db_dup.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: db__dup_8c-source.html,v 1.1 2008/06/08 10:17:27 sebdiaz Exp $";
#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 "hash.h"
#include "lock.h"
#include "db_am.h"

/*
 * CDB___db_ditem --
 *      Remove an item from a page.
 *
 * PUBLIC:  int CDB___db_ditem __P((DBC *, PAGE *, u_int32_t, u_int32_t));
 */
int
CDB___db_ditem(dbc, pagep, indx, nbytes)
        DBC *dbc;
        PAGE *pagep;
        u_int32_t indx, nbytes;
{
        DB *dbp;
        DBT ldbt;
        db_indx_t cnt, offset;
        int ret;
        u_int8_t *from;

        dbp = dbc->dbp;
        if (DB_LOGGING(dbc)) {
                ldbt.data = P_ENTRY(pagep, indx);
                ldbt.size = nbytes;
                if ((ret = CDB___db_addrem_log(dbp->dbenv, dbc->txn,
                    &LSN(pagep), 0, DB_REM_DUP, dbp->log_fileid, PGNO(pagep),
                    (u_int32_t)indx, nbytes, &ldbt, NULL, &LSN(pagep))) != 0)
                        return (ret);
        }

        /*
         * If there's only a single item on the page, we don't have to
         * work hard.
         */
        if (NUM_ENT(pagep) == 1) {
                NUM_ENT(pagep) = 0;
                HOFFSET(pagep) = dbp->pgsize;
                return (0);
        }

        /*
         * Pack the remaining key/data items at the end of the page.  Use
         * memmove(3), the regions may overlap.
         */
        from = (u_int8_t *)pagep + HOFFSET(pagep);
        memmove(from + nbytes, from, pagep->inp[indx] - HOFFSET(pagep));
        HOFFSET(pagep) += nbytes;

        /* Adjust the indices' offsets. */
        offset = pagep->inp[indx];
        for (cnt = 0; cnt < NUM_ENT(pagep); ++cnt)
                if (pagep->inp[cnt] < offset)
                        pagep->inp[cnt] += nbytes;

        /* Shift the indices down. */
        --NUM_ENT(pagep);
        if (indx != NUM_ENT(pagep))
                memmove(&pagep->inp[indx], &pagep->inp[indx + 1],
                    sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));

        return (0);
}

/*
 * CDB___db_pitem --
 *      Put an item on a page.
 *
 * PUBLIC: int CDB___db_pitem
 * PUBLIC:     __P((DBC *, PAGE *, u_int32_t, u_int32_t, DBT *, DBT *));
 */
int
CDB___db_pitem(dbc, pagep, indx, nbytes, hdr, data)
        DBC *dbc;
        PAGE *pagep;
        u_int32_t indx;
        u_int32_t nbytes;
        DBT *hdr, *data;
{
        DB *dbp;
        BKEYDATA bk;
        DBT thdr;
        int ret;
        u_int8_t *p;

        /*
         * Put a single item onto a page.  The logic figuring out where to
         * insert and whether it fits is handled in the caller.  All we do
         * here is manage the page shuffling.  We cheat a little bit in that
         * we don't want to copy the dbt on a normal put twice.  If hdr is
         * NULL, we create a BKEYDATA structure on the page, otherwise, just
         * copy the caller's information onto the page.
         *
         * This routine is also used to put entries onto the page where the
         * entry is pre-built, e.g., during recovery.  In this case, the hdr
         * will point to the entry, and the data argument will be NULL.
         *
         * !!!
         * There's a tremendous potential for off-by-one errors here, since
         * the passed in header sizes must be adjusted for the structure's
         * placeholder for the trailing variable-length data field.
         */
        dbp = dbc->dbp;
        if (DB_LOGGING(dbc))
                if ((ret = CDB___db_addrem_log(dbp->dbenv, dbc->txn,
                    &LSN(pagep), 0, DB_ADD_DUP, dbp->log_fileid, PGNO(pagep),
                    (u_int32_t)indx, nbytes, hdr, data, &LSN(pagep))) != 0)
                        return (ret);

        if (hdr == NULL) {
                B_TSET(bk.type, B_KEYDATA, 0);
                bk.len = data == NULL ? 0 : data->size;

                thdr.data = &bk;
                thdr.size = SSZA(BKEYDATA, data);
                hdr = &thdr;
        }

