| Current Path : /usr/src/lib/libc/db/btree/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/lib/libc/db/btree/bt_delete.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.
* 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_delete.c 8.13 (Berkeley) 7/28/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/lib/libc/db/btree/bt_delete.c 189327 2009-03-04 00:58:04Z delphij $");
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <db.h>
#include "btree.h"
static int __bt_bdelete(BTREE *, const DBT *);
static int __bt_curdel(BTREE *, const DBT *, PAGE *, u_int);
static int __bt_pdelete(BTREE *, PAGE *);
static int __bt_relink(BTREE *, PAGE *);
static int __bt_stkacq(BTREE *, PAGE **, CURSOR *);
/*
* __bt_delete
* Delete the item(s) referenced by a key.
*
* Return RET_SPECIAL if the key is not found.
*/
int
__bt_delete(const DB *dbp, const DBT *key, u_int flags)
{
BTREE *t;
CURSOR *c;
PAGE *h;
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;
}
/* Check for change to a read-only tree. */
if (F_ISSET(t, B_RDONLY)) {
errno = EPERM;
return (RET_ERROR);
}
switch (flags) {
case 0:
status = __bt_bdelete(t, key);
break;
case R_CURSOR:
/*
* If flags is R_CURSOR, delete the cursor. Must already
* have started a scan and not have already deleted it.
*/
c = &t->bt_cursor;
if (F_ISSET(c, CURS_INIT)) {
if (F_ISSET(c, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
return (RET_SPECIAL);
if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
return (RET_ERROR);
/*
* If the page is about to be emptied, we'll need to
* delete it, which means we have to acquire a stack.
*/
if (NEXTINDEX(h) == 1)
if (__bt_stkacq(t, &h, &t->bt_cursor))
return (RET_ERROR);
status = __bt_dleaf(t, NULL, h, c->pg.index);
if (NEXTINDEX(h) == 0 && status == RET_SUCCESS) {
if (__bt_pdelete(t, h))
return (RET_ERROR);
} else
mpool_put(t->bt_mp,
h, status == RET_SUCCESS ? MPOOL_DIRTY : 0);
break;
}
/* FALLTHROUGH */
default:
errno = EINVAL;
return (RET_ERROR);
}
if (status == RET_SUCCESS)
F_SET(t, B_MODIFIED);
return (status);
}
/*
* __bt_stkacq --
* Acquire a stack so we can delete a cursor entry.
*
* Parameters:
* t: tree
* hp: pointer to current, pinned PAGE pointer
* c: pointer to the cursor
*
* Returns:
* 0 on success, 1 on failure
*/
static int
__bt_stkacq(BTREE *t, PAGE **hp, CURSOR *c)
{
BINTERNAL *bi;
EPG *e;
EPGNO *parent;
PAGE *h;
indx_t idx;
pgno_t pgno;
recno_t nextpg, prevpg;
int exact, level;
/*
* Find the first occurrence of the key in the tree. Toss the
* currently locked page so we don't hit an already-locked page.
*/
h = *hp;
mpool_put(t->bt_mp, h, 0);
if ((e = __bt_search(t, &c->key, &exact)) == NULL)
return (1);
h = e->page;
/* See if we got it in one shot. */
if (h->pgno == c->pg.pgno)
goto ret;
/*
* Move right, looking for the page. At each move we have to move
* up the stack until we don't have to move to the next page. If
* we have to change pages at an internal level, we have to fix the
* stack back up.
