Import BSDDB 4.7.25 (as of svn r89086)
This commit is contained in:
Zachary Ware
467
examples_c/ex_rep/base/rep_msg.c
Normal file
467
examples_c/ex_rep/base/rep_msg.c
Normal file
@@ -0,0 +1,467 @@
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 2001,2008 Oracle. All rights reserved.
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*
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* $Id: rep_msg.c 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <db.h>
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#include "rep_base.h"
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static int connect_site __P((DB_ENV *, machtab_t *,
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const char *, repsite_t *, int *, thread_t *));
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static void *elect_thread __P((void *));
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static void *hm_loop __P((void *));
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typedef struct {
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DB_ENV *dbenv;
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machtab_t *machtab;
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} elect_args;
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typedef struct {
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DB_ENV *dbenv;
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const char *progname;
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const char *home;
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socket_t fd;
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u_int32_t eid;
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machtab_t *tab;
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} hm_loop_args;
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/*
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* This is a generic message handling loop that is used both by the
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* master to accept messages from a client as well as by clients
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* to communicate with other clients.
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*/
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static void *
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hm_loop(args)
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void *args;
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{
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DB_ENV *dbenv;
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DB_LSN permlsn;
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DBT rec, control;
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APP_DATA *app;
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const char *c, *home, *progname;
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elect_args *ea;
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hm_loop_args *ha;
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machtab_t *tab;
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thread_t elect_thr, *site_thrs, *tmp, tid;
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repsite_t self;
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u_int32_t timeout;
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int eid, n, nsites, nsites_allocd;
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int already_open, r, ret, t_ret;
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socket_t fd;
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void *status;
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ea = NULL;
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site_thrs = NULL;
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nsites_allocd = 0;
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nsites = 0;
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ha = (hm_loop_args *)args;
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dbenv = ha->dbenv;
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fd = ha->fd;
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home = ha->home;
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eid = ha->eid;
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progname = ha->progname;
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tab = ha->tab;
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free(ha);
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app = dbenv->app_private;
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memset(&rec, 0, sizeof(DBT));
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memset(&control, 0, sizeof(DBT));
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for (ret = 0; ret == 0;) {
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if ((ret = get_next_message(fd, &rec, &control)) != 0) {
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/*
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* Close this connection; if it's the master call
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* for an election.
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*/
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closesocket(fd);
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if ((ret = machtab_rem(tab, eid, 1)) != 0)
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break;
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/*
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* If I'm the master, I just lost a client and this
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* thread is done.
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*/
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if (master_eid == SELF_EID)
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break;
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/*
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* If I was talking with the master and the master
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* went away, I need to call an election; else I'm
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* done.
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*/
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if (master_eid != eid)
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break;
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master_eid = DB_EID_INVALID;
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machtab_parm(tab, &n, &timeout);
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(void)dbenv->rep_set_timeout(dbenv,
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DB_REP_ELECTION_TIMEOUT, timeout);
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if ((ret = dbenv->rep_elect(dbenv,
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n, (n/2+1), 0)) != 0)
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continue;
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/*
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* Regardless of the results, the site I was talking
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* to is gone, so I have nothing to do but exit.
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*/
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if (app->elected) {
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app->elected = 0;
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ret = dbenv->rep_start(dbenv,
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NULL, DB_REP_MASTER);
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}
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break;
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}
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switch (r = dbenv->rep_process_message(dbenv,
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&control, &rec, eid, &permlsn)) {
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case DB_REP_NEWSITE:
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/*
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* Check if we got sent connect information and if we
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* did, if this is me or if we already have a
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* connection to this new site. If we don't,
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* establish a new one.
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*/
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/* No connect info. */
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if (rec.size == 0)
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break;
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/* It's me, do nothing. */
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if (strncmp(myaddr, rec.data, rec.size) == 0)
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break;
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self.host = (char *)rec.data;
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self.host = strtok(self.host, ":");
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if ((c = strtok(NULL, ":")) == NULL) {
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dbenv->errx(dbenv, "Bad host specification");
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goto out;
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}
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self.port = atoi(c);
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/*
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* We try to connect to the new site. If we can't,
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* we treat it as an error since we know that the site
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* should be up if we got a message from it (even
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* indirectly).
