/* * 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 <errno.h> #include <stddef.h> #include <stdio.h> #include <db.h> #include "btree.h" /* * __BT_GET -- Get a record from the btree. * * Parameters: * dbp: pointer to access method * key: key to find * data: data to return * flag: currently unused * * Returns: * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. */ int __bt_get(dbp, key, data, flags) const DB *dbp; const DBT *key; DBT *data; u_int flags; { BTREE *t; EPG *e; int exact, status; t = dbp->internal; /* Toss any page pinned across calls. */ if (t->bt_pinned != NULL) { mpool_put(t->bt_mp, t->bt_pinned, 0); t->bt_pinned = NULL; } /* Get currently doesn't take any flags. */ if (flags) { errno = EINVAL; return (RET_ERROR); } if ((e = __bt_search(t, key, &exact)) == NULL) return (RET_ERROR); if (!exact) { mpool_put(t->bt_mp, e->page, 0); return (RET_SPECIAL); } /* * A special case is if we found the record but it's flagged for * deletion. In this case, we want to find another record with the * same key, if it exists. Rather than look around the tree we call * __bt_first and have it redo the search, as __bt_first will not * return keys marked for deletion. Slow, but should never happen. */ if (ISSET(t, B_DELCRSR) && e->page->pgno == t->bt_bcursor.pgno && e->index == t->bt_bcursor.index) { mpool_put(t->bt_mp, e->page, 0); if ((e = __bt_first(t, key, &exact)) == NULL) return (RET_ERROR); if (!exact) return (RET_SPECIAL); } status = __bt_ret(t, e, NULL, data); /* * If the user is doing concurrent access, we copied the * key/data, toss the page. */ if (ISSET(t, B_DB_LOCK)) mpool_put(t->bt_mp, e->page, 0); else t->bt_pinned = e->page; return (status); } /* * __BT_FIRST -- Find the first entry. * * Parameters: * t: the tree * key: the key * * Returns: * The first entry in the tree greater than or equal to key. */ EPG * __bt_first(t, key, exactp) BTREE *t; const DBT *key; int *exactp; { register PAGE *h; register EPG *e; EPG save; pgno_t cpgno, pg; indx_t cindex; int found; /* * Find any matching record; __bt_search pins the page. Only exact * matches are tricky, otherwise just return the location of the key * if it were to be inserted into the tree. */ if ((e = __bt_search(t, key, exactp)) == NULL) return (NULL); if (!*exactp) return (e); if (ISSET(t, B_DELCRSR)) { cpgno = t->bt_bcursor.pgno; cindex = t->bt_bcursor.index; } else { cpgno = P_INVALID; cindex = 0; /* GCC thinks it's uninitialized. */ } /* * Walk backwards, skipping empty pages, as long as the entry matches * and there are keys left in the tree. Save a copy of each match in * case we go too far. A special case is that we don't return a match * on records that the cursor references that have already been flagged * for deletion. */ save = *e; h = e->page; found = 0; do { if (cpgno != h->pgno || cindex != e->index) { if (save.page->pgno != e->page->pgno) { mpool_put(t->bt_mp, save.page, 0); save = *e; } else save.index = e->index; found = 1; } /* * Make a special effort not to unpin the page the last (or * original) match was on, but also make sure it's unpinned * if an error occurs. */ while (e->index == 0) { if (h->prevpg == P_INVALID) goto done1; if (h->pgno != save.page->pgno) mpool_put(t->bt_mp, h, 0); if ((h = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL) { if (h->pgno == save.page->pgno) mpool_put(t->bt_mp, save.page, 0); return (NULL); } e->page = h; e->index = NEXTINDEX(h); } --e->index; } while (__bt_cmp(t, key, e) == 0); /* * Reach here with the last page that was looked at pinned, which may * or may not be the same as the last (or original) match page. If * it's not useful, release it. */ done1: if (h->pgno != save.page->pgno) mpool_put(t->bt_mp, h, 0); /* * If still haven't found a record, the only possibility left is the * next one. Move forward one slot, skipping empty pages and check. */ if (!found) { h = save.page; if (++save.index == NEXTINDEX(h)) { do { pg = h->nextpg; mpool_put(t->bt_mp, h, 0); if (pg == P_INVALID) { *exactp = 0; return (e); } if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) return (NULL); } while ((save.index = NEXTINDEX(h)) == 0); save.page = h; } if (__bt_cmp(t, key, &save) != 0) { *exactp = 0; return (e); } } *e = save; *exactp = 1; return (e); }