source: trunk/third/rpm/db/rep/rep_method.c @ 19079

/*-
 * 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_method.c,v 1.78 2002/09/10 12:58:07 bostic Exp ";
#endif /* not lint */

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

#ifdef HAVE_RPC
#include <rpc/rpc.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.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"

#ifdef HAVE_RPC
#include "dbinc_auto/db_server.h"
#include "dbinc_auto/rpc_client_ext.h"
#endif

static int __rep_abort_prepared __P((DB_ENV *));
static int __rep_bt_cmp __P((DB *, const DBT *, const DBT *));
static int __rep_client_dbinit __P((DB_ENV *, int));
static int __rep_elect __P((DB_ENV *, int, int, u_int32_t, int *));
static int __rep_elect_init __P((DB_ENV *, DB_LSN *, int, int, int, int *));
static int __rep_flush __P((DB_ENV *));
static int __rep_restore_prepared __P((DB_ENV *));
static int __rep_set_limit __P((DB_ENV *, u_int32_t, u_int32_t));
static int __rep_set_request __P((DB_ENV *, u_int32_t, u_int32_t));
static int __rep_set_rep_transport __P((DB_ENV *, int,
    int (*)(DB_ENV *, const DBT *, const DBT *, int, u_int32_t)));
static int __rep_start __P((DB_ENV *, DBT *, u_int32_t));
static int __rep_stat __P((DB_ENV *, DB_REP_STAT **, u_int32_t));
static int __rep_wait __P((DB_ENV *, u_int32_t, int *, u_int32_t));

/*
 * __rep_dbenv_create --
 *      Replication-specific initialization of the DB_ENV structure.
 *
 * PUBLIC: int __rep_dbenv_create __P((DB_ENV *));
 */
int
__rep_dbenv_create(dbenv)
        DB_ENV *dbenv;
{
        DB_REP *db_rep;
        int ret;

#ifdef HAVE_RPC
        if (F_ISSET(dbenv, DB_ENV_RPCCLIENT)) {
                COMPQUIET(db_rep, NULL);
                COMPQUIET(ret, 0);
                dbenv->rep_elect = __dbcl_rep_elect;
                dbenv->rep_flush = __dbcl_rep_flush;
                dbenv->rep_process_message = __dbcl_rep_process_message;
                dbenv->rep_start = __dbcl_rep_start;
                dbenv->rep_stat = __dbcl_rep_stat;
                dbenv->set_rep_limit = __dbcl_rep_set_limit;
                dbenv->set_rep_request = __dbcl_rep_set_request;
                dbenv->set_rep_transport = __dbcl_rep_set_rep_transport;

        } else
#endif
        {
                dbenv->rep_elect = __rep_elect;
                dbenv->rep_flush = __rep_flush;
                dbenv->rep_process_message = __rep_process_message;
                dbenv->rep_start = __rep_start;
                dbenv->rep_stat = __rep_stat;
                dbenv->set_rep_limit = __rep_set_limit;
                dbenv->set_rep_request = __rep_set_request;
                dbenv->set_rep_transport = __rep_set_rep_transport;
                /*
                 * !!!
                 * Our caller has not yet had the opportunity to reset the panic
                 * state or turn off mutex locking, and so we can neither check
                 * the panic state or acquire a mutex in the DB_ENV create path.
                 */

                if ((ret = __os_calloc(dbenv, 1, sizeof(DB_REP), &db_rep)) != 0)
                        return (ret);
                dbenv->rep_handle = db_rep;

                /* Initialize the per-process replication structure. */
                db_rep->rep_send = NULL;
        }

        return (0);
}

/*
 * __rep_start --
 *      Become a master or client, and start sending messages to participate
 * in the replication environment.  Must be called after the environment
 * is open.
 */
static int
__rep_start(dbenv, dbt, flags)
        DB_ENV *dbenv;
        DBT *dbt;
        u_int32_t flags;
{
        DB_LOG *dblp;
        DB_LSN lsn;
        DB_REP *db_rep;
        REP *rep;
        int announce, init_db, redo_prepared, ret;

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

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

        if ((ret = __db_fchk(dbenv, "DB_ENV->rep_start", flags,
            DB_REP_CLIENT | DB_REP_LOGSONLY | DB_REP_MASTER)) != 0)
                return (ret);

        /* Exactly one of CLIENT and MASTER must be specified. */
        if ((ret = __db_fcchk(dbenv,
            "DB_ENV->rep_start", flags, DB_REP_CLIENT, DB_REP_MASTER)) != 0)
                return (ret);
        if (!LF_ISSET(DB_REP_CLIENT | DB_REP_MASTER | DB_REP_LOGSONLY)) {
                __db_err(dbenv,
        "DB_ENV->rep_start: replication mode must be specified");
                return (EINVAL);
        }

