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Sourcecode: db4.1 version File versions

rep_record.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2001-2002
 *    Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: rep_record.c,v 1.111 2002/09/11 19:39:11 bostic Exp $";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <stdlib.h>
#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/db_am.h"
#include "dbinc/log.h"
#include "dbinc/rep.h"
#include "dbinc/txn.h"

static int __rep_apply __P((DB_ENV *, REP_CONTROL *, DBT *));
static int __rep_collect_txn __P((DB_ENV *, DB_LSN *, LSN_COLLECTION *));
static int __rep_lsn_cmp __P((const void *, const void *));
static int __rep_newfile __P((DB_ENV *, REP_CONTROL *, DBT *, DB_LSN *));

#define     IS_SIMPLE(R)      ((R) != DB___txn_regop && \
    (R) != DB___txn_ckp && (R) != DB___dbreg_register)

/*
 * __rep_process_message --
 *
 * This routine takes an incoming message and processes it.
 *
 * control: contains the control fields from the record
 * rec: contains the actual record
 * eidp: contains the machine id of the sender of the message;
 *    in the case of a DB_NEWMASTER message, returns the eid
 *    of the new master.
 *
 * PUBLIC: int __rep_process_message __P((DB_ENV *, DBT *, DBT *, int *));
 */
int
__rep_process_message(dbenv, control, rec, eidp)
      DB_ENV *dbenv;
      DBT *control, *rec;
      int *eidp;
{
      DB_LOG *dblp;
      DB_LOGC *logc;
      DB_LSN init_lsn, lsn, newfilelsn, oldfilelsn;
      DB_REP *db_rep;
      DBT *d, data_dbt, lsndbt, mylog;
      LOG *lp;
      REP *rep;
      REP_CONTROL *rp;
      REP_VOTE_INFO *vi;
      u_int32_t bytes, gen, gbytes, type, unused;
      int check_limit, cmp, done, do_req, i;
      int master, old, recovering, ret, t_ret, *tally;

      PANIC_CHECK(dbenv);
      ENV_REQUIRES_CONFIG(dbenv, dbenv->tx_handle, "rep_stat", DB_INIT_TXN);

      /* Control argument must be non-Null. */
      if (control == NULL || control->size == 0) {
            __db_err(dbenv,
      "DB_ENV->rep_process_message: control argument must be specified");
            return (EINVAL);
      }

      ret = 0;
      db_rep = dbenv->rep_handle;
      rep = db_rep->region;
      dblp = dbenv->lg_handle;
      lp = dblp->reginfo.primary;

      MUTEX_LOCK(dbenv, db_rep->mutexp);
      gen = rep->gen;
      recovering = F_ISSET(rep, REP_F_RECOVER);

      rep->stat.st_msgs_processed++;
      MUTEX_UNLOCK(dbenv, db_rep->mutexp);

      rp = (REP_CONTROL *)control->data;

#if 0
      __rep_print_message(dbenv, *eidp, rp, "rep_process_message");
#endif

      /* Complain if we see an improper version number. */
      if (rp->rep_version != DB_REPVERSION) {
            __db_err(dbenv,
                "unexpected replication message version %d, expected %d",
                rp->rep_version, DB_REPVERSION);
            return (EINVAL);
      }
      if (rp->log_version != DB_LOGVERSION) {
            __db_err(dbenv,
                "unexpected log record version %d, expected %d",
                rp->log_version, DB_LOGVERSION);
            return (EINVAL);
      }

      /*
       * Check for generation number matching.  Ignore any old messages
       * except requests that are indicative of a new client that needs
       * to get in sync.
       */
      if (rp->gen < gen && rp->rectype != REP_ALIVE_REQ &&
          rp->rectype != REP_NEWCLIENT && rp->rectype != REP_MASTER_REQ) {
            /*
             * We don't hold the rep mutex, and could miscount if we race.
             */
            rep->stat.st_msgs_badgen++;
            return (0);
      }
      if (rp->gen > gen && rp->rectype != REP_ALIVE &&
          rp->rectype != REP_NEWMASTER)
            return (__rep_send_message(dbenv,
                DB_EID_BROADCAST, REP_MASTER_REQ, NULL, NULL, 0));

      /*
       * We need to check if we're in recovery and if we are
       * then we need to ignore any messages except VERIFY, VOTE,
       * ELECT (the master might fail while we are recovering), and
       * ALIVE_REQ.
       */
      if (recovering)
            switch(rp->rectype) {
                  case REP_ALIVE:
                  case REP_ALIVE_REQ:
                  case REP_ELECT:
                  case REP_NEWCLIENT:
                  case REP_NEWMASTER:
                  case REP_NEWSITE:
                  case REP_VERIFY:
                        R_LOCK(dbenv, &dblp->reginfo);
                        cmp = log_compare(&lp->verify_lsn, &rp->lsn);
                        R_UNLOCK(dbenv, &dblp->reginfo);
                        if (cmp != 0)
                              goto skip;
                        /* FALLTHROUGH */
                  case REP_VOTE1:
                  case REP_VOTE2:
                        break;
                  default:
skip:                   /*
                         * We don't hold the rep mutex, and could
                         * miscount if we race.
                         */
                        rep->stat.st_msgs_recover++;

                        /* Check for need to retransmit. */
                        R_LOCK(dbenv, &dblp->reginfo);
                        do_req = *eidp == rep->master_id &&
                            ++lp->rcvd_recs >= lp->wait_recs;
                        if (do_req) {
                              lp->wait_recs *= 2;
                              if (lp->wait_recs + rep->max_gap)
                                    lp->wait_recs = rep->max_gap;
                              lp->rcvd_recs = 0;
                              lsn = lp->verify_lsn;
                        }
                        R_UNLOCK(dbenv, &dblp->reginfo);
                        if (do_req)
                              ret = __rep_send_message(dbenv, *eidp,
                                  REP_VERIFY_REQ, &lsn, NULL, 0);

