gecko-dev/db/btree/bt_delete.c
1998-10-15 03:56:37 +00:00

648 lines
17 KiB
C

/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998
* 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_delete.c 10.31 (Sleepycat) 5/6/98";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <string.h>
#endif
#include "db_int.h"
#include "db_page.h"
#include "btree.h"
static int __bam_dpages __P((DB *, BTREE *));
/*
* __bam_delete --
* Delete the items referenced by a key.
*
* PUBLIC: int __bam_delete __P((DB *, DB_TXN *, DBT *, u_int32_t));
*/
int
__bam_delete(argdbp, txn, key, flags)
DB *argdbp;
DB_TXN *txn;
DBT *key;
u_int32_t flags;
{
BTREE *t;
DB *dbp;
PAGE *h;
db_indx_t cnt, i, indx;
int dpage, exact, ret, stack;
DEBUG_LWRITE(argdbp, txn, "bam_delete", key, NULL, flags);
stack = 0;
/* Check for invalid flags. */
if ((ret = __db_delchk(argdbp,
key, flags, F_ISSET(argdbp, DB_AM_RDONLY))) != 0)
return (ret);
GETHANDLE(argdbp, txn, &dbp, ret);
t = dbp->internal;
/* Search the tree for the key; delete only deletes exact matches. */
if ((ret = __bam_search(dbp, key, S_DELETE, 1, NULL, &exact)) != 0)
goto err;
stack = 1;
h = t->bt_csp->page;
indx = t->bt_csp->indx;
/* Delete the key/data pair, including any on-or-off page duplicates. */
for (cnt = 1, i = indx;; ++cnt)
if ((i += P_INDX) >= NUM_ENT(h) || h->inp[i] != h->inp[indx])
break;
for (; cnt > 0; --cnt, ++t->lstat.bt_deleted)
if (__bam_ca_delete(dbp, h->pgno, indx, NULL, 1) == 0) {
/*
* XXX
* Delete the key item first, otherwise the duplicate
* checks in __bam_ditem() won't work!
*/
if ((ret = __bam_ditem(dbp, h, indx)) != 0)
goto err;
if ((ret = __bam_ditem(dbp, h, indx)) != 0)
goto err;
} else {
B_DSET(GET_BKEYDATA(h, indx + O_INDX)->type);
indx += P_INDX;
}
/* If we're using record numbers, update internal page record counts. */
if (F_ISSET(dbp, DB_BT_RECNUM) && (ret = __bam_adjust(dbp, t, -1)) != 0)
goto err;
/* If the page is now empty, delete it. */
dpage = NUM_ENT(h) == 0 && h->pgno != PGNO_ROOT;
__bam_stkrel(dbp);
stack = 0;
ret = dpage ? __bam_dpage(dbp, key) : 0;
err: if (stack)
__bam_stkrel(dbp);
PUTHANDLE(dbp);
return (ret);
}
/*
* __ram_delete --
* Delete the items referenced by a key.
*
* PUBLIC: int __ram_delete __P((DB *, DB_TXN *, DBT *, u_int32_t));
*/
int
__ram_delete(argdbp, txn, key, flags)
DB *argdbp;
DB_TXN *txn;
DBT *key;
u_int32_t flags;
{
BKEYDATA bk;
BTREE *t;
DB *dbp;
DBT hdr, data;
PAGE *h;
db_indx_t indx;
db_recno_t recno;
int exact, ret, stack;
stack = 0;
/* Check for invalid flags. */
if ((ret = __db_delchk(argdbp,
key, flags, F_ISSET(argdbp, DB_AM_RDONLY))) != 0)
return (ret);
GETHANDLE(argdbp, txn, &dbp, ret);
t = dbp->internal;
/* Check the user's record number and fill in as necessary. */
if ((ret = __ram_getno(argdbp, key, &recno, 0)) != 0)
goto err;
/* Search the tree for the key; delete only deletes exact matches. */
if ((ret = __bam_rsearch(dbp, &recno, S_DELETE, 1, &exact)) != 0)
goto err;
if (!exact) {
ret = DB_NOTFOUND;
goto err;
}
h = t->bt_csp->page;
indx = t->bt_csp->indx;
stack = 1;
/* If the record has already been deleted, we couldn't have found it. */
if (B_DISSET(GET_BKEYDATA(h, indx)->type)) {
ret = DB_KEYEMPTY;
goto done;
}
/*
* If we're not renumbering records, replace the record with a marker
* and return.
