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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998, 1999
* 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. 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 "db_config.h"
#ifndef lint
static const char sccsid[] = "@(#)bt_delete.c 11.6 (Sleepycat) 9/9/99";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <string.h>
#endif
#include "db_int.h"
#include "db_page.h"
#include "db_shash.h"
#include "btree.h"
#include "lock.h"
/*
* CDB___bam_delete --
* Delete the items referenced by a key.
*
* PUBLIC: int CDB___bam_delete __P((DB *, DB_TXN *, DBT *, u_int32_t));
*/
int
CDB___bam_delete(dbp, txn, key, flags)
DB *dbp;
DB_TXN *txn;
DBT *key;
u_int32_t flags;
{
DBC *dbc;
DBT lkey;
DBT data;
u_int32_t f_init, f_next;
int ret, t_ret;
PANIC_CHECK(dbp->dbenv);
DB_ILLEGAL_BEFORE_OPEN(dbp, "DB->del");
/* Check for invalid flags. */
if ((ret =
CDB___db_delchk(dbp, key, flags, F_ISSET(dbp, DB_AM_RDONLY))) != 0)
return (ret);
/* Allocate a cursor. */
if ((ret = dbp->cursor(dbp, txn, &dbc, DB_WRITELOCK)) != 0)
return (ret);
DEBUG_LWRITE(dbc, txn, "bam_delete", key, NULL, flags);
/*
* Walk a cursor through the key/data pairs, deleting as we go. Set
* the DB_DBT_USERMEM flag, as this might be a threaded application
* and the flags checking will catch us. We don't actually want the
* keys or data, so request a partial of length 0.
*/
memset(&lkey, 0, sizeof(lkey));
F_SET(&lkey, DB_DBT_USERMEM | DB_DBT_PARTIAL);
memset(&data, 0, sizeof(data));
F_SET(&data, DB_DBT_USERMEM | DB_DBT_PARTIAL);
/* If locking, set read-modify-write flag. */
f_init = DB_SET;
f_next = DB_NEXT_DUP;
if (F_ISSET(dbp->dbenv, DB_ENV_LOCKING)) {
f_init |= DB_RMW;
f_next |= DB_RMW;
}
/* Walk through the set of key/data pairs, deleting as we go. */
if ((ret = dbc->c_get(dbc, key, &data, f_init)) != 0)
goto err;
for (;;) {
if ((ret = dbc->c_del(dbc, 0)) != 0)
goto err;
if ((ret = dbc->c_get(dbc, &lkey, &data, f_next)) != 0) {
if (ret == DB_NOTFOUND) {
ret = 0;
break;
}
goto err;
}
}
err: /* Discard the cursor. */
if ((t_ret = dbc->c_close(dbc)) != 0 && ret == 0)
ret = t_ret;
return (ret);
}
/*
* CDB___bam_ditem --
* Delete one or more entries from a page.
*
* PUBLIC: int CDB___bam_ditem __P((DBC *, PAGE *, u_int32_t));
*/
int
CDB___bam_ditem(dbc, h, indx)
DBC *dbc;
PAGE *h;
u_int32_t indx;
{
BINTERNAL *bi;
BKEYDATA *bk;
BOVERFLOW *bo;
DB *dbp;
u_int32_t nbytes;
int ret;
dbp = dbc->dbp;
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 (CDB___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 (CDB___bam_adjindx(dbc,
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 (CDB___bam_adjindx(dbc,
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 =
CDB___db_ddup(dbc, bo->pgno)) != 0)
return (ret);
} else
if ((ret =
CDB___db_doff(dbc, bo->pgno)) != 0)
return (ret);
break;
case B_KEYDATA:
nbytes = BKEYDATA_SIZE(bk->len);
break;
default:
return (CDB___db_pgfmt(dbp, h->pgno));
}
break;
default:
return (CDB___db_pgfmt(dbp, h->pgno));
}
/* Delete the item and update the cursors. */
if ((ret = CDB___db_ditem(dbc, h, indx, nbytes)) != 0)
return (ret);
CDB___bam_ca_di(dbp, PGNO(h), indx, -1);
/* Mark the page dirty. */
return (CDB_memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY));
}
/*
* CDB___bam_adjindx --
* Adjust an index on the page.