                        return (ret);
            }

      switch(rp->rectype) {
      case REP_ALIVE:
            ANYSITE(dbenv);
            if (rp->gen > gen && rp->flags)
                  return (__rep_new_master(dbenv, rp, *eidp));
            break;
      case REP_ALIVE_REQ:
            ANYSITE(dbenv);
            dblp = dbenv->lg_handle;
            R_LOCK(dbenv, &dblp->reginfo);
            lsn = ((LOG *)dblp->reginfo.primary)->lsn;
            R_UNLOCK(dbenv, &dblp->reginfo);
            return (__rep_send_message(dbenv,
                *eidp, REP_ALIVE, &lsn, NULL,
                F_ISSET(dbenv, DB_ENV_REP_MASTER) ? 1 : 0));
      case REP_ALL_REQ:
            MASTER_ONLY(dbenv);
            gbytes  = bytes = 0;
            MUTEX_LOCK(dbenv, db_rep->mutexp);
            gbytes = rep->gbytes;
            bytes = rep->bytes;
            MUTEX_UNLOCK(dbenv, db_rep->mutexp);
            check_limit = gbytes != 0 || bytes != 0;
            if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
                  return (ret);
            memset(&data_dbt, 0, sizeof(data_dbt));
            oldfilelsn = lsn = rp->lsn;
            type = REP_LOG;
            for (ret = logc->get(logc, &rp->lsn, &data_dbt, DB_SET);
                ret == 0 && type == REP_LOG;
                ret = logc->get(logc, &lsn, &data_dbt, DB_NEXT)) {
                  /*
                   * lsn.offset will only be 0 if this is the
                   * beginning of the log;  DB_SET, but not DB_NEXT,
                   * can set the log cursor to [n][0].
                   */
                  if (lsn.offset == 0)
                        ret = __rep_send_message(dbenv, *eidp,
                            REP_NEWFILE, &lsn, NULL, 0);
                  else {
                        /*
                         * DB_NEXT will never run into offsets
                         * of 0;  thus, when a log file changes,
                         * we'll have a real log record with
                         * some lsn [n][m], and we'll also want to send
                         * a NEWFILE message with lsn [n][0].
                         * So that the client can detect gaps,
                         * send in the rec parameter the
                         * last LSN in the old file.
                         */
                        if (lsn.file != oldfilelsn.file) {
                              newfilelsn.file = lsn.file;
                              newfilelsn.offset = 0;

                              memset(&lsndbt, 0, sizeof(DBT));
                              lsndbt.size = sizeof(DB_LSN);
                              lsndbt.data = &oldfilelsn;

                              if ((ret = __rep_send_message(dbenv,
                                  *eidp, REP_NEWFILE, &newfilelsn,
                                  &lsndbt, 0)) != 0)
                                    break;
                        }
                        if (check_limit) {
                              /*
                               * data_dbt.size is only the size of
                               * the log record;  it doesn't count
                               * the size of the control structure.
                               * Factor that in as well so we're
                               * not off by a lot if our log
                               * records are small.
                               */
                              while (bytes < data_dbt.size +
                                  sizeof(REP_CONTROL)) {
                                    if (gbytes > 0) {
                                          bytes += GIGABYTE;
                                          --gbytes;
                                          continue;
                                    }
                                    /*
                                     * We don't hold the rep mutex,
                                     * and may miscount.
                                     */
                                    rep->stat.st_nthrottles++;
                                    type = REP_LOG_MORE;
                                    goto send;
                              }
                              bytes -= (data_dbt.size +
                                  sizeof(REP_CONTROL));
                        }
send:                   ret = __rep_send_message(dbenv, *eidp,
                            type, &lsn, &data_dbt, 0);
                  }

                  /*
                   * In case we're about to change files and need it
                   * for a NEWFILE message, save the current LSN.
                   */
                  oldfilelsn = lsn;
            }

            if (ret == DB_NOTFOUND)
                  ret = 0;
            if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
                  ret = t_ret;
            return (ret);
      case REP_ELECT:
            if (F_ISSET(dbenv, DB_ENV_REP_MASTER)) {
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  MUTEX_LOCK(dbenv, db_rep->mutexp);
                  rep->gen++;
                  MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                  return (__rep_send_message(dbenv,
                      *eidp, REP_NEWMASTER, &lsn, NULL, 0));
            }
            MUTEX_LOCK(dbenv, db_rep->mutexp);
            ret = IN_ELECTION(rep) ? 0 : DB_REP_HOLDELECTION;
            MUTEX_UNLOCK(dbenv, db_rep->mutexp);
            return (ret);
#ifdef NOTYET
      case REP_FILE: /* TODO */
            CLIENT_ONLY(dbenv);
            break;
      case REP_FILE_REQ:
            MASTER_ONLY(dbenv);
            return (__rep_send_file(dbenv, rec, *eidp));
            break;
#endif
      case REP_LOG:
      case REP_LOG_MORE:
            CLIENT_ONLY(dbenv);
            if ((ret = __rep_apply(dbenv, rp, rec)) != 0)
                  return (ret);
            if (rp->rectype == REP_LOG_MORE) {
                  MUTEX_LOCK(dbenv, db_rep->db_mutexp);
                  master = rep->master_id;
                  MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  ret = __rep_send_message(dbenv, master,
                      REP_ALL_REQ, &lsn, NULL, 0);
            }
            return (ret);
      case REP_LOG_REQ:
            MASTER_ONLY(dbenv);
            if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
                  return (ret);
            memset(&data_dbt, 0, sizeof(data_dbt));
            lsn = rp->lsn;

            /*
             * There are three different cases here.
             * 1. We asked for a particular LSN and got it.
             * 2. We asked for an LSN of X,0 which is invalid and got the
             *    first log record in a particular file.
             * 3. We asked for an LSN and it's not found because it is
             *    beyond the end of a log file and we need a NEWFILE msg.
             */
            ret = logc->get(logc, &rp->lsn, &data_dbt, DB_SET);
            cmp = log_compare(&lsn, &rp->lsn);

            if (ret == 0 && cmp == 0) /* Case 1 */
                  ret = __rep_send_message(dbenv, *eidp,
                            REP_LOG, &rp->lsn, &data_dbt, 0);
            else if (ret == DB_NOTFOUND ||
                (ret == 0 && cmp < 0 && rp->lsn.offset == 0))
                  /* Cases 2 and 3: Send a NEWFILE message. */
                  ret = __rep_send_message(dbenv, *eidp,
                      REP_NEWFILE, &lsn, NULL, 0);

            if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
                  ret = t_ret;
            return (ret);
      case REP_NEWSITE:
            /* We don't hold the rep mutex, and may miscount. */
            rep->stat.st_newsites++;

            /* This is a rebroadcast; simply tell the application. */
            if (F_ISSET(dbenv, DB_ENV_REP_MASTER)) {
                  dblp = dbenv->lg_handle;
                  lp = dblp->reginfo.primary;
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  (void)__rep_send_message(dbenv,
                      *eidp, REP_NEWMASTER, &lsn, NULL, 0);
            }
            return (DB_REP_NEWSITE);
      case REP_NEWCLIENT:
            /*
             * This message was received and should have resulted in the
             * application entering the machine ID in its machine table.
             * We respond to this with an ALIVE to send relevant information
             * to the new client.  But first, broadcast the new client's
             * record to all the clients.
             */
            if ((ret = __rep_send_message(dbenv,
                DB_EID_BROADCAST, REP_NEWSITE, &rp->lsn, rec, 0)) != 0)
                  return (ret);

            if (F_ISSET(dbenv, DB_ENV_REP_CLIENT))
                  return (0);

