env_recover.c

这是国外的resip协议栈

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2004
 *	Sleepycat Software.  All rights reserved.
 *
 * $Id: env_recover.c,v 11.126 2004/09/22 03:43:52 bostic Exp $
 */

#include "db_config.h"

#ifndef lint
static const char copyright[] =
    "Copyright (c) 1996-2004\nSleepycat Software Inc.  All rights reserved.\n";
#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 "dbinc/db_page.h"
#include "dbinc/db_shash.h"
#include "dbinc/log.h"
#include "dbinc/txn.h"
#include "dbinc/mp.h"
#include "dbinc/db_am.h"

static int    __db_log_corrupt __P((DB_ENV *, DB_LSN *));
static int    __log_earliest __P((DB_ENV *, DB_LOGC *, int32_t *, DB_LSN *));
static double __lsn_diff __P((DB_LSN *, DB_LSN *, DB_LSN *, u_int32_t, int));

/*
 * __db_apprec --
 *	Perform recovery.  If max_lsn is non-NULL, then we are trying
 * to synchronize this system up with another system that has a max
 * LSN of max_lsn, so we need to roll back sufficiently far for that
 * to work.  See __log_backup for details.
 *
 * PUBLIC: int __db_apprec __P((DB_ENV *, DB_LSN *, DB_LSN *, int, u_int32_t));
 */
int
__db_apprec(dbenv, max_lsn, trunclsn, update, flags)
	DB_ENV *dbenv;
	DB_LSN *max_lsn, *trunclsn;
	int update;
	u_int32_t flags;
{
	DBT data;
	DB_LOGC *logc;
	DB_LSN ckp_lsn, first_lsn, last_lsn, lowlsn, lsn, stop_lsn, tlsn;
	DB_TXNREGION *region;
	REGENV *renv;
	REGINFO *infop;
	__txn_ckp_args *ckp_args;
	time_t now, tlow;
	double nfiles;
	u_int32_t hi_txn, log_size, txnid;
	int32_t low;
	int have_rec, progress, ret, t_ret;
	int (**dtab) __P((DB_ENV *, DBT *, DB_LSN *, db_recops, void *));
	char *p, *pass, t1[60], t2[60];
	void *txninfo;

	COMPQUIET(nfiles, (double)0);

	logc = NULL;
	ckp_args = NULL;
	dtab = NULL;
	hi_txn = TXN_MAXIMUM;
	txninfo = NULL;
	pass = "initial";

	/*
	 * XXX
	 * Get the log size.  No locking required because we're single-threaded
	 * during recovery.
	 */
	log_size =
	   ((LOG *)(((DB_LOG *)dbenv->lg_handle)->reginfo.primary))->log_size;

	/*
	 * If we need to, update the env handle timestamp.
	 */
	if (update) {
		infop = dbenv->reginfo;
		renv = infop->primary;
		(void)time(&renv->rep_timestamp);
	}

	/* Set in-recovery flags. */
	F_SET((DB_LOG *)dbenv->lg_handle, DBLOG_RECOVER);
	region = ((DB_TXNMGR *)dbenv->tx_handle)->reginfo.primary;
	F_SET(region, TXN_IN_RECOVERY);

	/* Allocate a cursor for the log. */
	if ((ret = __log_cursor(dbenv, &logc)) != 0)
		goto err;

	/*
	 * If the user is specifying recovery to a particular point in time
	 * or to a particular LSN, find the point to start recovery from.
	 */
	ZERO_LSN(lowlsn);
	if (max_lsn != NULL) {
		if ((ret = __log_backup(dbenv, logc, max_lsn, &lowlsn,
		    CKPLSN_CMP)) != 0)
			goto err;
	} else if (dbenv->tx_timestamp != 0) {
		if ((ret = __log_earliest(dbenv, logc, &low, &lowlsn)) != 0)
			goto err;
		if ((int32_t)dbenv->tx_timestamp < low) {
			(void)snprintf(t1, sizeof(t1),
			    "%s", ctime(&dbenv->tx_timestamp));
			if ((p = strchr(t1, '\n')) != NULL)
				*p = '\0';
			tlow = (time_t)low;
			(void)snprintf(t2, sizeof(t2), "%s", ctime(&tlow));
			if ((p = strchr(t2, '\n')) != NULL)
				*p = '\0';
			__db_err(dbenv,
		    "Invalid recovery timestamp %s; earliest time is %s",
			    t1, t2);
			ret = EINVAL;
			goto err;
		}
	}

