/* * Copyright (c) 1999 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * The contents of this file constitute Original Code as defined in and * are subject to the Apple Public Source License Version 1.1 (the * "License"). You may not use this file except in compliance with the * License. Please obtain a copy of the License at * http://www.apple.com/publicsource and read it before using this file. * * This Original Code and all software distributed under the License are * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the * License for the specific language governing rights and limitations * under the License. * * @APPLE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Mike Olson. * * 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. */ #include <sys/types.h> #include <stdio.h> #include <db.h> #include "btree.h" static int bt_snext __P((BTREE *, PAGE *, const DBT *, int *)); static int bt_sprev __P((BTREE *, PAGE *, const DBT *, int *)); /* * __BT_SEARCH -- Search a btree for a key. * * Parameters: * t: tree to search * key: key to find * exactp: pointer to exact match flag * * Returns: * The EPG for matching record, if any, or the EPG for the location * of the key, if it were inserted into the tree, is entered into * the bt_cur field of the tree. A pointer to the field is returned. */ EPG * __bt_search(t, key, exactp) BTREE *t; const DBT *key; int *exactp; { PAGE *h; indx_t base, index, lim; pgno_t pg; int cmp; BT_CLR(t); for (pg = P_ROOT;;) { if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (NULL); /* Do a binary search on the current page. */ t->bt_cur.page = h; for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) { t->bt_cur.index = index = base + (lim >> 1); if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) { if (h->flags & P_BLEAF) { *exactp = 1; return (&t->bt_cur); } goto next; } if (cmp > 0) { base = index + 1; --lim; } } /* * If it's a leaf page, and duplicates aren't allowed, we're * done. If duplicates are allowed, it's possible that there * were duplicate keys on duplicate pages, and they were later * deleted, so we could be on a page with no matches while * there are matches on other pages. If we're at the start or * end of a page, check on both sides. */ if (h->flags & P_BLEAF) { t->bt_cur.index = base; *exactp = 0; if (!ISSET(t, B_NODUPS)) { if (base == 0 && bt_sprev(t, h, key, exactp)) return (&t->bt_cur); if (base == NEXTINDEX(h) && bt_snext(t, h, key, exactp)) return (&t->bt_cur); } return (&t->bt_cur); } /* * No match found. Base is the smallest index greater than * key and may be zero or a last + 1 index. If it's non-zero, * decrement by one, and record the internal page which should * be a parent page for the key. If a split later occurs, the * inserted page will be to the right of the saved page. */ index = base ? base - 1 : base; next: if (__bt_push(t, h->pgno, index) == RET_ERROR) return (NULL); pg = GETBINTERNAL(h, index)->pgno; mpool_put(t->bt_mp, h, 0); } } /* * BT_SNEXT -- Check for an exact match after the key. * * Parameters: * t: tree to search * h: current page. * key: key to find * exactp: pointer to exact match flag * * Returns: * If an exact match found. */ static int bt_snext(t, h, key, exactp) BTREE *t; PAGE *h; const DBT *key; int *exactp; { EPG e; PAGE *tp; pgno_t pg; /* Skip until reach the end of the tree or a key. */ for (pg = h->nextpg; pg != P_INVALID;) { if ((tp = mpool_get(t->bt_mp, pg, 0)) == NULL) { mpool_put(t->bt_mp, h, 0); return (NULL); } if (NEXTINDEX(tp) != 0) break; pg = tp->prevpg; mpool_put(t->bt_mp, tp, 0); } /* * The key is either an exact match, or not as good as * the one we already have. */ if (pg != P_INVALID) { e.page = tp; e.index = NEXTINDEX(tp) - 1; if (__bt_cmp(t, key, &e) == 0) { mpool_put(t->bt_mp, h, 0); t->bt_cur = e; *exactp = 1; return (1); } } return (0); } /* * BT_SPREV -- Check for an exact match before the key. * * Parameters: * t: tree to search * h: current page. * key: key to find * exactp: pointer to exact match flag * * Returns: * If an exact match found. */ static int bt_sprev(t, h, key, exactp) BTREE *t; PAGE *h; const DBT *key; int *exactp; { EPG e; PAGE *tp; pgno_t pg; /* Skip until reach the beginning of the tree or a key. */ for (pg = h->prevpg; pg != P_INVALID;) { if ((tp = mpool_get(t->bt_mp, pg, 0)) == NULL) { mpool_put(t->bt_mp, h, 0); return (NULL); } if (NEXTINDEX(tp) != 0) break; pg = tp->prevpg; mpool_put(t->bt_mp, tp, 0); } /* * The key is either an exact match, or not as good as * the one we already have. */ if (pg != P_INVALID) { e.page = tp; e.index = NEXTINDEX(tp) - 1; if (__bt_cmp(t, key, &e) == 0) { mpool_put(t->bt_mp, h, 0); t->bt_cur = e; *exactp = 1; return (1); } } return (0); }