/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999
 *	Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1996, 1997, 1998, 1999\n\
	Sleepycat Software Inc.  All rights reserved.\n";
static const char sccsid[] = "@(#)env_recover.c	11.6 (Sleepycat) 10/1/99";
#endif

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

#if TIME_WITH_SYS_TIME
#include <sys/time.h>
#include <time.h>
#else
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <time.h>
#endif
#endif

#include <string.h>
#endif

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

static float CDB___lsn_diff __P((DB_LSN *, DB_LSN *, DB_LSN *, u_int32_t, int));

/*
 * CDB___db_apprec --
 *	Perform recovery.
 *
 * PUBLIC: int CDB___db_apprec __P((DB_ENV *, u_int32_t));
 */
int
CDB___db_apprec(dbenv, flags)
	DB_ENV *dbenv;
	u_int32_t flags;
{
	DBT data;
	DB_LSN ckp_lsn, first_lsn, last_lsn, lsn, open_lsn;
	DB_TXNREGION *region;
	__txn_ckp_args *ckp_args;
	time_t now;
	float nfiles;
	int is_thread, progress, ret;
	void *txninfo;

	COMPQUIET(nfiles, (float)0);

	/* Initialize the transaction list. */
	if ((ret = CDB___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(dbenv, DB_ENV_THREAD) ? 1 : 0;
	F_CLR(dbenv, DB_ENV_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
	 *	CDB___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.
	 */

	/*
	 * Pass #0
	 * 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 = CDB_log_get(dbenv, &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 = CDB_log_get(dbenv, &ckp_lsn, &data, DB_FIRST)) != 0) {
			if (ret == DB_NOTFOUND)
				ret = 0;
			else
				CDB___db_err(dbenv, "First log record not found");
			goto out;
		}
		open_lsn = ckp_lsn;
	} else if ((ret = CDB___txn_ckp_read(data.data, &ckp_args)) != 0) {
		CDB___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 = CDB_log_get(dbenv, &ckp_args->last_ckp, &data, DB_SET)) != 0)
		goto first;
	else
		open_lsn = ckp_args->last_ckp;

	/*
	 * Find out the last lsn, so that we can estimate how far along we
	 * are in recovery.  This will help us determine how much log there
	 * is between the first LSN that we're going to be working with and
	 * the last one.  We assume that each of the three phases takes the
	 * same amount of time (a false assumption) and then use the %-age
	 * of the amount of log traversed to figure out how much of the
	 * pass we've accomplished.
	 */
	if (dbenv->db_feedback != NULL) {
		if ((ret = CDB_log_get(dbenv, &last_lsn, &data, DB_LAST)) != 0)
			goto out;
		if (last_lsn.file == ckp_lsn.file)
			nfiles = (float)(last_lsn.offset - ckp_lsn.offset) /
			    dbenv->lg_max;
		else
			nfiles = (float)(last_lsn.file - ckp_lsn.file) +
			    (float)(dbenv->lg_max - ckp_lsn.offset +
			    last_lsn.offset) / dbenv->lg_max;
	}

	/*
	 * Pass #1
	 * Now, ckp_lsn is either the lsn of the second to 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(dbenv,
			    &data, &lsn, TXN_OPENFILES, txninfo);
		else
			ret = CDB___db_dispatch(dbenv,
			    &data, &lsn, TXN_OPENFILES, txninfo);
		if (ret != 0 && ret != DB_TXN_CKP)
			goto msgerr;
		if ((ret = CDB_log_get(dbenv, &lsn, &data, DB_NEXT)) != 0) {
			if (ret == DB_NOTFOUND)
				break;
			goto out;
		}
		if (dbenv->db_feedback != NULL) {
			progress = (int)(33 * CDB___lsn_diff(&ckp_lsn,
			   &last_lsn, &lsn, dbenv->lg_max, 1) / nfiles);
			dbenv->db_feedback(dbenv, DB_RECOVER, progress);
		}
	}

