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glibc/db2/btree/bt_cursor.c
Ulrich Drepper ec239360d1 Update. 
* db2/Makefile (distribute): Remove files which do not exist
	anymore.
1999-06-13 13:36:34 +00:00

1914 lines
47 KiB
C
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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998
* Sleepycat Software. All rights reserved.
*/
#include "config.h"
#ifndef lint
static const char sccsid[] = "@(#)bt_cursor.c 10.81 (Sleepycat) 12/16/98";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#endif
#include "db_int.h"
#include "db_page.h"
#include "btree.h"
#include "shqueue.h"
#include "db_shash.h"
#include "lock.h"
#include "lock_ext.h"
static int __bam_c_close __P((DBC *));
static int __bam_c_del __P((DBC *, u_int32_t));
static int __bam_c_destroy __P((DBC *));
static int __bam_c_first __P((DBC *, CURSOR *));
static int __bam_c_get __P((DBC *, DBT *, DBT *, u_int32_t));
static int __bam_c_getstack __P((DBC *, CURSOR *));
static int __bam_c_last __P((DBC *, CURSOR *));
static int __bam_c_next __P((DBC *, CURSOR *, int));
static int __bam_c_physdel __P((DBC *, CURSOR *, PAGE *));
static int __bam_c_prev __P((DBC *, CURSOR *));
static int __bam_c_put __P((DBC *, DBT *, DBT *, u_int32_t));
static void __bam_c_reset __P((CURSOR *));
static int __bam_c_rget __P((DBC *, DBT *, u_int32_t));
static int __bam_c_search __P((DBC *, CURSOR *, const DBT *, u_int32_t, int *));
static int __bam_dsearch __P((DBC *, CURSOR *, DBT *, u_int32_t *));
/* Discard the current page/lock held by a cursor. */
#undef DISCARD
#define DISCARD(dbc, cp) { \
if ((cp)->page != NULL) { \
(void)memp_fput((dbc)->dbp->mpf, (cp)->page, 0); \
(cp)->page = NULL; \
} \
if ((cp)->lock != LOCK_INVALID) { \
(void)__BT_TLPUT((dbc), (cp)->lock); \
(cp)->lock = LOCK_INVALID; \
} \
}
/* If the cursor references a deleted record. */
#undef IS_CUR_DELETED
#define IS_CUR_DELETED(cp) \
(((cp)->dpgno == PGNO_INVALID && \
B_DISSET(GET_BKEYDATA((cp)->page, \
(cp)->indx + O_INDX)->type)) || \
((cp)->dpgno != PGNO_INVALID && \
B_DISSET(GET_BKEYDATA((cp)->page, (cp)->dindx)->type)))
/* If the cursor and index combination references a deleted record. */
#undef IS_DELETED
#define IS_DELETED(cp, indx) \
(((cp)->dpgno == PGNO_INVALID && \
B_DISSET(GET_BKEYDATA((cp)->page, (indx) + O_INDX)->type)) || \
((cp)->dpgno != PGNO_INVALID && \
B_DISSET(GET_BKEYDATA((cp)->page, (indx))->type)))
/*
* Test to see if two cursors could point to duplicates of the same key,
* whether on-page or off-page. The leaf page numbers must be the same
* in both cases. In the case of off-page duplicates, the key indices
* on the leaf page will be the same. In the case of on-page duplicates,
* the duplicate page number must not be set, and the key index offsets
* must be the same. For the last test, as the saved copy of the cursor
* will not have a valid page pointer, we use the cursor's.
*/
#undef POSSIBLE_DUPLICATE
#define POSSIBLE_DUPLICATE(cursor, saved_copy) \
((cursor)->pgno == (saved_copy).pgno && \
((cursor)->indx == (saved_copy).indx || \
((cursor)->dpgno == PGNO_INVALID && \
(saved_copy).dpgno == PGNO_INVALID && \
(cursor)->page->inp[(cursor)->indx] == \
(cursor)->page->inp[(saved_copy).indx])))
/*
* __bam_c_reset --
* Initialize internal cursor structure.
*/
static void
__bam_c_reset(cp)
CURSOR *cp;
{
cp->sp = cp->csp = cp->stack;
cp->esp = cp->stack + sizeof(cp->stack) / sizeof(cp->stack[0]);
cp->page = NULL;
cp->pgno = PGNO_INVALID;
cp->indx = 0;
cp->dpgno = PGNO_INVALID;
cp->dindx = 0;
cp->lock = LOCK_INVALID;
cp->mode = DB_LOCK_NG;
cp->recno = RECNO_OOB;
cp->flags = 0;
}
/*
* __bam_c_init --
* Initialize the access private portion of a cursor
*
* PUBLIC: int __bam_c_init __P((DBC *));
*/
int
__bam_c_init(dbc)
DBC *dbc;
{
DB *dbp;
CURSOR *cp;
int ret;
if ((ret = __os_calloc(1, sizeof(CURSOR), &cp)) != 0)
return (ret);
dbp = dbc->dbp;
cp->dbc = dbc;
/*
* Logical record numbers are always the same size, and we don't want
* to have to check for space every time we return one. Allocate it
* in advance.
*/
if (dbp->type == DB_RECNO || F_ISSET(dbp, DB_BT_RECNUM)) {
if ((ret = __os_malloc(sizeof(db_recno_t),
NULL, &dbc->rkey.data)) != 0) {
__os_free(cp, sizeof(CURSOR));
return (ret);
}
dbc->rkey.ulen = sizeof(db_recno_t);
}
/* Initialize methods. */
dbc->internal = cp;
if (dbp->type == DB_BTREE) {
dbc->c_am_close = __bam_c_close;
dbc->c_am_destroy = __bam_c_destroy;
dbc->c_del = __bam_c_del;
dbc->c_get = __bam_c_get;
dbc->c_put = __bam_c_put;
} else {
dbc->c_am_close = __bam_c_close;
dbc->c_am_destroy = __bam_c_destroy;
dbc->c_del = __ram_c_del;
dbc->c_get = __ram_c_get;
dbc->c_put = __ram_c_put;
}
/* Initialize dynamic information. */
__bam_c_reset(cp);
return (0);
}
/*
* __bam_c_close --
* Close down the cursor from a single use.
*/
static int
__bam_c_close(dbc)
DBC *dbc;
{
CURSOR *cp;
DB *dbp;
int ret;
dbp = dbc->dbp;
cp = dbc->internal;
ret = 0;
/*
* If a cursor deleted a btree key, perform the actual deletion.
* (Recno keys are either deleted immediately or never deleted.)
*/
if (dbp->type == DB_BTREE && F_ISSET(cp, C_DELETED))
ret = __bam_c_physdel(dbc, cp, NULL);
/* Discard any locks not acquired inside of a transaction. */
if (cp->lock != LOCK_INVALID) {
(void)__BT_TLPUT(dbc, cp->lock);
cp->lock = LOCK_INVALID;
}
/* Sanity checks. */
#ifdef DIAGNOSTIC
if (cp->csp != cp->stack)
__db_err(dbp->dbenv, "btree cursor close: stack not empty");
#endif
/* Initialize dynamic information. */
__bam_c_reset(cp);
return (ret);
}
/*
* __bam_c_destroy --
* Close a single cursor -- internal version.