	/*
	 * 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 earlier of the
	 *	most recent checkpoint LSN and a checkpoint LSN before the
	 *	recovery timestamp, if specified.  We need to be before the
	 *	most recent checkpoint LSN because we are going to collect
	 *	information about which transactions were begun before we
	 *	start rolling forward.  Those that were should never be undone
	 *	because queue cannot use LSNs to determine what operations can
	 *	safely be aborted and it cannot rollback operations in
	 *	transactions for which there may be records not processed
	 *	during recovery.  We need to consider earlier points in time
	 *	in case we are recovering to a particular timestamp.
	 *
	 * Pass #1:
	 *	Read forward through the log from the position found in pass 0
	 *	opening and closing files, and recording transactions for which
	 *	we've seen their first record (the transaction's prev_lsn is
	 *	0,0).  At the end of this pass, we know all transactions for
	 *	which we've seen begins and we have the "current" set of files
	 *	open.
	 *
	 * Pass #2:
	 *	Read backward through the log undoing any uncompleted TXNs.
	 *	There are four cases:
	 *	    1.  If doing catastrophic recovery, we read to the
	 *		beginning of the log
	 *	    2.  If we are doing normal reovery, then we have to roll
	 *		back to the most recent checkpoint LSN.
	 *	    3.  If we are recovering to a point in time, then we have
	 *		to roll back to the checkpoint whose ckp_lsn is earlier
	 *		than the specified time.  __log_earliest will figure
	 *		this out for us.
	 *	    4.	If we are recovering back to a particular LSN, then
	 *		we have to roll back to the checkpoint whose ckp_lsn
	 *		is earlier than the max_lsn.  __log_backup will figure
	 *		that out for us.
	 *	In case 2, "uncompleted TXNs" include all those who committed
	 *	after the user's specified timestamp.
	 *
	 * Pass #3:
	 *	Read forward through the log from the LSN found in pass #2,
	 *	redoing any committed TXNs (which committed after any user-
	 *	specified rollback point).  During this pass, checkpoint
	 *	file information is ignored, and file openings and closings
	 *	are redone.
	 *
	 * ckp_lsn   -- lsn of the last checkpoint or the first in the log.
	 * first_lsn -- the lsn where the forward passes begin.
	 * last_lsn  -- the last lsn in the log, used for feedback
	 * lowlsn    -- the lsn we are rolling back to, if we are recovering
	 *		to a point in time.
	 * lsn       -- temporary use lsn.
	 * stop_lsn  -- the point at which forward roll should stop
	 */

	/*
	 * 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 we can't find any log records, we're kind of done.
	 */
#ifdef UMRW
	ZERO_LSN(last_lsn);
#endif
	memset(&data, 0, sizeof(data));
	if ((ret = __log_c_get(logc, &last_lsn, &data, DB_LAST)) != 0) {
		if (ret == DB_NOTFOUND)
			ret = 0;
		else
			__db_err(dbenv, "Last log record not found");
		goto err;
	}

	do {
		/* txnid is after rectype, which is a u_int32. */
		memcpy(&txnid,
		    (u_int8_t *)data.data + sizeof(u_int32_t), sizeof(txnid));

		if (txnid != 0)
			break;
	} while ((ret = __log_c_get(logc, &lsn, &data, DB_PREV)) == 0);

	/*
	 * There are no transactions, so there is nothing to do unless
	 * we're recovering to an LSN.  If we are, we need to proceed since
	 * we'll still need to do a vtruncate based on information we haven't
	 * yet collected.
	 */
	if (ret == DB_NOTFOUND)
		ret = 0;
	else if (ret != 0)
		goto err;

	hi_txn = txnid;

	/*
	 * Pass #0
	 * Find the LSN from which we begin OPENFILES.
	 *
	 * If this is a catastrophic recovery, or if no checkpoint exists
	 * in the log, the LSN is the first LSN in the log.
	 *
	 * Otherwise, it is the minimum of (1) the LSN in the last checkpoint
	 * and (2) the LSN in the checkpoint before any specified recovery
	 * timestamp or max_lsn.
	 */
	/*
	 * Get the first LSN in the log; it's an initial default
	 * even if this is not a catastrophic recovery.
	 */
	if ((ret = __log_c_get(logc, &ckp_lsn, &data, DB_FIRST)) != 0) {
		if (ret == DB_NOTFOUND)
			ret = 0;
		else
			__db_err(dbenv, "First log record not found");
		goto err;
	}
	first_lsn = ckp_lsn;
	have_rec = 1;

	if (!LF_ISSET(DB_RECOVER_FATAL)) {
		if ((ret = __txn_getckp(dbenv, &ckp_lsn)) == 0 &&
		    (ret = __log_c_get(logc, &ckp_lsn, &data, DB_SET)) == 0) {
			/* We have a recent checkpoint.  This is LSN (1). */
			if ((ret = __txn_ckp_read(dbenv,
			    data.data, &ckp_args)) != 0) {
				__db_err(dbenv,
			    "Invalid checkpoint record at [%ld][%ld]",
				    (u_long)ckp_lsn.file,
				    (u_long)ckp_lsn.offset);
				goto err;
			}
			first_lsn = ckp_args->ckp_lsn;
			__os_free(dbenv, ckp_args);
			have_rec = 0;
		}