        /* Masters can't be logs-only. */
        if ((ret = __db_fcchk(dbenv,
            "DB_ENV->rep_start", flags, DB_REP_LOGSONLY, DB_REP_MASTER)) != 0)
                return (ret);

        /* We need a transport function. */
        if (db_rep->rep_send == NULL) {
                __db_err(dbenv,
    "DB_ENV->set_rep_transport must be called before DB_ENV->rep_start");
                return (EINVAL);
        }
        
        /* We'd better not have any logged files open if we are a client. */
        if (LF_ISSET(DB_REP_CLIENT) && (ret = __dbreg_nofiles(dbenv)) != 0) {
                __db_err(dbenv, "DB_ENV->rep_start called with open files");
                return (ret);
        }

        MUTEX_LOCK(dbenv, db_rep->mutexp);
        if (rep->eid == DB_EID_INVALID)
                rep->eid = dbenv->rep_eid;

        if (LF_ISSET(DB_REP_MASTER)) {
                if (F_ISSET(dbenv, DB_ENV_REP_CLIENT)) {
                        /*
                         * If we're upgrading from having been a client,
                         * preclose, so that we close our temporary database.
                         *
                         * Do not close files that we may have opened while
                         * doing a rep_apply;  they'll get closed when we
                         * finally close the environment, but for now, leave
                         * them open, as we don't want to recycle their
                         * fileids, and we may need the handles again if
                         * we become a client and the original master
                         * that opened them becomes a master again.
                         */
                        if ((ret = __rep_preclose(dbenv, 0)) != 0)
                                return (ret);

                        /*
                         * Now write a __txn_recycle record so that
                         * clients don't get confused with our txnids
                         * and txnids of previous masters.
                         */
                        F_CLR(dbenv, DB_ENV_REP_CLIENT);
                        if ((ret = __txn_reset(dbenv)) != 0)
                                return (ret);
                }

                redo_prepared = 0;
                if (!F_ISSET(rep, REP_F_MASTER)) {
                        /* Master is not yet set. */
                        if (F_ISSET(rep, REP_ISCLIENT)) {
                                F_CLR(rep, REP_ISCLIENT);
                                rep->gen = ++rep->w_gen;
                                redo_prepared = 1;
                        } else if (rep->gen == 0)
                                rep->gen = 1;
                }

                F_SET(rep, REP_F_MASTER);
                F_SET(dbenv, DB_ENV_REP_MASTER);
                MUTEX_UNLOCK(dbenv, db_rep->mutexp);
                dblp = (DB_LOG *)dbenv->lg_handle;
                R_LOCK(dbenv, &dblp->reginfo);
                lsn = ((LOG *)dblp->reginfo.primary)->lsn;
                R_UNLOCK(dbenv, &dblp->reginfo);

                /*
                 * Send the NEWMASTER message, then restore prepared txns
                 * if and only if we just upgraded from being a client.
                 */
                if ((ret = __rep_send_message(dbenv,
                    DB_EID_BROADCAST, REP_NEWMASTER, &lsn, NULL, 0)) == 0 &&
                    redo_prepared)
                        ret = __rep_restore_prepared(dbenv);
        } else {
                F_CLR(dbenv, DB_ENV_REP_MASTER);
                F_SET(dbenv, DB_ENV_REP_CLIENT);
                if (LF_ISSET(DB_REP_LOGSONLY))
                        F_SET(dbenv, DB_ENV_REP_LOGSONLY);

                announce = !F_ISSET(rep, REP_ISCLIENT) ||
                    rep->master_id == DB_EID_INVALID;
                init_db = 0;
                if (!F_ISSET(rep, REP_ISCLIENT)) {
                        F_CLR(rep, REP_F_MASTER);
                        if (LF_ISSET(DB_REP_LOGSONLY))
                                F_SET(rep, REP_F_LOGSONLY);
                        else
                                F_SET(rep, REP_F_UPGRADE);

                        /*
                         * We initialize the client's generation number to 0.
                         * Upon startup, it looks for a master and updates the
                         * generation number as necessary, exactly as it does
                         * during normal operation and a master failure.
                         */
                        rep->gen = 0;
                        rep->master_id = DB_EID_INVALID;
                        init_db = 1;
                }
                MUTEX_UNLOCK(dbenv, db_rep->mutexp);

                /*
                 * Abort any prepared transactions that were restored
                 * by recovery.  We won't be able to create any txns of
                 * our own until they're resolved, but we can't resolve
                 * them ourselves;  the master has to.  If any get
                 * resolved as commits, we'll redo them when commit
                 * records come in.  Aborts will simply be ignored.
                 */
                if ((ret = __rep_abort_prepared(dbenv)) != 0)
                        return (ret);

                if ((ret = __rep_client_dbinit(dbenv, init_db)) != 0)
                        return (ret);