*/
static int
__bam_c_destroy(dbc)
DBC *dbc;
{
/* Discard the structures. */
__os_free(dbc->internal, sizeof(CURSOR));
return (0);
}
/*
* __bam_c_del --
* Delete using a cursor.
*/
static int
__bam_c_del(dbc, flags)
DBC *dbc;
u_int32_t flags;
{
CURSOR *cp;
DB *dbp;
DB_LOCK lock;
PAGE *h;
db_pgno_t pgno;
db_indx_t indx;
int ret;
dbp = dbc->dbp;
cp = dbc->internal;
h = NULL;
DB_PANIC_CHECK(dbp);
/* Check for invalid flags. */
if ((ret = __db_cdelchk(dbp, flags,
F_ISSET(dbp, DB_AM_RDONLY), cp->pgno != PGNO_INVALID)) != 0)
return (ret);
/*
* If we are running CDB, this had better be either a write
* cursor or an immediate writer.
*/
if (F_ISSET(dbp, DB_AM_CDB))
if (!F_ISSET(dbc, DBC_RMW | DBC_WRITER))
return (EINVAL);
DEBUG_LWRITE(dbc, dbc->txn, "bam_c_del", NULL, NULL, flags);
/* If already deleted, return failure. */
if (F_ISSET(cp, C_DELETED))
return (DB_KEYEMPTY);
/*
* We don't physically delete the record until the cursor moves,
* so we have to have a long-lived write lock on the page instead
* of a long-lived read lock. Note, we have to have a read lock
* to even get here, so we simply discard it.
*/
if (F_ISSET(dbp, DB_AM_LOCKING) && cp->mode != DB_LOCK_WRITE) {
if ((ret = __bam_lget(dbc,
0, cp->pgno, DB_LOCK_WRITE, &lock)) != 0)
goto err;
(void)__BT_TLPUT(dbc, cp->lock);
cp->lock = lock;
cp->mode = DB_LOCK_WRITE;
}
/*
* Acquire the underlying page (which may be different from the above
* page because it may be a duplicate page), and set the on-page and
* in-cursor delete flags. We don't need to lock it as we've already
* write-locked the page leading to it.
*/
if (cp->dpgno == PGNO_INVALID) {
pgno = cp->pgno;
indx = cp->indx;
} else {
pgno = cp->dpgno;
indx = cp->dindx;
}
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
goto err;
/* Log the change. */
if (DB_LOGGING(dbc) &&
(ret = __bam_cdel_log(dbp->dbenv->lg_info, dbc->txn, &LSN(h),
0, dbp->log_fileid, PGNO(h), &LSN(h), indx)) != 0) {
(void)memp_fput(dbp->mpf, h, 0);
goto err;
}
/*
* Set the intent-to-delete flag on the page and update all cursors. */
if (cp->dpgno == PGNO_INVALID)
B_DSET(GET_BKEYDATA(h, indx + O_INDX)->type);
else
B_DSET(GET_BKEYDATA(h, indx)->type);
(void)__bam_ca_delete(dbp, pgno, indx, 1);
ret = memp_fput(dbp->mpf, h, DB_MPOOL_DIRTY);
h = NULL;
/*
* If the tree has record numbers, we have to adjust the counts.
*
* !!!
* This test is right -- we don't yet support duplicates and record
* numbers in the same tree, so ignore duplicates if DB_BT_RECNUM
* set.
*/
if (F_ISSET(dbp, DB_BT_RECNUM)) {
if ((ret = __bam_c_getstack(dbc, cp)) != 0)
goto err;
if ((ret = __bam_adjust(dbc, -1)) != 0)
goto err;
(void)__bam_stkrel(dbc, 0);
}
err: if (h != NULL)
(void)memp_fput(dbp->mpf, h, 0);
return (ret);
}
/*
* __bam_c_get --
* Get using a cursor (btree).
*/
static int
__bam_c_get(dbc, key, data, flags)
DBC *dbc;
DBT *key, *data;
u_int32_t flags;
{
CURSOR *cp, copy, start;
DB *dbp;
PAGE *h;
int exact, ret, tmp_rmw;
dbp = dbc->dbp;
cp = dbc->internal;
DB_PANIC_CHECK(dbp);
/* Check for invalid flags. */
if ((ret = __db_cgetchk(dbp,
key, data, flags, cp->pgno != PGNO_INVALID)) != 0)
return (ret);
/* Clear OR'd in additional bits so we can check for flag equality. */
tmp_rmw = 0;
if (LF_ISSET(DB_RMW)) {
if (!F_ISSET(dbp, DB_AM_CDB)) {
tmp_rmw = 1;
F_SET(dbc, DBC_RMW);
}
LF_CLR(DB_RMW);
}
DEBUG_LREAD(dbc, dbc->txn, "bam_c_get",
flags == DB_SET || flags == DB_SET_RANGE ? key : NULL, NULL, flags);
/*
* Return a cursor's record number. It has nothing to do with the
* cursor get code except that it's been rammed into the interface.
*/
if (flags == DB_GET_RECNO) {
ret = __bam_c_rget(dbc, data, flags);
if (tmp_rmw)
F_CLR(dbc, DBC_RMW);
return (ret);
}
/*
* Initialize the cursor for a new retrieval. Clear the cursor's
* page pointer, it was set before this operation, and no longer
* has any meaning.
*/
cp->page = NULL;
copy = *cp;
cp->lock = LOCK_INVALID;
switch (flags) {
case DB_CURRENT:
/* It's not possible to return a deleted record. */
if (F_ISSET(cp, C_DELETED)) {
ret = DB_KEYEMPTY;
goto err;
}
/* Acquire the current page. */
if ((ret = __bam_lget(dbc,
0, cp->pgno, DB_LOCK_READ, &cp->lock)) == 0)
ret = memp_fget(dbp->mpf,
cp->dpgno == PGNO_INVALID ? &cp->pgno : &cp->dpgno,
0, &cp->page);
if (ret != 0)
goto err;
break;
case DB_NEXT_DUP:
if (cp->pgno == PGNO_INVALID) {
ret = EINVAL;
goto err;
}
if ((ret = __bam_c_next(dbc, cp, 1)) != 0)
goto err;
/* Make sure we didn't go past the end of the duplicates. */
if (!POSSIBLE_DUPLICATE(cp, copy)) {
ret = DB_NOTFOUND;
goto err;
}
break;
case DB_NEXT:
if (cp->pgno != PGNO_INVALID) {
if ((ret = __bam_c_next(dbc, cp, 1)) != 0)
goto err;
break;
}
/* FALLTHROUGH */
case DB_FIRST:
if ((ret = __bam_c_first(dbc, cp)) != 0)
goto err;
break;
case DB_PREV:
if (cp->pgno != PGNO_INVALID) {
if ((ret = __bam_c_prev(dbc, cp)) != 0)
goto err;
break;
}
/* FALLTHROUGH */
case DB_LAST:
if ((ret = __bam_c_last(dbc, cp)) != 0)
goto err;
break;
case DB_SET:
if ((ret = __bam_c_search(dbc, cp, key, flags, &exact)) != 0)
goto err;
/*
* We cannot currently be referencing a deleted record, but we
* may be referencing off-page duplicates.
