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-rw-r--r--db2/btree/bt_rsearch.c347
1 files changed, 347 insertions, 0 deletions
diff --git a/db2/btree/bt_rsearch.c b/db2/btree/bt_rsearch.c
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+/*-
+ * 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
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * 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_rsearch.c	10.8 (Sleepycat) 8/24/97";
+#endif /* not lint */
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#endif
+
+#include "db_int.h"
+#include "db_page.h"
+#include "btree.h"
+
+/*
+ * __bam_rsearch --
+ *	Search a btree for a record number.
+ *
+ * PUBLIC: int __bam_rsearch __P((DB *, db_recno_t *, u_int, int, int *));
+ */
+int
+__bam_rsearch(dbp, recnop, flags, stop, exactp)
+	DB *dbp;
+	db_recno_t *recnop;
+	u_int flags;
+	int stop, *exactp;
+{
+	BINTERNAL *bi;
+	BTREE *t;
+	DB_LOCK lock;
+	PAGE *h;
+	RINTERNAL *ri;
+	db_indx_t indx, top;
+	db_pgno_t pg;
+	db_recno_t recno, total;
+	int isappend, ret, stack;
+
+	t = dbp->internal;
+
+	/*
+	 * We test for groups of flags, S_APPEND is the only one that can be
+	 * OR'd into the set.  Clear it now so that the tests for equality
+	 * will work.
+	 */
+	if ((isappend = LF_ISSET(S_APPEND)) != 0)
+		LF_CLR(S_APPEND);
+
+	/*
+	 * There are several ways we search a btree tree.  The flags argument
+	 * specifies if we're acquiring read or write locks and if we are
+	 * locking pairs of pages.  See btree.h for more details.
+	 *
+	 * 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;
+	if ((ret = __bam_lget(dbp, 0, PGNO_ROOT,
+	    flags == S_INSERT || flags == S_DELETE ?
+	    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);
+	}
+	total = RE_NREC(h);
+
+	/*
+	 * If appending to the tree, set the record number now -- we have the
+	 * root page locked.
+	 *
+	 * Delete only deletes exact matches, read only returns exact matches.
+	 * Note, this is different from __bam_search(), which returns non-exact
+	 * matches for read.
+	 *
+	 * The record may not exist.  We can only return the correct location
+	 * for the record immediately after the last record in the tree, so do
+	 * a fast check now.
+	 */
+	if (isappend) {
+		*exactp = 0;
+		*recnop = recno = total + 1;
+	} else {
+		recno = *recnop;
+		if (recno <= total)
+			*exactp = 1;
+		else {
+			*exactp = 0;
+			if (flags == S_DELETE ||
+			    flags == S_FIND || recno > total + 1) {
+				(void)memp_fput(dbp->mpf, h, 0);
+				(void)__BT_LPUT(dbp, lock);
+				return (DB_NOTFOUND);
+			}
+		}
+	}
+
+	/* Decide if we're building a stack based on the operation. */
+	BT_STK_CLR(t);
+	stack = flags == S_DELETE || flags == S_INSERT;
+
+	/*
+	 * Decide if we need to save this page; if we do, write lock it, and
+	 * start to build a stack.
+	 */
+	if (LF_ISSET(S_PARENT) && (u_int8_t)(stop + 1) >= h->level) {
+		(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;
+	}
+
+	/* Records in the tree are 0-based, and record numbers are 1-based. */
+	--recno;
+
+	for (total = 0;;) {
+		switch (TYPE(h)) {
+		case P_LBTREE:
+			BT_STK_ENTER(t, h, (recno - total) * P_INDX, lock, ret);
+			return (ret);
+		case P_IBTREE:
+			for (indx = 0, top = NUM_ENT(h);;) {
+				bi = GET_BINTERNAL(h, indx);
+				if (++indx == top || total + bi->nrecs > recno)
+					break;
+				total += bi->nrecs;
+			}
+			pg = bi->pgno;
+			break;
+		case P_LRECNO:
+			BT_STK_ENTER(t, h, recno - total, lock, ret);
+			return (ret);
+		case P_IRECNO:
+			for (indx = 0, top = NUM_ENT(h);;) {
+				ri = GET_RINTERNAL(h, indx);
+				if (++indx == top || total + ri->nrecs > recno)
+					break;
+				total += ri->nrecs;
+			}
+			pg = ri->pgno;
+			break;
+		default:
+			return (__db_pgfmt(dbp, h->pgno));
+		}
+		--indx;
+
+		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)
+				goto err;
+
+			if ((ret = __bam_lget(dbp, 0, pg,
+			    LF_ISSET(S_WRITE) ? DB_LOCK_WRITE : DB_LOCK_READ,
+			    &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))
+				stack = 1;
+
+			if ((ret = __bam_lget(dbp, 1, pg,
+			    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 */
+
+err:	BT_STK_POP(t);
+	__bam_stkrel(dbp);
+	return (ret);
+}
+
+/*
+ * __bam_adjust --
+ *	Adjust the tree after adding or deleting a record.
