db/db/db_dispatch.c

	db_dispatch.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *  Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1995, 1996
 *  The President and Fellows of Harvard University.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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[] = "@(#)db_dispatch.c 10.20 (Sleepycat) 10/10/98";
#endif /* not lint */

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

#include <errno.h>
#include <shqueue.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "db_dispatch.h"
#include "db_am.h"
#include "common_ext.h"
#include "log_auto.h"
#include "txn.h"
#include "txn_auto.h"

/*
 * Data structures to manage the DB dispatch table.  The dispatch table
 * is a dynamically allocated array of pointers to dispatch functions.
 * The dispatch_size is the number of entries possible in the current
 * dispatch table and the dispatch_valid is the number of valid entries
 * in the dispatch table.
 */
static int (**dispatch_table) __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
static u_int32_t dispatch_size = 0;

/*
 * __db_dispatch --
 *
 * This is the transaction dispatch function used by the db access methods.
 * It is designed to handle the record format used by all the access
 * methods (the one automatically generated by the db_{h,log,read}.sh
 * scripts in the tools directory).  An application using a different
 * recovery paradigm will supply a different dispatch function to txn_open.
 *
 * PUBLIC: int __db_dispatch __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
 */
int
__db_dispatch(logp, db, lsnp, redo, info)
    DB_LOG *logp;       /* The log file. */
    DBT *db;        /* The log record upon which to dispatch. */
    DB_LSN *lsnp;       /* The lsn of the record being dispatched. */
    int redo;       /* Redo this op (or undo it). */
    void *info;
{
    u_int32_t rectype, txnid;

    memcpy(&rectype, db->data, sizeof(rectype));
    memcpy(&txnid, (u_int8_t *)db->data + sizeof(rectype), sizeof(txnid));

    switch (redo) {
    case TXN_REDO:
    case TXN_UNDO:
        return ((dispatch_table[rectype])(logp, db, lsnp, redo, info));
    case TXN_OPENFILES:
        if (rectype < DB_txn_BEGIN )
            return ((dispatch_table[rectype])(logp,
                db, lsnp, redo, info));
        break;
    case TXN_BACKWARD_ROLL:
        /*
         * Running full recovery in the backward pass.  If we've
         * seen this txnid before and added to it our commit list,
         * then we do nothing during this pass.  If we've never
         * seen it, then we call the appropriate recovery routine
         * in "abort mode".
         */
        if (rectype == DB_log_register || rectype == DB_txn_ckp ||
            (__db_txnlist_find(info, txnid) == DB_NOTFOUND &&
            txnid != 0))
            return ((dispatch_table[rectype])(logp,
                db, lsnp, TXN_UNDO, info));
        break;
    case TXN_FORWARD_ROLL:
        /*
         * In the forward pass, if we haven't seen the transaction,
         * do nothing, else recovery it.
         */
        if (rectype == DB_log_register || rectype == DB_txn_ckp ||
            __db_txnlist_find(info, txnid) != DB_NOTFOUND)
            return ((dispatch_table[rectype])(logp,
                db, lsnp, TXN_REDO, info));
        break;
    default:
        abort();
    }
    return (0);
}

/*
 * __db_add_recovery --
 *
 * PUBLIC: int __db_add_recovery __P((DB_ENV *,
 * PUBLIC:    int (*)(DB_LOG *, DBT *, DB_LSN *, int, void *), u_int32_t));
 */
int
__db_add_recovery(dbenv, func, ndx)
    DB_ENV *dbenv;
    int (*func) __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
    u_int32_t ndx;
{
    u_int32_t i;
    int ret;

    COMPQUIET(dbenv, NULL);     /* !!!: not currently used. */

    /* Check if we have to grow the table. */
    if (ndx >= dispatch_size) {
        if ((ret = __os_realloc(&dispatch_table,
            (DB_user_BEGIN + dispatch_size) *
            sizeof(dispatch_table[0]))) != 0)
            return (ret);
        for (i = dispatch_size,
            dispatch_size += DB_user_BEGIN; i < dispatch_size; ++i)
            dispatch_table[i] = NULL;
    }

    dispatch_table[ndx] = func;
    return (0);
}

/*
 * __db_txnlist_init --
 *  Initialize transaction linked list.
 *
 * PUBLIC: int __db_txnlist_init __P((void *));
 */
int
__db_txnlist_init(retp)
    void *retp;
{
    DB_TXNHEAD *headp;
    int ret;

    if ((ret = __os_malloc(sizeof(DB_TXNHEAD), NULL, &headp)) != 0)
        return (ret);