                /*
                 * If this client created a newly replicated environment,
                 * then announce the existence of this client.  The master
                 * should respond with a message that will tell this client
                 * the current generation number and the current LSN.  This
                 * will allow the client to either perform recovery or
                 * simply join in.
                 */
                if (announce)
                        ret = __rep_send_message(dbenv,
                            DB_EID_BROADCAST, REP_NEWCLIENT, NULL, dbt, 0);
        }
        return (ret);
}

/*
 * __rep_client_dbinit --
 *
 * Initialize the LSN database on the client side.  This is called from the
 * client initialization code.  The startup flag value indicates if
 * this is the first thread/process starting up and therefore should create
 * the LSN database.  This routine must be called once by each process acting
 * as a client.
 */
static int
__rep_client_dbinit(dbenv, startup)
        DB_ENV *dbenv;
        int startup;
{
        DB_REP *db_rep;
        DB *dbp;
        int ret, t_ret;
        u_int32_t flags;

        PANIC_CHECK(dbenv);
        db_rep = dbenv->rep_handle;
        dbp = NULL;

#define REPDBNAME       "__db.rep.db"

        /* Check if this has already been called on this environment. */
        if (db_rep->rep_db != NULL)
                return (0);

        MUTEX_LOCK(dbenv, db_rep->db_mutexp);

        if (startup) {
                if ((ret = db_create(&dbp, dbenv, 0)) != 0)
                        goto err;
                /*
                 * Ignore errors, because if the file doesn't exist, this
                 * is perfectly OK.
                 */
                (void)dbp->remove(dbp, REPDBNAME, NULL, 0);
        }

        if ((ret = db_create(&dbp, dbenv, 0)) != 0)
                goto err;
        if ((ret = dbp->set_bt_compare(dbp, __rep_bt_cmp)) != 0)
                goto err;

        /* Allow writes to this database on a client. */
        F_SET(dbp, DB_AM_CL_WRITER);

        flags = (F_ISSET(dbenv, DB_ENV_THREAD) ? DB_THREAD : 0) |
            (startup ? DB_CREATE : 0);
        if ((ret = dbp->open(dbp, NULL,
            "__db.rep.db", NULL, DB_BTREE, flags, 0)) != 0)
                goto err;

        db_rep->rep_db = dbp;

        if (0) {
err:            if (dbp != NULL &&
                    (t_ret = dbp->close(dbp, DB_NOSYNC)) != 0 && ret == 0)
                        ret = t_ret;
                db_rep->rep_db = NULL;
        }

        MUTEX_UNLOCK(dbenv, db_rep->db_mutexp);

        return (ret);
}

/*
 * __rep_bt_cmp --
 *
 * Comparison function for the LSN table.  We use the entire control
 * structure as a key (for simplicity, so we don't have to merge the
 * other fields in the control with the data field), but really only
 * care about the LSNs.
 */
static int
__rep_bt_cmp(dbp, dbt1, dbt2)
        DB *dbp;
        const DBT *dbt1, *dbt2;
{
        DB_LSN lsn1, lsn2;
        REP_CONTROL *rp1, *rp2;

        COMPQUIET(dbp, NULL);

        rp1 = dbt1->data;
        rp2 = dbt2->data;

        __ua_memcpy(&lsn1, &rp1->lsn, sizeof(DB_LSN));
        __ua_memcpy(&lsn2, &rp2->lsn, sizeof(DB_LSN));

        if (lsn1.file > lsn2.file)
                return (1);

        if (lsn1.file < lsn2.file)
                return (-1);

        if (lsn1.offset > lsn2.offset)
                return (1);

        if (lsn1.offset < lsn2.offset)
                return (-1);

        return (0);
}

/*
 * __rep_abort_prepared --
 *      Abort any prepared transactions that recovery restored.
 *
 *      This is used by clients that have just run recovery, since
 * they cannot/should not call txn_recover and handle prepared transactions
 * themselves.
 */
static int
__rep_abort_prepared(dbenv)
        DB_ENV *dbenv;
{
#define PREPLISTSIZE    50
        DB_PREPLIST prep[PREPLISTSIZE], *p;
        DB_TXNMGR *mgr;
        DB_TXNREGION *region;
        int do_aborts, ret;
        long count, i;
        u_int32_t op;

        mgr = dbenv->tx_handle;
        region = mgr->reginfo.primary;

        do_aborts = 0;
        R_LOCK(dbenv, &mgr->reginfo);
        if (region->stat.st_nrestores != 0)
                do_aborts = 1;
        R_UNLOCK(dbenv, &mgr->reginfo);