             /* FALLTHROUGH */
      case REP_MASTER_REQ:
            ANYSITE(dbenv);
            if (F_ISSET(dbenv, DB_ENV_REP_CLIENT))
                  return (0);
            dblp = dbenv->lg_handle;
            lp = dblp->reginfo.primary;
            R_LOCK(dbenv, &dblp->reginfo);
            lsn = lp->lsn;
            R_UNLOCK(dbenv, &dblp->reginfo);
            return (__rep_send_message(dbenv,
                *eidp, REP_NEWMASTER, &lsn, NULL, 0));
      case REP_NEWFILE:
            CLIENT_ONLY(dbenv);
            return (__rep_apply(dbenv, rp, rec));
      case REP_NEWMASTER:
            ANYSITE(dbenv);
            if (F_ISSET(dbenv, DB_ENV_REP_MASTER) &&
                *eidp != dbenv->rep_eid) {
                  /* We don't hold the rep mutex, and may miscount. */
                  rep->stat.st_dupmasters++;
                  return (DB_REP_DUPMASTER);
            }
            return (__rep_new_master(dbenv, rp, *eidp));
      case REP_PAGE: /* TODO */
            CLIENT_ONLY(dbenv);
            break;
      case REP_PAGE_REQ: /* TODO */
            MASTER_ONLY(dbenv);
            break;
      case REP_PLIST: /* TODO */
            CLIENT_ONLY(dbenv);
            break;
      case REP_PLIST_REQ: /* TODO */
            MASTER_ONLY(dbenv);
            break;
      case REP_VERIFY:
            CLIENT_ONLY(dbenv);
            DB_ASSERT((F_ISSET(rep, REP_F_RECOVER) &&
                !IS_ZERO_LSN(lp->verify_lsn)) ||
                (!F_ISSET(rep, REP_F_RECOVER) &&
                IS_ZERO_LSN(lp->verify_lsn)));
            if (IS_ZERO_LSN(lp->verify_lsn))
                  return (0);

            if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
                  return (ret);
            memset(&mylog, 0, sizeof(mylog));
            if ((ret = logc->get(logc, &rp->lsn, &mylog, DB_SET)) != 0)
                  goto rep_verify_err;
            if (mylog.size == rec->size &&
                memcmp(mylog.data, rec->data, rec->size) == 0) {
                  /*
                   * If we're a logs-only client, we can simply truncate
                   * the log to the point where it last agreed with the
                   * master's;  otherwise, recover to that point.
                   */
                  R_LOCK(dbenv, &dblp->reginfo);
                  ZERO_LSN(lp->verify_lsn);
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  if (F_ISSET(dbenv, DB_ENV_REP_LOGSONLY)) {
                        INIT_LSN(init_lsn);
                        if ((ret = dbenv->log_flush(dbenv,
                            &rp->lsn)) != 0 ||
                            (ret = __log_vtruncate(dbenv,
                            &rp->lsn, &init_lsn)) != 0)
                              goto rep_verify_err;
                  } else if ((ret = __db_apprec(dbenv, &rp->lsn, 0)) != 0)
                        goto rep_verify_err;

                  /*
                   * The log has been truncated (either by __db_apprec or
                   * directly).  We want to make sure we're waiting for
                   * the LSN at the new end-of-log, not some later point.
                   */
                  R_LOCK(dbenv, &dblp->reginfo);
                  lp->ready_lsn = lp->lsn;
                  ZERO_LSN(lp->waiting_lsn);
                  R_UNLOCK(dbenv, &dblp->reginfo);

                  /*
                   * Discard any log records we have queued;  we're
                   * about to re-request them, and can't trust the
                   * ones in the queue.
                   */
                  MUTEX_LOCK(dbenv, db_rep->db_mutexp);
                  if ((ret = db_rep->rep_db->truncate(db_rep->rep_db,
                      NULL, &unused, 0)) != 0) {
                        MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);
                        goto rep_verify_err;
                  }
                  rep->stat.st_log_queued = 0;
                  MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);

                  MUTEX_LOCK(dbenv, db_rep->mutexp);
                  F_CLR(rep, REP_F_RECOVER);

                  /*
                   * If the master_id is invalid, this means that since
                   * the last record was sent, somebody declared an
                   * election and we may not have a master to request
                   * things of.
                   *
                   * This is not an error;  when we find a new master,
                   * we'll re-negotiate where the end of the log is and
                   * try to bring ourselves up to date again anyway.
                   */
                  if ((master = rep->master_id) == DB_EID_INVALID) {
                        DB_ASSERT(IN_ELECTION(rep));
                        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                        ret = 0;
                  } else {
                        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                        ret = __rep_send_message(dbenv, master,
                            REP_ALL_REQ, &rp->lsn, NULL, 0);
                  }
            } else if ((ret =
                logc->get(logc, &lsn, &mylog, DB_PREV)) == 0) {
                  R_LOCK(dbenv, &dblp->reginfo);
                  lp->verify_lsn = lsn;
                  lp->rcvd_recs = 0;
                  lp->wait_recs = rep->request_gap;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  ret = __rep_send_message(dbenv,
                      *eidp, REP_VERIFY_REQ, &lsn, NULL, 0);
            }

rep_verify_err:   if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
                  ret = t_ret;
            return (ret);
      case REP_VERIFY_FAIL:
            rep->stat.st_outdated++;
            return (DB_REP_OUTDATED);
      case REP_VERIFY_REQ:
            MASTER_ONLY(dbenv);
            type = REP_VERIFY;
            if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
                  return (ret);
            d = &data_dbt;
            memset(d, 0, sizeof(data_dbt));
            F_SET(logc, DB_LOG_SILENT_ERR);
            ret = logc->get(logc, &rp->lsn, d, DB_SET);
            /*
             * If the LSN was invalid, then we might get a not
             * found, we might get an EIO, we could get anything.
             * If we get a DB_NOTFOUND, then there is a chance that
             * the LSN comes before the first file present in which
             * case we need to return a fail so that the client can return
             * a DB_OUTDATED.
             */
            if (ret == DB_NOTFOUND &&
                __log_is_outdated(dbenv, rp->lsn.file, &old) == 0 &&
                old != 0)
                  type = REP_VERIFY_FAIL;

            if (ret != 0)
                  d = NULL;

            ret = __rep_send_message(dbenv, *eidp, type, &rp->lsn, d, 0);
            if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
                  ret = t_ret;
            return (ret);
      case REP_VOTE1:
            if (F_ISSET(dbenv, DB_ENV_REP_MASTER)) {
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv, "Master received vote");
#endif
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  return (__rep_send_message(dbenv,
                      *eidp, REP_NEWMASTER, &lsn, NULL, 0));
            }

            vi = (REP_VOTE_INFO *)rec->data;
            MUTEX_LOCK(dbenv, db_rep->mutexp);

