bt_curadj.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999, 2000
 *      Sleepycat Software.  All rights reserved.
 */

#include "config.h"

#ifndef lint
static const char revid[] = "$Id: bt__curadj_8c-source.html,v 1.1 2008/06/08 10:13:30 sebdiaz Exp $";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "btree.h"

static int __bam_opd_cursor __P((DB *, DBC *, db_pgno_t, u_int32_t, u_int32_t));

#ifdef DEBUG
/*
 * CDB___bam_cprint --
 *      Display the current internal cursor.
 *
 * PUBLIC: void CDB___bam_cprint __P((DBC *));
 */
void
CDB___bam_cprint(dbc)
        DBC *dbc;
{
        BTREE_CURSOR *cp;

        cp = (BTREE_CURSOR *)dbc->internal;

        fprintf(stderr, "\tinternal: ovflsize: %lu", (u_long)cp->ovflsize);
        if (dbc->dbtype == DB_RECNO)
                fprintf(stderr, " recno: %lu", (u_long)cp->recno);
        if (F_ISSET(cp, C_DELETED))
                fprintf(stderr, " (deleted)");
        fprintf(stderr, "\n");
}
#endif

/*
 * CDB___bam_ca_delete --
 *      Update the cursors when items are deleted and when already deleted
 *      items are overwritten.  Return the number of relevant cursors found.
 *
 * PUBLIC: int CDB___bam_ca_delete __P((DB *, db_pgno_t, u_int32_t, int));
 */
int
CDB___bam_ca_delete(dbp, pgno, indx, delete)
        DB *dbp;
        db_pgno_t pgno;
        u_int32_t indx;
        int delete;
{
        BTREE_CURSOR *cp;
        DBC *dbc;
        int count;              /* !!!: Has to contain max number of cursors. */

        /*
         * Adjust the cursors.  We don't have to review the cursors for any
         * thread of control other than the current one, because we have the
         * page write locked at this point, and any other thread of control
         * had better be using a different locker ID, meaning only cursors in
         * our thread of control can be on the page.
         *
         * It's possible for multiple cursors within the thread to have write
         * locks on the same page, but, cursors within a thread must be single
         * threaded, so all we're locking here is the cursor linked list.
         */
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (count = 0, dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                cp = (BTREE_CURSOR *)dbc->internal;
                if (cp->pgno == pgno && cp->indx == indx) {
                        if (delete)
                                F_SET(cp, C_DELETED);
                        else
                                F_CLR(cp, C_DELETED);
                        ++count;
                }
        }
        MUTEX_THREAD_UNLOCK(dbp->mutexp);

        return (count);
}

/*
 * CDB___ram_ca_delete --
 *      Return the number of relevant cursors.
 *
 * PUBLIC: int CDB___ram_ca_delete __P((DB *, db_pgno_t));
 */
int
CDB___ram_ca_delete(dbp, root_pgno)
        DB *dbp;
        db_pgno_t root_pgno;
{
        DBC *dbc;

        /*
         * Review the cursors.  See the comment in CDB___bam_ca_delete().
         */
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links))
                if (dbc->internal->root == root_pgno)
                        break;
        MUTEX_THREAD_UNLOCK(dbp->mutexp);
        return (dbc == NULL ? 0 : 1);
}

/*
 * CDB___bam_ca_di --
 *      Adjust the cursors during a delete or insert.
 *
 * PUBLIC: void CDB___bam_ca_di __P((DB *, db_pgno_t, u_int32_t, int));
 */
void
CDB___bam_ca_di(dbp, pgno, indx, adjust)
        DB *dbp;
        db_pgno_t pgno;
        u_int32_t indx;
        int adjust;
{
        DBC *dbc;
        DBC_INTERNAL *cp;

        /*
         * Adjust the cursors.  See the comment in CDB___bam_ca_delete().
         */
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                if (dbc->dbtype == DB_RECNO)
                        continue;
                cp = dbc->internal;
                if (cp->pgno == pgno && cp->indx >= indx) {
                        /* Cursor indices should never be negative. */
                        DB_ASSERT(cp->indx != 0 || adjust > 0);

                        cp->indx += adjust;
                }
        }
        MUTEX_THREAD_UNLOCK(dbp->mutexp);
}

/*
 * __bam_opd_cursor -- create a new opd cursor.
 */
static int
__bam_opd_cursor(dbp, dbc, first, tpgno, ti)
        DB *dbp;
        DBC *dbc;
        db_pgno_t tpgno;
        u_int32_t first, ti;
{
        BTREE_CURSOR *cp, *orig_cp;
        DBC *dbc_nopd;
        int ret;

        orig_cp = (BTREE_CURSOR *)dbc->internal;
        dbc_nopd = NULL;