        if (do_aborts) {
                op = DB_FIRST;
                do {
                        if ((ret = dbenv->txn_recover(dbenv,
                            prep, PREPLISTSIZE, &count, op)) != 0)
                                return (ret);
                        for (i = 0; i < count; i++) {
                                p = &prep[i];
                                if ((ret = p->txn->abort(p->txn)) != 0)
                                        return (ret);
                        }
                        op = DB_NEXT;
                } while (count == PREPLISTSIZE);
        }

        return (0);
}

/*
 * __rep_restore_prepared --
 *      Restore to a prepared state any prepared but not yet committed
 * transactions.
 *
 *      This performs, in effect, a "mini-recovery";  it is called from
 * __rep_start by newly upgraded masters.  There may be transactions that an
 * old master prepared but did not resolve, which we need to restore to an
 * active state.
 */
static int
__rep_restore_prepared(dbenv)
        DB_ENV *dbenv;
{
        DB_LOGC *logc;
        DB_LSN ckp_lsn, lsn;
        DBT rec;
        __txn_ckp_args *ckp_args;
        __txn_regop_args *regop_args;
        __txn_xa_regop_args *prep_args;
        int ret, t_ret;
        u_int32_t hi_txn, low_txn, rectype;
        void *txninfo;

        txninfo = NULL;
        ckp_args = NULL;
        prep_args = NULL;
        regop_args = NULL;
        ZERO_LSN(ckp_lsn);
        ZERO_LSN(lsn);

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

        /*
         * We need to consider the set of records between the most recent
         * checkpoint LSN and the end of the log;  any txn in that
         * range, and only txns in that range, could still have been
         * active, and thus prepared but not yet committed (PBNYC),
         * when the old master died.
         *
         * Find the most recent checkpoint LSN, and get the record there.
         * If there is no checkpoint in the log, start off by getting
         * the very first record in the log instead.
         */
        memset(&rec, 0, sizeof(DBT));
        if ((ret = __txn_getckp(dbenv, &lsn)) == 0) {
                if ((ret = logc->get(logc, &lsn, &rec, DB_SET)) != 0)  {
                        __db_err(dbenv,
                            "Checkpoint record at LSN [%lu][%lu] not found",
                            (u_long)lsn.file, (u_long)lsn.offset);
                        goto err;
                }

                if ((ret = __txn_ckp_read(dbenv, rec.data, &ckp_args)) != 0) {
                        __db_err(dbenv,
                            "Invalid checkpoint record at [%lu][%lu]",
                            (u_long)lsn.file, (u_long)lsn.offset);
                        goto err;
                }

                ckp_lsn = ckp_args->ckp_lsn;
                __os_free(dbenv, ckp_args);

                if ((ret = logc->get(logc, &ckp_lsn, &rec, DB_SET)) != 0) {
                        __db_err(dbenv,
                            "Checkpoint LSN record [%lu][%lu] not found",
                            (u_long)ckp_lsn.file, (u_long)ckp_lsn.offset);
                        goto err;
                }
        } else if ((ret = logc->get(logc, &lsn, &rec, DB_FIRST)) != 0) {
                if (ret == DB_NOTFOUND) {
                        /* An empty log means no PBNYC txns. */
                        ret = 0;
                        goto done;
                }
                __db_err(dbenv, "Attempt to get first log record failed");
                goto err;
        }

        /*
         * We use the same txnlist infrastructure that recovery does;
         * it demands an estimate of the high and low txnids for
         * initialization.
         *
         * First, the low txnid.
         */
        do {
                /* txnid is after rectype, which is a u_int32. */
                memcpy(&low_txn,
                    (u_int8_t *)rec.data + sizeof(u_int32_t), sizeof(low_txn));
                if (low_txn != 0)
                        break;
        } while ((ret = logc->get(logc, &lsn, &rec, DB_NEXT)) == 0);

        /* If there are no txns, there are no PBNYC txns. */
        if (ret == DB_NOTFOUND) {
                ret = 0;
                goto done;
        } else if (ret != 0)
                goto err;

        /* Now, the high txnid. */
        if ((ret = logc->get(logc, &lsn, &rec, DB_LAST)) != 0) {
                /*
                 * Note that DB_NOTFOUND is unacceptable here because we
                 * had to have looked at some log record to get this far.
                 */
                __db_err(dbenv, "Final log record not found");
                goto err;
        }
        do {
                /* txnid is after rectype, which is a u_int32. */
                memcpy(&hi_txn,
                    (u_int8_t *)rec.data + sizeof(u_int32_t), sizeof(hi_txn));
                if (hi_txn != 0)
                        break;
        } while ((ret = logc->get(logc, &lsn, &rec, DB_PREV)) == 0);
        if (ret == DB_NOTFOUND) {
                ret = 0;
                goto done;
        } else if (ret != 0)
                goto err;