*
* If we're referencing off-page duplicates, move off-page.
* If we moved off-page, move to the next non-deleted record.
* If we moved to the next non-deleted record, check to make
* sure we didn't switch records because our current record
* had no non-deleted data items.
*/
start = *cp;
if ((ret = __bam_dup(dbc, cp, cp->indx, 0)) != 0)
goto err;
if (cp->dpgno != PGNO_INVALID && IS_CUR_DELETED(cp)) {
if ((ret = __bam_c_next(dbc, cp, 0)) != 0)
goto err;
if (!POSSIBLE_DUPLICATE(cp, start)) {
ret = DB_NOTFOUND;
goto err;
}
}
break;
case DB_SET_RECNO:
if ((ret = __bam_c_search(dbc, cp, key, flags, &exact)) != 0)
goto err;
break;
case DB_GET_BOTH:
if (F_ISSET(dbc, DBC_CONTINUE | DBC_KEYSET)) {
/* Acquire the current page. */
if ((ret = memp_fget(dbp->mpf,
cp->dpgno == PGNO_INVALID ? &cp->pgno : &cp->dpgno,
0, &cp->page)) != 0)
goto err;
/* If DBC_CONTINUE, move to the next item. */
if (F_ISSET(dbc, DBC_CONTINUE) &&
(ret = __bam_c_next(dbc, cp, 1)) != 0)
goto err;
} else {
if ((ret =
__bam_c_search(dbc, cp, key, flags, &exact)) != 0)
goto err;
/*
* We may be referencing a duplicates page. Move to
* the first duplicate.
*/
if ((ret = __bam_dup(dbc, cp, cp->indx, 0)) != 0)
goto err;
}
/* Search for a matching entry. */
if ((ret = __bam_dsearch(dbc, cp, data, NULL)) != 0)
goto err;
/* Ignore deleted entries. */
if (IS_CUR_DELETED(cp)) {
ret = DB_NOTFOUND;
goto err;
}
break;
case DB_SET_RANGE:
if ((ret = __bam_c_search(dbc, cp, key, flags, &exact)) != 0)
goto err;
/*
* As we didn't require an exact match, the search function
* may have returned an entry past the end of the page. If
* so, move to the next entry.
*/
if (cp->indx == NUM_ENT(cp->page) &&
(ret = __bam_c_next(dbc, cp, 0)) != 0)
goto err;
/*
* We may be referencing off-page duplicates, if so, move
* off-page.
*/
if ((ret = __bam_dup(dbc, cp, cp->indx, 0)) != 0)
goto err;
/*
* We may be referencing a deleted record, if so, move to
* the next non-deleted record.
*/
if (IS_CUR_DELETED(cp) && (ret = __bam_c_next(dbc, cp, 0)) != 0)
goto err;
break;
}
/*
* Return the key if the user didn't give us one. If we've moved to
* a duplicate page, we may no longer have a pointer to the main page,
* so we have to go get it. We know that it's already read-locked,
* however, so we don't have to acquire a new lock.
*/
if (flags != DB_SET) {
if (cp->dpgno != PGNO_INVALID) {
if ((ret = memp_fget(dbp->mpf, &cp->pgno, 0, &h)) != 0)
goto err;
} else
h = cp->page;
ret = __db_ret(dbp,
h, cp->indx, key, &dbc->rkey.data, &dbc->rkey.ulen);
if (cp->dpgno != PGNO_INVALID)
(void)memp_fput(dbp->mpf, h, 0);
if (ret)
goto err;
}
/* Return the data. */
if ((ret = __db_ret(dbp, cp->page,
cp->dpgno == PGNO_INVALID ? cp->indx + O_INDX : cp->dindx,
data, &dbc->rdata.data, &dbc->rdata.ulen)) != 0)
goto err;
/*
* If the previous cursor record has been deleted, physically delete
* the entry from the page. We clear the deleted flag before we call
* the underlying delete routine so that, if an error occurs, and we
* restore the cursor, the deleted flag is cleared. This is because,
* if we manage to physically modify the page, and then restore the
* cursor, we might try to repeat the page modification when closing
* the cursor.
*/
if (F_ISSET(&copy, C_DELETED)) {
F_CLR(&copy, C_DELETED);
if ((ret = __bam_c_physdel(dbc, &copy, cp->page)) != 0)
goto err;
}
F_CLR(cp, C_DELETED);
/* Release the previous lock, if any; the current lock is retained. */
if (copy.lock != LOCK_INVALID)
(void)__BT_TLPUT(dbc, copy.lock);
/* Release the current page. */
if ((ret = memp_fput(dbp->mpf, cp->page, 0)) != 0)
goto err;
if (0) {
err: if (cp->page != NULL)
(void)memp_fput(dbp->mpf, cp->page, 0);
if (cp->lock != LOCK_INVALID)
(void)__BT_TLPUT(dbc, cp->lock);
*cp = copy;
}
/* Release temporary lock upgrade. */
if (tmp_rmw)
F_CLR(dbc, DBC_RMW);
return (ret);
}
/*
* __bam_dsearch --
* Search for a matching data item (or the first data item that's
* equal to or greater than the one we're searching for).
*/
static int
__bam_dsearch(dbc, cp, data, iflagp)
DBC *dbc;
CURSOR *cp;
DBT *data;
u_int32_t *iflagp;
{
DB *dbp;
CURSOR copy, last;
int cmp, ret;
dbp = dbc->dbp;
/*
* If iflagp is non-NULL, we're doing an insert.
*
* If the duplicates are off-page, use the duplicate search routine.
*/
if (cp->dpgno != PGNO_INVALID) {
if ((ret = __db_dsearch(dbc, iflagp != NULL,
data, cp->dpgno, &cp->dindx, &cp->page, &cmp)) != 0)
return (ret);
cp->dpgno = cp->page->pgno;
if (iflagp == NULL) {
if (cmp != 0)
return (DB_NOTFOUND);
return (0);
}
*iflagp = DB_BEFORE;
return (0);
}
/* Otherwise, do the search ourselves. */
copy = *cp;
for (;;) {
/* Save the last interesting cursor position. */
last = *cp;
/* See if the data item matches the one we're looking for. */
if ((cmp = __bam_cmp(dbp, data, cp->page, cp->indx + O_INDX,
dbp->dup_compare == NULL ?
__bam_defcmp : dbp->dup_compare)) == 0) {
if (iflagp != NULL)
*iflagp = DB_AFTER;
return (0);
}
/*
* If duplicate entries are sorted, we're done if we find a
* page entry that sorts greater than the application item.
* If doing an insert, return success, otherwise DB_NOTFOUND.
