/*-
 * 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);
}