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*/
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if (nsites == nsites_allocd) {
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/* Need to allocate more space. */
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if ((tmp = realloc(
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site_thrs, (10 + nsites) *
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sizeof(thread_t))) == NULL) {
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ret = errno;
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goto out;
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}
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site_thrs = tmp;
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nsites_allocd += 10;
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}
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if ((ret = connect_site(dbenv, tab, progname,
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&self, &already_open, &tid)) != 0)
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goto out;
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if (!already_open)
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memcpy(&site_thrs
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[nsites++], &tid, sizeof(thread_t));
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break;
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case DB_REP_HOLDELECTION:
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if (master_eid == SELF_EID)
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break;
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/* Make sure that previous election has finished. */
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if (ea != NULL) {
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if (thread_join(elect_thr, &status) != 0) {
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dbenv->errx(dbenv,
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"thread join failure");
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goto out;
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}
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ea = NULL;
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}
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if ((ea = calloc(sizeof(elect_args), 1)) == NULL) {
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dbenv->errx(dbenv, "can't allocate memory");
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ret = errno;
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goto out;
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}
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ea->dbenv = dbenv;
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ea->machtab = tab;
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if ((ret = thread_create(&elect_thr,
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NULL, elect_thread, (void *)ea)) != 0) {
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dbenv->errx(dbenv,
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"can't create election thread");
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}
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break;
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case DB_REP_ISPERM:
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break;
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case 0:
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if (app->elected) {
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app->elected = 0;
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if ((ret = dbenv->rep_start(dbenv,
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NULL, DB_REP_MASTER)) != 0) {
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dbenv->err(dbenv, ret,
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"can't start as master");
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goto out;
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}
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}
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break;
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default:
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dbenv->err(dbenv, r, "DB_ENV->rep_process_message");
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break;
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}
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}
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out: if ((t_ret = machtab_rem(tab, eid, 1)) != 0 && ret == 0)
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ret = t_ret;
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/* Don't close the environment before any children exit. */
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if (ea != NULL && thread_join(elect_thr, &status) != 0)
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dbenv->errx(dbenv, "can't join election thread");
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if (site_thrs != NULL)
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while (--nsites >= 0)
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if (thread_join(site_thrs[nsites], &status) != 0)
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dbenv->errx(dbenv, "can't join site thread");
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return ((void *)(uintptr_t)ret);
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}
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/*
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* This is a generic thread that spawns a thread to listen for connections
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* on a socket and then spawns off child threads to handle each new
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* connection.
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*/
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void *
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connect_thread(args)
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void *args;
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{
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DB_ENV *dbenv;
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const char *home, *progname;
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hm_loop_args *ha;
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connect_args *cargs;
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machtab_t *machtab;
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thread_t hm_thrs[MAX_THREADS];
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void *status;
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int i, eid, port, ret;
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socket_t fd, ns;
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ha = NULL;
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cargs = (connect_args *)args;
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dbenv = cargs->dbenv;
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home = cargs->home;
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progname = cargs->progname;
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machtab = cargs->machtab;
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port = cargs->port;
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/*
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* Loop forever, accepting connections from new machines,
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* and forking off a thread to handle each.
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*/
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if ((fd = listen_socket_init(progname, port)) < 0) {
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ret = errno;
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goto err;
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}
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for (i = 0; i < MAX_THREADS; i++) {
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if ((ns = listen_socket_accept(machtab,
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progname, fd, &eid)) == SOCKET_CREATION_FAILURE) {
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ret = errno;
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goto err;
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}
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if ((ha = calloc(sizeof(hm_loop_args), 1)) == NULL) {
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dbenv->errx(dbenv, "can't allocate memory");
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ret = errno;
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goto err;
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}
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ha->progname = progname;
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ha->home = home;
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ha->fd = ns;
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ha->eid = eid;
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ha->tab = machtab;
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ha->dbenv = dbenv;
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if ((ret = thread_create(&hm_thrs[i++], NULL,
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hm_loop, (void *)ha)) != 0) {
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dbenv->errx(dbenv, "can't create thread for site");
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goto err;
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}
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ha = NULL;
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}
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/* If we fell out, we ended up with too many threads. */
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dbenv->errx(dbenv, "Too many threads");
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ret = ENOMEM;
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/* Do not return until all threads have exited. */
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while (--i >= 0)
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if (thread_join(hm_thrs[i], &status) != 0)
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dbenv->errx(dbenv, "can't join site thread");
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err: return (ret == 0 ? (void *)EXIT_SUCCESS : (void *)EXIT_FAILURE);
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}
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/*
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* Open a connection to everyone that we've been told about. If we
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* cannot open some connections, keep trying.