*/
if (dbp->dup_compare != NULL && cmp < 0) {
if (iflagp == NULL)
return (DB_NOTFOUND);
*iflagp = DB_BEFORE;
return (0);
}
/*
* Move to the next item. If we reach the end of the page and
* we're doing an insert, set the cursor to the last item and
* set the referenced memory location so callers know to insert
* after the item, instead of before it. If not inserting, we
* return DB_NOTFOUND.
*/
if ((cp->indx += P_INDX) >= NUM_ENT(cp->page)) {
if (iflagp == NULL)
return (DB_NOTFOUND);
goto use_last;
}
/*
* Make sure we didn't go past the end of the duplicates. The
* error conditions are the same as above.
*/
if (!POSSIBLE_DUPLICATE(cp, copy)) {
if (iflagp == NULL)
return (DB_NOTFOUND);
use_last: *cp = last;
*iflagp = DB_AFTER;
return (0);
}
}
/* NOTREACHED */
}
/*
* __bam_c_rget --
* Return the record number for a cursor.
*/
static int
__bam_c_rget(dbc, data, flags)
DBC *dbc;
DBT *data;
u_int32_t flags;
{
CURSOR *cp;
DB *dbp;
DBT dbt;
db_recno_t recno;
int exact, ret;
COMPQUIET(flags, 0);
dbp = dbc->dbp;
cp = dbc->internal;
/* Get the page with the current item on it. */
if ((ret = memp_fget(dbp->mpf, &cp->pgno, 0, &cp->page)) != 0)
return (ret);
/* Get a copy of the key. */
memset(&dbt, 0, sizeof(DBT));
dbt.flags = DB_DBT_MALLOC | DB_DBT_INTERNAL;
if ((ret = __db_ret(dbp, cp->page, cp->indx, &dbt, NULL, NULL)) != 0)
goto err;
exact = 1;
if ((ret = __bam_search(dbc, &dbt,
F_ISSET(dbc, DBC_RMW) ? S_FIND_WR : S_FIND,
1, &recno, &exact)) != 0)
goto err;
ret = __db_retcopy(data, &recno, sizeof(recno),
&dbc->rdata.data, &dbc->rdata.ulen, dbp->db_malloc);
/* Release the stack. */
__bam_stkrel(dbc, 0);
err: (void)memp_fput(dbp->mpf, cp->page, 0);
__os_free(dbt.data, dbt.size);
return (ret);
}
/*
* __bam_c_put --
* Put using a cursor.
*/
static int
__bam_c_put(dbc, key, data, flags)
DBC *dbc;
DBT *key, *data;
u_int32_t flags;
{
CURSOR *cp, copy;
DB *dbp;
DBT dbt;
db_indx_t indx;
db_pgno_t pgno;
u_int32_t iiflags, iiop;
int exact, needkey, ret, stack;
void *arg;
dbp = dbc->dbp;
cp = dbc->internal;
DB_PANIC_CHECK(dbp);
DEBUG_LWRITE(dbc, dbc->txn, "bam_c_put",
flags == DB_KEYFIRST || flags == DB_KEYLAST ? key : NULL,
data, flags);
if ((ret = __db_cputchk(dbp, key, data, flags,
F_ISSET(dbp, DB_AM_RDONLY), cp->pgno != PGNO_INVALID)) != 0)
return (ret);
/*
* If we are running CDB, this had better be either a write
* cursor or an immediate writer. If it's a regular writer,
* that means we have an IWRITE lock and we need to upgrade
* it to a write lock.
*/
if (F_ISSET(dbp, DB_AM_CDB)) {
if (!F_ISSET(dbc, DBC_RMW | DBC_WRITER))
return (EINVAL);
if (F_ISSET(dbc, DBC_RMW) &&
(ret = lock_get(dbp->dbenv->lk_info, dbc->locker,
DB_LOCK_UPGRADE, &dbc->lock_dbt, DB_LOCK_WRITE,
&dbc->mylock)) != 0)
return (EAGAIN);
}
if (0) {
split: /*
* To split, we need a valid key for the page. Since it's a
* cursor, we have to build one.
*
* Acquire a copy of a key from the page.
*/
if (needkey) {
memset(&dbt, 0, sizeof(DBT));
if ((ret = __db_ret(dbp, cp->page, indx,
&dbt, &dbc->rkey.data, &dbc->rkey.ulen)) != 0)
goto err;
arg = &dbt;
} else
arg = key;
/*
* Discard any locks and pinned pages (the locks are discarded
* even if we're running with transactions, as they lock pages
* that we're sorry we ever acquired). If stack is set and the
* cursor entries are valid, they point to the same entries as
* the stack, don't free them twice.
*/
if (stack) {
(void)__bam_stkrel(dbc, 1);
stack = 0;
} else
DISCARD(dbc, cp);
/*
* Restore the cursor to its original value. This is necessary
* for two reasons. First, we are about to copy it in case of
* error, again. Second, we adjust cursors during the split,
* and we have to ensure this cursor is adjusted appropriately,
* along with all the other cursors.
*/
*cp = copy;
if ((ret = __bam_split(dbc, arg)) != 0)
goto err;
}
/*
* Initialize the cursor for a new retrieval. Clear the cursor's
* page pointer, it was set before this operation, and no longer
* has any meaning.
*/
cp->page = NULL;
copy = *cp;
cp->lock = LOCK_INVALID;
iiflags = needkey = ret = stack = 0;
switch (flags) {
case DB_AFTER:
case DB_BEFORE:
case DB_CURRENT:
needkey = 1;
if (cp->dpgno == PGNO_INVALID) {
pgno = cp->pgno;
indx = cp->indx;
} else {
pgno = cp->dpgno;
indx = cp->dindx;
}
/*
* !!!
* This test is right -- we don't yet support duplicates and
* record numbers in the same tree, so ignore duplicates if
* DB_BT_RECNUM set.
*/
if (F_ISSET(dbp, DB_BT_RECNUM) &&
(flags != DB_CURRENT || F_ISSET(cp, C_DELETED))) {
/* Acquire a complete stack. */
if ((ret = __bam_c_getstack(dbc, cp)) != 0)
goto err;
cp->page = cp->csp->page;
stack = 1;
iiflags = BI_DOINCR;
} else {
/* Acquire the current page. */
if ((ret = __bam_lget(dbc,
0, cp->pgno, DB_LOCK_WRITE, &cp->lock)) == 0)
ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page);
if (ret != 0)
goto err;
iiflags = 0;
}
/*
* If the user has specified a duplicate comparison function,
* we return an error if DB_CURRENT was specified and the
* replacement data doesn't compare equal to the current data.
* This stops apps from screwing up the duplicate sort order.
*/
if (flags == DB_CURRENT && dbp->dup_compare != NULL)
if (__bam_cmp(dbp, data,
cp->page, indx, dbp->dup_compare) != 0) {
ret = EINVAL;
goto err;
}
iiop = flags;
break;
case DB_KEYFIRST:
case DB_KEYLAST:
/*
* If we have a duplicate comparison function, we position to
* the first of any on-page duplicates, and use __bam_dsearch
* to search for the right slot. Otherwise, we position to
* the first/last of any on-page duplicates based on the flag
* value.
*/
if ((ret = __bam_c_search(dbc, cp, key,
flags == DB_KEYFIRST || dbp->dup_compare != NULL ?