*
* PUBLIC: int CDB___bam_adjindx __P((DBC *, PAGE *, u_int32_t, u_int32_t, int));
*/
int
CDB___bam_adjindx(dbc, h, indx, indx_copy, is_insert)
DBC *dbc;
PAGE *h;
u_int32_t indx, indx_copy;
int is_insert;
{
DB *dbp;
db_indx_t copy;
int ret;
dbp = dbc->dbp;
/* Log the change. */
if (DB_LOGGING(dbc) &&
(ret = CDB___bam_adj_log(dbp->dbenv, dbc->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 = CDB_memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY);
/* Adjust the cursors. */
CDB___bam_ca_di(dbp, h->pgno, indx, is_insert ? 1 : -1);
return (0);
}
/*
* CDB___bam_dpage --
* Delete a page from the tree.
*
* PUBLIC: int CDB___bam_dpage __P((DBC *, const DBT *));
*/
int
CDB___bam_dpage(dbc, key)
DBC *dbc;
const DBT *key;
{
BTREE_CURSOR *cp;
DB *dbp;
DB_LOCK lock;
PAGE *h;
db_pgno_t pgno, root_pgno;
int level; /* !!!: has to hold number of tree levels. */
int exact, ret;
dbp = dbc->dbp;
cp = dbc->internal;
ret = 0;
/*
* The locking protocol is that we acquire locks by walking down the
* tree, to avoid the obvious deadlocks.
*
* Call CDB___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.
*/
root_pgno = ((BTREE *)dbp->bt_internal)->bt_root;
for (level = LEAFLEVEL;; ++level) {
/* Acquire a page and its parent, locked. */
if ((ret =
CDB___bam_search(dbc, 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 = cp->csp[-1].page;
if (h->pgno == root_pgno || NUM_ENT(h) != 1)
break;
/* Release the two locked pages. */
(void)CDB_memp_fput(dbp->mpf, cp->csp[-1].page, 0);
(void)__TLPUT(dbc, cp->csp[-1].lock);
(void)CDB_memp_fput(dbp->mpf, cp->csp[0].page, 0);
(void)__TLPUT(dbc, cp->csp[0].lock);
}
/*
* Leave the stack pointer one after the last entry, we may be about
* to push more items on the stack.
*/
++cp->csp;
/*
* cp->csp[-2].page is the top page, which we're not going to delete,
* and cp->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 = cp->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 =
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &lock)) != 0)
goto release;
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
goto release;
BT_STK_PUSH(cp, h, 0, lock, DB_LOCK_WRITE, ret);
}
/* Adjust back to reference the last page on the stack. */
BT_STK_POP(cp);
/* Delete the pages. */
return (CDB___bam_dpages(dbc));
release:
/* Adjust back to reference the last page on the stack. */
BT_STK_POP(cp);
/* Discard any locked pages and return. */
CDB___bam_stkrel(dbc, 0);
return (ret);
}
/*
* CDB___bam_dpages --
* Delete a set of locked pages.
*
* PUBLIC: int CDB___bam_dpages __P((DBC *));
*/
int
CDB___bam_dpages(dbc)
DBC *dbc;
{
BTREE_CURSOR *cp;
DB *dbp;
DBT a, b;
DB_LOCK c_lock, p_lock;
EPG *epg;
PAGE *child, *parent;
db_indx_t nitems;
db_pgno_t pgno, root_pgno;
db_recno_t rcnt;
int done, ret;
dbp = dbc->dbp;
cp = dbc->internal;
root_pgno = ((BTREE *)dbp->bt_internal)->bt_root;
epg = cp->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 = CDB___db_relink(dbc, DB_REM_PAGE, cp->csp->page, NULL, 1)) != 0)
goto release;
/*
* We have the entire stack of deletable pages locked.
*
* Delete the highest page in the tree's reference to the underlying
* stack of pages. Then, release that page, letting the rest of the
* tree get back to business.
