/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996,2007 Oracle. All rights reserved. */ /* * Copyright (c) 1990, 1993, 1994, 1995, 1996 * Keith Bostic. All rights reserved. */ /* * Copyright (c) 1990, 1993, 1994, 1995 * 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. 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. * * $Id: bt_compare.c,v 12.9 2007/05/17 15:14:46 bostic Exp $ */ #include "db_config.h" #include "db_int.h" #include "dbinc/db_page.h" #include "dbinc/btree.h" /* * __bam_cmp -- * Compare a key to a given record. * * PUBLIC: int __bam_cmp __P((DB *, DB_TXN *, const DBT *, PAGE *, u_int32_t, * PUBLIC: int (*)(DB *, const DBT *, const DBT *), int *)); */ int __bam_cmp(dbp, txn, dbt, h, indx, func, cmpp) DB *dbp; DB_TXN *txn; const DBT *dbt; PAGE *h; u_int32_t indx; int (*func)__P((DB *, const DBT *, const DBT *)); int *cmpp; { BINTERNAL *bi; BKEYDATA *bk; BOVERFLOW *bo; DBT pg_dbt; /* * Returns: * < 0 if dbt is < page record * = 0 if dbt is = page record * > 0 if dbt is > page record * * !!! * We do not clear the pg_dbt DBT even though it's likely to contain * random bits. That should be okay, because the app's comparison * routine had better not be looking at fields other than data, size * and app_data. We don't clear it because we go through this path a * lot and it's expensive. */ switch (TYPE(h)) { case P_LBTREE: case P_LDUP: case P_LRECNO: bk = GET_BKEYDATA(dbp, h, indx); if (B_TYPE(bk->type) == B_OVERFLOW) bo = (BOVERFLOW *)bk; else { pg_dbt.app_data = NULL; pg_dbt.data = bk->data; pg_dbt.size = bk->len; *cmpp = func(dbp, dbt, &pg_dbt); return (0); } break; case P_IBTREE: /* * The following code guarantees that the left-most key on an * internal page at any place in the tree sorts less than any * user-specified key. The reason is that if we have reached * this internal page, we know the user key must sort greater * than the key we're storing for this page in any internal * pages at levels above us in the tree. It then follows that * any user-specified key cannot sort less than the first page * which we reference, and so there's no reason to call the * comparison routine. While this may save us a comparison * routine call or two, the real reason for this is because * we don't maintain a copy of the smallest key in the tree, * so that we don't have to update all the levels of the tree * should the application store a new smallest key. And, so, * we may not have a key to compare, which makes doing the * comparison difficult and error prone. */ if (indx == 0) { *cmpp = 1; return (0); } bi = GET_BINTERNAL(dbp, h, indx); if (B_TYPE(bi->type) == B_OVERFLOW) bo = (BOVERFLOW *)(bi->data); else { pg_dbt.app_data = NULL; pg_dbt.data = bi->data; pg_dbt.size = bi->len; *cmpp = func(dbp, dbt, &pg_dbt); return (0); } break; default: return (__db_pgfmt(dbp->dbenv, PGNO(h))); } /* * Overflow. */ return (__db_moff(dbp, txn, dbt, bo->pgno, bo->tlen, func == __bam_defcmp ? NULL : func, cmpp)); } /* * __bam_defcmp -- * Default comparison routine. * * PUBLIC: int __bam_defcmp __P((DB *, const DBT *, const DBT *)); */ int __bam_defcmp(dbp, a, b) DB *dbp; const DBT *a, *b; { size_t len; u_int8_t *p1, *p2; COMPQUIET(dbp, NULL); /* * Returns: * < 0 if a is < b * = 0 if a is = b * > 0 if a is > b * * XXX * If a size_t doesn't fit into a long, or if the difference between * any two characters doesn't fit into an int, this routine can lose. * What we need is a signed integral type that's guaranteed to be at * least as large as a size_t, and there is no such thing. */ len = a->size > b->size ? b->size : a->size; for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2) if (*p1 != *p2) return ((long)*p1 - (long)*p2); return ((long)a->size - (long)b->size); } /* * __bam_defpfx -- * Default prefix routine. * * PUBLIC: size_t __bam_defpfx __P((DB *, const DBT *, const DBT *)); */ size_t __bam_defpfx(dbp, a, b) DB *dbp; const DBT *a, *b; { size_t cnt, len; u_int8_t *p1, *p2; COMPQUIET(dbp, NULL); cnt = 1; len = a->size > b->size ? b->size : a->size; for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt) if (*p1 != *p2) return (cnt); /* * They match up to the smaller of the two sizes. * Collate the longer after the shorter. */ if (a->size < b->size) return (a->size + 1); if (b->size < a->size) return (b->size + 1); return (b->size); }