    LIST_INIT(&headp->head);
    headp->maxid = 0;
    headp->generation = 1;

    *(void **)retp = headp;
    return (0);
}

/*
 * __db_txnlist_add --
 *  Add an element to our transaction linked list.
 *
 * PUBLIC: int __db_txnlist_add __P((void *, u_int32_t));
 */
int
__db_txnlist_add(listp, txnid)
    void *listp;
    u_int32_t txnid;
{
    DB_TXNHEAD *hp;
    DB_TXNLIST *elp;
    int ret;

    if ((ret = __os_malloc(sizeof(DB_TXNLIST), NULL, &elp)) != 0)
        return (ret);

    elp->txnid = txnid;
    hp = (DB_TXNHEAD *)listp;
    LIST_INSERT_HEAD(&hp->head, elp, links);
    if (txnid > hp->maxid)
        hp->maxid = txnid;
    elp->generation = hp->generation;

    return (0);
}

/*
 * __db_txnlist_find --
 *  Checks to see if a txnid with the current generation is in the
 *  txnid list.
 *
 * PUBLIC: int __db_txnlist_find __P((void *, u_int32_t));
 */
int
__db_txnlist_find(listp, txnid)
    void *listp;
    u_int32_t txnid;
{
    DB_TXNHEAD *hp;
    DB_TXNLIST *p;

    if ((hp = (DB_TXNHEAD *)listp) == NULL)
        return (DB_NOTFOUND);

    for (p = hp->head.lh_first; p != NULL; p = p->links.le_next)
        if (p->txnid == txnid && hp->generation == p->generation)
            return (0);

    return (DB_NOTFOUND);
}

/*
 * __db_txnlist_end --
 *  Discard transaction linked list.
 *
 * PUBLIC: void __db_txnlist_end __P((void *));
 */
void
__db_txnlist_end(listp)
    void *listp;
{
    DB_TXNHEAD *hp;
    DB_TXNLIST *p;

    hp = (DB_TXNHEAD *)listp;
    while ((p = LIST_FIRST(&hp->head)) != LIST_END(&hp->head)) {
        LIST_REMOVE(p, links);
        __os_free(p, 0);
    }
    __os_free(listp, sizeof(DB_TXNHEAD));
}

/*
 * __db_txnlist_gen --
 *  Change the current generation number.
 *
 * PUBLIC: void __db_txnlist_gen __P((void *, int));
 */
void
__db_txnlist_gen(listp, incr)
    void *listp;
    int incr;
{
    DB_TXNHEAD *hp;

    /*
     * During recovery generation numbers keep track of how many "restart"
     * checkpoints we've seen.  Restart checkpoints occur whenever we take
     * a checkpoint and there are no outstanding transactions.  When that
     * happens, we can reset transaction IDs back to 1.  It always happens
     * at recovery and it prevents us from exhausting the transaction IDs
     * name space.
     */
    hp = (DB_TXNHEAD *)listp;
    hp->generation += incr;
}

#ifdef DEBUG
/*
 * __db_txnlist_print --
 *  Print out the transaction list.
 *
 * PUBLIC: void __db_txnlist_print __P((void *));
 */
void
__db_txnlist_print(listp)
    void *listp;
{
    DB_TXNHEAD *hp;
    DB_TXNLIST *p;

    hp = (DB_TXNHEAD *)listp;
    printf("Maxid: %lu Generation: %lu\n", (u_long)hp->maxid,
        (u_long)hp->generation);
    for (p = hp->head.lh_first; p != NULL; p = p->links.le_next)
        printf("TXNID: %lu(%lu)\n", (u_long)p->txnid,
        (u_long)p->generation);
}
#endif