*/
if (!F_ISSET(dbp, DB_RE_RENUMBER)) {
if ((ret = __bam_ditem(dbp, h, indx)) != 0)
goto err;
B_TSET(bk.type, B_KEYDATA, 1);
bk.len = 0;
memset(&hdr, 0, sizeof(hdr));
hdr.data = &bk;
hdr.size = SSZA(BKEYDATA, data);
memset(&data, 0, sizeof(data));
data.data = (char *)"";
data.size = 0;
if ((ret = __db_pitem(dbp,
h, indx, BKEYDATA_SIZE(0), &hdr, &data)) != 0)
goto err;
++t->lstat.bt_deleted;
goto done;
}
/* Delete the item. */
if ((ret = __bam_ditem(dbp, h, indx)) != 0)
goto err;
++t->lstat.bt_deleted;
if (t->bt_recno != NULL)
F_SET(t->bt_recno, RECNO_MODIFIED);
/* Adjust the counts. */
__bam_adjust(dbp, t, -1);
/* Adjust the cursors. */
__ram_ca(dbp, recno, CA_DELETE);
/*
* If the page is now empty, delete it -- we have the whole tree
* locked, so there are no preparations to make. Else, release
* the pages.
*/
if (NUM_ENT(h) == 0 && h->pgno != PGNO_ROOT) {
stack = 0;
ret = __bam_dpages(dbp, t);
}
done:
err: if (stack)
__bam_stkrel(dbp);
PUTHANDLE(dbp);
return (ret);
}
/*
* __bam_ditem --
* Delete one or more entries from a page.
*
* PUBLIC: int __bam_ditem __P((DB *, PAGE *, u_int32_t));
*/
int
__bam_ditem(dbp, h, indx)
DB *dbp;
PAGE *h;
u_int32_t indx;
{
BINTERNAL *bi;
BKEYDATA *bk;
BOVERFLOW *bo;
u_int32_t nbytes;
int ret;
switch (TYPE(h)) {
case P_IBTREE:
bi = GET_BINTERNAL(h, indx);
switch (B_TYPE(bi->type)) {
case B_DUPLICATE:
case B_OVERFLOW:
nbytes = BINTERNAL_SIZE(bi->len);
bo = (BOVERFLOW *)bi->data;
goto offpage;
case B_KEYDATA:
nbytes = BINTERNAL_SIZE(bi->len);
break;
default:
return (__db_pgfmt(dbp, h->pgno));
}
break;
case P_IRECNO:
nbytes = RINTERNAL_SIZE;
break;
case P_LBTREE:
/*
* If it's a duplicate key, discard the index and don't touch
* the actual page item.
*
* XXX
* This works because no data item can have an index matching
* any other index so even if the data item is in a key "slot",
* it won't match any other index.
*/
if ((indx % 2) == 0) {
/*
* Check for a duplicate after us on the page. NOTE:
* we have to delete the key item before deleting the
* data item, otherwise the "indx + P_INDX" calculation
* won't work!
*/
if (indx + P_INDX < (u_int32_t)NUM_ENT(h) &&
h->inp[indx] == h->inp[indx + P_INDX])
return (__bam_adjindx(dbp,
h, indx, indx + O_INDX, 0));
/*
* Check for a duplicate before us on the page. It
* doesn't matter if we delete the key item before or
* after the data item for the purposes of this one.
*/
if (indx > 0 && h->inp[indx] == h->inp[indx - P_INDX])
return (__bam_adjindx(dbp,
h, indx, indx - P_INDX, 0));
}
/* FALLTHROUGH */
case P_LRECNO:
bk = GET_BKEYDATA(h, indx);
switch (B_TYPE(bk->type)) {
case B_DUPLICATE:
case B_OVERFLOW:
nbytes = BOVERFLOW_SIZE;
bo = GET_BOVERFLOW(h, indx);
offpage: /* Delete duplicate/offpage chains. */
if (B_TYPE(bo->type) == B_DUPLICATE) {
if ((ret =
__db_ddup(dbp, bo->pgno, __bam_free)) != 0)
return (ret);
} else
if ((ret =
__db_doff(dbp, bo->pgno, __bam_free)) != 0)
return (ret);
break;
case B_KEYDATA:
nbytes = BKEYDATA_SIZE(bk->len);
break;
default:
return (__db_pgfmt(dbp, h->pgno));
}
break;
default:
return (__db_pgfmt(dbp, h->pgno));
}
/* Delete the item. */
if ((ret = __db_ditem(dbp, h, indx, nbytes)) != 0)
return (ret);
/* Mark the page dirty. */
return (memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY));
}
/*
* __bam_adjindx --
* Adjust an index on the page.
