpage_nkeys = halfcapac;
|
|
}
|
|
|
|
/* Move newpage_nkeys keys into newpage. */
|
|
memcpy(newpage + BT_KEYS_OFF,
|
|
fullpage + BT_KEYS_OFF + fullpage_nkeys * keylength,
|
|
keylength * newpage_nkeys);
|
|
|
|
/* If non-leaf, move corresponding entries from block number table. */
|
|
if (level > 0) {
|
|
memcpy(newpage + ISPAGESIZE - newpage_nkeys * BLKNOSIZE,
|
|
fullpage + ISPAGESIZE - nkeys * BLKNOSIZE,
|
|
newpage_nkeys * BLKNOSIZE);
|
|
}
|
|
|
|
stshort((short) fullpage_nkeys, fullpage + BT_NKEYS_OFF);
|
|
stshort((short) newpage_nkeys, newpage + BT_NKEYS_OFF);
|
|
}
|