*/
if ((ret = CDB___bam_ditem(dbc, epg->page, epg->indx)) != 0) {
release: (void)CDB___bam_stkrel(dbc, 0);
return (ret);
}
pgno = epg->page->pgno;
nitems = NUM_ENT(epg->page);
(void)CDB_memp_fput(dbp->mpf, epg->page, 0);
(void)__TLPUT(dbc, epg->lock);
/*
* Free the rest of the stack of pages.
*
* !!!
* Don't bother checking for errors. We've unlinked the subtree from
* the tree, and there's no possibility of recovery outside of doing
* TXN rollback.
*/
while (++epg <= cp->csp) {
/*
* Delete page entries so they will be restored as part of
* recovery.
*/
if (NUM_ENT(epg->page) != 0)
(void)CDB___bam_ditem(dbc, epg->page, epg->indx);
(void)CDB___db_free(dbc, epg->page);
(void)__TLPUT(dbc, epg->lock);
}
BT_STK_CLR(cp);
/*
* Try and collapse the tree a level -- this is only applicable
* if we've deleted the next-to-last element from the root page.
*
* There are two cases when collapsing a tree.
*
* If we've just deleted the last item from the root page, there is no
* further work to be done. The code above has emptied the root page
* and freed all pages below it.
*/
if (pgno != root_pgno || nitems != 1)
return (0);
/*
* If we just deleted the next-to-last item from the root page, the
* tree can collapse one or more levels. While there remains only a
* single item on the root page, 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 stays deeper than we'd like.
*/
for (done = 0; !done;) {
/* Initialize. */
parent = child = NULL;
p_lock.off = c_lock.off = LOCK_INVALID;
/* Lock the root. */
pgno = root_pgno;
if ((ret =
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &p_lock)) != 0)
goto stop;
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &parent)) != 0)
goto stop;
if (NUM_ENT(parent) != 1 ||
(TYPE(parent) != P_IBTREE && TYPE(parent) != P_IRECNO))
goto stop;
pgno = TYPE(parent) == P_IBTREE ?
GET_BINTERNAL(parent, 0)->pgno :
GET_RINTERNAL(parent, 0)->pgno;
/* Lock the child page. */
if ((ret =
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &c_lock)) != 0)
goto stop;
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &child)) != 0)
goto stop;
/* Log the change. */
if (DB_LOGGING(dbc)) {
memset(&a, 0, sizeof(a));
a.data = child;
a.size = dbp->pgsize;
memset(&b, 0, sizeof(b));
b.data = P_ENTRY(parent, 0);
b.size = BINTERNAL_SIZE(((BINTERNAL *)b.data)->len);
CDB___bam_rsplit_log(dbp->dbenv, dbc->txn,
&child->lsn, 0, dbp->log_fileid, child->pgno, &a,
RE_NREC(parent), &b, &parent->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. Note that we are about to overwrite everything
* on the parent, including its LSN. This is actually OK,
* because the above log message, which describes this update,
* stores its LSN on the child page. When the child is copied
* to the parent, the correct LSN is going to copied into
* place in the parent.
*/
COMPQUIET(rcnt, 0);
if (TYPE(child) == P_IRECNO ||
(TYPE(child) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
rcnt = RE_NREC(parent);
memcpy(parent, child, dbp->pgsize);
parent->pgno = root_pgno;
if (TYPE(child) == P_IRECNO ||
(TYPE(child) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
RE_NREC_SET(parent, rcnt);
/* Mark the pages dirty. */
CDB_memp_fset(dbp->mpf, parent, DB_MPOOL_DIRTY);
CDB_memp_fset(dbp->mpf, child, DB_MPOOL_DIRTY);
/* Adjust the cursors. */
CDB___bam_ca_rsplit(dbp, child->pgno, root_pgno);
/*
* Free the page copied onto the root page and discard its
* lock. (The call to CDB___db_free() discards our reference
* to the page.)
*/
(void)CDB___db_free(dbc, child);
child = NULL;
if (0) {
stop: done = 1;
}
if (p_lock.off != LOCK_INVALID)
(void)__TLPUT(dbc, p_lock);
if (parent != NULL)
CDB_memp_fput(dbp->mpf, parent, 0);
if (c_lock.off != LOCK_INVALID)
(void)__TLPUT(dbc, c_lock);
if (child != NULL)
CDB_memp_fput(dbp->mpf, child, 0);
}
return (0);
}