DB_KEYFIRST : DB_KEYLAST, &exact)) != 0)
goto err;
stack = 1;
/*
* If an exact match:
* If duplicates aren't supported, replace the current
* item. (When implementing the DB->put function, our
* caller has already checked the DB_NOOVERWRITE flag.)
*
* If there's a duplicate comparison function, find the
* correct slot for this duplicate item.
*
* If there's no duplicate comparison function, set the
* insert flag based on the argument flags.
*
* If there's no match, the search function returned the
* smallest slot greater than the key, use it.
*/
if (exact) {
if (F_ISSET(dbp, DB_AM_DUP)) {
/*
* If at off-page duplicate page, move to the
* first or last entry -- if a comparison
* function was specified, start searching at
* the first entry. Otherwise, move based on
* the DB_KEYFIRST/DB_KEYLAST flags.
*/
if ((ret = __bam_dup(dbc, cp, cp->indx,
dbp->dup_compare == NULL &&
flags != DB_KEYFIRST)) != 0)
goto err;
/*
* If there's a comparison function, search for
* the correct slot. Otherwise, set the insert
* flag based on the argment flag.
*/
if (dbp->dup_compare == NULL)
iiop = flags == DB_KEYFIRST ?
DB_BEFORE : DB_AFTER;
else
if ((ret = __bam_dsearch(dbc,
cp, data, &iiop)) != 0)
goto err;
} else
iiop = DB_CURRENT;
iiflags = 0;
} else {
iiop = DB_BEFORE;
iiflags = BI_NEWKEY;
}
if (cp->dpgno == PGNO_INVALID) {
pgno = cp->pgno;
indx = cp->indx;
} else {
pgno = cp->dpgno;
indx = cp->dindx;
}
break;
}
ret = __bam_iitem(dbc, &cp->page, &indx, key, data, iiop, iiflags);
if (ret == DB_NEEDSPLIT)
goto split;
if (ret != 0)
goto err;
/*
* Reset any cursors referencing this item that might have the item
* marked for deletion.
*/
if (iiop == DB_CURRENT) {
(void)__bam_ca_delete(dbp, pgno, indx, 0);
/*
* It's also possible that we are the cursor that had the
* item marked for deletion, in which case we want to make
* sure that we don't delete it because we had the delete
* flag set already.
*/
if (cp->pgno == copy.pgno && cp->indx == copy.indx &&
cp->dpgno == copy.dpgno && cp->dindx == copy.dindx)
F_CLR(&copy, C_DELETED);
}
/*
* Update the cursor to point to the new entry. The new entry was
* stored on the current page, because we split pages until it was
* possible.
*/
if (cp->dpgno == PGNO_INVALID)
cp->indx = indx;
else
cp->dindx = indx;
/*
* If the previous cursor record has been deleted, physically delete
* the entry from the page. We clear the deleted flag before we call
* the underlying delete routine so that, if an error occurs, and we
* restore the cursor, the deleted flag is cleared. This is because,
* if we manage to physically modify the page, and then restore the
* cursor, we might try to repeat the page modification when closing
* the cursor.
*/
if (F_ISSET(&copy, C_DELETED)) {
F_CLR(&copy, C_DELETED);
if ((ret = __bam_c_physdel(dbc, &copy, cp->page)) != 0)
goto err;
}
F_CLR(cp, C_DELETED);
/* Release the previous lock, if any; the current lock is retained. */
if (copy.lock != LOCK_INVALID)
(void)__BT_TLPUT(dbc, copy.lock);
/*
* Discard any pages pinned in the tree and their locks, except for
* the leaf page, for which we only discard the pin, not the lock.
*
* Note, the leaf page participated in the stack we acquired, and so
* we have to adjust the stack as necessary. If there was only a
* single page on the stack, we don't have to free further stack pages.
*/
if (stack && BT_STK_POP(cp) != NULL)
(void)__bam_stkrel(dbc, 0);
/* Release the current page. */
if ((ret = memp_fput(dbp->mpf, cp->page, 0)) != 0)
goto err;
if (0) {
err: /* Discard any pinned pages. */
if (stack)
(void)__bam_stkrel(dbc, 0);
else
DISCARD(dbc, cp);
*cp = copy;
}
if (F_ISSET(dbp, DB_AM_CDB) && F_ISSET(dbc, DBC_RMW))
(void)__lock_downgrade(dbp->dbenv->lk_info, dbc->mylock,
DB_LOCK_IWRITE, 0);
return (ret);
}
/*
* __bam_c_first --
* Return the first record.
*/
static int
__bam_c_first(dbc, cp)
DBC *dbc;
CURSOR *cp;
{
DB *dbp;
db_pgno_t pgno;
int ret;
dbp = dbc->dbp;
/* Walk down the left-hand side of the tree. */
for (pgno = PGNO_ROOT;;) {
if ((ret =
__bam_lget(dbc, 0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
/* If we find a leaf page, we're done. */
if (ISLEAF(cp->page))
break;
pgno = GET_BINTERNAL(cp->page, 0)->pgno;
DISCARD(dbc, cp);
}
cp->pgno = cp->page->pgno;
cp->indx = 0;
cp->dpgno = PGNO_INVALID;
/* Check for duplicates. */
if ((ret = __bam_dup(dbc, cp, cp->indx, 0)) != 0)
return (ret);
/* If on an empty page or a deleted record, move to the next one. */
if (NUM_ENT(cp->page) == 0 || IS_CUR_DELETED(cp))
if ((ret = __bam_c_next(dbc, cp, 0)) != 0)
return (ret);
return (0);
}
/*
* __bam_c_last --
* Return the last record.
*/
static int
__bam_c_last(dbc, cp)
DBC *dbc;
CURSOR *cp;
{
DB *dbp;
db_pgno_t pgno;
int ret;
dbp = dbc->dbp;
/* Walk down the right-hand side of the tree. */
for (pgno = PGNO_ROOT;;) {
if ((ret =
__bam_lget(dbc, 0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
/* If we find a leaf page, we're done. */
if (ISLEAF(cp->page))
break;
pgno =
GET_BINTERNAL(cp->page, NUM_ENT(cp->page) - O_INDX)->pgno;
DISCARD(dbc, cp);
}
cp->pgno = cp->page->pgno;
cp->indx = NUM_ENT(cp->page) == 0 ? 0 : NUM_ENT(cp->page) - P_INDX;
cp->dpgno = PGNO_INVALID;
/* Check for duplicates. */
if ((ret = __bam_dup(dbc, cp, cp->indx, 1)) != 0)
return (ret);
/* If on an empty page or a deleted record, move to the next one. */
if (NUM_ENT(cp->page) == 0 || IS_CUR_DELETED(cp))
if ((ret = __bam_c_prev(dbc, cp)) != 0)
return (ret);
return (0);
}
/*
* __bam_c_next --
* Move to the next record.
*/
static int
__bam_c_next(dbc, cp, initial_move)
DBC *dbc;
CURSOR *cp;
int initial_move;
{
DB *dbp;
db_indx_t adjust, indx;
db_pgno_t pgno;
int ret;
dbp = dbc->dbp;
/*
* We're either moving through a page of duplicates or a btree leaf
* page.