*/
while (h->pgno != c->pg.pgno) {
if ((nextpg = h->nextpg) == P_INVALID)
break;
mpool_put(t->bt_mp, h, 0);
/* Move up the stack. */
for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
/* Get the parent page. */
if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
return (1);
/* Move to the next index. */
if (parent->index != NEXTINDEX(h) - 1) {
idx = parent->index + 1;
BT_PUSH(t, h->pgno, idx);
break;
}
mpool_put(t->bt_mp, h, 0);
}
/* Restore the stack. */
while (level--) {
/* Push the next level down onto the stack. */
bi = GETBINTERNAL(h, idx);
pgno = bi->pgno;
BT_PUSH(t, pgno, 0);
/* Lose the currently pinned page. */
mpool_put(t->bt_mp, h, 0);
/* Get the next level down. */
if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
return (1);
idx = 0;
}
mpool_put(t->bt_mp, h, 0);
if ((h = mpool_get(t->bt_mp, nextpg, 0)) == NULL)
return (1);
}
if (h->pgno == c->pg.pgno)
goto ret;
/* Reacquire the original stack. */
mpool_put(t->bt_mp, h, 0);
if ((e = __bt_search(t, &c->key, &exact)) == NULL)
return (1);
h = e->page;
/*
* Move left, looking for the page. At each move we have to move
* up the stack until we don't have to change pages to move to the
* next page. If we have to change pages at an internal level, we
* have to fix the stack back up.
*/
while (h->pgno != c->pg.pgno) {
if ((prevpg = h->prevpg) == P_INVALID)
break;
mpool_put(t->bt_mp, h, 0);
/* Move up the stack. */
for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
/* Get the parent page. */
if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
return (1);
/* Move to the next index. */
if (parent->index != 0) {
idx = parent->index - 1;
BT_PUSH(t, h->pgno, idx);
break;
}
mpool_put(t->bt_mp, h, 0);
}
/* Restore the stack. */
while (level--) {
/* Push the next level down onto the stack. */
bi = GETBINTERNAL(h, idx);
pgno = bi->pgno;
/* Lose the currently pinned page. */
mpool_put(t->bt_mp, h, 0);
/* Get the next level down. */
if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
return (1);
idx = NEXTINDEX(h) - 1;
BT_PUSH(t, pgno, idx);
}
mpool_put(t->bt_mp, h, 0);
if ((h = mpool_get(t->bt_mp, prevpg, 0)) == NULL)
return (1);
}
ret: mpool_put(t->bt_mp, h, 0);
return ((*hp = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL);
}
/*
* __bt_bdelete --
* Delete all key/data pairs matching the specified key.
*
* Parameters:
* t: tree
* key: key to delete
*
* Returns:
* RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
*/
static int
__bt_bdelete(BTREE *t, const DBT *key)
{
EPG *e;
PAGE *h;
int deleted, exact, redo;
deleted = 0;
/* Find any matching record; __bt_search pins the page. */
loop: if ((e = __bt_search(t, key, &exact)) == NULL)
return (deleted ? RET_SUCCESS : RET_ERROR);
if (!exact) {
mpool_put(t->bt_mp, e->page, 0);
return (deleted ? RET_SUCCESS : RET_SPECIAL);
}
/*
* Delete forward, then delete backward, from the found key. If
* there are duplicates and we reach either side of the page, do
* the key search again, so that we get them all.
*/
redo = 0;
h = e->page;
do {
if (__bt_dleaf(t, key, h, e->index)) {
mpool_put(t->bt_mp, h, 0);
return (RET_ERROR);
}
if (F_ISSET(t, B_NODUPS)) {
if (NEXTINDEX(h) == 0) {
if (__bt_pdelete(t, h))
return (RET_ERROR);
} else
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
return (RET_SUCCESS);
}
deleted = 1;
} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);
/* Check for right-hand edge of the page. */
if (e->index == NEXTINDEX(h))
redo = 1;
/* Delete from the key to the beginning of the page. */
while (e->index-- > 0) {
if (__bt_cmp(t, key, e) != 0)
break;
if (__bt_dleaf(t, key, h, e->index) == RET_ERROR) {
mpool_put(t->bt_mp, h, 0);
return (RET_ERROR);
}
if (e->index == 0)
redo = 1;
}
/* Check for an empty page. */
if (NEXTINDEX(h) == 0) {
if (__bt_pdelete(t, h))
return (RET_ERROR);
goto loop;
}
/* Put the page. */
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
if (redo)
goto loop;
return (RET_SUCCESS);
}
/*
* __bt_pdelete --
* Delete a single page from the tree.