	/*
	 * 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 = CDB___log_findckp(dbenv, &first_lsn)) == DB_NOTFOUND) {
			/*
			 * We don't require that log files exist if recovery
			 * was specified.
			 */
			ret = 0;
			goto out;
		}

	if (FLD_ISSET(dbenv->verbose, DB_VERB_RECOVERY))
		CDB___db_err(dbenv, "Recovery starting from [%lu][%lu]",
		    (u_long)first_lsn.file, (u_long)first_lsn.offset);

	for (ret = CDB_log_get(dbenv, &lsn, &data, DB_LAST);
	    ret == 0 && CDB_log_compare(&lsn, &first_lsn) > 0;
	    ret = CDB_log_get(dbenv, &lsn, &data, DB_PREV)) {
		if (dbenv->tx_recover != NULL)
			ret = dbenv->tx_recover(dbenv,
			    &data, &lsn, TXN_BACKWARD_ROLL, txninfo);
		else
			ret = CDB___db_dispatch(dbenv,
			    &data, &lsn, TXN_BACKWARD_ROLL, txninfo);
		if (ret != 0) {
			if (ret != DB_TXN_CKP)
				goto msgerr;
			else
				ret = 0;
		}
		if (dbenv->db_feedback != NULL) {
			progress = 34 + (int)(33 * CDB___lsn_diff(&ckp_lsn,
			    &last_lsn, &lsn, dbenv->lg_max, 0) / nfiles);
			dbenv->db_feedback(dbenv, DB_RECOVER, progress);
		}
	}
	if (ret != 0 && ret != DB_NOTFOUND)
		goto out;

	/*
	 * Pass #3.
	 */
	for (ret = CDB_log_get(dbenv, &lsn, &data, DB_NEXT);
	    ret == 0; ret = CDB_log_get(dbenv, &lsn, &data, DB_NEXT)) {
		if (dbenv->tx_recover != NULL)
			ret = dbenv->tx_recover(dbenv,
			    &data, &lsn, TXN_FORWARD_ROLL, txninfo);
		else
			ret = CDB___db_dispatch(dbenv,
			    &data, &lsn, TXN_FORWARD_ROLL, txninfo);
		if (ret != 0) {
			if (ret != DB_TXN_CKP)
				goto msgerr;
			else
				ret = 0;
		}
		if (dbenv->db_feedback != NULL) {
			progress = 67 + (int)(33 * CDB___lsn_diff(&ckp_lsn,
			    &last_lsn, &lsn, dbenv->lg_max, 1) / nfiles);
			dbenv->db_feedback(dbenv, DB_RECOVER, progress);
		}
	}
	if (ret != DB_NOTFOUND)
		goto out;

	/* Now close all the db files that are open. */
	CDB___log_close_files(dbenv);

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

	if (FLD_ISSET(dbenv->verbose, DB_VERB_RECOVERY)) {
		CDB___db_err(dbenv, "Recovery complete at %.24s", ctime(&now));
		CDB___db_err(dbenv, "%s %lx %s [%lu][%lu]",
		    "Maximum transaction ID",
		    ((DB_TXNHEAD *)txninfo)->maxid,
		    "Recovery checkpoint",
		    (u_long)region->last_ckp.file,
		    (u_long)region->last_ckp.offset);
	}

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

out:	if (is_thread)
		F_SET(dbenv, DB_ENV_THREAD);
	CDB___db_txnlist_end(dbenv, txninfo);
	if (ckp_args != NULL)
		CDB___os_free(ckp_args, sizeof(*ckp_args));

	return (ret);
}

/*
 * Figure out how many logfiles we have processed.  If we are moving
 * forward (is_forward != 0), then we're computing current - low.  If
 * we are moving backward, we are compouting high - current.  max is
 * the number of bytes per logfile.
 */
static float
CDB___lsn_diff(low, high, current, max, is_forward)
	DB_LSN *low, *high, *current;
	u_int32_t max;
	int is_forward;
{
	float nf;

	/*
	 * There are three cases in each direction.  If you are in the
	 * same file, then all you need worry about is the difference in
	 * offsets.  If you are in different files, then either your offsets
	 * put you either more or less than the integral difference in the
	 * number of files -- we need to handle both of these.
	 */
	if (is_forward) {
		if (current->file == low->file)
			nf = (float)(current->offset - low->offset) / max;
		else if (current->offset < low->offset)
			nf = (float)(current->file - low->file - 1) +
			    (float)(max - low->offset + current->offset) / max;
		else
			nf = (float)(current->file - low->file) +
			    (float)(current->offset - low->offset) / max;
	} else {
		if (current->file == high->file)
			nf = (float)(high->offset - current->offset) / max;
		else if (current->offset > high->offset)
			nf = (float)(high->file - current->file - 1) +
			    (float)(max - current->offset + high->offset) / max;
		else
			nf = (float)(high->file - current->file) +
			    (float)(high->offset - current->offset) / max;
	}
	return (nf);
}