*/
if (cp->dpgno == PGNO_INVALID) {
adjust = dbp->type == DB_BTREE ? P_INDX : O_INDX;
pgno = cp->pgno;
indx = cp->indx;
} else {
adjust = O_INDX;
pgno = cp->dpgno;
indx = cp->dindx;
}
if (cp->page == NULL) {
if ((ret =
__bam_lget(dbc, 0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
}
/*
* If at the end of the page, move to a subsequent page.
*
* !!!
* Check for >= NUM_ENT. If we're here as the result of a search that
* landed us on NUM_ENT, we'll increment indx before we test.
*
* !!!
* This code handles empty pages and pages with only deleted entries.
*/
if (initial_move)
indx += adjust;
for (;;) {
if (indx >= NUM_ENT(cp->page)) {
/*
* If we're in a btree leaf page, we've reached the end
* of the tree. If we've reached the end of a page of
* duplicates, continue from the btree leaf page where
* we found this page of duplicates.
*/
pgno = cp->page->next_pgno;
if (pgno == PGNO_INVALID) {
/* If in a btree leaf page, it's EOF. */
if (cp->dpgno == PGNO_INVALID)
return (DB_NOTFOUND);
/* Continue from the last btree leaf page. */
cp->dpgno = PGNO_INVALID;
adjust = P_INDX;
pgno = cp->pgno;
indx = cp->indx + P_INDX;
} else
indx = 0;
DISCARD(dbc, cp);
if ((ret = __bam_lget(dbc,
0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret =
memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
continue;
}
/* Ignore deleted records. */
if (IS_DELETED(cp, indx)) {
indx += adjust;
continue;
}
/*
* If we're not in a duplicates page, check to see if we've
* found a page of duplicates, in which case we move to the
* first entry.
*/
if (cp->dpgno == PGNO_INVALID) {
cp->pgno = cp->page->pgno;
cp->indx = indx;
if ((ret = __bam_dup(dbc, cp, indx, 0)) != 0)
return (ret);
if (cp->dpgno != PGNO_INVALID) {
indx = cp->dindx;
adjust = O_INDX;
continue;
}
} else {
cp->dpgno = cp->page->pgno;
cp->dindx = indx;
}
break;
}
return (0);
}
/*
* __bam_c_prev --
* Move to the previous record.
*/
static int
__bam_c_prev(dbc, cp)
DBC *dbc;
CURSOR *cp;
{
DB *dbp;
db_indx_t indx, adjust;
db_pgno_t pgno;
int ret, set_indx;
dbp = dbc->dbp;
/*
* We're either moving through a page of duplicates or a btree leaf
* page.
*/
if (cp->dpgno == PGNO_INVALID) {
adjust = dbp->type == DB_BTREE ? P_INDX : O_INDX;
pgno = cp->pgno;
indx = cp->indx;
} else {
adjust = O_INDX;
pgno = cp->dpgno;
indx = cp->dindx;
}
if (cp->page == NULL) {
if ((ret =
__bam_lget(dbc, 0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
}
/*
* If at the beginning of the page, move to any previous one.
*
* !!!
* This code handles empty pages and pages with only deleted entries.
*/
for (;;) {
if (indx == 0) {
/*
* If we're in a btree leaf page, we've reached the
* beginning of the tree. If we've reached the first
* of a page of duplicates, continue from the btree
* leaf page where we found this page of duplicates.
*/
pgno = cp->page->prev_pgno;
if (pgno == PGNO_INVALID) {
/* If in a btree leaf page, it's SOF. */
if (cp->dpgno == PGNO_INVALID)
return (DB_NOTFOUND);
/* Continue from the last btree leaf page. */
cp->dpgno = PGNO_INVALID;
adjust = P_INDX;
pgno = cp->pgno;
indx = cp->indx;
set_indx = 0;
} else
set_indx = 1;
DISCARD(dbc, cp);
if ((ret = __bam_lget(dbc,
0, pgno, DB_LOCK_READ, &cp->lock)) != 0)
return (ret);
if ((ret =
memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
if (set_indx)
indx = NUM_ENT(cp->page);
if (indx == 0)
continue;
}
/* Ignore deleted records. */
indx -= adjust;
if (IS_DELETED(cp, indx))
continue;
/*
* If we're not in a duplicates page, check to see if we've
* found a page of duplicates, in which case we move to the
* last entry.
*/
if (cp->dpgno == PGNO_INVALID) {
cp->pgno = cp->page->pgno;
cp->indx = indx;
if ((ret = __bam_dup(dbc, cp, indx, 1)) != 0)
return (ret);
if (cp->dpgno != PGNO_INVALID) {
indx = cp->dindx + O_INDX;
adjust = O_INDX;
continue;
}
} else {
cp->dpgno = cp->page->pgno;
cp->dindx = indx;
}
break;
}
return (0);
}
/*
* __bam_c_search --
* Move to a specified record.
*/
static int
__bam_c_search(dbc, cp, key, flags, exactp)
DBC *dbc;
CURSOR *cp;
const DBT *key;
u_int32_t flags;
int *exactp;
{
BTREE *t;
DB *dbp;
DB_LOCK lock;
PAGE *h;
db_recno_t recno;
db_indx_t indx;
u_int32_t sflags;
int cmp, needexact, ret;
dbp = dbc->dbp;
t = dbp->internal;
/* Find an entry in the database. */
switch (flags) {
case DB_SET_RECNO:
if ((ret = __ram_getno(dbc, key, &recno, 0)) != 0)
return (ret);
sflags = F_ISSET(dbc, DBC_RMW) ? S_FIND_WR : S_FIND;
needexact = *exactp = 1;
ret = __bam_rsearch(dbc, &recno, sflags, 1, exactp);
break;
case DB_SET:
case DB_GET_BOTH:
sflags = F_ISSET(dbc, DBC_RMW) ? S_FIND_WR : S_FIND;
needexact = *exactp = 1;
goto search;
case DB_SET_RANGE:
sflags = F_ISSET(dbc, DBC_RMW) ? S_FIND_WR : S_FIND;
needexact = *exactp = 0;
goto search;
case DB_KEYFIRST:
sflags = S_KEYFIRST;
goto fast_search;
case DB_KEYLAST:
sflags = S_KEYLAST;
fast_search: needexact = *exactp = 0;
/*
* If the application has a history of inserting into the first
* or last pages of the database, we check those pages first to
* avoid doing a full search.
*
* Record numbers can't be fast-tracked, the entire tree has to
* be locked.
*/
h = NULL;
lock = LOCK_INVALID;
if (F_ISSET(dbp, DB_BT_RECNUM))
goto search;
/* Check if the application has a history of sorted input. */
if (t->bt_lpgno == PGNO_INVALID)
goto search;
/*
* Lock and retrieve the page on which we did the last insert.
* It's okay if it doesn't exist, or if it's not the page type
* we expected, it just means that the world changed.
