db2/common/db_apprec.c

   1 /*-
   2  * See the file LICENSE for redistribution information.
   3  *
   4  * Copyright (c) 1996, 1997, 1998
   5  *      Sleepycat Software.  All rights reserved.
   6  */
   7
   8 #include "config.h"
   9
  10 #ifndef lint
  11 static const char copyright[] =
  12 "@(#) Copyright (c) 1996, 1997, 1998\n\
  13         Sleepycat Software Inc.  All rights reserved.\n";
  14 static const char sccsid[] = "@(#)db_apprec.c   10.30 (Sleepycat) 5/3/98";
  15 #endif
  16
  17 #ifndef NO_SYSTEM_INCLUDES
  18 #include <sys/types.h>
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <time.h>
  23 #endif
  24
  25 #include "db_int.h"
  26 #include "shqueue.h"
  27 #include "db_page.h"
  28 #include "db_dispatch.h"
  29 #include "db_am.h"
  30 #include "log.h"
  31 #include "txn.h"
  32 #include "common_ext.h"
  33
  34 /*
  35  * __db_apprec --
  36  *      Perform recovery.
  37  *
  38  * PUBLIC: int __db_apprec __P((DB_ENV *, u_int32_t));
  39  */
  40 int
  41 __db_apprec(dbenv, flags)
  42         DB_ENV *dbenv;
  43         u_int32_t flags;
  44 {
  45         DBT data;
  46         DB_LOG *lp;
  47         DB_LSN ckp_lsn, first_lsn, lsn;
  48         time_t now;
  49         u_int32_t is_thread;
  50         int ret;
  51         void *txninfo;
  52
  53         lp = dbenv->lg_info;
  54
  55         /* Initialize the transaction list. */
  56         if ((ret = __db_txnlist_init(&txninfo)) != 0)
  57                 return (ret);
  58
  59         /*
  60          * Save the state of the thread flag -- we don't need it on at the
  61          * moment because we're single-threaded until recovery is complete.
  62          */
  63         is_thread = F_ISSET(lp, DB_AM_THREAD);
  64         F_CLR(lp, DB_AM_THREAD);
  65
  66         /*
  67          * Recovery is done in three passes:
  68          * Pass #1:
  69          *      Read forward through the log from the last checkpoint to the
  70          *      end of the log, opening and closing files so that at the end
  71          *      of the log we have the "current" set of files open.
  72          * Pass #2:
  73          *      Read backward through the log undoing any uncompleted TXNs.
  74          *      If doing catastrophic recovery, we read to the beginning of
  75          *      the log, otherwise, to the most recent checkpoint that occurs
  76          *      before the most recent checkpoint LSN, which is returned by
  77          *      __log_findckp().  During this pass, checkpoint file information
  78          *      is ignored, and file openings and closings are undone.
  79          * Pass #3:
  80          *      Read forward through the log from the LSN found in pass #2,
  81          *      redoing any committed TXNs.  During this pass, checkpoint
  82          *      file information is ignored, and file openings and closings
  83          *      are redone.
  84          */
  85
  86         /*
  87          * Find the last checkpoint in the log.  This is the point from which
  88          * we want to begin pass #1 (the TXN_OPENFILES pass).
  89          */
  90         memset(&data, 0, sizeof(data));
  91         if ((ret = log_get(lp, &ckp_lsn, &data, DB_CHECKPOINT)) != 0) {
  92                 /*
  93                  * If we don't find a checkpoint, start from the beginning.
  94                  * If that fails, we're done.  Note, we do not require that
  95                  * there be log records if we're performing recovery.
  96                  */
  97                 if ((ret = log_get(lp, &ckp_lsn, &data, DB_FIRST)) != 0) {
  98                         if (ret == DB_NOTFOUND)
  99                                 ret = 0;
 100                         else
 101                                 __db_err(dbenv, "First log record not found");
 102                         goto out;
 103                 }
 104         }
 105
 106         /*
 107          * Now, ckp_lsn is either the lsn of the last checkpoint or the lsn
 108          * of the first record in the log.  Begin the TXN_OPENFILES pass from
 109          * that lsn, and proceed to the end of the log.