		/*
		 * If LSN (2) exists, use it if it's before LSN (1).
		 * (If LSN (1) doesn't exist, first_lsn is the
		 * beginning of the log, so will "win" this check.)
		 *
		 * XXX
		 * In the recovery-to-a-timestamp case, lowlsn is chosen by
		 * __log_earliest, and is the checkpoint LSN of the
		 * *earliest* checkpoint in the unreclaimed log.  I
		 * (krinsky) believe that we could optimize this by looking
		 * instead for the LSN of the *latest* checkpoint before
		 * the timestamp of interest, but I'm not sure that this
		 * is worth doing right now.  (We have to look for lowlsn
		 * and low anyway, to make sure the requested timestamp is
		 * somewhere in the logs we have, and all that's required
		 * is that we pick *some* checkpoint after the beginning of
		 * the logs and before the timestamp.
		 */
		if ((dbenv->tx_timestamp != 0 || max_lsn != NULL) &&
		    log_compare(&lowlsn, &first_lsn) < 0) {
			DB_ASSERT(have_rec == 0);
			first_lsn = lowlsn;
		}
	}

	/* Get the record at first_lsn if we don't have it already. */
	if (!have_rec &&
	    (ret = __log_c_get(logc, &first_lsn, &data, DB_SET)) != 0) {
		__db_err(dbenv, "Checkpoint LSN record [%ld][%ld] not found",
		    (u_long)first_lsn.file, (u_long)first_lsn.offset);
		goto err;
	}

	if (dbenv->db_feedback != NULL) {
		if (last_lsn.file == first_lsn.file)
			nfiles = (double)
			    (last_lsn.offset - first_lsn.offset) / log_size;
		else
			nfiles = (double)(last_lsn.file - first_lsn.file) +
			    (double)((log_size - first_lsn.offset) +
			    last_lsn.offset) / log_size;
		/* We are going to divide by nfiles; make sure it isn't 0. */
		if (nfiles == 0)
			nfiles = (double)0.001;
	}

	/* Find a low txnid. */
	ret = 0;
	if (hi_txn != 0) do {
		/* txnid is after rectype, which is a u_int32. */
		memcpy(&txnid,
		    (u_int8_t *)data.data + sizeof(u_int32_t), sizeof(txnid));

		if (txnid != 0)
			break;
	} while ((ret = __log_c_get(logc, &lsn, &data, DB_NEXT)) == 0);

	/*
	 * There are no transactions and we're not recovering to an LSN (see
	 * above), so there is nothing to do.
	 */
	if (ret == DB_NOTFOUND) {
		if (log_compare(&lsn, &last_lsn) != 0)
			ret = __db_log_corrupt(dbenv, &lsn);
		else
			ret = 0;
	}

	/* Reset to the first lsn. */
	if (ret != 0 ||
	    (ret = __log_c_get(logc, &first_lsn, &data, DB_SET)) != 0)
		goto err;

	/* Initialize the transaction list. */
	if ((ret =
	    __db_txnlist_init(dbenv, txnid, hi_txn, max_lsn, &txninfo)) != 0)
		goto err;

	/*
	 * Pass #1
	 * Run forward through the log starting at the first relevant lsn.
	 */
	if ((ret = __env_openfiles(dbenv, logc,
	    txninfo, &data, &first_lsn, &last_lsn, nfiles, 1)) != 0)
		goto err;

	/* If there were no transactions, then we can bail out early. */
	if (hi_txn == 0 && max_lsn == NULL)
		goto done;

	/*
	 * Pass #2.
	 *
	 * We used first_lsn to tell us how far back we need to recover,
	 * use it here.
	 */

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

	pass = "backward";
	for (ret = __log_c_get(logc, &lsn, &data, DB_LAST);
	    ret == 0 && log_compare(&lsn, &first_lsn) >= 0;
	    ret = __log_c_get(logc, &lsn, &data, DB_PREV)) {
		if (dbenv->db_feedback != NULL) {
			progress = 34 + (int)(33 * (__lsn_diff(&first_lsn,
			    &last_lsn, &lsn, log_size, 0) / nfiles));
			dbenv->db_feedback(dbenv, DB_RECOVER, progress);
		}
		tlsn = lsn;
		ret = __db_dispatch(dbenv, dbenv->recover_dtab,
		    dbenv->recover_dtab_size, &data, &tlsn,
		    DB_TXN_BACKWARD_ROLL, txninfo);
		if (ret != 0) {
			if (ret != DB_TXN_CKP)
				goto msgerr;
			else
				ret = 0;
		}
	}
	if (ret == DB_NOTFOUND) {
		if (log_compare(&lsn, &first_lsn) > 0)
			ret = __db_log_corrupt(dbenv, &lsn);
		else
			ret = 0;
	}
	if (ret != 0)
		goto err;

	/*
	 * Pass #3.  If we are recovering to a timestamp or to an LSN,
	 * we need to make sure that we don't roll-forward beyond that
	 * point because there may be non-transactional operations (e.g.,
	 * closes that would fail).  The last_lsn variable is used for
	 * feedback calculations, but use it to set an initial stopping
	 * point for the forward pass, and then reset appropriately to
	 * derive a real stop_lsn that tells how far the forward pass
	 * should go.
	 */
	pass = "forward";
	stop_lsn = last_lsn;
	if (max_lsn != NULL || dbenv->tx_timestamp != 0)
		stop_lsn = ((DB_TXNHEAD *)txninfo)->maxlsn;