463 lines
11 KiB
C
463 lines
11 KiB
C
/*-
|
|
* 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_seq.c 8.7 (Berkeley) 7/20/94";
|
|
#endif /* LIBC_SCCS and not lint */
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <errno.h>
|
|
#include <stddef.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
#include <db.h>
|
|
#include "btree.h"
|
|
|
|
static int __bt_first(BTREE *, const DBT *, EPG *, int *);
|
|
static int __bt_seqadv(BTREE *, EPG *, int);
|
|
static int __bt_seqset(BTREE *, EPG *, DBT *, int);
|
|
|
|
/*
|
|
* Sequential scan support.
|
|
*
|
|
* The tree can be scanned sequentially, starting from either end of the
|
|
* tree or from any specific key. A scan request before any scanning is
|
|
* done is initialized as starting from the least node.
|
|
*/
|
|
|
|
/*
|
|
* __bt_seq --
|
|
* Btree sequential scan interface.
|
|
*
|
|
* Parameters:
|
|
* dbp: pointer to access method
|
|
* key: key for positioning and return value
|
|
* data: data return value
|
|
* flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
|
|
*
|
|
* Returns:
|
|
* RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
|
|
*/
|
|
int
|
|
__bt_seq(dbp, key, data, flags)
|
|
const DB *dbp;
|
|
DBT *key, *data;
|
|
u_int flags;
|
|
{
|
|
BTREE *t;
|
|
EPG e;
|
|
int 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;
|
|
}
|
|
|
|
/*
|
|
* If scan unitialized as yet, or starting at a specific record, set
|
|
* the scan to a specific key. Both __bt_seqset and __bt_seqadv pin
|
|
* the page the cursor references if they're successful.
|
|
*/
|
|
switch (flags) {
|
|
case R_NEXT:
|
|
case R_PREV:
|
|
if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
|
|
status = __bt_seqadv(t, &e, flags);
|
|
break;
|
|
}
|
|
/* FALLTHROUGH */
|
|
case R_FIRST:
|
|
case R_LAST:
|
|
case R_CURSOR:
|
|
status = __bt_seqset(t, &e, key, flags);
|
|
break;
|
|
default:
|
|
errno = EINVAL;
|
|
return (RET_ERROR);
|
|
}
|
|
|
|
if (status == RET_SUCCESS) {
|
|
__bt_setcur(t, e.page->pgno, e.index);
|
|
|
|
status =
|
|
__bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0);
|
|
|
|
/*
|
|
* If the user is doing concurrent access, we copied the
|
|
* key/data, toss the page.
|
|
*/
|
|
if (F_ISSET(t, B_DB_LOCK))
|
|
mpool_put(t->bt_mp, e.page, 0);
|
|
else
|
|
t->bt_pinned = e.page;
|
|
}
|
|
return (status);
|
|
}
|
|
|
|
/*
|
|
* __bt_seqset --
|
|
* Set the sequential scan to a specific key.
|
|
*
|
|
* Parameters:
|
|
* t: tree
|
|
* ep: storage for returned key
|
|
* key: key for initial scan position
|
|
* flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV
|
|
*
|
|
* Side effects:
|
|
* Pins the page the cursor references.
|
|
*
|
|
* Returns:
|
|
* RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
|
|
*/
|
|
static int
|
|
__bt_seqset(t, ep, key, flags)
|
|
BTREE *t;
|
|
EPG *ep;
|
|
DBT *key;
|
|
int flags;
|
|
{
|
|
PAGE *h;
|
|
pgno_t pg;
|
|
int exact;
|
|
|
|
/*
|
|
* Find the first, last or specific key in the tree and point the
|
|
* cursor at it. The cursor may not be moved until a new key has
|
|
* been found.
|
|
*/
|
|
switch (flags) {
|
|
case R_CURSOR: /* Keyed scan. */
|
|
/*
|
|
* Find the first instance of the key or the smallest key
|
|
* which is greater than or equal to the specified key.