 110          */
 111         lsn = ckp_lsn;
 112         for (;;) {
 113                 ret = __db_dispatch(lp, &data, &lsn, TXN_OPENFILES, txninfo);
 114                 if (ret != 0 && ret != DB_TXN_CKP)
 115                         goto msgerr;
 116                 if ((ret = log_get(lp, &lsn, &data, DB_NEXT)) != 0) {
 117                         if (ret == DB_NOTFOUND)
 118                                 break;
 119                         goto out;
 120                 }
 121         }
 122
 123         /*
 124          * Pass #2.
 125          *
 126          * Before we can begin pass #2, backward roll phase, we determine how
 127          * far back in the log to recover.  If we are doing catastrophic
 128          * recovery, then we go as far back as we have files.  If we are
 129          * doing normal recovery, we go as back to the most recent checkpoint
 130          * that occurs before the most recent checkpoint LSN.
 131          */
 132         if (LF_ISSET(DB_RECOVER_FATAL)) {
 133                 ZERO_LSN(first_lsn);
 134         } else
 135                 if ((ret = __log_findckp(lp, &first_lsn)) == DB_NOTFOUND) {
 136                         /*
 137                          * We don't require that log files exist if recovery
 138                          * was specified.
 139                          */
 140                         ret = 0;
 141                         goto out;
 142                 }
 143
 144         if (dbenv->db_verbose)
 145                 __db_err(lp->dbenv, "Recovery starting from [%lu][%lu]",
 146                     (u_long)first_lsn.file, (u_long)first_lsn.offset);
 147
 148         for (ret = log_get(lp, &lsn, &data, DB_LAST);
 149             ret == 0 && log_compare(&lsn, &first_lsn) > 0;
 150             ret = log_get(lp, &lsn, &data, DB_PREV)) {
 151                 ret = __db_dispatch(lp,
 152                     &data, &lsn, TXN_BACKWARD_ROLL, txninfo);
 153                 if (ret != 0) {
 154                         if (ret != DB_TXN_CKP)
 155                                 goto msgerr;
 156                         else
 157                                 ret = 0;
 158                 }
 159         }
 160         if (ret != 0 && ret != DB_NOTFOUND)
 161                 goto out;
 162
 163         /*
 164          * Pass #3.
 165          */
 166         for (ret = log_get(lp, &lsn, &data, DB_NEXT);
 167             ret == 0; ret = log_get(lp, &lsn, &data, DB_NEXT)) {
 168                 ret = __db_dispatch(lp, &data, &lsn, TXN_FORWARD_ROLL, txninfo);
 169                 if (ret != 0) {
 170                         if (ret != DB_TXN_CKP)
 171                                 goto msgerr;
 172                         else
 173                                 ret = 0;
 174                 }
 175         }
 176         if (ret != DB_NOTFOUND)
 177                 goto out;
 178
 179         /* Now close all the db files that are open. */
 180         __log_close_files(lp);
 181
 182         /*
 183          * Now set the last checkpoint lsn and the current time,
 184          * take a checkpoint, and reset the txnid.
 185          */
 186         (void)time(&now);
 187         dbenv->tx_info->region->last_ckp = ckp_lsn;
 188         dbenv->tx_info->region->time_ckp = (u_int32_t)now;
 189         if ((ret = txn_checkpoint(dbenv->tx_info, 0, 0)) != 0)
 190                 goto out;
 191         dbenv->tx_info->region->last_txnid = TXN_MINIMUM;
 192
 193         if (dbenv->db_verbose) {
 194                 __db_err(lp->dbenv, "Recovery complete at %.24s", ctime(&now));
 195                 __db_err(lp->dbenv, "%s %lx %s [%lu][%lu]",
 196                     "Maximum transaction id",
 197                     ((DB_TXNHEAD *)txninfo)->maxid,
 198                     "Recovery checkpoint",
 199                     (u_long)dbenv->tx_info->region->last_ckp.file,
 200                     (u_long)dbenv->tx_info->region->last_ckp.offset);
 201         }
 202
 203         if (0) {
 204 msgerr:         __db_err(dbenv, "Recovery function for LSN %lu %lu failed",
 205                     (u_long)lsn.file, (u_long)lsn.offset);
 206         }
 207
 208 out:    F_SET(lp, is_thread);
 209         __db_txnlist_end(txninfo);
 210
 211         return (ret);
 212 }