+ *
+ * PUBLIC: int __bam_adjust __P((DB *, BTREE *, int));
+ */
+int
+__bam_adjust(dbp, t, adjust)
+	DB *dbp;
+	BTREE *t;
+	int adjust;
+{
+	EPG *epg;
+	PAGE *h;
+	int ret;
+
+	/* Update the record counts for the tree. */
+	for (epg = t->bt_sp; epg <= t->bt_csp; ++epg) {
+		h = epg->page;
+		if (TYPE(h) == P_IBTREE || TYPE(h) == P_IRECNO) {
+			if (DB_LOGGING(dbp) &&
+			    (ret = __bam_cadjust_log(dbp->dbenv->lg_info,
+			    dbp->txn, &LSN(h), 0, dbp->log_fileid,
+			    PGNO(h), &LSN(h), (u_int32_t)epg->indx,
+			    (int32_t)adjust, 1)) != 0)
+				return (ret);
+
+			if (TYPE(h) == P_IBTREE)
+				GET_BINTERNAL(h, epg->indx)->nrecs += adjust;
+			else
+				GET_RINTERNAL(h, epg->indx)->nrecs += adjust;
+
+			if (PGNO(h) == PGNO_ROOT)
+				RE_NREC_ADJ(h, adjust);
+
+			if ((ret = memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY)) != 0)
+				return (ret);
+		}
+	}
+	return (0);
+}
+
+/*
+ * __bam_nrecs --
+ *	Return the number of records in the tree.
+ *
+ * PUBLIC: int __bam_nrecs __P((DB *, db_recno_t *));
+ */
+int
+__bam_nrecs(dbp, rep)
+	DB *dbp;
+	db_recno_t *rep;
+{
+	DB_LOCK lock;
+	PAGE *h;
+	db_pgno_t pgno;
+	int ret;
+
+	pgno = PGNO_ROOT;
+	if ((ret = __bam_lget(dbp, 0, pgno, DB_LOCK_READ, &lock)) != 0)
+		return (ret);
+	if ((ret = __bam_pget(dbp, &h, &pgno, 0)) != 0)
+		return (ret);
+
+	*rep = RE_NREC(h);
+
+	(void)memp_fput(dbp->mpf, h, 0);
+	(void)__BT_TLPUT(dbp, lock);
+
+	return (0);
+}
+
+/*
+ * __bam_total --
+ *	Return the number of records below a page.
+ *
+ * PUBLIC: db_recno_t __bam_total __P((PAGE *));
+ */
+db_recno_t
+__bam_total(h)
+	PAGE *h;
+{
+	db_recno_t recs;
+	db_indx_t nxt, top;
+
+	switch (TYPE(h)) {
+	case P_LBTREE:
+		recs = NUM_ENT(h) / 2;
+		break;
+	case P_IBTREE:
+		for (recs = 0, nxt = 0, top = NUM_ENT(h); nxt < top; ++nxt)
+			recs += GET_BINTERNAL(h, nxt)->nrecs;
+		break;
+	case P_LRECNO:
+		recs = NUM_ENT(h);
+		break;
+	case P_IRECNO:
+		for (recs = 0, nxt = 0, top = NUM_ENT(h); nxt < top; ++nxt)
+			recs += GET_RINTERNAL(h, nxt)->nrecs;
+		break;
+	default:
+		abort();
+	}
+	return (recs);
+}
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