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Diffstat (limited to 'db2/btree/bt_search.c')
| -rw-r--r-- | db2/btree/bt_search.c | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/db2/btree/bt_search.c b/db2/btree/bt_search.c new file mode 100644 index 0000000000..d5f20d4c61 --- /dev/null +++ b/db2/btree/bt_search.c @@ -0,0 +1,335 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. 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. 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 "config.h" + +#ifndef lint +static const char sccsid[] = "@(#)bt_search.c 10.6 (Sleepycat) 8/22/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> + +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#endif + +#include "db_int.h" +#include "db_page.h" +#include "btree.h" + +/* + * __bam_search -- + * Search a btree for a key. + * + * PUBLIC: int __bam_search __P((DB *, + * PUBLIC: const DBT *, u_int, int, db_recno_t *, int *)); + */ +int +__bam_search(dbp, key, flags, stop, recnop, exactp) + DB *dbp; + const DBT *key; + u_int flags; + int stop, *exactp; + db_recno_t *recnop; +{ + BTREE *t; + DB_LOCK lock; + EPG cur; + PAGE *h; + db_indx_t base, i, indx, lim; + db_pgno_t pg; + db_recno_t recno; + int cmp, jump, ret, stack; + + t = dbp->internal; + recno = 0; + + BT_STK_CLR(t); + + /* + * There are several ways we search a btree tree. The flags argument + * specifies if we're acquiring read or write locks, if we position + * to the first or last item in a set of duplicates, if we return + * deleted items, and if we are locking pairs of pages. See btree.h + * for more details. In addition, if we're doing record numbers, we + * have to lock the entire tree regardless. + * + * If write-locking pages, we need to know whether or not to acquire a + * write lock on a page before getting it. This depends on how deep it + * is in tree, which we don't know until we acquire the root page. So, + * if we need to lock the root page we may have to upgrade it later, + * because we won't get the correct lock initially. + * + * Retrieve the root page. + */ + pg = PGNO_ROOT; + stack = F_ISSET(dbp, DB_BT_RECNUM) && + (flags == S_INSERT || flags == S_DELETE); + if ((ret = __bam_lget(dbp, + 0, pg, stack ? DB_LOCK_WRITE : DB_LOCK_READ, &lock)) != 0) + return (ret); + if ((ret = __bam_pget(dbp, &h, &pg, 0)) != 0) { + (void)__BT_LPUT(dbp, lock); + return (ret); + } + + /* Decide if we need to save this page; if we do, write lock it. */ + if (!stack && + ((LF_ISSET(S_PARENT) && (u_int8_t)(stop + 1) >= h->level) || + (LF_ISSET(S_WRITE) && h->level == LEAFLEVEL))) { + (void)memp_fput(dbp->mpf, h, 0); + if ((ret = __bam_lget(dbp, 1, pg, DB_LOCK_WRITE, &lock)) != 0) + return (ret); + if ((ret = __bam_pget(dbp, &h, &pg, 0)) != 0) { + (void)__BT_LPUT(dbp, lock); + return (ret); + } + + stack = 1; + } + + for (;;) { + /* + * Do a binary search on the current page. If we're searching + * a leaf page, we have to manipulate the indices in groups of + * two. If we're searching an internal page, they're an index + * per page item. If we find an exact match on a leaf page, + * we're done. + */ + cur.page = h; + jump = TYPE(h) == P_LBTREE ? P_INDX : O_INDX; + for (base = 0, + lim = NUM_ENT(h) / (db_indx_t)jump; lim != 0; lim >>= 1) { + cur.indx = indx = base + ((lim >> 1) * jump); + if ((cmp = __bam_cmp(dbp, key, &cur)) == 0) { + if (TYPE(h) == P_LBTREE) + goto match; + goto next; + } + if (cmp > 0) { + base = indx + jump; + --lim; + } + } + + /* + * No match found. Base is the smallest index greater than + * key and may be zero or a last + O_INDX index. + * + * If it's a leaf page, return base as the "found" value. + * Delete only deletes exact matches. + */ + if (TYPE(h) == P_LBTREE) { + *exactp = 0; + + if (LF_ISSET(S_EXACT)) + goto notfound; + + BT_STK_ENTER(t, h, base, lock, ret); + return (ret); + } + + /* + * If it's not a leaf page, record the internal page (which is + * a parent page for the key). Decrement the base by 1 if it's + * non-zero so that if a split later occurs, the inserted page + * will be to the right of the saved page. + */ + indx = base > 0 ? base - O_INDX : base; + + /* + * If we're trying to calculate the record number, sum up + * all the record numbers on this page up to the indx point. + */ + if (recnop != NULL) + for (i = 0; i < indx; ++i) + recno += GET_BINTERNAL(h, i)->nrecs; + +next: pg = GET_BINTERNAL(h, indx)->pgno; + if (stack) { + /* Return if this is the lowest page wanted. */ + if (LF_ISSET(S_PARENT) && stop == h->level) { + BT_STK_ENTER(t, h, indx, lock, ret); + return (ret); + } + BT_STK_PUSH(t, h, indx, lock, ret); + if (ret != 0) + goto err; + + if ((ret = + __bam_lget(dbp, 0, pg, DB_LOCK_WRITE, &lock)) != 0) + goto err; + } else { + (void)memp_fput(dbp->mpf, h, 0); + + /* + * Decide if we want to return a pointer to the next + * page in the stack. If we do, write lock it and + * never unlock it. + */ + if ((LF_ISSET(S_PARENT) && + (u_int8_t)(stop + 1) >= (u_int8_t)(h->level - 1)) || + (h->level - 1) == LEAFLEVEL) + stack = 1; + + if ((ret = + __bam_lget(dbp, 1, pg, stack && LF_ISSET(S_WRITE) ? + DB_LOCK_WRITE : DB_LOCK_READ, &lock)) != 0) + goto err; + } + if ((ret = __bam_pget(dbp, &h, &pg, 0)) != 0) + goto err; + } + + /* NOTREACHED */ +match: *exactp = 1; + + /* + * If we're trying to calculate the record number, add in the + * offset on this page and correct for the fact that records + * in the tree are 0-based. + */ + if (recnop != NULL) + *recnop = recno + (indx / P_INDX) + 1; + + /* + * If we got here, we know that we have a btree leaf page. + * + * If there are duplicates, go to the first/last one. + */ + if (LF_ISSET(S_DUPLAST)) + while (indx < (db_indx_t)(NUM_ENT(h) - P_INDX) && + h->inp[indx] == h->inp[indx + P_INDX]) + indx += P_INDX; + else + while (indx > 0 && + h->inp[indx] == h->inp[indx - P_INDX]) + indx -= P_INDX; + + /* + * Now check if we are allowed to return deleted item; if not + * find/last the first non-deleted item. + */ + if (LF_ISSET(S_DELNO)) { + if (LF_ISSET(S_DUPLAST)) + while (GET_BKEYDATA(h, indx + O_INDX)->deleted && + indx > 0 && + h->inp[indx] == h->inp[indx - P_INDX]) + indx -= P_INDX; + else + while (GET_BKEYDATA(h, indx + O_INDX)->deleted && + indx < (db_indx_t)(NUM_ENT(h) - P_INDX) && + h->inp[indx] == h->inp[indx + P_INDX]) + indx += P_INDX; + + if (GET_BKEYDATA(h, indx + O_INDX)->deleted) + goto notfound; + } + + BT_STK_ENTER(t, h, indx, lock, ret); + return (ret); + +notfound: + (void)memp_fput(dbp->mpf, h, 0); + (void)__BT_LPUT(dbp, lock); + ret = DB_NOTFOUND; + +err: if (t->bt_csp > t->bt_sp) { + BT_STK_POP(t); + __bam_stkrel(dbp); + } + return (ret); +} + +/* + * __bam_stkrel -- + * Release all pages currently held in the stack. + * + * PUBLIC: int __bam_stkrel __P((DB *)); + */ +int +__bam_stkrel(dbp) + DB *dbp; +{ + BTREE *t; + EPG *epg; + + t = dbp->internal; + for (epg = t->bt_sp; epg <= t->bt_csp; ++epg) { + (void)memp_fput(dbp->mpf, epg->page, 0); + (void)__BT_TLPUT(dbp, epg->lock); + } + return (0); +} + +/* + * __bam_stkgrow -- + * Grow the stack. + * + * PUBLIC: int __bam_stkgrow __P((BTREE *)); + */ +int +__bam_stkgrow(t) + BTREE *t; +{ + EPG *p; + size_t entries; + + entries = t->bt_esp - t->bt_sp; + + if ((p = (EPG *)calloc(entries * 2, sizeof(EPG))) == NULL) + return (ENOMEM); + memcpy(p, t->bt_sp, entries * sizeof(EPG)); + if (t->bt_sp != t->bt_stack) + FREE(t->bt_sp, entries * sizeof(EPG)); + t->bt_sp = p; + t->bt_csp = p + entries; + t->bt_esp = p + entries * 2; + return (0); +} |