            /*
             * If you get a vote and you're not in an election, simply
             * return an indicator to hold an election which will trigger
             * this site to send its vote again.
             */
            if (!IN_ELECTION(rep)) {
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv,
                            "Not in election, but received vote1");
#endif
                  ret = DB_REP_HOLDELECTION;
                  goto unlock;
            }

            if (F_ISSET(rep, REP_F_EPHASE2))
                  goto unlock;

            /* Check if this site knows about more sites than we do. */
            if (vi->nsites > rep->nsites)
                  rep->nsites = vi->nsites;

            /* Check if we've heard from this site already. */
            tally = R_ADDR((REGINFO *)dbenv->reginfo, rep->tally_off);
            for (i = 0; i < rep->sites; i++) {
                  if (tally[i] == *eidp)
                        /* Duplicate vote. */
                        goto unlock;
            }

            /*
             * We are keeping vote, let's see if that changes our count of
             * the number of sites.
             */
            if (rep->sites + 1 > rep->nsites)
                  rep->nsites = rep->sites + 1;
            if (rep->nsites > rep->asites &&
                (ret = __rep_grow_sites(dbenv, rep->nsites)) != 0)
                        goto unlock;

            tally[rep->sites] = *eidp;
            rep->sites++;

            /*
             * Change winners if the incoming record has a higher
             * priority, or an equal priority but a larger LSN, or
             * an equal priority and LSN but higher "tiebreaker" value.
             */
#ifdef DIAGNOSTIC
            if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION)) {
                  __db_err(dbenv,
                      "%s(eid)%d (pri)%d (gen)%d (sites)%d [%d,%d]",
                      "Existing vote: ",
                      rep->winner, rep->w_priority, rep->w_gen,
                      rep->sites, rep->w_lsn.file, rep->w_lsn.offset);
                  __db_err(dbenv,
                      "Incoming vote: (eid)%d (pri)%d (gen)%d [%d,%d]",
                      *eidp, vi->priority, rp->gen, rp->lsn.file,
                      rp->lsn.offset);
            }
#endif
            cmp = log_compare(&rp->lsn, &rep->w_lsn);
            if (vi->priority > rep->w_priority ||
                (vi->priority != 0 && vi->priority == rep->w_priority &&
                (cmp > 0 ||
                (cmp == 0 && vi->tiebreaker > rep->w_tiebreaker)))) {
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv, "Accepting new vote");
#endif
                  rep->winner = *eidp;
                  rep->w_priority = vi->priority;
                  rep->w_lsn = rp->lsn;
                  rep->w_gen = rp->gen;
            }
            master = rep->winner;
            lsn = rep->w_lsn;
            done = rep->sites == rep->nsites && rep->w_priority != 0;
            if (done) {
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION)) {
                        __db_err(dbenv, "Phase1 election done");
                        __db_err(dbenv, "Voting for %d%s",
                            master, master == rep->eid ? "(self)" : "");
                  }
#endif
                  F_CLR(rep, REP_F_EPHASE1);
                  F_SET(rep, REP_F_EPHASE2);
            }

            if (done && master == rep->eid) {
                  rep->votes++;
                  MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                  return (0);
            }
            MUTEX_UNLOCK(dbenv, db_rep->mutexp);

            /* Vote for someone else. */
            if (done)
                  return (__rep_send_message(dbenv,
                      master, REP_VOTE2, NULL, NULL, 0));

            /* Election is still going on. */
            break;
      case REP_VOTE2:
#ifdef DIAGNOSTIC
            if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                  __db_err(dbenv, "We received a vote%s",
                      F_ISSET(dbenv, DB_ENV_REP_MASTER) ?
                      " (master)" : "");
#endif
            if (F_ISSET(dbenv, DB_ENV_REP_MASTER)) {
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  rep->stat.st_elections_won++;
                  return (__rep_send_message(dbenv,
                      *eidp, REP_NEWMASTER, &lsn, NULL, 0));
            }

            MUTEX_LOCK(dbenv, db_rep->mutexp);

            /* If we have priority 0, we should never get a vote. */
            DB_ASSERT(rep->priority != 0);

            if (!IN_ELECTION(rep)) {
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv, "Not in election, got vote");
#endif
                  MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                  return (DB_REP_HOLDELECTION);
            }
            /* avoid counting duplicates. */
            rep->votes++;
            done = rep->votes > rep->nsites / 2;
            if (done) {
                  rep->master_id = rep->eid;
                  rep->gen = rep->w_gen + 1;
                  ELECTION_DONE(rep);
                  F_CLR(rep, REP_F_UPGRADE);
                  F_SET(rep, REP_F_MASTER);
                  *eidp = rep->master_id;
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv,
                  "Got enough votes to win; election done; winner is %d",
                            rep->master_id);
#endif
            }
            MUTEX_UNLOCK(dbenv, db_rep->mutexp);
            if (done) {
                  R_LOCK(dbenv, &dblp->reginfo);
                  lsn = lp->lsn;
                  R_UNLOCK(dbenv, &dblp->reginfo);

                  /* Declare me the winner. */
#ifdef DIAGNOSTIC
                  if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv, "I won, sending NEWMASTER");
#endif
                  rep->stat.st_elections_won++;
                  if ((ret = __rep_send_message(dbenv, DB_EID_BROADCAST,
                      REP_NEWMASTER, &lsn, NULL, 0)) != 0)
                        break;
                  return (DB_REP_NEWMASTER);
            }
            break;
      default:
            __db_err(dbenv,
      "DB_ENV->rep_process_message: unknown replication message: type %lu",
               (u_long)rp->rectype);
            return (EINVAL);
      }

      return (0);

unlock:     MUTEX_UNLOCK(dbenv, db_rep->mutexp);
      return (ret);
}

/*
 * __rep_apply --
 *
 * Handle incoming log records on a client, applying when possible and
 * entering into the bookkeeping table otherwise.  This is the guts of
 * the routine that handles the state machine that describes how we
 * process and manage incoming log records.
 */
static int
__rep_apply(dbenv, rp, rec)
      DB_ENV *dbenv;
      REP_CONTROL *rp;
      DBT *rec;
{
      __dbreg_register_args dbreg_args;
      __txn_ckp_args ckp_args;
      DB_REP *db_rep;
      DBT control_dbt, key_dbt, lsn_dbt, nextrec_dbt, rec_dbt;
      DB *dbp;
      DBC *dbc;
      DB_LOG *dblp;
      DB_LSN ckp_lsn, lsn, newfile_lsn, next_lsn, waiting_lsn;
      LOG *lp;
      REP *rep;
      REP_CONTROL lsn_rc;
      u_int32_t rectype, txnid;
      int cmp, do_req, eid, have_mutex, ret, t_ret;

      db_rep = dbenv->rep_handle;
      rep = db_rep->region;
      dbp = db_rep->rep_db;
      dbc = NULL;
      have_mutex = ret = 0;
      memset(&control_dbt, 0, sizeof(control_dbt));
      memset(&rec_dbt, 0, sizeof(rec_dbt));