*/
if (__bam_lget(dbc, 0, t->bt_lpgno, DB_LOCK_WRITE, &lock))
goto fast_miss;
if (memp_fget(dbp->mpf, &t->bt_lpgno, 0, &h))
goto fast_miss;
if (TYPE(h) != P_LBTREE)
goto fast_miss;
if (NUM_ENT(h) == 0)
goto fast_miss;
/*
* What we do here is test to see if we're at the beginning or
* end of the tree and if the new item sorts before/after the
* first/last page entry. We don't try and catch inserts into
* the middle of the tree (although we could, as long as there
* were two keys on the page and we saved both the index and
* the page number of the last insert).
*/
if (h->next_pgno == PGNO_INVALID) {
indx = NUM_ENT(h) - P_INDX;
if ((cmp =
__bam_cmp(dbp, key, h, indx, t->bt_compare)) < 0)
goto try_begin;
if (cmp > 0) {
indx += P_INDX;
goto fast_hit;
}
/*
* Found a duplicate. If doing DB_KEYLAST, we're at
* the correct position, otherwise, move to the first
* of the duplicates.
*/
if (flags == DB_KEYLAST)
goto fast_hit;
for (;
indx > 0 && h->inp[indx - P_INDX] == h->inp[indx];
indx -= P_INDX)
;
goto fast_hit;
}
try_begin: if (h->prev_pgno == PGNO_INVALID) {
indx = 0;
if ((cmp =
__bam_cmp(dbp, key, h, indx, t->bt_compare)) > 0)
goto fast_miss;
if (cmp < 0)
goto fast_hit;
/*
* Found a duplicate. If doing DB_KEYFIRST, we're at
* the correct position, otherwise, move to the last
* of the duplicates.
*/
if (flags == DB_KEYFIRST)
goto fast_hit;
for (;
indx < (db_indx_t)(NUM_ENT(h) - P_INDX) &&
h->inp[indx] == h->inp[indx + P_INDX];
indx += P_INDX)
;
goto fast_hit;
}
goto fast_miss;
fast_hit: /* Set the exact match flag, we may have found a duplicate. */
*exactp = cmp == 0;
/* Enter the entry in the stack. */
BT_STK_CLR(cp);
BT_STK_ENTER(cp, h, indx, lock, ret);
break;
fast_miss: if (h != NULL)
(void)memp_fput(dbp->mpf, h, 0);
if (lock != LOCK_INVALID)
(void)__BT_LPUT(dbc, lock);
search: ret = __bam_search(dbc, key, sflags, 1, NULL, exactp);
break;
default: /* XXX: Impossible. */
abort();
/* NOTREACHED */
}
if (ret != 0)
return (ret);
/*
* Initialize the cursor to reference it. This has to be done
* before we return (even with DB_NOTFOUND) because we have to
* free the page(s) we locked in __bam_search.
*/
cp->page = cp->csp->page;
cp->pgno = cp->csp->page->pgno;
cp->indx = cp->csp->indx;
cp->lock = cp->csp->lock;
cp->dpgno = PGNO_INVALID;
/*
* If we inserted a key into the first or last slot of the tree,
* remember where it was so we can do it more quickly next time.
*/
if (flags == DB_KEYFIRST || flags == DB_KEYLAST)
t->bt_lpgno =
((cp->page->next_pgno == PGNO_INVALID &&
cp->indx >= NUM_ENT(cp->page)) ||
(cp->page->prev_pgno == PGNO_INVALID && cp->indx == 0)) ?
cp->pgno : PGNO_INVALID;
/* If we need an exact match and didn't find one, we're done. */
if (needexact && *exactp == 0)
return (DB_NOTFOUND);
return (0);
}
/*
* __bam_dup --
* Check for an off-page duplicates entry, and if found, move to the
* first or last entry.
*
* PUBLIC: int __bam_dup __P((DBC *, CURSOR *, u_int32_t, int));
*/
int
__bam_dup(dbc, cp, indx, last_dup)
DBC *dbc;
CURSOR *cp;
u_int32_t indx;
int last_dup;
{
BOVERFLOW *bo;
DB *dbp;
db_pgno_t pgno;
int ret;
dbp = dbc->dbp;
/*
* Check for an overflow entry. If we find one, move to the
* duplicates page, and optionally move to the last record on
* that page.
*
* !!!
* We don't lock duplicates pages, we've already got the correct
* lock on the main page.
*/
bo = GET_BOVERFLOW(cp->page, indx + O_INDX);
if (B_TYPE(bo->type) != B_DUPLICATE)
return (0);
pgno = bo->pgno;
if ((ret = memp_fput(dbp->mpf, cp->page, 0)) != 0)
return (ret);
cp->page = NULL;
if (last_dup) {
if ((ret = __db_dend(dbc, pgno, &cp->page)) != 0)
return (ret);
indx = NUM_ENT(cp->page) - O_INDX;
} else {
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &cp->page)) != 0)
return (ret);
indx = 0;
}
/* Update the cursor's duplicate information. */
cp->dpgno = cp->page->pgno;
cp->dindx = indx;
return (0);
}
/*
* __bam_c_physdel --
* Actually do the cursor deletion.
*/
static int
__bam_c_physdel(dbc, cp, h)
DBC *dbc;
CURSOR *cp;
PAGE *h;
{
enum { DELETE_ITEM, DELETE_PAGE, NOTHING_FURTHER } cmd;
BOVERFLOW bo;
DB *dbp;
DBT dbt;
DB_LOCK lock;
db_indx_t indx;
db_pgno_t pgno, next_pgno, prev_pgno;
int delete_page, local_page, ret;
dbp = dbc->dbp;
delete_page = ret = 0;
/* Figure out what we're deleting. */
if (cp->dpgno == PGNO_INVALID) {
pgno = cp->pgno;
indx = cp->indx;
} else {
pgno = cp->dpgno;
indx = cp->dindx;
}
/*
* If the item is referenced by another cursor, set that cursor's
* delete flag and leave it up to it to do the delete.
*
* !!!
* This test for > 0 is a tricky. There are two ways that we can
* be called here. Either we are closing the cursor or we've moved
* off the page with the deleted entry. In the first case, we've
* already removed the cursor from the active queue, so we won't see
* it in __bam_ca_delete. In the second case, it will be on a different
* item, so we won't bother with it in __bam_ca_delete.
*/
if (__bam_ca_delete(dbp, pgno, indx, 1) > 0)
return (0);
/*
* If this is concurrent DB, upgrade the lock if necessary.
*/
if (F_ISSET(dbp, DB_AM_CDB) && F_ISSET(dbc, DBC_RMW) &&
(ret = lock_get(dbp->dbenv->lk_info,
dbc->locker, DB_LOCK_UPGRADE, &dbc->lock_dbt, DB_LOCK_WRITE,
&dbc->mylock)) != 0)
return (EAGAIN);
/*
* If we don't already have the page locked, get it and delete the
* items.
*/
if ((h == NULL || h->pgno != pgno)) {
if ((ret = __bam_lget(dbc, 0, pgno, DB_LOCK_WRITE, &lock)) != 0)
return (ret);
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
return (ret);
local_page = 1;
} else
local_page = 0;
/*
* If we're deleting a duplicate entry and there are other duplicate
* entries remaining, call the common code to do the work and fix up
* the parent page as necessary. Otherwise, do a normal btree delete.