*
* Parameters:
* t: tree
* h: leaf page
*
* Returns:
* RET_SUCCESS, RET_ERROR.
*
* Side-effects:
* mpool_put's the page
*/
static int
__bt_pdelete(BTREE *t, PAGE *h)
{
BINTERNAL *bi;
PAGE *pg;
EPGNO *parent;
indx_t cnt, idx, *ip, offset;
u_int32_t nksize;
char *from;
/*
* Walk the parent page stack -- a LIFO stack of the pages that were
* traversed when we searched for the page where the delete occurred.
* Each stack entry is a page number and a page index offset. The
* offset is for the page traversed on the search. We've just deleted
* a page, so we have to delete the key from the parent page.
*
* If the delete from the parent page makes it empty, this process may
* continue all the way up the tree. We stop if we reach the root page
* (which is never deleted, it's just not worth the effort) or if the
* delete does not empty the page.
*/
while ((parent = BT_POP(t)) != NULL) {
/* Get the parent page. */
if ((pg = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
return (RET_ERROR);
idx = parent->index;
bi = GETBINTERNAL(pg, idx);
/* Free any overflow pages. */
if (bi->flags & P_BIGKEY &&
__ovfl_delete(t, bi->bytes) == RET_ERROR) {
mpool_put(t->bt_mp, pg, 0);
return (RET_ERROR);
}
/*
* Free the parent if it has only the one key and it's not the
* root page. If it's the rootpage, turn it back into an empty
* leaf page.
*/
if (NEXTINDEX(pg) == 1) {
if (pg->pgno == P_ROOT) {
pg->lower = BTDATAOFF;
pg->upper = t->bt_psize;
pg->flags = P_BLEAF;
} else {
if (__bt_relink(t, pg) || __bt_free(t, pg))
return (RET_ERROR);
continue;
}
} else {
/* Pack remaining key items at the end of the page. */
nksize = NBINTERNAL(bi->ksize);
from = (char *)pg + pg->upper;
memmove(from + nksize, from, (char *)bi - from);
pg->upper += nksize;
/* Adjust indices' offsets, shift the indices down. */
offset = pg->linp[idx];
for (cnt = idx, ip = &pg->linp[0]; cnt--; ++ip)
if (ip[0] < offset)
ip[0] += nksize;
for (cnt = NEXTINDEX(pg) - idx; --cnt; ++ip)
ip[0] = ip[1] < offset ? ip[1] + nksize : ip[1];
pg->lower -= sizeof(indx_t);
}
mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
break;
}
/* Free the leaf page, as long as it wasn't the root. */
if (h->pgno == P_ROOT) {
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
return (RET_SUCCESS);
}
return (__bt_relink(t, h) || __bt_free(t, h));
}
/*
* __bt_dleaf --
* Delete a single record from a leaf page.
*
* Parameters:
* t: tree
* key: referenced key
* h: page
* idx: index on page to delete
*
* Returns:
* RET_SUCCESS, RET_ERROR.