      /*
       * If this is a log record and it's the next one in line, simply
       * write it to the log.  If it's a "normal" log record, i.e., not
       * a COMMIT or CHECKPOINT or something that needs immediate processing,
       * just return.  If it's a COMMIT, CHECKPOINT or LOG_REGISTER (i.e.,
       * not SIMPLE), handle it now.  If it's a NEWFILE record, then we
       * have to be prepared to deal with a logfile change.
       */
      dblp = dbenv->lg_handle;
      R_LOCK(dbenv, &dblp->reginfo);
      lp = dblp->reginfo.primary;
      cmp = log_compare(&rp->lsn, &lp->ready_lsn);

      /*
       * This is written to assume that you don't end up with a lot of
       * records after a hole.  That is, it optimizes for the case where
       * there is only a record or two after a hole.  If you have a lot
       * of records after a hole, what you'd really want to do is write
       * all of them and then process all the commits, checkpoints, etc.
       * together.  That is more complicated processing that we can add
       * later if necessary.
       *
       * That said, I really don't want to do db operations holding the
       * log mutex, so the synchronization here is tricky.
       */
      if (cmp == 0) {
            /* We got the log record that we are expecting. */
            if (rp->rectype == REP_NEWFILE) {
newfile:          ret = __rep_newfile(dbenv, rp, rec, &lp->ready_lsn);

                  /* Make this evaluate to a simple rectype. */
                  rectype = 0;
            } else {
                  DB_ASSERT(log_compare(&rp->lsn, &lp->lsn) == 0);
                  ret = __log_rep_put(dbenv, &rp->lsn, rec);
                  lp->ready_lsn = lp->lsn;
                  memcpy(&rectype, rec->data, sizeof(rectype));
                  if (ret == 0)
                        /*
                         * We may miscount if we race, since we
                         * don't currently hold the rep mutex.
                         */
                        rep->stat.st_log_records++;
            }
            while (ret == 0 && IS_SIMPLE(rectype) &&
                log_compare(&lp->ready_lsn, &lp->waiting_lsn) == 0) {
                  /*
                   * We just filled in a gap in the log record stream.
                   * Write subsequent records to the log.
                   */
gap_check:        lp->wait_recs = 0;
                  lp->rcvd_recs = 0;
                  R_UNLOCK(dbenv, &dblp->reginfo);
                  if (have_mutex == 0) {
                        MUTEX_LOCK(dbenv, db_rep->db_mutexp);
                        have_mutex = 1;
                  }
                  if (dbc == NULL &&
                      (ret = dbp->cursor(dbp, NULL, &dbc, 0)) != 0)
                        goto err;

                  /* The DBTs need to persist through another call. */
                  F_SET(&control_dbt, DB_DBT_REALLOC);
                  F_SET(&rec_dbt, DB_DBT_REALLOC);
                  if ((ret = dbc->c_get(dbc,
                      &control_dbt, &rec_dbt, DB_RMW | DB_FIRST)) != 0)
                        goto err;

                  rp = (REP_CONTROL *)control_dbt.data;
                  rec = &rec_dbt;
                  memcpy(&rectype, rec->data, sizeof(rectype));
                  R_LOCK(dbenv, &dblp->reginfo);
                  /*
                   * We need to check again, because it's possible that
                   * some other thread of control changed the waiting_lsn
                   * or removed that record from the database.
                   */
                  if (log_compare(&lp->ready_lsn, &rp->lsn) == 0) {
                        if (rp->rectype != REP_NEWFILE) {
                              DB_ASSERT(log_compare
                                  (&rp->lsn, &lp->lsn) == 0);
                              ret = __log_rep_put(dbenv,
                                  &rp->lsn, rec);
                              lp->ready_lsn = lp->lsn;

                              /*
                               * We may miscount if we race, since we
                               * don't currently hold the rep mutex.
                               */
                              if (ret == 0)
                                    rep->stat.st_log_records++;
                        } else {
                              ret = __rep_newfile(dbenv,
                                  rp, rec, &lp->ready_lsn);
                              rectype = 0;
                        }
                        waiting_lsn = lp->waiting_lsn;
                        R_UNLOCK(dbenv, &dblp->reginfo);
                        if ((ret = dbc->c_del(dbc, 0)) != 0)
                              goto err;

                        /*
                         * We may miscount, as we don't hold the rep
                         * mutex.
                         */
                        --rep->stat.st_log_queued;

                        /*
                         * Update waiting_lsn.  We need to move it
                         * forward to the LSN of the next record
                         * in the queue.
                         */
                        memset(&lsn_dbt, 0, sizeof(lsn_dbt));
                        F_SET(&lsn_dbt, DB_DBT_USERMEM);
                        lsn_dbt.data = &lsn_rc;
                        lsn_dbt.ulen = sizeof(lsn_rc);
                        memset(&lsn_rc, 0, sizeof(lsn_rc));

                        /*
                         * If the next item in the database is a log
                         * record--the common case--we're not
                         * interested in its contents, just in its LSN.
                         * If it's a newfile message, though, the
                         * data field may be the LSN of the last
                         * record in the old file, and we need to use
                         * that to determine whether or not there's
                         * a gap.
                         *
                         * Optimize both these cases by doing a partial
                         * get of the data item.  If it's a newfile
                         * record, we'll get the whole LSN, and if
                         * it's not, we won't waste time allocating.
                         */
                        memset(&nextrec_dbt, 0, sizeof(nextrec_dbt));
                        F_SET(&nextrec_dbt,
                            DB_DBT_USERMEM | DB_DBT_PARTIAL);
                        nextrec_dbt.ulen =
                            nextrec_dbt.dlen = sizeof(newfile_lsn);
                        ZERO_LSN(newfile_lsn);
                        nextrec_dbt.data = &newfile_lsn;

                        ret = dbc->c_get(dbc,
                            &lsn_dbt, &nextrec_dbt, DB_NEXT);
                        if (ret != DB_NOTFOUND && ret != 0)
                              goto err;

                        R_LOCK(dbenv, &dblp->reginfo);
                        if (ret == DB_NOTFOUND) {
                              /*
                               * Do a quick double-check to make
                               * sure waiting_lsn hasn't changed.
                               * It's possible that between the
                               * DB_NOTFOUND return and the R_LOCK,
                               * some record was added to the
                               * database, and we don't want to lose
                               * sight of the fact that it's there.
                               */
                              if (log_compare(&waiting_lsn,
                                  &lp->waiting_lsn) == 0)
                                    ZERO_LSN(
                                        lp->waiting_lsn);