*
* There are 5 possible cases:
*
* 1. It's not a duplicate item: do a normal btree delete.
* 2. It's a duplicate item:
* 2a: We delete an item from a page of duplicates, but there are
* more items on the page.
* 2b: We delete the last item from a page of duplicates, deleting
* the last duplicate.
* 2c: We delete the last item from a page of duplicates, but there
* is a previous page of duplicates.
* 2d: We delete the last item from a page of duplicates, but there
* is a following page of duplicates.
*
* In the case of:
*
* 1: There's nothing further to do.
* 2a: There's nothing further to do.
* 2b: Do the normal btree delete instead of a duplicate delete, as
* that deletes both the duplicate chain and the parent page's
* entry.
* 2c: There's nothing further to do.
* 2d: Delete the duplicate, and update the parent page's entry.
*/
if (TYPE(h) == P_DUPLICATE) {
pgno = PGNO(h);
prev_pgno = PREV_PGNO(h);
next_pgno = NEXT_PGNO(h);
if (NUM_ENT(h) == 1 &&
prev_pgno == PGNO_INVALID && next_pgno == PGNO_INVALID)
cmd = DELETE_PAGE;
else {
cmd = DELETE_ITEM;
/* Delete the duplicate. */
if ((ret = __db_drem(dbc, &h, indx, __bam_free)) != 0)
goto err;
/*
* 2a: h != NULL, h->pgno == pgno
* 2b: We don't reach this clause, as the above test
* was true.
* 2c: h == NULL, prev_pgno != PGNO_INVALID
* 2d: h != NULL, next_pgno != PGNO_INVALID
*
* Test for 2a and 2c: if we didn't empty the current
* page or there was a previous page of duplicates, we
* don't need to touch the parent page.
*/
if ((h != NULL && pgno == h->pgno) ||
prev_pgno != PGNO_INVALID)
cmd = NOTHING_FURTHER;
}
/*
* Release any page we're holding and its lock.
*
* !!!
* If there is no subsequent page in the duplicate chain, then
* __db_drem will have put page "h" and set it to NULL.
*/
if (local_page) {
if (h != NULL)
(void)memp_fput(dbp->mpf, h, 0);
(void)__BT_TLPUT(dbc, lock);
local_page = 0;
}
if (cmd == NOTHING_FURTHER)
goto done;
/* Acquire the parent page and switch the index to its entry. */
if ((ret =
__bam_lget(dbc, 0, cp->pgno, DB_LOCK_WRITE, &lock)) != 0)
goto err;
if ((ret = memp_fget(dbp->mpf, &cp->pgno, 0, &h)) != 0) {
(void)__BT_TLPUT(dbc, lock);
goto err;
}
local_page = 1;
indx = cp->indx;
if (cmd == DELETE_PAGE)
goto btd;
/*
* Copy, delete, update, add-back the parent page's data entry.
*
* XXX
* This may be a performance/logging problem. We should add a
* log message which simply logs/updates a random set of bytes
* on a page, and use it instead of doing a delete/add pair.
*/
indx += O_INDX;
bo = *GET_BOVERFLOW(h, indx);
(void)__db_ditem(dbc, h, indx, BOVERFLOW_SIZE);
bo.pgno = next_pgno;
memset(&dbt, 0, sizeof(dbt));
dbt.data = &bo;
dbt.size = BOVERFLOW_SIZE;
(void)__db_pitem(dbc, h, indx, BOVERFLOW_SIZE, &dbt, NULL);
(void)memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY);
goto done;
}
btd: /*
* If the page is going to be emptied, delete it. To delete a leaf
* page we need a copy of a key from the page. We use the 0th page
* index since it's the last key that the page held.
*
* We malloc the page information instead of using the return key/data
* memory because we've already set them -- the reason we've already
* set them is because we're (potentially) about to do a reverse split,
* which would make our saved page information useless.
*
* !!!
* The following operations to delete a page might deadlock. I think
* that's OK. The problem is if we're deleting an item because we're
* closing cursors because we've already deadlocked and want to call
* txn_abort(). If we fail due to deadlock, we leave a locked empty
* page in the tree, which won't be empty long because we're going to
* undo the delete.
*/
if (NUM_ENT(h) == 2 && h->pgno != PGNO_ROOT) {
memset(&dbt, 0, sizeof(DBT));
dbt.flags = DB_DBT_MALLOC | DB_DBT_INTERNAL;
if ((ret = __db_ret(dbp, h, 0, &dbt, NULL, NULL)) != 0)
goto err;
delete_page = 1;
}
/*
* Do a normal btree delete.
*
* !!!
* Delete the key item first, otherwise the duplicate checks in
* __bam_ditem() won't work!
*/
if ((ret = __bam_ditem(dbc, h, indx)) != 0)
goto err;
if ((ret = __bam_ditem(dbc, h, indx)) != 0)
goto err;
/* Discard any remaining locks/pages. */
if (local_page) {
(void)memp_fput(dbp->mpf, h, 0);
(void)__BT_TLPUT(dbc, lock);
local_page = 0;
}
/* Delete the page if it was emptied. */
if (delete_page)
ret = __bam_dpage(dbc, &dbt);
err:
done: if (delete_page)
__os_free(dbt.data, dbt.size);
if (local_page) {
/*
* It's possible for h to be NULL, as __db_drem may have
* been relinking pages by the time that it deadlocked.
*/
if (h != NULL)
(void)memp_fput(dbp->mpf, h, 0);
(void)__BT_TLPUT(dbc, lock);
}
if (F_ISSET(dbp, DB_AM_CDB) && F_ISSET(dbc, DBC_RMW))
(void)__lock_downgrade(dbp->dbenv->lk_info, dbc->mylock,
DB_LOCK_IWRITE, 0);
return (ret);
}
/*
* __bam_c_getstack --
* Acquire a full stack for a cursor.
*/
static int
__bam_c_getstack(dbc, cp)
DBC *dbc;
CURSOR *cp;
{
DB *dbp;
DBT dbt;
PAGE *h;
db_pgno_t pgno;
int exact, ret;
dbp = dbc->dbp;
h = NULL;
memset(&dbt, 0, sizeof(DBT));
ret = 0;
/* Get the page with the current item on it. */
pgno = cp->pgno;
if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
return (ret);
/* Get a copy of a key from the page. */
dbt.flags = DB_DBT_MALLOC | DB_DBT_INTERNAL;
if ((ret = __db_ret(dbp, h, 0, &dbt, NULL, NULL)) != 0)
goto err;
/* Get a write-locked stack for that page. */
exact = 0;
ret = __bam_search(dbc, &dbt, S_KEYFIRST, 1, NULL, &exact);
/* We no longer need the key or the page. */
err: if (h != NULL)
(void)memp_fput(dbp->mpf, h, 0);
if (dbt.data != NULL)
__os_free(dbt.data, dbt.size);
return (ret);
}
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