        /* We have a high and low txnid.  Initialise the txn list. */
        if ((ret =
            __db_txnlist_init(dbenv, low_txn, hi_txn, NULL, &txninfo)) != 0)
                goto err;

        /*
         * Now, walk backward from the end of the log to ckp_lsn.  Any
         * prepares that we hit without first hitting a commit or
         * abort belong to PBNYC txns, and we need to apply them and
         * restore them to a prepared state.
         *
         * Note that we wind up applying transactions out of order.
         * Since all PBNYC txns still held locks on the old master and
         * were isolated, this should be safe.
         */
        for (ret = logc->get(logc, &lsn, &rec, DB_LAST);
            ret == 0 && log_compare(&lsn, &ckp_lsn) > 0;
            ret = logc->get(logc, &lsn, &rec, DB_PREV)) {
                memcpy(&rectype, rec.data, sizeof(rectype));
                switch (rectype) {
                case DB___txn_regop:
                        /*
                         * It's a commit or abort--but we don't care
                         * which!  Just add it to the list of txns
                         * that are resolved.
                         */
                        if ((ret = __txn_regop_read(dbenv, rec.data,
                            &regop_args)) != 0)
                                goto err;

                        ret = __db_txnlist_find(dbenv,
                            txninfo, regop_args->txnid->txnid);
                        if (ret == DB_NOTFOUND)
                                ret = __db_txnlist_add(dbenv, txninfo,
                                    regop_args->txnid->txnid,
                                    regop_args->opcode, &lsn);
                        __os_free(dbenv, regop_args);
                        break;
                case DB___txn_xa_regop:
                        /*
                         * It's a prepare.  If we haven't put the
                         * txn on our list yet, it hasn't been
                         * resolved, so apply and restore it.
                         */
                        if ((ret = __txn_xa_regop_read(dbenv, rec.data,
                            &prep_args)) != 0)
                                goto err;
                        ret = __db_txnlist_find(dbenv, txninfo,
                            prep_args->txnid->txnid);
                        if (ret == DB_NOTFOUND)
                                if ((ret = __rep_process_txn(dbenv, &rec)) == 0)
                                        ret = __txn_restore_txn(dbenv,
                                            &lsn, prep_args);
                        __os_free(dbenv, prep_args);
                        break;
                default:
                        continue;
                }
        }

        /* It's not an error to have hit the beginning of the log. */
        if (ret == DB_NOTFOUND)
                ret = 0;

done:
err:    t_ret = logc->close(logc, 0);

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

        return (ret == 0 ? t_ret : ret);
}

/*
 * __rep_set_limit --
 *      Set a limit on the amount of data that will be sent during a single
 * invocation of __rep_process_message.
 */
static int
__rep_set_limit(dbenv, gbytes, bytes)
        DB_ENV *dbenv;
        u_int32_t gbytes;
        u_int32_t bytes;
{
        DB_REP *db_rep;
        REP *rep;

        PANIC_CHECK(dbenv);

        if ((db_rep = dbenv->rep_handle) == NULL) {
                __db_err(dbenv,
    "DB_ENV->set_rep_limit: database environment not properly initialized");
                return (__db_panic(dbenv, EINVAL));
        }
        rep = db_rep->region;
        MUTEX_LOCK(dbenv, db_rep->mutexp);
        if (bytes > GIGABYTE) {
                gbytes += bytes / GIGABYTE;
                bytes = bytes % GIGABYTE;
        }
        rep->gbytes = gbytes;
        rep->bytes = bytes;
        MUTEX_UNLOCK(dbenv, db_rep->mutexp);

        return (0);
}

/*
 * __rep_set_request --
 *      Set the minimum and maximum number of log records that we wait
 * before retransmitting.
 * UNDOCUMENTED.
 */
static int
__rep_set_request(dbenv, min, max)
        DB_ENV *dbenv;
        u_int32_t min;
        u_int32_t max;
{
        LOG *lp;
        DB_LOG *dblp;
        DB_REP *db_rep;
        REP *rep;