*
* PUBLIC: int __bam_adjindx __P((DB *, PAGE *, u_int32_t, u_int32_t, int));
*/
int
__bam_adjindx(dbp, h, indx, indx_copy, is_insert)
DB *dbp;
PAGE *h;
u_int32_t indx, indx_copy;
int is_insert;
{
db_indx_t copy;
int ret;
/* Log the change. */
if (DB_LOGGING(dbp) &&
(ret = __bam_adj_log(dbp->dbenv->lg_info, dbp->txn, &LSN(h),
0, dbp->log_fileid, PGNO(h), &LSN(h), indx, indx_copy,
(u_int32_t)is_insert)) != 0)
return (ret);
if (is_insert) {
copy = h->inp[indx_copy];
if (indx != NUM_ENT(h))
memmove(&h->inp[indx + O_INDX], &h->inp[indx],
sizeof(db_indx_t) * (NUM_ENT(h) - indx));
h->inp[indx] = copy;
++NUM_ENT(h);
} else {
--NUM_ENT(h);
if (indx != NUM_ENT(h))
memmove(&h->inp[indx], &h->inp[indx + O_INDX],
sizeof(db_indx_t) * (NUM_ENT(h) - indx));
}
/* Mark the page dirty. */
ret = memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY);
/* Adjust the cursors. */
__bam_ca_di(dbp, h->pgno, indx, is_insert ? 1 : -1);
return (0);
}
/*
* __bam_dpage --
* Delete a page from the tree.
*
* PUBLIC: int __bam_dpage __P((DB *, const DBT *));
*/
int
__bam_dpage(dbp, key)
DB *dbp;
const DBT *key;
{
BTREE *t;
DB_LOCK lock;
PAGE *h;
db_pgno_t pgno;
int level; /* !!!: has to hold number of tree levels. */
int exact, ret;
ret = 0;
t = dbp->internal;
/*
* The locking protocol is that we acquire locks by walking down the
* tree, to avoid the obvious deadlocks.
*
* Call __bam_search to reacquire the empty leaf page, but this time
* get both the leaf page and it's parent, locked. Walk back up the
* tree, until we have the top pair of pages that we want to delete.
* Once we have the top page that we want to delete locked, lock the
* underlying pages and check to make sure they're still empty. If
* they are, delete them.
*/
for (level = LEAFLEVEL;; ++level) {
/* Acquire a page and its parent, locked. */
if ((ret =
__bam_search(dbp, key, S_WRPAIR, level, NULL, &exact)) != 0)
return (ret);
/*
* If we reach the root or the page isn't going to be empty
* when we delete one record, quit.
*/
h = t->bt_csp[-1].page;
if (h->pgno == PGNO_ROOT || NUM_ENT(h) != 1)
break;
/* Release the two locked pages. */
(void)memp_fput(dbp->mpf, t->bt_csp[-1].page, 0);
(void)__BT_TLPUT(dbp, t->bt_csp[-1].lock);
(void)memp_fput(dbp->mpf, t->bt_csp[0].page, 0);
(void)__BT_TLPUT(dbp, t->bt_csp[0].lock);
}
/*
* Leave the stack pointer one after the last entry, we may be about
* to push more items on the stack.
*/
++t->bt_csp;
/*
* t->bt_csp[-2].page is the top page, which we're not going to delete,
* and t->bt_csp[-1].page is the first page we are going to delete.
*
* Walk down the chain, acquiring the rest of the pages until we've
* retrieved the leaf page. If we find any pages that aren't going
* to be emptied by the delete, someone else added something while we
* were walking the tree, and we discontinue the delete.
*/
for (h = t->bt_csp[-1].page;;) {
if (ISLEAF(h)) {
if (NUM_ENT(h) != 0)
goto release;
break;
} else
if (NUM_ENT(h) != 1)
goto release;
/*
* Get the next page, write lock it and push it onto the stack.
* We know it's index 0, because it can only have one element.
*/
pgno = TYPE(h) == P_IBTREE ?
GET_BINTERNAL(h, 0)->pgno : GET_RINTERNAL(h, 0)->pgno;
if ((ret = __bam_lget(dbp, 0, pgno, DB_LOCK_WRITE, &lock)) != 0)
goto release;
if ((ret = __bam_pget(dbp, &h, &pgno, 0)) != 0)
goto release;
BT_STK_PUSH(t, h, 0, lock, ret);
if (ret != 0)
goto release;
}
BT_STK_POP(t);
return (__bam_dpages(dbp, t));
release:
/* Discard any locked pages and return. */
BT_STK_POP(t);
__bam_stkrel(dbp);
return (ret);
}
/*
* __bam_dpages --
* Delete a set of locked pages.