        /*
         * Allocate a new cursor and create the stack.  If duplicates
         * are sorted, we've just created an off-page duplicate Btree.
         * If duplicates aren't sorted, we've just created a Recno tree.
         */
        if ((ret = CDB___db_icursor(dbp, dbc->txn,
            dbp->dup_compare == NULL ? DB_RECNO : DB_BTREE,
            tpgno, 1, &dbc_nopd)) != 0)
                return (ret);

        cp = (BTREE_CURSOR *)dbc_nopd->internal;
        cp->pgno = tpgno;
        cp->indx = ti;

        if (dbp->dup_compare == NULL) {
                /*
                 * Converting to off-page Recno trees is tricky.  The
                 * record number for the cursor is the index + 1 (to
                 * convert to 1-based record numbers).
                 */
                cp->recno = ti + 1;
        }

        /*
         * Transfer the deleted flag from the top-level cursor to the
         * created one.
         */
        if (F_ISSET(orig_cp, C_DELETED)) {
                F_SET(cp, C_DELETED);
                F_CLR(orig_cp, C_DELETED);
        }

        /* Stack the cursors and reset the initial cursor's index. */
        orig_cp->opd = dbc_nopd;
        orig_cp->indx = first;
        return (0);
}

/*
 * CDB___bam_ca_dup --
 *      Adjust the cursors when moving items from a leaf page to a duplicates
 *      page.
 *
 * PUBLIC: int CDB___bam_ca_dup __P((DB *,
 * PUBLIC:    db_pgno_t, u_int32_t, u_int32_t, db_pgno_t, u_int32_t));
 */
int
CDB___bam_ca_dup(dbp, first, fpgno, fi, tpgno, ti)
        DB *dbp;
        db_pgno_t fpgno, tpgno;
        u_int32_t first, fi, ti;
{
        BTREE_CURSOR *orig_cp;
        DBC *dbc;
        int ret;

        /*
         * Adjust the cursors.  See the comment in CDB___bam_ca_delete().
         */
loop:
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                /*
                 * Ignore matching entries that have already been moved,
                 * we move from the same location on the leaf page more
                 * than once.
                 */
                orig_cp = (BTREE_CURSOR *)dbc->internal;
                if (orig_cp->opd != NULL ||
                    orig_cp->pgno != fpgno || orig_cp->indx != fi)
                        continue;

                MUTEX_THREAD_UNLOCK(dbp->mutexp);
                if ((ret = __bam_opd_cursor(dbp, dbc, first, tpgno, ti)) !=0)
                        return (ret);
                /* We released the MUTEX to get a cursor, start over. */
                goto loop;
        }
        MUTEX_THREAD_UNLOCK(dbp->mutexp);

        return (0);
}

/*
 * CDB___bam_ca_rsplit --
 *      Adjust the cursors when doing reverse splits.
 *
 * PUBLIC: void CDB___bam_ca_rsplit __P((DB *, db_pgno_t, db_pgno_t));
 */
void
CDB___bam_ca_rsplit(dbp, fpgno, tpgno)
        DB *dbp;
        db_pgno_t fpgno, tpgno;
{
        DBC *dbc;

        /*
         * Adjust the cursors.  See the comment in CDB___bam_ca_delete().
         */
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                if (dbc->dbtype == DB_RECNO)
                        continue;
                if (dbc->internal->pgno == fpgno)
                        dbc->internal->pgno = tpgno;
        }
        MUTEX_THREAD_UNLOCK(dbp->mutexp);
}

/*
 * CDB___bam_ca_split --
 *      Adjust the cursors when splitting a page.
 *
 * PUBLIC: void CDB___bam_ca_split __P((DB *,
 * PUBLIC:    db_pgno_t, db_pgno_t, db_pgno_t, u_int32_t, int));
 */
void
CDB___bam_ca_split(dbp, ppgno, lpgno, rpgno, split_indx, cleft)
        DB *dbp;
        db_pgno_t ppgno, lpgno, rpgno;
        u_int32_t split_indx;
        int cleft;
{
        DBC *dbc;
        DBC_INTERNAL *cp;

        /*
         * Adjust the cursors.  See the comment in CDB___bam_ca_delete().
         *
         * If splitting the page that a cursor was on, the cursor has to be
         * adjusted to point to the same record as before the split.  Most
         * of the time we don't adjust pointers to the left page, because
         * we're going to copy its contents back over the original page.  If
         * the cursor is on the right page, it is decremented by the number of
         * records split to the left page.
         */
        MUTEX_THREAD_LOCK(dbp->mutexp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                if (dbc->dbtype == DB_RECNO)
                        continue;
                cp = dbc->internal;
                if (cp->pgno == ppgno) {
                        if (cp->indx < split_indx) {
                                if (cleft)
                                        cp->pgno = lpgno;
                        } else {
                                cp->pgno = rpgno;
                                cp->indx -= split_indx;
                        }
                }
        }
        MUTEX_THREAD_UNLOCK(dbp->mutexp);
}

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