                              /*
                               * Whether or not the current record is
                               * simple, there's no next one, and
                               * therefore we haven't got anything
                               * else to do right now.  Break out.
                               */
                              break;
                        }

                        DB_ASSERT(lsn_dbt.size == sizeof(lsn_rc));

                        /*
                         * NEWFILE records have somewhat convoluted
                         * semantics, so there are five cases
                         * pertaining to what the newly-gotten record
                         * is and what we want to do about it.
                         *
                         * 1) This isn't a NEWFILE record.  Advance
                         *    waiting_lsn and proceed.
                         *
                         * 2) NEWFILE, no LSN stored as the datum,
                         *    lsn_rc.lsn == ready_lsn.  The NEWFILE
                         *    record is next, so set waiting_lsn =
                         *    ready_lsn.
                         *
                         * 3) NEWFILE, no LSN stored as the datum, but
                         *    lsn_rc.lsn > ready_lsn.  There's still a
                         *    gap; set waiting_lsn = lsn_rc.lsn.
                         *
                         * 4) NEWFILE, newfile_lsn in datum, and it's <
                         *    ready_lsn. (If the datum is non-empty,
                         *    it's the LSN of the last record in a log
                         *    file, not the end of the log, and
                         *    lsn_rc.lsn is the LSN of the start of
                         *    the new file--we didn't have the end of
                         *    the old log handy when we sent the
                         *    record.)  No gap--we're ready to
                         *    proceed.  Set both waiting and ready_lsn
                         *    to lsn_rc.lsn.
                         *
                         * 5) NEWFILE, newfile_lsn in datum, and it's >=
                         *    ready_lsn.  We're still missing at
                         *    least one record;  set waiting_lsn,
                         *    but not ready_lsn, to lsn_rc.lsn.
                         */
                        if (lsn_rc.rectype == REP_NEWFILE &&
                            nextrec_dbt.size > 0 && log_compare(
                            &newfile_lsn, &lp->ready_lsn) < 0)
                              /* Case 4. */
                              lp->ready_lsn =
                                  lp->waiting_lsn = lsn_rc.lsn;
                        else {
                              /* Cases 1, 2, 3, and 5. */
                              DB_ASSERT(log_compare(&lsn_rc.lsn,
                                  &lp->ready_lsn) >= 0);
                              lp->waiting_lsn = lsn_rc.lsn;
                        }

                        /*
                         * If the current rectype is simple, we're
                         * done with it, and we should check and see
                         * whether the next record queued is the next
                         * one we're ready for.  This is just the loop
                         * condition, so we continue.
                         *
                         * Otherwise, we need to break out of this loop
                         * and process this record first.
                         */
                        if (!IS_SIMPLE(rectype))
                              break;
                  }
            }

            /*
             * Check if we're at a gap in the table and if so, whether we
             * need to ask for any records.
             */
            do_req = 0;
            if (!IS_ZERO_LSN(lp->waiting_lsn) &&
                log_compare(&lp->ready_lsn, &lp->waiting_lsn) != 0) {
                  next_lsn = lp->ready_lsn;
                  do_req = ++lp->rcvd_recs >= lp->wait_recs;
                  if (do_req) {
                        lp->wait_recs = rep->request_gap;
                        lp->rcvd_recs = 0;
                  }
            }

            R_UNLOCK(dbenv, &dblp->reginfo);
            if (dbc != NULL) {
                  if ((ret = dbc->c_close(dbc)) != 0)
                        goto err;
                  MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);
                  have_mutex = 0;
            }
            dbc = NULL;

            if (do_req) {
                  MUTEX_LOCK(dbenv, db_rep->mutexp);
                  eid = db_rep->region->master_id;
                  MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                  if (eid != DB_EID_INVALID) {
                        rep->stat.st_log_requested++;
                        if ((ret = __rep_send_message(dbenv,
                            eid, REP_LOG_REQ, &next_lsn, NULL, 0)) != 0)
                              goto err;
                  }
            }
      } else if (cmp > 0) {
            /*
             * The LSN is higher than the one we were waiting for.
             * If it is a NEWFILE message, this may not mean that
             * there's a gap;  in some cases, NEWFILE messages contain
             * the LSN of the beginning of the new file instead
             * of the end of the old.
             *
             * In these cases, the rec DBT will contain the last LSN
             * of the old file, so we can tell whether there's a gap.
             */
            if (rp->rectype == REP_NEWFILE &&
                rp->lsn.file == lp->ready_lsn.file + 1 &&
                rp->lsn.offset == 0) {
                  DB_ASSERT(rec != NULL && rec->data != NULL &&
                      rec->size == sizeof(DB_LSN));
                  memcpy(&lsn, rec->data, sizeof(DB_LSN));
                  if (log_compare(&lp->ready_lsn, &lsn) > 0)
                        /*
                         * The last LSN in the old file is smaller
                         * than the one we're expecting, so there's
                         * no gap--the one we're expecting just
                         * doesn't exist.
                         */
                        goto newfile;
            }

            /*
             * This record isn't in sequence; add it to the table and
             * update waiting_lsn if necessary.
             */
            memset(&key_dbt, 0, sizeof(key_dbt));
            key_dbt.data = rp;
            key_dbt.size = sizeof(*rp);
            next_lsn = lp->lsn;
            do_req = 0;
            if (lp->wait_recs == 0) {
                  /*
                   * This is a new gap. Initialize the number of
                   * records that we should wait before requesting
                   * that it be resent.  We grab the limits out of
                   * the rep without the mutex.
                   */
                  lp->wait_recs = rep->request_gap;
                  lp->rcvd_recs = 0;
            }

            if (++lp->rcvd_recs >= lp->wait_recs) {
                  /*
                   * If we've waited long enough, request the record
                   * and double the wait interval.
                   */
                  do_req = 1;
                  lp->wait_recs <<= 1;
                  lp->rcvd_recs = 0;
                  if (lp->wait_recs > rep->max_gap)
                        lp->wait_recs = rep->max_gap;
            }
            R_UNLOCK(dbenv, &dblp->reginfo);

            MUTEX_LOCK(dbenv, db_rep->db_mutexp);
            ret = dbp->put(dbp, NULL, &key_dbt, rec, 0);
            rep->stat.st_log_queued++;
            rep->stat.st_log_queued_total++;
            if (rep->stat.st_log_queued_max < rep->stat.st_log_queued)
                  rep->stat.st_log_queued_max = rep->stat.st_log_queued;
            MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);

            if (ret != 0)
                  return (ret);

            R_LOCK(dbenv, &dblp->reginfo);
            if (IS_ZERO_LSN(lp->waiting_lsn) ||
                log_compare(&rp->lsn, &lp->waiting_lsn) < 0)
                  lp->waiting_lsn = rp->lsn;
            R_UNLOCK(dbenv, &dblp->reginfo);

            if (do_req) {
                  /* Request the LSN we are still waiting for. */
                  MUTEX_LOCK(dbenv, db_rep->mutexp);