*/
int
__bt_dleaf(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
BLEAF *bl;
indx_t cnt, *ip, offset;
u_int32_t nbytes;
void *to;
char *from;
/* If this record is referenced by the cursor, delete the cursor. */
if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
!F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index == idx &&
__bt_curdel(t, key, h, idx))
return (RET_ERROR);
/* If the entry uses overflow pages, make them available for reuse. */
to = bl = GETBLEAF(h, idx);
if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
return (RET_ERROR);
if (bl->flags & P_BIGDATA &&
__ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
return (RET_ERROR);
/* Pack the remaining key/data items at the end of the page. */
nbytes = NBLEAF(bl);
from = (char *)h + h->upper;
memmove(from + nbytes, from, (char *)to - from);
h->upper += nbytes;
/* Adjust the indices' offsets, shift the indices down. */
offset = h->linp[idx];
for (cnt = idx, ip = &h->linp[0]; cnt--; ++ip)
if (ip[0] < offset)
ip[0] += nbytes;
for (cnt = NEXTINDEX(h) - idx; --cnt; ++ip)
ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
h->lower -= sizeof(indx_t);
/* If the cursor is on this page, adjust it as necessary. */
if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
!F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index > idx)
--t->bt_cursor.pg.index;
return (RET_SUCCESS);
}
/*
* __bt_curdel --
* Delete the cursor.
*
* Parameters:
* t: tree
* key: referenced key (or NULL)
* h: page
* idx: index on page to delete
*
* Returns:
* RET_SUCCESS, RET_ERROR.
*/
static int
__bt_curdel(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
CURSOR *c;
EPG e;
PAGE *pg;
int curcopy, status;
/*
* If there are duplicates, move forward or backward to one.
* Otherwise, copy the key into the cursor area.
*/
c = &t->bt_cursor;
F_CLR(c, CURS_AFTER | CURS_BEFORE | CURS_ACQUIRE);
curcopy = 0;
if (!F_ISSET(t, B_NODUPS)) {
/*
* We're going to have to do comparisons. If we weren't
* provided a copy of the key, i.e. the user is deleting
* the current cursor position, get one.
*/
if (key == NULL) {
e.page = h;
e.index = idx;
if ((status = __bt_ret(t, &e,
&c->key, &c->key, NULL, NULL, 1)) != RET_SUCCESS)
return (status);
curcopy = 1;
key = &c->key;
}
/* Check previous key, if not at the beginning of the page. */
if (idx > 0) {
e.page = h;
e.index = idx - 1;
if (__bt_cmp(t, key, &e) == 0) {
F_SET(c, CURS_BEFORE);
goto dup2;
}
}
/* Check next key, if not at the end of the page. */
if (idx < NEXTINDEX(h) - 1) {
e.page = h;
e.index = idx + 1;
if (__bt_cmp(t, key, &e) == 0) {
F_SET(c, CURS_AFTER);
goto dup2;
}
}
/* Check previous key if at the beginning of the page. */
if (idx == 0 && h->prevpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
return (RET_ERROR);
e.page = pg;
e.index = NEXTINDEX(pg) - 1;
if (__bt_cmp(t, key, &e) == 0) {
F_SET(c, CURS_BEFORE);
goto dup1;
}
mpool_put(t->bt_mp, pg, 0);
}
/* Check next key if at the end of the page. */
if (idx == NEXTINDEX(h) - 1 && h->nextpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
return (RET_ERROR);
e.page = pg;
e.index = 0;
if (__bt_cmp(t, key, &e) == 0) {
F_SET(c, CURS_AFTER);
dup1: mpool_put(t->bt_mp, pg, 0);
dup2: c->pg.pgno = e.page->pgno;
c->pg.index = e.index;
return (RET_SUCCESS);
}
mpool_put(t->bt_mp, pg, 0);
}
}
e.page = h;
e.index = idx;
if (curcopy || (status =
__bt_ret(t, &e, &c->key, &c->key, NULL, NULL, 1)) == RET_SUCCESS) {
F_SET(c, CURS_ACQUIRE);
return (RET_SUCCESS);
}
return (status);
}
/*
* __bt_relink --
* Link around a deleted page.
*
* Parameters:
* t: tree
* h: page to be deleted
*/
static int
__bt_relink(BTREE *t, PAGE *h)
{
PAGE *pg;
if (h->nextpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
return (RET_ERROR);
pg->prevpg = h->prevpg;
mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
}
if (h->prevpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
return (RET_ERROR);
pg->nextpg = h->nextpg;
mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
}
return (0);
}