8322 nl: misleading-indentation

[unleashed/tickless.git] / usr / src / cmd / sendmail / db / btree / bt_delete.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   10.43 (Sleepycat) 12/7/98";
#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"

/*
 * __bam_delete --
 *      Delete the items referenced by a key.
 *
 * PUBLIC: int __bam_delete __P((DB *, DB_TXN *, DBT *, u_int32_t));
 */
int
__bam_delete(dbp, txn, key, flags)
        DB *dbp;
        DB_TXN *txn;
        DBT *key;
        u_int32_t flags;
{
        DBC *dbc;
        DBT data;
        u_int32_t f_init, f_next;
        int ret, t_ret;

        DB_PANIC_CHECK(dbp);

        /* Check for invalid flags. */
        if ((ret =
            __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(&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 (dbp->dbenv != NULL && dbp->dbenv->lk_info != NULL) {
                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, key, &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 == DB_NOTFOUND))
                ret = t_ret;

        return (ret);
}

/*
 * __bam_ditem --
 *      Delete one or more entries from a page.
 *
 * PUBLIC: int __bam_ditem __P((DBC *, PAGE *, u_int32_t));
 */
int
__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 (__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(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 (__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 =
                                    __db_ddup(dbc, bo->pgno, __bam_free)) != 0)
                                        return (ret);
                        } else
                                if ((ret =
                                    __db_doff(dbc, 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(dbc, 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((DBC *, PAGE *, u_int32_t, u_int32_t, int));
 */
int
__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 = __bam_adj_log(dbp->dbenv->lg_info, 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 = 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((DBC *, const DBT *));
 */
int
__bam_dpage(dbc, key)
        DBC *dbc;
        const DBT *key;
{
        CURSOR *cp;
        DB *dbp;
        DB_LOCK lock;
        PAGE *h;
        db_pgno_t 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 __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(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 == PGNO_ROOT || NUM_ENT(h) != 1)
                        break;

                /* Release the two locked pages. */
                (void)memp_fput(dbp->mpf, cp->csp[-1].page, 0);
                (void)__BT_TLPUT(dbc, cp->csp[-1].lock);
                (void)memp_fput(dbp->mpf, cp->csp[0].page, 0);
                (void)__BT_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 = __bam_lget(dbc, 0, pgno, DB_LOCK_WRITE, &lock)) != 0)
                        goto release;
                if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
                        goto release;
                BT_STK_PUSH(cp, h, 0, lock, ret);
        }

        /* Adjust back to reference the last page on the stack. */
        BT_STK_POP(cp);

        /* Delete the pages. */
        return (__bam_dpages(dbc));

release:
        /* Adjust back to reference the last page on the stack. */
        BT_STK_POP(cp);

        /* Discard any locked pages and return. */
        __bam_stkrel(dbc, 0);

        return (ret);
}

/*
 * __bam_dpages --
 *      Delete a set of locked pages.
 *
 * PUBLIC: int __bam_dpages __P((DBC *));
 */
int
__bam_dpages(dbc)
        DBC *dbc;
{
        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;
        db_recno_t rcnt;
        int done, ret;

        dbp = dbc->dbp;
        cp = dbc->internal;
        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 = __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 = __bam_ditem(dbc, epg->page, epg->indx)) != 0) {
release:        (void)__bam_stkrel(dbc, 0);
                return (ret);
        }

        pgno = epg->page->pgno;
        nitems = NUM_ENT(epg->page);

        (void)memp_fput(dbp->mpf, epg->page, 0);
        (void)__BT_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)__bam_ditem(dbc, epg->page, epg->indx);

                (void)__bam_free(dbc, epg->page);
                (void)__BT_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 != PGNO_ROOT || 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 = c_lock = LOCK_INVALID;

                /* Lock the root. */
                pgno = PGNO_ROOT;
                if ((ret =
                    __bam_lget(dbc, 0, pgno, DB_LOCK_WRITE, &p_lock)) != 0)
                        goto stop;
                if ((ret = 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 =
                    __bam_lget(dbc, 0, pgno, DB_LOCK_WRITE, &c_lock)) != 0)
                        goto stop;
                if ((ret = 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);
                        __bam_rsplit_log(dbp->dbenv->lg_info, 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 = PGNO_ROOT;
                if (TYPE(child) == P_IRECNO ||
                    (TYPE(child) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
                        RE_NREC_SET(parent, rcnt);

                /* Mark the pages dirty. */
                memp_fset(dbp->mpf, parent, DB_MPOOL_DIRTY);
                memp_fset(dbp->mpf, child, DB_MPOOL_DIRTY);

                /* Adjust the cursors. */
                __bam_ca_rsplit(dbp, child->pgno, PGNO_ROOT);

                /*
                 * Free the page copied onto the root page and discard its
                 * lock.  (The call to __bam_free() discards our reference
                 * to the page.)
                 */
                (void)__bam_free(dbc, child);
                child = NULL;

                if (0) {
stop:                   done = 1;
                }
                if (p_lock != LOCK_INVALID)
                        (void)__BT_TLPUT(dbc, p_lock);
                if (parent != NULL)
                        memp_fput(dbp->mpf, parent, 0);
                if (c_lock != LOCK_INVALID)
                        (void)__BT_TLPUT(dbc, c_lock);
                if (child != NULL)
                        memp_fput(dbp->mpf, child, 0);
        }

        return (0);
}