                  /* May as well do this after we grab the mutex. */
                  eid = db_rep->region->master_id;

                  /*
                   * If the master_id is invalid, this means that since
                   * the last record was sent, somebody declared an
                   * election and we may not have a master to request
                   * things of.
                   *
                   * This is not an error;  when we find a new master,
                   * we'll re-negotiate where the end of the log is and
                   * try to to bring ourselves up to date again anyway.
                   */
                  if (eid != DB_EID_INVALID) {
                        rep->stat.st_log_requested++;
                        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                        ret = __rep_send_message(dbenv,
                            eid, REP_LOG_REQ, &next_lsn, NULL, 0);
                  } else
                        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
            }
            return (ret);
      } else {
            R_UNLOCK(dbenv, &dblp->reginfo);

            /*
             * We may miscount if we race, since we
             * don't currently hold the rep mutex.
             */
            rep->stat.st_log_duplicated++;
      }
      if (ret != 0 || cmp < 0 || (cmp == 0 && IS_SIMPLE(rectype)))
            goto done;

      /*
       * If we got here, then we've got a log record in rp and rec that
       * we need to process.
       */
      switch(rectype) {
      case DB___dbreg_register:
            /*
             * DB opens occur in the context of a transaction, so we can
             * simply handle them when we process the transaction.  Closes,
             * however, are not transaction-protected, so we have to
             * handle them here.
             *
             * Note that it should be unsafe for the master to do a close
             * of a file that was opened in an active transaction, so we
             * should be guaranteed to get the ordering right.
             */
            memcpy(&txnid, (u_int8_t *)rec->data +
                ((u_int8_t *)&dbreg_args.txnid - (u_int8_t *)&dbreg_args),
                sizeof(u_int32_t));
            if (txnid == TXN_INVALID &&
                !F_ISSET(dbenv, DB_ENV_REP_LOGSONLY))
                  ret = __db_dispatch(dbenv, dbenv->recover_dtab,
                      dbenv->recover_dtab_size, rec, &rp->lsn,
                      DB_TXN_APPLY, NULL);
            break;
      case DB___txn_ckp:
            /* Sync the memory pool. */
            memcpy(&ckp_lsn, (u_int8_t *)rec->data +
                ((u_int8_t *)&ckp_args.ckp_lsn - (u_int8_t *)&ckp_args),
                sizeof(DB_LSN));
            if (!F_ISSET(dbenv, DB_ENV_REP_LOGSONLY))
                  ret = dbenv->memp_sync(dbenv, &ckp_lsn);
            else
                  /*
                   * We ought to make sure the logs on a logs-only
                   * replica get flushed now and again.
                   */
                  ret = dbenv->log_flush(dbenv, &ckp_lsn);
            /* Update the last_ckp in the txn region. */
            if (ret == 0)
                  __txn_updateckp(dbenv, &rp->lsn);
            break;
      case DB___txn_regop:
            if (!F_ISSET(dbenv, DB_ENV_REP_LOGSONLY))
                  do {
                        /*
                         * If an application is doing app-specific
                         * recovery and acquires locks while applying
                         * a transaction, it can deadlock.  Any other
                         * locks held by this thread should have been
                         * discarded in the __rep_process_txn error
                         * path, so if we simply retry, we should
                         * eventually succeed.
                         */
                        ret = __rep_process_txn(dbenv, rec);
                  } while (ret == DB_LOCK_DEADLOCK);
            break;
      default:
            goto err;
      }

      /* Check if we need to go back into the table. */
      if (ret == 0) {
            R_LOCK(dbenv, &dblp->reginfo);
            if (log_compare(&lp->ready_lsn, &lp->waiting_lsn) == 0)
                  goto gap_check;
            R_UNLOCK(dbenv, &dblp->reginfo);
      }

done:
err:  if (dbc != NULL && (t_ret = dbc->c_close(dbc)) != 0 && ret == 0)
            ret = t_ret;
      if (have_mutex)
            MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);

      if (control_dbt.data != NULL)
            __os_ufree(dbenv, control_dbt.data);
      if (rec_dbt.data != NULL)
            __os_ufree(dbenv, rec_dbt.data);

      return (ret);
}

/*
 * __rep_process_txn --
 *
 * This is the routine that actually gets a transaction ready for
 * processing.
 *
 * PUBLIC: int __rep_process_txn __P((DB_ENV *, DBT *));
 */
int
__rep_process_txn(dbenv, rec)
      DB_ENV *dbenv;
      DBT *rec;
{
      DBT data_dbt;
      DB_LOCKREQ req, *lvp;
      DB_LOGC *logc;
      DB_LSN prev_lsn, *lsnp;
      DB_REP *db_rep;
      LSN_COLLECTION lc;
      REP *rep;
      __txn_regop_args *txn_args;
      __txn_xa_regop_args *prep_args;
      u_int32_t lockid, op, rectype;
      int i, ret, t_ret;
      int (**dtab)__P((DB_ENV *, DBT *, DB_LSN *, db_recops, void *));
      size_t dtabsize;
      void *txninfo;

      db_rep = dbenv->rep_handle;
      rep = db_rep->region;

      logc = NULL;
      txninfo = NULL;
      memset(&data_dbt, 0, sizeof(data_dbt));
      if (F_ISSET(dbenv, DB_ENV_THREAD))
            F_SET(&data_dbt, DB_DBT_REALLOC);

      /*
       * There are two phases:  First, we have to traverse
       * backwards through the log records gathering the list
       * of all LSNs in the transaction.  Once we have this information,
       * we can loop through, acquire the locks we need for each record,
       * and then apply it.
       */
      dtab = NULL;

      /*
       * We may be passed a prepare (if we're restoring a prepare
       * on upgrade) instead of a commit (the common case).
       * Check which and behave appropriately.
       */
      memcpy(&rectype, rec->data, sizeof(rectype));
      memset(&lc, 0, sizeof(lc));
      if (rectype == DB___txn_regop) {
            /*
             * We're the end of a transaction.  Make sure this is
             * really a commit and not an abort!
             */
            if ((ret = __txn_regop_read(dbenv, rec->data, &txn_args)) != 0)
                  return (ret);
            op = txn_args->opcode;
            prev_lsn = txn_args->prev_lsn;
            __os_free(dbenv, txn_args);
            if (op != TXN_COMMIT)
                  return (0);
      } else {
            /* We're a prepare. */
            DB_ASSERT(rectype == DB___txn_xa_regop);

            if ((ret =
                __txn_xa_regop_read(dbenv, rec->data, &prep_args)) != 0)
                  return (ret);
            prev_lsn = prep_args->prev_lsn;
            __os_free(dbenv, prep_args);
      }

