db/db/db_apprec.c

	db_apprec.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*-
 * 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 copyright[] =
"@(#) Copyright (c) 1996, 1997, 1998\n\
    Sleepycat Software Inc.  All rights reserved.\n";
static const char sccsid[] = "@(#)db_apprec.c   10.33 (Sleepycat) 10/5/98";
#endif

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

#include <errno.h>
#include <string.h>
#include <time.h>
#endif

#include "db_int.h"
#include "shqueue.h"
#include "db_page.h"
#include "db_dispatch.h"
#include "db_am.h"
#include "log.h"
#include "txn.h"
#include "common_ext.h"

/*
 * __db_apprec --
 *  Perform recovery.
 *
 * PUBLIC: int __db_apprec __P((DB_ENV *, u_int32_t));
 */
int
__db_apprec(dbenv, flags)
    DB_ENV *dbenv;
    u_int32_t flags;
{
    DBT data;
    DB_LOG *lp;
    DB_LSN ckp_lsn, first_lsn, lsn, open_lsn;
    __txn_ckp_args *ckp_args;
    time_t now;
    u_int32_t is_thread;
    int ret;
    void *txninfo;

    lp = dbenv->lg_info;

    /* Initialize the transaction list. */
    if ((ret = __db_txnlist_init(&txninfo)) != 0)
        return (ret);

    /*
     * Save the state of the thread flag -- we don't need it on at the
     * moment because we're single-threaded until recovery is complete.
     */
    is_thread = F_ISSET(lp, DB_AM_THREAD);
    F_CLR(lp, DB_AM_THREAD);

    /*
     * Recovery is done in three passes:
     * Pass #0:
     *  We need to find the position from which we will open files
     *  We need to open files beginning with the last to next
     *  checkpoint because we might have crashed after writing the
     *  last checkpoint record, but before having written out all
     *  the open file information.
     * Pass #1:
     *  Read forward through the log from the second to last checkpoint
     *  opening and closing files so that at the end of the log we have
     *  the "current" set of files open.
     * Pass #2:
     *  Read backward through the log undoing any uncompleted TXNs.
     *  If doing catastrophic recovery, we read to the beginning of
     *  the log, otherwise, to the most recent checkpoint that occurs
     *  before the most recent checkpoint LSN, which is returned by
     *  __log_findckp().  During this pass, checkpoint file information
     *  is ignored, and file openings and closings are undone.
     * Pass #3:
     *  Read forward through the log from the LSN found in pass #2,
     *  redoing any committed TXNs.  During this pass, checkpoint
     *  file information is ignored, and file openings and closings
     *  are redone.
     */

    /*
     * Find the second to last checkpoint in the log.  This is the point
     * from which we want to begin pass #1 (the TXN_OPENFILES pass).
     */
    memset(&data, 0, sizeof(data));
    ckp_args = NULL;

    if ((ret = log_get(lp, &ckp_lsn, &data, DB_CHECKPOINT)) != 0) {
        /*
         * If we don't find a checkpoint, start from the beginning.
         * If that fails, we're done.  Note, we do not require that
         * there be log records if we're performing recovery.
         */
first:      if ((ret = log_get(lp, &ckp_lsn, &data, DB_FIRST)) != 0) {
            if (ret == DB_NOTFOUND)
                ret = 0;
            else
                __db_err(dbenv, "First log record not found");
            goto out;
        }
        open_lsn = ckp_lsn;
    } else if ((ret = __txn_ckp_read(data.data, &ckp_args)) != 0) {
        __db_err(dbenv, "Invalid checkpoint record at [%ld][%ld]\n",
            (u_long)ckp_lsn.file, (u_long)ckp_lsn.offset);
        goto out;
    } else if (IS_ZERO_LSN(ckp_args->last_ckp) ||
        (ret = log_get(lp, &ckp_args->last_ckp, &data, DB_SET)) != 0)
        goto first;
    else
        open_lsn = ckp_args->last_ckp;

