131 lines
3.7 KiB
C
131 lines
3.7 KiB
C
/*-
|
|
* See the file LICENSE for redistribution information.
|
|
*
|
|
* Copyright (c) 1996, 1997
|
|
* Sleepycat Software. All rights reserved.
|
|
*/
|
|
|
|
#include "config.h"
|
|
|
|
#ifndef lint
|
|
static const char sccsid[] = "@(#)log_findckp.c 10.12 (Sleepycat) 10/25/97";
|
|
#endif /* not lint */
|
|
|
|
#ifndef NO_SYSTEM_INCLUDES
|
|
#include <sys/types.h>
|
|
|
|
#include <errno.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#endif
|
|
|
|
#include "db_int.h"
|
|
#include "shqueue.h"
|
|
#include "log.h"
|
|
#include "txn.h"
|
|
#include "common_ext.h"
|
|
|
|
/*
|
|
* __log_findckp --
|
|
*
|
|
* Looks for the most recent checkpoint that occurs before the most recent
|
|
* checkpoint LSN. This is the point from which recovery can start and the
|
|
* point up to which archival/truncation can take place. Checkpoints in
|
|
* the log look like:
|
|
*
|
|
* -------------------------------------------------------------------
|
|
* | ckp A, ckplsn 100 | .... record .... | ckp B, ckplsn 600 | ...
|
|
* -------------------------------------------------------------------
|
|
* LSN 500 LSN 1000
|
|
*
|
|
* If we read what log returns from using the DB_CKP parameter to logput,
|
|
* we'll get the record at LSN 1000. The checkpoint LSN there is 600.
|
|
* Now we have to scan backwards looking for a checkpoint before LSN 600.
|
|
* We find one at 500. This means that we can truncate the log before
|
|
* 500 or run recovery beginning at 500.
|
|
*
|
|
* Returns 0 if we find a checkpoint.
|
|
* Returns errno on error.
|
|
* Returns DB_NOTFOUND if we could not find a suitable start point and
|
|
* we should start from the beginning.
|
|
*
|
|
* PUBLIC: int __log_findckp __P((DB_LOG *, DB_LSN *));
|
|
*/
|
|
int
|
|
__log_findckp(lp, lsnp)
|
|
DB_LOG *lp;
|
|
DB_LSN *lsnp;
|
|
{
|
|
DBT data;
|
|
DB_LSN ckp_lsn, last_ckp, next_lsn;
|
|
__txn_ckp_args *ckp_args;
|
|
int ret, verbose;
|
|
|
|
verbose = lp->dbenv != NULL && lp->dbenv->db_verbose != 0;
|
|
|
|
/*
|
|
* Need to find the appropriate point from which to begin
|
|
* recovery.
|
|
*/
|
|
memset(&data, 0, sizeof(data));
|
|
if (F_ISSET(lp, DB_AM_THREAD))
|
|
F_SET(&data, DB_DBT_MALLOC);
|
|
if ((ret = log_get(lp, &last_ckp, &data, DB_CHECKPOINT)) != 0)
|
|
return (ret == ENOENT ? DB_NOTFOUND : ret);
|
|
ZERO_LSN(ckp_lsn);
|
|
|
|
next_lsn = last_ckp;
|
|
do {
|
|
if (F_ISSET(lp, DB_AM_THREAD))
|
|
__db_free(data.data);
|
|
|
|
if ((ret = log_get(lp, &next_lsn, &data, DB_SET)) != 0)
|
|
return (ret);
|
|
if ((ret = __txn_ckp_read(data.data, &ckp_args)) != 0) {
|
|
if (F_ISSET(lp, DB_AM_THREAD))
|
|
__db_free(data.data);
|
|
return (ret);
|
|
}
|
|
if (IS_ZERO_LSN(ckp_lsn))
|
|
ckp_lsn = ckp_args->ckp_lsn;
|
|
if (verbose) {
|
|
__db_err(lp->dbenv, "Checkpoint at: [%lu][%lu]",
|
|
(u_long)last_ckp.file, (u_long)last_ckp.offset);
|
|
__db_err(lp->dbenv, "Checkpoint LSN: [%lu][%lu]",
|
|
(u_long)ckp_args->ckp_lsn.file,
|
|
(u_long)ckp_args->ckp_lsn.offset);
|
|
__db_err(lp->dbenv, "Previous checkpoint: [%lu][%lu]",
|
|
(u_long)ckp_args->last_ckp.file,
|
|
(u_long)ckp_args->last_ckp.offset);
|
|
}
|
|
last_ckp = next_lsn;
|
|
next_lsn = ckp_args->last_ckp;
|
|
__db_free(ckp_args);
|
|
} while (!IS_ZERO_LSN(next_lsn) &&
|
|
log_compare(&last_ckp, &ckp_lsn) > 0);
|
|
|
|
if (F_ISSET(lp, DB_AM_THREAD))
|
|
__db_free(data.data);
|
|
|
|
/*
|
|
* At this point, either, next_lsn is ZERO or ckp_lsn is the
|
|
* checkpoint lsn and last_ckp is the LSN of the last checkpoint
|
|
* before ckp_lsn. If the compare in the loop is still true, then
|
|
* next_lsn must be 0 and we need to roll forward from the
|
|
* beginning of the log.
|
|
*/
|
|
if (log_compare(&last_ckp, &ckp_lsn) > 0) {
|
|
if ((ret = log_get(lp, &last_ckp, &data, DB_FIRST)) != 0)
|
|
return (ret);
|
|
if (F_ISSET(lp, DB_AM_THREAD))
|
|
__db_free(data.data);
|
|
}
|
|
*lsnp = last_ckp;
|
|
|
|
if (verbose)
|
|
__db_err(lp->dbenv, "Rolling forward from [%lu][%lu]",
|
|
(u_long)last_ckp.file, (u_long)last_ckp.offset);
|
|
|
|
return (IS_ZERO_LSN(last_ckp) ? DB_NOTFOUND : 0);
|
|
}
|