|
|
*/
|
|
if (key->data == NULL || key->size == 0) {
|
|
errno = EINVAL;
|
|
return (RET_ERROR);
|
|
}
|
|
return (__bt_first(t, key, ep, &exact));
|
|
case R_FIRST: /* First record. */
|
|
case R_NEXT:
|
|
/* Walk down the left-hand side of the tree. */
|
|
for (pg = P_ROOT;;) {
|
|
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
|
|
/* Check for an empty tree. */
|
|
if (NEXTINDEX(h) == 0) {
|
|
mpool_put(t->bt_mp, h, 0);
|
|
return (RET_SPECIAL);
|
|
}
|
|
|
|
if (h->flags & (P_BLEAF | P_RLEAF))
|
|
break;
|
|
pg = GETBINTERNAL(h, 0)->pgno;
|
|
mpool_put(t->bt_mp, h, 0);
|
|
}
|
|
ep->page = h;
|
|
ep->index = 0;
|
|
break;
|
|
case R_LAST: /* Last record. */
|
|
case R_PREV:
|
|
/* Walk down the right-hand side of the tree. */
|
|
for (pg = P_ROOT;;) {
|
|
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
|
|
/* Check for an empty tree. */
|
|
if (NEXTINDEX(h) == 0) {
|
|
mpool_put(t->bt_mp, h, 0);
|
|
return (RET_SPECIAL);
|
|
}
|
|
|
|
if (h->flags & (P_BLEAF | P_RLEAF))
|
|
break;
|
|
pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
|
|
mpool_put(t->bt_mp, h, 0);
|
|
}
|
|
|
|
ep->page = h;
|
|
ep->index = NEXTINDEX(h) - 1;
|
|
break;
|
|
}
|
|
return (RET_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* __bt_seqadvance --
|
|
* Advance the sequential scan.
|
|
*
|
|
* Parameters:
|
|
* t: tree
|
|
* flags: R_NEXT, R_PREV
|
|
*
|
|
* Side effects:
|
|
* Pins the page the new key/data record is on.
|
|
*
|
|
* Returns:
|
|
* RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
|
|
*/
|
|
static int
|
|
__bt_seqadv(t, ep, flags)
|
|
BTREE *t;
|
|
EPG *ep;
|
|
int flags;
|
|
{
|
|
CURSOR *c;
|
|
PAGE *h;
|
|
indx_t index;
|
|
pgno_t pg;
|
|
int exact;
|
|
|
|
/*
|
|
* There are a couple of states that we can be in. The cursor has
|
|
* been initialized by the time we get here, but that's all we know.
|
|
*/
|
|
c = &t->bt_cursor;
|
|
|
|
/*
|
|
* The cursor was deleted where there weren't any duplicate records,
|
|
* so the key was saved. Find out where that key would go in the
|
|
* current tree. It doesn't matter if the returned key is an exact
|
|
* match or not -- if it's an exact match, the record was added after
|
|
* the delete so we can just return it. If not, as long as there's
|
|
* a record there, return it.
|
|
*/
|
|
if (F_ISSET(c, CURS_ACQUIRE))
|
|
return (__bt_first(t, &c->key, ep, &exact));
|
|
|
|
/* Get the page referenced by the cursor. */
|
|
if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
|
|
/*
|
|
* Find the next/previous record in the tree and point the cursor at
|
|
* it. The cursor may not be moved until a new key has been found.
|
|
*/
|
|
switch (flags) {
|
|
case R_NEXT: /* Next record. */
|
|
/*
|
|
* The cursor was deleted in duplicate records, and moved
|
|
* forward to a record that has yet to be returned. Clear
|
|
* that flag, and return the record.
|
|
*/
|
|
if (F_ISSET(c, CURS_AFTER))
|
|
goto usecurrent;
|
|
index = c->pg.index;
|
|
if (++index == NEXTINDEX(h)) {
|
|
pg = h->nextpg;
|
|
mpool_put(t->bt_mp, h, 0);
|
|
if (pg == P_INVALID)
|
|
return (RET_SPECIAL);
|
|
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
index = 0;
|
|
}
|
|
break;
|
|
case R_PREV: /* Previous record. */
|
|
/*
|
|
* The cursor was deleted in duplicate records, and moved
|
|
* backward to a record that has yet to be returned. Clear
|
|
* that flag, and return the record.