    /*
     * Now, ckp_lsn is either the lsn of the last checkpoint or the lsn
     * of the first record in the log.  Open_lsn is the second to last
     * checkpoint or the beinning of the log; begin the TXN_OPENFILES
     * pass from that lsn, and proceed to the end of the log.
     */
    lsn = open_lsn;
    for (;;) {
        if (dbenv->tx_recover != NULL)
            ret = dbenv->tx_recover(lp,
                &data, &lsn, TXN_OPENFILES, txninfo);
        else
            ret = __db_dispatch(lp,
                &data, &lsn, TXN_OPENFILES, txninfo);
        if (ret != 0 && ret != DB_TXN_CKP)
            goto msgerr;
        if ((ret = log_get(lp, &lsn, &data, DB_NEXT)) != 0) {
            if (ret == DB_NOTFOUND)
                break;
            goto out;
        }
    }

    /*
     * Pass #2.
     *
     * Before we can begin pass #2, backward roll phase, we determine how
     * far back in the log to recover.  If we are doing catastrophic
     * recovery, then we go as far back as we have files.  If we are
     * doing normal recovery, we go as back to the most recent checkpoint
     * that occurs before the most recent checkpoint LSN.
     */
    if (LF_ISSET(DB_RECOVER_FATAL)) {
        ZERO_LSN(first_lsn);
    } else
        if ((ret = __log_findckp(lp, &first_lsn)) == DB_NOTFOUND) {
            /*
             * We don't require that log files exist if recovery
             * was specified.
             */
            ret = 0;
            goto out;
        }

    if (dbenv->db_verbose)
        __db_err(lp->dbenv, "Recovery starting from [%lu][%lu]",
            (u_long)first_lsn.file, (u_long)first_lsn.offset);

    for (ret = log_get(lp, &lsn, &data, DB_LAST);
        ret == 0 && log_compare(&lsn, &first_lsn) > 0;
        ret = log_get(lp, &lsn, &data, DB_PREV)) {
        if (dbenv->tx_recover != NULL)
            ret = dbenv->tx_recover(lp,
                &data, &lsn, TXN_BACKWARD_ROLL, txninfo);
        else
            ret = __db_dispatch(lp,
                &data, &lsn, TXN_BACKWARD_ROLL, txninfo);
        if (ret != 0)
            if (ret != DB_TXN_CKP)
                goto msgerr;
            else
                ret = 0;
    }
    if (ret != 0 && ret != DB_NOTFOUND)
        goto out;

    /*
     * Pass #3.
     */
    for (ret = log_get(lp, &lsn, &data, DB_NEXT);
        ret == 0; ret = log_get(lp, &lsn, &data, DB_NEXT)) {
        if (dbenv->tx_recover != NULL)
            ret = dbenv->tx_recover(lp,
                &data, &lsn, TXN_FORWARD_ROLL, txninfo);
        else
            ret = __db_dispatch(lp,
                &data, &lsn, TXN_FORWARD_ROLL, txninfo);
        if (ret != 0)
            if (ret != DB_TXN_CKP)
                goto msgerr;
            else
                ret = 0;
    }
    if (ret != DB_NOTFOUND)
        goto out;

    /* Now close all the db files that are open. */
    __log_close_files(lp);

    /*
     * Now set the last checkpoint lsn and the current time,
     * take a checkpoint, and reset the txnid.
     */
    (void)time(&now);
    dbenv->tx_info->region->last_ckp = ckp_lsn;
    dbenv->tx_info->region->time_ckp = (u_int32_t)now;
    if ((ret = txn_checkpoint(dbenv->tx_info, 0, 0)) != 0)
        goto out;
    dbenv->tx_info->region->last_txnid = TXN_MINIMUM;

    if (dbenv->db_verbose) {
        __db_err(lp->dbenv, "Recovery complete at %.24s", ctime(&now));
        __db_err(lp->dbenv, "%s %lx %s [%lu][%lu]",
            "Maximum transaction id",
            ((DB_TXNHEAD *)txninfo)->maxid,
            "Recovery checkpoint",
            (u_long)dbenv->tx_info->region->last_ckp.file,
            (u_long)dbenv->tx_info->region->last_ckp.offset);
    }

    if (0) {
msgerr:     __db_err(dbenv, "Recovery function for LSN %lu %lu failed",
            (u_long)lsn.file, (u_long)lsn.offset);
    }

out:    F_SET(lp, is_thread);
    __db_txnlist_end(txninfo);
    if (ckp_args != NULL)
        __os_free(ckp_args, sizeof(*ckp_args));

    return (ret);
}