        PANIC_CHECK(dbenv);

        if ((db_rep = dbenv->rep_handle) == NULL) {
                __db_err(dbenv,
    "DB_ENV->set_rep_request: database environment not properly initialized");
                return (__db_panic(dbenv, EINVAL));
        }
        rep = db_rep->region;
        MUTEX_LOCK(dbenv, db_rep->mutexp);
        rep->request_gap = min;
        rep->max_gap = max;
        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
        dblp = dbenv->lg_handle;
        if (dblp != NULL && (lp = dblp->reginfo.primary) != NULL) {
                R_LOCK(dbenv, &dblp->reginfo);
                lp->wait_recs = 0;
                lp->rcvd_recs = 0;
                R_UNLOCK(dbenv, &dblp->reginfo);
        }

        return (0);
}

/*
 * __rep_set_transport --
 *      Set the transport function for replication.
 */
static int
__rep_set_rep_transport(dbenv, eid, f_send)
        DB_ENV *dbenv;
        int eid;
        int (*f_send) __P((DB_ENV *, const DBT *, const DBT *, int, u_int32_t));
{
        DB_REP *db_rep;

        PANIC_CHECK(dbenv);

        if ((db_rep = dbenv->rep_handle) == NULL) {
                __db_err(dbenv,
    "DB_ENV->set_rep_transport: database environment not properly initialized");
                return (__db_panic(dbenv, EINVAL));
        }

        if (f_send == NULL) {
                __db_err(dbenv,
        "DB_ENV->set_rep_transport: no send function specified");
                return (EINVAL);
        }

        if (eid < 0) {
                __db_err(dbenv,
        "DB_ENV->set_rep_transport: eid must be greater than or equal to 0");
                return (EINVAL);
        }

        db_rep->rep_send = f_send;

        dbenv->rep_eid = eid;
        return (0);
}

/*
 * __rep_elect --
 *      Called after master failure to hold/participate in an election for
 *      a new master.
 */
static int
__rep_elect(dbenv, nsites, priority, timeout, eidp)
        DB_ENV *dbenv;
        int nsites, priority;
        u_int32_t timeout;
        int *eidp;
{
        DB_LOG *dblp;
        DB_LSN lsn;
        DB_REP *db_rep;
        REP *rep;
        int in_progress, ret, send_vote, tiebreaker;
        u_int32_t pid, sec, usec;

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

        /* Error checking. */
        if (nsites <= 0) {
                __db_err(dbenv,
                    "DB_ENV->rep_elect: nsites must be greater than 0");
                return (EINVAL);
        }
        if (priority < 0) {
                __db_err(dbenv,
                    "DB_ENV->rep_elect: priority may not be negative");
                return (EINVAL);
        }

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

        R_LOCK(dbenv, &dblp->reginfo);
        lsn = ((LOG *)dblp->reginfo.primary)->lsn;
        R_UNLOCK(dbenv, &dblp->reginfo);

        /* Generate a randomized tiebreaker value. */
        __os_id(&pid);
        if ((ret = __os_clock(dbenv, &sec, &usec)) != 0)
                return (ret);
        tiebreaker = pid ^ sec ^ usec ^ (u_int)rand() ^ P_TO_UINT32(&pid);

        if ((ret = __rep_elect_init(dbenv,
            &lsn, nsites, priority, tiebreaker, &in_progress)) != 0) {
                if (ret == DB_REP_NEWMASTER) {
                        ret = 0;
                        *eidp = dbenv->rep_eid;
                }
                return (ret);
        }

        if (!in_progress) {
#ifdef DIAGNOSTIC
                if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv, "Beginning an election");
#endif
                if ((ret = __rep_send_message(dbenv,
                    DB_EID_BROADCAST, REP_ELECT, NULL, NULL, 0)) != 0)
                        goto err;
                DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTSEND, ret, NULL);
        }

        /* Now send vote */
        if ((ret =
            __rep_send_vote(dbenv, &lsn, nsites, priority, tiebreaker)) != 0)
                goto err;
        DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTVOTE1, ret, NULL);

        ret = __rep_wait(dbenv, timeout, eidp, REP_F_EPHASE1);
        DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTWAIT1, ret, NULL);
        switch (ret) {
                case 0:
                        /* Check if election complete or phase complete. */
                        if (*eidp != DB_EID_INVALID)
                                return (0);
                        goto phase2;
                case DB_TIMEOUT:
                        break;
                default:
                        goto err;
        }
        /*
         * If we got here, we haven't heard from everyone, but we've
         * run out of time, so it's time to decide if we have enough
         * votes to pick a winner and if so, to send out a vote to
         * the winner.
         */
        MUTEX_LOCK(dbenv, db_rep->mutexp);
        send_vote = DB_EID_INVALID;
        if (rep->sites > rep->nsites / 2) {
                /* We think we've seen enough to cast a vote. */
                send_vote = rep->winner;
                if (rep->winner == rep->eid)
                        rep->votes++;
                F_CLR(rep, REP_F_EPHASE1);
                F_SET(rep, REP_F_EPHASE2);
        }
        MUTEX_UNLOCK(dbenv, db_rep->mutexp);
        if (send_vote == DB_EID_INVALID) {
                /* We do not have enough votes to elect. */
#ifdef DIAGNOSTIC
                if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                        __db_err(dbenv,
                            "Not enough votes to elect: received %d of %d",
                            rep->sites, rep->nsites);
#endif
                ret = DB_REP_UNAVAIL;
                goto err;