        /* Adjust the index table, then put the item on the page. */
        if (indx != NUM_ENT(pagep))
                memmove(&pagep->inp[indx + 1], &pagep->inp[indx],
                    sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));
        HOFFSET(pagep) -= nbytes;
        pagep->inp[indx] = HOFFSET(pagep);
        ++NUM_ENT(pagep);

        p = P_ENTRY(pagep, indx);
        memcpy(p, hdr->data, hdr->size);
        if (data != NULL)
                memcpy(p + hdr->size, data->data, data->size);

        return (0);
}

/*
 * CDB___db_relink --
 *      Relink around a deleted page.
 *
 * PUBLIC: int CDB___db_relink __P((DBC *, u_int32_t, PAGE *, PAGE **, int));
 */
int
CDB___db_relink(dbc, add_rem, pagep, new_next, needlock)
        DBC *dbc;
        u_int32_t add_rem;
        PAGE *pagep, **new_next;
        int needlock;
{
        DB *dbp;
        PAGE *np, *pp;
        DB_LOCK npl, ppl;
        DB_LSN *nlsnp, *plsnp, ret_lsn;
        int ret;

        ret = 0;
        np = pp = NULL;
        npl.off = ppl.off = LOCK_INVALID;
        nlsnp = plsnp = NULL;
        dbp = dbc->dbp;

        /*
         * Retrieve and lock the one/two pages.  For a remove, we may need
         * two pages (the before and after).  For an add, we only need one
         * because, the split took care of the prev.
         */
        if (pagep->next_pgno != PGNO_INVALID) {
                if (needlock && (ret = CDB___db_lget(dbc,
                    0, pagep->next_pgno, DB_LOCK_WRITE, 0, &npl)) != 0)
                        goto err;
                if ((ret = CDB_memp_fget(dbp->mpf,
                    &pagep->next_pgno, 0, &np)) != 0) {
                        (void)CDB___db_pgerr(dbp, pagep->next_pgno);
                        goto err;
                }
                nlsnp = &np->lsn;
        }
        if (add_rem == DB_REM_PAGE && pagep->prev_pgno != PGNO_INVALID) {
                if (needlock && (ret = CDB___db_lget(dbc,
                    0, pagep->prev_pgno, DB_LOCK_WRITE, 0, &ppl)) != 0)
                        goto err;
                if ((ret = CDB_memp_fget(dbp->mpf,
                    &pagep->prev_pgno, 0, &pp)) != 0) {
                        (void)CDB___db_pgerr(dbp, pagep->next_pgno);
                        goto err;
                }
                plsnp = &pp->lsn;
        }

        /* Log the change. */
        if (DB_LOGGING(dbc)) {
                if ((ret = CDB___db_relink_log(dbp->dbenv, dbc->txn,
                    &ret_lsn, 0, add_rem, dbp->log_fileid,
                    pagep->pgno, &pagep->lsn,
                    pagep->prev_pgno, plsnp, pagep->next_pgno, nlsnp)) != 0)
                        goto err;
                if (np != NULL)
                        np->lsn = ret_lsn;
                if (pp != NULL)
                        pp->lsn = ret_lsn;
                if (add_rem == DB_REM_PAGE)
                        pagep->lsn = ret_lsn;
        }

        /*
         * Modify and release the two pages.
         *
         * !!!
         * The parameter new_next gets set to the page following the page we
         * are removing.  If there is no following page, then new_next gets
         * set to NULL.
         */
        if (np != NULL) {
                if (add_rem == DB_ADD_PAGE)
                        np->prev_pgno = pagep->pgno;
                else
                        np->prev_pgno = pagep->prev_pgno;
                if (new_next == NULL)
                        ret = CDB_memp_fput(dbp->mpf, np, DB_MPOOL_DIRTY);
                else {
                        *new_next = np;
                        ret = CDB_memp_fset(dbp->mpf, np, DB_MPOOL_DIRTY);
                }
                if (ret != 0)
                        goto err;
                if (needlock)
                        (void)__TLPUT(dbc, npl);
        } else if (new_next != NULL)
                *new_next = NULL;

        if (pp != NULL) {
                pp->next_pgno = pagep->next_pgno;
                if ((ret = CDB_memp_fput(dbp->mpf, pp, DB_MPOOL_DIRTY)) != 0)
                        goto err;
                if (needlock)
                        (void)__TLPUT(dbc, ppl);
        }
        return (0);

err:    if (np != NULL)
                (void)CDB_memp_fput(dbp->mpf, np, 0);
        if (needlock && npl.off != LOCK_INVALID)
                (void)__TLPUT(dbc, npl);
        if (pp != NULL)
                (void)CDB_memp_fput(dbp->mpf, pp, 0);
        if (needlock && ppl.off != LOCK_INVALID)
                (void)__TLPUT(dbc, ppl);
        return (ret);
}

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