|
|
*/
|
|
if (F_ISSET(c, CURS_BEFORE)) {
|
|
usecurrent: F_CLR(c, CURS_AFTER | CURS_BEFORE);
|
|
ep->page = h;
|
|
ep->index = c->pg.index;
|
|
return (RET_SUCCESS);
|
|
}
|
|
index = c->pg.index;
|
|
if (index == 0) {
|
|
pg = h->prevpg;
|
|
mpool_put(t->bt_mp, h, 0);
|
|
if (pg == P_INVALID)
|
|
return (RET_SPECIAL);
|
|
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
index = NEXTINDEX(h) - 1;
|
|
} else
|
|
--index;
|
|
break;
|
|
}
|
|
|
|
ep->page = h;
|
|
ep->index = index;
|
|
return (RET_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* __bt_first --
|
|
* Find the first entry.
|
|
*
|
|
* Parameters:
|
|
* t: the tree
|
|
* key: the key
|
|
* erval: return EPG
|
|
* exactp: pointer to exact match flag
|
|
*
|
|
* Returns:
|
|
* The first entry in the tree greater than or equal to key,
|
|
* or RET_SPECIAL if no such key exists.
|
|
*/
|
|
static int
|
|
__bt_first(t, key, erval, exactp)
|
|
BTREE *t;
|
|
const DBT *key;
|
|
EPG *erval;
|
|
int *exactp;
|
|
{
|
|
PAGE *h;
|
|
EPG *ep, save;
|
|
pgno_t pg;
|
|
|
|
/*
|
|
* Find any matching record; __bt_search pins the page.
|
|
*
|
|
* If it's an exact match and duplicates are possible, walk backwards
|
|
* in the tree until we find the first one. Otherwise, make sure it's
|
|
* a valid key (__bt_search may return an index just past the end of a
|
|
* page) and return it.
|
|
*/
|
|
if ((ep = __bt_search(t, key, exactp)) == NULL)
|
|
return (0);
|
|
if (*exactp) {
|
|
if (F_ISSET(t, B_NODUPS)) {
|
|
*erval = *ep;
|
|
return (RET_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* Walk backwards, 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.
|
|
*/
|
|
save = *ep;
|
|
h = ep->page;
|
|
do {
|
|
if (save.page->pgno != ep->page->pgno) {
|
|
mpool_put(t->bt_mp, save.page, 0);
|
|
save = *ep;
|
|
} else
|
|
save.index = ep->index;
|
|
|
|
/*
|
|
* Don't unpin the page the last (or original) match
|
|
* was on, but make sure it's unpinned if an error
|
|
* occurs.
|
|
*/
|
|
if (ep->index == 0) {
|
|
if (h->prevpg == P_INVALID)
|
|
break;
|
|
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 (RET_ERROR);
|
|
}
|
|
ep->page = h;
|
|
ep->index = NEXTINDEX(h);
|
|
}
|
|
--ep->index;
|
|
} while (__bt_cmp(t, key, ep) == 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.
|
|
*/
|
|
if (h->pgno != save.page->pgno)
|
|
mpool_put(t->bt_mp, h, 0);
|
|
|
|
*erval = save;
|
|
return (RET_SUCCESS);
|
|
}
|
|
|
|
/* If at the end of a page, find the next entry. */
|
|
if (ep->index == NEXTINDEX(ep->page)) {
|
|
h = ep->page;
|
|
pg = h->nextpg;
|
|
mpool_put(t->bt_mp, h, 0);
|
|
if (pg == P_INVALID)
|
|
return (RET_SPECIAL);
|
|
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
|
|
return (RET_ERROR);
|
|
ep->index = 0;
|
|
ep->page = h;
|
|
}
|
|
*erval = *ep;
|
|
return (RET_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* __bt_setcur --
|
|
* Set the cursor to an entry in the tree.
|
|
*
|
|
* Parameters:
|
|
* t: the tree
|
|
* pgno: page number
|
|
* index: page index
|
|
*/
|
|
void
|
|
__bt_setcur(t, pgno, index)
|
|
BTREE *t;
|
|
pgno_t pgno;
|
|
u_int index;
|
|
{
|
|
/* Lose any already deleted key. */
|
|
if (t->bt_cursor.key.data != NULL) {
|
|
free(t->bt_cursor.key.data);
|
|
t->bt_cursor.key.size = 0;
|
|
t->bt_cursor.key.data = NULL;
|
|
}
|
|
F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);
|
|
|
|
/* Update the cursor. */
|
|
t->bt_cursor.pg.pgno = pgno;
|
|
t->bt_cursor.pg.index = index;
|
|
F_SET(&t->bt_cursor, CURS_INIT);
|
|
}
|