11573Srgrimes/*- 214272Spst * Copyright (c) 1990, 1993, 1994 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Mike Olson. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 4. Neither the name of the University nor the names of its contributors 171573Srgrimes * may be used to endorse or promote products derived from this software 181573Srgrimes * without specific prior written permission. 191573Srgrimes * 201573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 211573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 221573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 231573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 241573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 251573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 261573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 271573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 281573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 291573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 301573Srgrimes * SUCH DAMAGE. 311573Srgrimes */ 321573Srgrimes 331573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 3414272Spststatic char sccsid[] = "@(#)bt_search.c 8.8 (Berkeley) 7/31/94"; 351573Srgrimes#endif /* LIBC_SCCS and not lint */ 3692905Sobrien#include <sys/cdefs.h> 3792905Sobrien__FBSDID("$FreeBSD$"); 381573Srgrimes 391573Srgrimes#include <sys/types.h> 401573Srgrimes 411573Srgrimes#include <stdio.h> 421573Srgrimes 431573Srgrimes#include <db.h> 441573Srgrimes#include "btree.h" 451573Srgrimes 4692905Sobrienstatic int __bt_snext(BTREE *, PAGE *, const DBT *, int *); 4792905Sobrienstatic int __bt_sprev(BTREE *, PAGE *, const DBT *, int *); 481573Srgrimes 491573Srgrimes/* 5014272Spst * __bt_search -- 5114272Spst * Search a btree for a key. 521573Srgrimes * 531573Srgrimes * Parameters: 541573Srgrimes * t: tree to search 551573Srgrimes * key: key to find 561573Srgrimes * exactp: pointer to exact match flag 571573Srgrimes * 581573Srgrimes * Returns: 591573Srgrimes * The EPG for matching record, if any, or the EPG for the location 601573Srgrimes * of the key, if it were inserted into the tree, is entered into 611573Srgrimes * the bt_cur field of the tree. A pointer to the field is returned. 621573Srgrimes */ 631573SrgrimesEPG * 64189291Sdelphij__bt_search(BTREE *t, const DBT *key, int *exactp) 651573Srgrimes{ 661573Srgrimes PAGE *h; 67189292Sdelphij indx_t base, idx, lim; 681573Srgrimes pgno_t pg; 691573Srgrimes int cmp; 701573Srgrimes 711573Srgrimes BT_CLR(t); 721573Srgrimes for (pg = P_ROOT;;) { 731573Srgrimes if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 741573Srgrimes return (NULL); 751573Srgrimes 761573Srgrimes /* Do a binary search on the current page. */ 771573Srgrimes t->bt_cur.page = h; 781573Srgrimes for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) { 79189292Sdelphij t->bt_cur.index = idx = base + (lim >> 1); 801573Srgrimes if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) { 811573Srgrimes if (h->flags & P_BLEAF) { 821573Srgrimes *exactp = 1; 831573Srgrimes return (&t->bt_cur); 841573Srgrimes } 851573Srgrimes goto next; 861573Srgrimes } 871573Srgrimes if (cmp > 0) { 88189292Sdelphij base = idx + 1; 891573Srgrimes --lim; 901573Srgrimes } 911573Srgrimes } 921573Srgrimes 931573Srgrimes /* 9414272Spst * If it's a leaf page, we're almost done. If no duplicates 9514272Spst * are allowed, or we have an exact match, we're done. Else, 9614272Spst * it's possible that there were matching keys on this page, 9714272Spst * which later deleted, and we're on a page with no matches 9814272Spst * while there