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*/
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void *
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connect_all(args)
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void *args;
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{
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DB_ENV *dbenv;
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all_args *aa;
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const char *home, *progname;
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hm_loop_args *ha;
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int failed, i, nsites, open, ret, *success;
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machtab_t *machtab;
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thread_t *hm_thr;
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repsite_t *sites;
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ha = NULL;
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aa = (all_args *)args;
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dbenv = aa->dbenv;
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progname = aa->progname;
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home = aa->home;
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machtab = aa->machtab;
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nsites = aa->nsites;
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sites = aa->sites;
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ret = 0;
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hm_thr = NULL;
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success = NULL;
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/* Some implementations of calloc are sad about allocating 0 things. */
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if ((success = calloc(nsites > 0 ? nsites : 1, sizeof(int))) == NULL) {
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dbenv->err(dbenv, errno, "connect_all");
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ret = 1;
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goto err;
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}
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if (nsites > 0 && (hm_thr = calloc(nsites, sizeof(int))) == NULL) {
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dbenv->err(dbenv, errno, "connect_all");
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ret = 1;
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goto err;
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}
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for (failed = nsites; failed > 0;) {
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for (i = 0; i < nsites; i++) {
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if (success[i])
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continue;
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ret = connect_site(dbenv, machtab,
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progname, &sites[i], &open, &hm_thr[i]);
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/*
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* If we couldn't make the connection, this isn't
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* fatal to the loop, but we have nothing further
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* to do on this machine at the moment.
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*/
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if (ret == DB_REP_UNAVAIL)
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continue;
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if (ret != 0)
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goto err;
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failed--;
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success[i] = 1;
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/* If the connection is already open, we're done. */
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if (ret == 0 && open == 1)
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continue;
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}
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sleep(1);
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}
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err: if (success != NULL)
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free(success);
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if (hm_thr != NULL)
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free(hm_thr);
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return (ret ? (void *)EXIT_FAILURE : (void *)EXIT_SUCCESS);
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}
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static int
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connect_site(dbenv, machtab, progname, site, is_open, hm_thrp)
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DB_ENV *dbenv;
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machtab_t *machtab;
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const char *progname;
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repsite_t *site;
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int *is_open;
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thread_t *hm_thrp;
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{
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int eid, ret;
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socket_t s;
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hm_loop_args *ha;
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if ((s = get_connected_socket(machtab, progname,
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site->host, site->port, is_open, &eid)) < 0)
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return (DB_REP_UNAVAIL);
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if (*is_open)
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return (0);
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if ((ha = calloc(sizeof(hm_loop_args), 1)) == NULL) {
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dbenv->errx(dbenv, "can't allocate memory");
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ret = errno;
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goto err;
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}
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ha->progname = progname;
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ha->fd = s;
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ha->eid = eid;
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ha->tab = machtab;
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ha->dbenv = dbenv;
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if ((ret = thread_create(hm_thrp, NULL,
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hm_loop, (void *)ha)) != 0) {
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dbenv->errx(dbenv, "can't create thread for connected site");
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goto err1;
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}
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return (0);
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err1: free(ha);
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err:
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return (ret);
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}
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/*
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* We need to spawn off a new thread in which to hold an election in
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* case we are the only thread listening on for messages.
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*/
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static void *
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elect_thread(args)
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void *args;
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{
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DB_ENV *dbenv;
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elect_args *eargs;
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machtab_t *machtab;
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u_int32_t timeout;
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int n, ret;
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APP_DATA *app;
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eargs = (elect_args *)args;
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dbenv = eargs->dbenv;
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machtab = eargs->machtab;
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free(eargs);
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app = dbenv->app_private;
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machtab_parm(machtab, &n, &timeout);
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(void)dbenv->rep_set_timeout(dbenv, DB_REP_ELECTION_TIMEOUT, timeout);
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while ((ret = dbenv->rep_elect(dbenv, n, (n/2+1), 0)) != 0)
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sleep(2);
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if (app->elected) {
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app->elected = 0;
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if ((ret = dbenv->rep_start(dbenv, NULL, DB_REP_MASTER)) != 0)
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dbenv->err(dbenv, ret,
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"can't start as master in election thread");
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}
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return (NULL);
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}
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