        }
#ifdef DIAGNOSTIC
        if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION) &&
            send_vote != rep->eid)
                __db_err(dbenv, "Sending vote");
#endif

        if (send_vote != rep->eid && (ret = __rep_send_message(dbenv,
            send_vote, REP_VOTE2, NULL, NULL, 0)) != 0)
                goto err;
        DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTVOTE2, ret, NULL);

phase2: ret = __rep_wait(dbenv, timeout, eidp, REP_F_EPHASE2);
        DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTWAIT2, ret, NULL);
        switch (ret) {
                case 0:
                        return (0);
                case DB_TIMEOUT:
                        ret = DB_REP_UNAVAIL;
                        break;
                default:
                        goto err;
        }

DB_TEST_RECOVERY_LABEL
err:    MUTEX_LOCK(dbenv, db_rep->mutexp);
        ELECTION_DONE(rep);
        MUTEX_UNLOCK(dbenv, db_rep->mutexp);

#ifdef DIAGNOSTIC
        if (FLD_ISSET(dbenv->verbose, DB_VERB_REPLICATION))
                __db_err(dbenv, "Ended election with %d", ret);
#endif
        return (ret);
}

/*
 * __rep_elect_init
 *      Initialize an election.  Sets beginp non-zero if the election is
 * already in progress; makes it 0 otherwise.
 */
static int
__rep_elect_init(dbenv, lsnp, nsites, priority, tiebreaker, beginp)
        DB_ENV *dbenv;
        DB_LSN *lsnp;
        int nsites, priority, tiebreaker, *beginp;
{
        DB_REP *db_rep;
        REP *rep;
        int ret, *tally;

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

        ret = 0;

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

        /* If we are already a master; simply broadcast that fact and return. */
        if (F_ISSET(dbenv, DB_ENV_REP_MASTER)) {
                (void)__rep_send_message(dbenv,
                    DB_EID_BROADCAST, REP_NEWMASTER, lsnp, NULL, 0);
                rep->stat.st_elections_won++;
                return (DB_REP_NEWMASTER);
        }

        MUTEX_LOCK(dbenv, db_rep->mutexp);
        *beginp = IN_ELECTION(rep);
        if (!*beginp) {
                /*
                 * Make sure that we always initialize all the election fields
                 * before putting ourselves in an election state.  That means
                 * issuing calls that can fail (allocation) before setting all
                 * the variables.
                 */
                if (nsites > rep->asites &&
                    (ret = __rep_grow_sites(dbenv, nsites)) != 0)
                        goto err;
                DB_ENV_TEST_RECOVERY(dbenv, DB_TEST_ELECTINIT, ret, NULL);
                rep->nsites = nsites;
                rep->priority = priority;
                rep->votes = 0;
                rep->master_id = DB_EID_INVALID;
                F_SET(rep, REP_F_EPHASE1);

                /* We have always heard from ourselves. */
                rep->sites = 1;
                tally = R_ADDR((REGINFO *)dbenv->reginfo, rep->tally_off);
                tally[0] = rep->eid;

                if (priority != 0) {
                        /* Make ourselves the winner to start. */
                        rep->winner = rep->eid;
                        rep->w_priority = priority;
                        rep->w_gen = rep->gen;
                        rep->w_lsn = *lsnp;
                        rep->w_tiebreaker = tiebreaker;
                } else {
                        rep->winner = DB_EID_INVALID;
                        rep->w_priority = 0;
                        rep->w_gen = 0;
                        ZERO_LSN(rep->w_lsn);
                        rep->w_tiebreaker = 0;
                }
        }
DB_TEST_RECOVERY_LABEL
err:    MUTEX_UNLOCK(dbenv, db_rep->mutexp);
        return (ret);
}

static int
__rep_wait(dbenv, timeout, eidp, flags)
        DB_ENV *dbenv;
        u_int32_t timeout;
        int *eidp;
        u_int32_t flags;
{
        DB_REP *db_rep;
        REP *rep;
        int done, ret;
        u_int32_t sleeptime;

        done = 0;
        db_rep = dbenv->rep_handle;
        rep = db_rep->region;

        /*
         * The user specifies an overall timeout function, but checking
         * is cheap and the timeout may be a generous upper bound.
         * Sleep repeatedly for the smaller of .5s and timeout/10.
         */
        sleeptime = (timeout > 5000000) ? 500000 : timeout / 10;
        if (sleeptime == 0)
                sleeptime++;
        while (timeout > 0) {
                if ((ret = __os_sleep(dbenv, 0, sleeptime)) != 0)
                        return (ret);
                MUTEX_LOCK(dbenv, db_rep->mutexp);
                done = !F_ISSET(rep, flags) && rep->master_id != DB_EID_INVALID;