      /* Phase 1.  Get a list of the LSNs in this transaction, and sort it. */
      if ((ret = __rep_collect_txn(dbenv, &prev_lsn, &lc)) != 0)
            return (ret);
      qsort(lc.array, lc.nlsns, sizeof(DB_LSN), __rep_lsn_cmp);

      if ((ret = dbenv->lock_id(dbenv, &lockid)) != 0)
            goto err;

      /* Initialize the getpgno dispatch table. */
      if ((ret = __rep_lockpgno_init(dbenv, &dtab, &dtabsize)) != 0)
            goto err;

      /*
       * The set of records for a transaction may include dbreg_register
       * records.  Create a txnlist so that they can keep track of file
       * state between records.
       */
      if ((ret = __db_txnlist_init(dbenv, 0, 0, NULL, &txninfo)) != 0)
            goto err;

      /* Phase 2: Apply updates. */
      if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
            goto err;
      for (lsnp = &lc.array[0], i = 0; i < lc.nlsns; i++, lsnp++) {
            if ((ret = __rep_lockpages(dbenv,
                dtab, dtabsize, lsnp, NULL, NULL, lockid)) != 0)
                  goto err;
            if ((ret = logc->get(logc, lsnp, &data_dbt, DB_SET)) != 0)
                  goto err;
            if ((ret = __db_dispatch(dbenv, dbenv->recover_dtab,
                dbenv->recover_dtab_size, &data_dbt, lsnp,
                DB_TXN_APPLY, txninfo)) != 0)
                  goto err;
      }

err:  memset(&req, 0, sizeof(req));
      req.op = DB_LOCK_PUT_ALL;
      if ((t_ret = dbenv->lock_vec(dbenv, lockid,
          DB_LOCK_FREE_LOCKER, &req, 1, &lvp)) != 0 && ret == 0)
            ret = t_ret;

      if (lc.nalloc != 0)
            __os_free(dbenv, lc.array);

      if ((t_ret =
          dbenv->lock_id_free(dbenv, lockid)) != 0 && ret == 0)
            ret = t_ret;

      if (logc != NULL && (t_ret = logc->close(logc, 0)) != 0 && ret == 0)
            ret = t_ret;

      if (txninfo != NULL)
            __db_txnlist_end(dbenv, txninfo);

      if (F_ISSET(&data_dbt, DB_DBT_REALLOC) && data_dbt.data != NULL)
            __os_ufree(dbenv, data_dbt.data);

      if (dtab != NULL)
            __os_free(dbenv, dtab);

      if (ret == 0)
            /*
             * We don't hold the rep mutex, and could miscount if we race.
             */
            rep->stat.st_txns_applied++;

      return (ret);
}

/*
 * __rep_collect_txn
 *    Recursive function that will let us visit every entry in a transaction
 *    chain including all child transactions so that we can then apply
 *    the entire transaction family at once.
 */
static int
__rep_collect_txn(dbenv, lsnp, lc)
      DB_ENV *dbenv;
      DB_LSN *lsnp;
      LSN_COLLECTION *lc;
{
      __txn_child_args *argp;
      DB_LOGC *logc;
      DB_LSN c_lsn;
      DBT data;
      u_int32_t rectype;
      int nalloc, ret, t_ret;

      memset(&data, 0, sizeof(data));
      F_SET(&data, DB_DBT_REALLOC);

      if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
            return (ret);

      while (!IS_ZERO_LSN(*lsnp) &&
          (ret = logc->get(logc, lsnp, &data, DB_SET)) == 0) {
            memcpy(&rectype, data.data, sizeof(rectype));
            if (rectype == DB___txn_child) {
                  if ((ret = __txn_child_read(dbenv,
                      data.data, &argp)) != 0)
                        goto err;
                  c_lsn = argp->c_lsn;
                  *lsnp = argp->prev_lsn;
                  __os_free(dbenv, argp);
                  ret = __rep_collect_txn(dbenv, &c_lsn, lc);
            } else {
                  if (lc->nalloc < lc->nlsns + 1) {
                        nalloc = lc->nalloc == 0 ? 20 : lc->nalloc * 2;
                        if ((ret = __os_realloc(dbenv,
                            nalloc * sizeof(DB_LSN), &lc->array)) != 0)
                              goto err;
                        lc->nalloc = nalloc;
                  }
                  lc->array[lc->nlsns++] = *lsnp;

                  /*
                   * Explicitly copy the previous lsn.  The record
                   * starts with a u_int32_t record type, a u_int32_t
                   * txn id, and then the DB_LSN (prev_lsn) that we
                   * want.  We copy explicitly because we have no idea
                   * what kind of record this is.
                   */
                  memcpy(lsnp, (u_int8_t *)data.data +
                      sizeof(u_int32_t) + sizeof(u_int32_t),
                      sizeof(DB_LSN));
            }

            if (ret != 0)
                  goto err;
      }

err:  if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
            ret = t_ret;
      if (data.data != NULL)
            __os_ufree(dbenv, data.data);
      return (ret);
}

/*
 * __rep_lsn_cmp --
 *    qsort-type-compatible wrapper for log_compare.
 */
static int
__rep_lsn_cmp(lsn1, lsn2)
      const void *lsn1, *lsn2;
{

      return (log_compare((DB_LSN *)lsn1, (DB_LSN *)lsn2));
}

/*
 * __rep_newfile --
 *    NEWFILE messages can contain either the last LSN of the old file
 * or the first LSN of the new one, depending on which we have available
 * when the message is sent.  When applying a NEWFILE message, make sure
 * we haven't already swapped files, as it's possible (given the right sequence
 * of out-of-order messages) to wind up with a NEWFILE message of each
 * variety, and __rep_apply won't detect the two as duplicates of each other.
 */
static int
__rep_newfile(dbenv, rc, msgdbt, lsnp)
      DB_ENV *dbenv;
      REP_CONTROL *rc;
      DBT *msgdbt;
      DB_LSN *lsnp;
{
      DB_LOG *dblp;
      LOG *lp;
      u_int32_t newfile;

      dblp = dbenv->lg_handle;
      lp = dblp->reginfo.primary;

      /*
       * A NEWFILE message containing the old file's LSN will be
       * accompanied by a NULL rec DBT;  one containing the new one's LSN
       * will need to supply the last record in the old file by
       * sending it in the rec DBT.
       */
      if (msgdbt == NULL || msgdbt->size == 0)
            newfile = rc->lsn.file + 1;
      else
            newfile = rc->lsn.file;

      if (newfile > lp->lsn.file)
            return (__log_newfile(dblp, lsnp));
      else {
            /* We've already applied this NEWFILE.  Just ignore it. */
            *lsnp = lp->lsn;
            return (0);
      }
}

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