are matches on other pages. If at the start or 9914272Spst * end of a page, check the adjacent page. 1001573Srgrimes */ 1011573Srgrimes if (h->flags & P_BLEAF) { 10214272Spst if (!F_ISSET(t, B_NODUPS)) { 1031573Srgrimes if (base == 0 && 10414272Spst h->prevpg != P_INVALID && 10514272Spst __bt_sprev(t, h, key, exactp)) 1061573Srgrimes return (&t->bt_cur); 1071573Srgrimes if (base == NEXTINDEX(h) && 10814272Spst h->nextpg != P_INVALID && 10914272Spst __bt_snext(t, h, key, exactp)) 1101573Srgrimes return (&t->bt_cur); 1111573Srgrimes } 11214272Spst *exactp = 0; 11314272Spst t->bt_cur.index = base; 1141573Srgrimes return (&t->bt_cur); 1151573Srgrimes } 1161573Srgrimes 1171573Srgrimes /* 1181573Srgrimes * No match found. Base is the smallest index greater than 1191573Srgrimes * key and may be zero or a last + 1 index. If it's non-zero, 1201573Srgrimes * decrement by one, and record the internal page which should 1211573Srgrimes * be a parent page for the key. If a split later occurs, the 1221573Srgrimes * inserted page will be to the right of the saved page. 1231573Srgrimes */ 124189292Sdelphij idx = base ? base - 1 : base; 1251573Srgrimes 126189292Sdelphijnext: BT_PUSH(t, h->pgno, idx); 127189292Sdelphij pg = GETBINTERNAL(h, idx)->pgno; 1281573Srgrimes mpool_put(t->bt_mp, h, 0); 1291573Srgrimes } 1301573Srgrimes} 1311573Srgrimes 1321573Srgrimes/* 13314272Spst * __bt_snext -- 13414272Spst * Check for an exact match after the key. 1351573Srgrimes * 1361573Srgrimes * Parameters: 13714272Spst * t: tree 13814272Spst * h: current page 13914272Spst * key: key 1401573Srgrimes * exactp: pointer to exact match flag 1411573Srgrimes * 1421573Srgrimes * Returns: 1431573Srgrimes * If an exact match found. 1441573Srgrimes */ 1451573Srgrimesstatic int 146189291Sdelphij__bt_snext(BTREE *t, PAGE *h, const DBT *key, int *exactp) 1471573Srgrimes{ 1481573Srgrimes EPG e; 1491573Srgrimes 1501573Srgrimes /* 15114272Spst * Get the next page. The key is either an exact 15214272Spst * match, or not as good as the one we already have. 1531573Srgrimes */ 15414272Spst if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) 15514272Spst return (0); 15614272Spst e.index = 0; 15714272Spst if (__bt_cmp(t, key, &e) == 0) { 15814272Spst mpool_put(t->bt_mp, h, 0); 15914272Spst t->bt_cur = e; 16014272Spst *exactp = 1; 16114272Spst return (1); 1621573Srgrimes } 16314272Spst mpool_put(t->bt_mp, e.page, 0); 1641573Srgrimes return (0); 1651573Srgrimes} 1661573Srgrimes 1671573Srgrimes/* 16814272Spst * __bt_sprev -- 16914272Spst * Check for an exact match before the key. 1701573Srgrimes * 1711573Srgrimes * Parameters: 17214272Spst * t: tree 17314272Spst * h: current page 17414272Spst * key: key 1751573Srgrimes * exactp: pointer to exact match flag 1761573Srgrimes * 1771573Srgrimes * Returns: 1781573Srgrimes * If an exact match found. 1791573Srgrimes */ 1801573Srgrimesstatic int 181189291Sdelphij__bt_sprev(BTREE *t, PAGE *h, const DBT *key, int *exactp) 1821573Srgrimes{ 1831573Srgrimes EPG e; 1841573Srgrimes 1851573Srgrimes /* 18614272Spst * Get the previous page. The key is either an exact 18714272Spst * match, or not as good as the one we already have. 1881573Srgrimes */ 18914272Spst if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL) 19014272Spst return (0); 19114272Spst e.index = NEXTINDEX(e.page) - 1; 19214272Spst if (__bt_cmp(t, key, &e) == 0) { 19314272Spst mpool_put(t->bt_mp, h, 0); 19414272Spst t->bt_cur = e; 19514272Spst *exactp = 1; 19614272Spst return (1); 1971573Srgrimes } 19814272Spst mpool_put(t->bt_mp, e.page, 0); 1991573Srgrimes return (0); 2001573Srgrimes} 201