                *eidp = rep->master_id;
                MUTEX_UNLOCK(dbenv, db_rep->mutexp);

                if (done)
                        return (0);

                if (timeout > sleeptime)
                        timeout -= sleeptime;
                else
                        timeout = 0;
        }
        return (DB_TIMEOUT);
}

/*
 * __rep_flush --
 *      Re-push the last log record to all clients, in case they've lost
 * messages and don't know it.
 */
static int
__rep_flush(dbenv)
        DB_ENV *dbenv;
{
        DBT rec;
        DB_LOGC *logc;
        DB_LSN lsn;
        int ret, t_ret;

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

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

        memset(&rec, 0, sizeof(rec));
        memset(&lsn, 0, sizeof(lsn));

        if ((ret = logc->get(logc, &lsn, &rec, DB_LAST)) != 0)
                goto err;

        ret = __rep_send_message(dbenv,
            DB_EID_BROADCAST, REP_LOG, &lsn, &rec, 0);

err:    if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
                ret = t_ret;
        return (ret);
}

/*
 * __rep_stat --
 *      Fetch replication statistics.
 */
static int
__rep_stat(dbenv, statp, flags)
        DB_ENV *dbenv;
        DB_REP_STAT **statp;
        u_int32_t flags;
{
        DB_LOG *dblp;
        DB_REP *db_rep;
        DB_REP_STAT *stats;
        LOG *lp;
        REP *rep;
        u_int32_t queued;
        int ret;

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

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

        *statp = NULL;
        if ((ret = __db_fchk(dbenv,
            "DB_ENV->rep_stat", flags, DB_STAT_CLEAR)) != 0)
                return (ret);

        /* Allocate a stat struct to return to the user. */
        if ((ret = __os_umalloc(dbenv, sizeof(DB_REP_STAT), &stats)) != 0)
                return (ret);

        MUTEX_LOCK(dbenv, db_rep->mutexp);
        memcpy(stats, &rep->stat, sizeof(*stats));

        /* Copy out election stats. */
        if (IN_ELECTION(rep)) {
                if (F_ISSET(rep, REP_F_EPHASE1))
                        stats->st_election_status = 1;
                else if (F_ISSET(rep, REP_F_EPHASE2))
                        stats->st_election_status = 2;

                stats->st_election_nsites = rep->sites;
                stats->st_election_cur_winner = rep->winner;
                stats->st_election_priority = rep->w_priority;
                stats->st_election_gen = rep->w_gen;
                stats->st_election_lsn = rep->w_lsn;
                stats->st_election_votes = rep->votes;
                stats->st_election_tiebreaker = rep->w_tiebreaker;
        }

        /* Copy out other info that's protected by the rep mutex. */
        stats->st_env_id = rep->eid;
        stats->st_env_priority = rep->priority;
        stats->st_nsites = rep->nsites;
        stats->st_master = rep->master_id;
        stats->st_gen = rep->gen;

        if (F_ISSET(rep, REP_F_MASTER))
                stats->st_status = DB_REP_MASTER;
        else if (F_ISSET(rep, REP_F_LOGSONLY))
                stats->st_status = DB_REP_LOGSONLY;
        else if (F_ISSET(rep, REP_F_UPGRADE))
                stats->st_status = DB_REP_CLIENT;
        else
                stats->st_status = 0;

        if (LF_ISSET(DB_STAT_CLEAR)) {
                queued = rep->stat.st_log_queued;
                memset(&rep->stat, 0, sizeof(rep->stat));
                rep->stat.st_log_queued = rep->stat.st_log_queued_total =
                    rep->stat.st_log_queued_max = queued;
        }
        MUTEX_UNLOCK(dbenv, db_rep->mutexp);

        /*
         * Log-related replication info is stored in the log system and
         * protected by the log region lock.
         */
        R_LOCK(dbenv, &dblp->reginfo);
        if (F_ISSET(rep, REP_ISCLIENT)) {
                stats->st_next_lsn = lp->ready_lsn;
                stats->st_waiting_lsn = lp->waiting_lsn;
        } else {
                if (F_ISSET(rep, REP_F_MASTER))
                        stats->st_next_lsn = lp->lsn;
                else
                        ZERO_LSN(stats->st_next_lsn);
                ZERO_LSN(stats->st_waiting_lsn);
        }
        R_UNLOCK(dbenv, &dblp->reginfo);

        *statp = stats;
        return (0);
}