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authorTerry Wilson <twilson@digium.com>2011-07-06 20:58:12 +0000
committerTerry Wilson <twilson@digium.com>2011-07-06 20:58:12 +0000
commitefd040cd11cff99a9dccf54c030a134d9a1e2e07 (patch)
treeb4a3f36ffe91a5226485088c3bb2c5c6ac698fa1 /utils/db1-ast/btree/bt_search.c
parenta7c6f0445e7bbd1f7aea1687eae52c3ca7cd5756 (diff)
Replace Berkeley DB with SQLite 3
There were some bugs in the very ancient version of Berkeley DB that Asterisk used. Instead of spending the time tracking down the bugs in the Berkeley code we move to the much better documented SQLite 3. Conversion of the old astdb happens at runtime by running the included astdb2sqlite3 utility. The ast_db API with SQLite 3 backend should behave identically to the old Berkeley backend, but in the future we could offer a much more robust interface. We do not include the SQLite 3 library in the source tree, but instead rely upon the distribution-provided libraries. SQLite is so ubiquitous that this should not place undue burden on administrators. git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@326589 65c4cc65-6c06-0410-ace0-fbb531ad65f3
Diffstat (limited to 'utils/db1-ast/btree/bt_search.c')
-rw-r--r--utils/db1-ast/btree/bt_search.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/utils/db1-ast/btree/bt_search.c b/utils/db1-ast/btree/bt_search.c
new file mode 100644
index 000000000..623f43949
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+++ b/utils/db1-ast/btree/bt_search.c
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+/*-
+ * Copyright (c) 1990, 1993, 1994
+ * 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.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)bt_search.c 8.8 (Berkeley) 7/31/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+
+#include "../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, we're almost done. If no duplicates
+ * are allowed, or we have an exact match, we're done. Else,
+ * it's possible that there were matching keys on this page,
+ * which later deleted, and we're on a page with no matches
+ * while there are matches on other pages. If at the start or
+ * end of a page, check the adjacent page.
+ */
+ if (h->flags & P_BLEAF) {
+ if (!F_ISSET(t, B_NODUPS)) {
+ if (base == 0 &&
+ h->prevpg != P_INVALID &&
+ __bt_sprev(t, h, key, exactp))
+ return (&t->bt_cur);
+ if (base == NEXTINDEX(h) &&
+ h->nextpg != P_INVALID &&
+ __bt_snext(t, h, key, exactp))
+ return (&t->bt_cur);
+ }
+ *exactp = 0;
+ t->bt_cur.index = base;
+ 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: BT_PUSH(t, h->pgno, index);
+ 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
+ * h: current page
+ * key: key
+ * 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;
+
+ /*
+ * Get the next page. The key is either an exact
+ * match, or not as good as the one we already have.
+ */
+ if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
+ return (0);
+ e.index = 0;
+ if (__bt_cmp(t, key, &e) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ t->bt_cur = e;
+ *exactp = 1;
+ return (1);
+ }
+ mpool_put(t->bt_mp, e.page, 0);
+ return (0);
+}
+
+/*
+ * __bt_sprev --
+ * Check for an exact match before the key.
+ *
+ * Parameters:
+ * t: tree
+ * h: current page
+ * key: key
+ * 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;
+
+ /*
+ * Get the previous page. The key is either an exact
+ * match, or not as good as the one we already have.
+ */
+ if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
+ return (0);
+ e.index = NEXTINDEX(e.page) - 1;
+ if (__bt_cmp(t, key, &e) == 0) {
+ mpool_put(t->bt_mp, h, 0);
+ t->bt_cur = e;
+ *exactp = 1;
+ return (1);
+ }
+ mpool_put(t->bt_mp, e.page, 0);
+ return (0);
+}