*/
static int
__bam_dpages(dbp, t)
DB *dbp;
BTREE *t;
{
DBT a, b;
DB_LOCK lock;
EPG *epg;
PAGE *h;
db_pgno_t pgno;
db_recno_t rcnt;
int ret;
COMPQUIET(rcnt, 0);
epg = t->bt_sp;
/*
* !!!
* There is an interesting deadlock situation here. We have to relink
* the leaf page chain around the leaf page being deleted. Consider
* a cursor walking through the leaf pages, that has the previous page
* read-locked and is waiting on a lock for the page we're deleting.
* It will deadlock here. This is a problem, because if our process is
* selected to resolve the deadlock, we'll leave an empty leaf page
* that we can never again access by walking down the tree. So, before
* we unlink the subtree, we relink the leaf page chain.
*/
if ((ret = __db_relink(dbp, t->bt_csp->page, NULL, 1)) != 0)
goto release;
/*
* We have the entire stack of deletable pages locked. Start from the
* top of the tree and move to the bottom, as it's better to release
* the inner pages as soon as possible.
*/
if ((ret = __bam_ditem(dbp, epg->page, epg->indx)) != 0)
goto release;
/*
* If we just deleted the last or next-to-last item from the root page,
* the tree can collapse a level. Write lock the last page referenced
* by the root page and copy it over the root page. If we can't get a
* write lock, that's okay, the tree just remains a level deeper than
* we'd like.
*/
h = epg->page;
if (h->pgno == PGNO_ROOT && NUM_ENT(h) <= 1) {
pgno = TYPE(epg->page) == P_IBTREE ?
GET_BINTERNAL(epg->page, 0)->pgno :
GET_RINTERNAL(epg->page, 0)->pgno;
if ((ret = __bam_lget(dbp, 0, pgno, DB_LOCK_WRITE, &lock)) != 0)
goto release;
if ((ret = __bam_pget(dbp, &h, &pgno, 0)) != 0)
goto release;
/* Log the change. */
if (DB_LOGGING(dbp)) {
memset(&a, 0, sizeof(a));
a.data = h;
a.size = dbp->pgsize;
memset(&b, 0, sizeof(b));
b.data = P_ENTRY(epg->page, 0);
b.size = BINTERNAL_SIZE(((BINTERNAL *)b.data)->len);
__bam_rsplit_log(dbp->dbenv->lg_info, dbp->txn,
&h->lsn, 0, dbp->log_fileid, h->pgno, &a,
RE_NREC(epg->page), &b, &epg->page->lsn);
}
/*
* Make the switch.
*
* One fixup -- if the tree has record numbers and we're not
* converting to a leaf page, we have to preserve the total
* record count.
*/
if (TYPE(h) == P_IRECNO ||
(TYPE(h) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
rcnt = RE_NREC(epg->page);
memcpy(epg->page, h, dbp->pgsize);
epg->page->pgno = PGNO_ROOT;
if (TYPE(h) == P_IRECNO ||
(TYPE(h) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
RE_NREC_SET(epg->page, rcnt);
(void)memp_fset(dbp->mpf, epg->page, DB_MPOOL_DIRTY);
/*
* Free the page copied onto the root page and discard its
* lock. (The call to __bam_free() discards our reference
* to the page.)
*
* It's possible that the reverse split we're doing involves
* pages from the stack of pages we're deleting. Don't free
* the page twice.
*/
if (h->pgno == (epg + 1)->page->pgno)
(void)memp_fput(dbp->mpf, h, 0);
else {
(void)__bam_free(dbp, h);
++t->lstat.bt_freed;
}
(void)__BT_TLPUT(dbp, lock);
/* Adjust the cursors. */
__bam_ca_move(dbp, h->pgno, PGNO_ROOT);
}
/* Release the top page in the subtree. */
(void)memp_fput(dbp->mpf, epg->page, 0);
(void)__BT_TLPUT(dbp, epg->lock);
/*
* Free the rest of the pages.
*
* XXX
* Don't bother checking for errors. We've unlinked the subtree from
* the tree, and there's no possibility of recovery.
*/
while (++epg <= t->bt_csp) {
/*
* XXX
* Why do we need to do this? Isn't the page already empty?
*/
if (NUM_ENT(epg->page) != 0)
(void)__bam_ditem(dbp, epg->page, epg->indx);
(void)__bam_free(dbp, epg->page);
(void)__BT_TLPUT(dbp, epg->lock);
++t->lstat.bt_freed;
}
return (0);
release:
/* Discard any remaining pages and return. */
for (; epg <= t->bt_csp; ++epg) {
(void)memp_fput(dbp->mpf, epg->page, 0);
(void)__BT_TLPUT(dbp, epg->lock);
}
return (ret);
}