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Annotation of 43BSDTahoe/etc/timed/candidate.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1983 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #ifndef lint
                     19: static char sccsid[] = "@(#)candidate.c        2.5 (Berkeley) 6/18/88";
                     20: #endif /* not lint */
                     21: 
                     22: #include "globals.h"
                     23: #include <protocols/timed.h>
                     24: 
                     25: #define ELECTIONWAIT   3       /* seconds */
                     26: 
                     27: /*
                     28:  * `election' candidates a host as master: it is called by a slave 
                     29:  * which runs with the -M option set when its election timeout expires. 
                     30:  * Note the conservative approach: if a new timed comes up, or another
                     31:  * candidate sends an election request, the candidature is withdrawn.
                     32:  */
                     33: 
                     34: election(net)
                     35: struct netinfo *net;
                     36: {
                     37:        int ret;
                     38:        struct tsp *resp, msg, *readmsg();
                     39:        struct timeval wait;
                     40:        struct tsp *answer, *acksend();
                     41:        long casual();
                     42:        struct sockaddr_in server;
                     43: 
                     44:        syslog(LOG_INFO, "THIS MACHINE IS A CANDIDATE");
                     45:        if (trace) {
                     46:                fprintf(fd, "THIS MACHINE IS A CANDIDATE\n");
                     47:        }
                     48: 
                     49:        ret = MASTER;
                     50:        slvcount = 1;
                     51: 
                     52:        msg.tsp_type = TSP_ELECTION;
                     53:        msg.tsp_vers = TSPVERSION;
                     54:        (void)strcpy(msg.tsp_name, hostname);
                     55:        bytenetorder(&msg);
                     56:        if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, &net->dest_addr,
                     57:            sizeof(struct sockaddr_in)) < 0) {
                     58:                syslog(LOG_ERR, "sendto: %m");
                     59:                exit(1);
                     60:        }
                     61: 
                     62:        do {
                     63:                wait.tv_sec = ELECTIONWAIT;
                     64:                wait.tv_usec = 0;
                     65:                resp = readmsg(TSP_ANY, (char *)ANYADDR, &wait, net);
                     66:                if (resp != NULL) {
                     67:                        switch (resp->tsp_type) {
                     68: 
                     69:                        case TSP_ACCEPT:
                     70:                                (void) addmach(resp->tsp_name, &from);
                     71:                                break;
                     72: 
                     73:                        case TSP_MASTERUP:
                     74:                        case TSP_MASTERREQ:
                     75:                                /*
                     76:                                 * If a timedaemon is coming up at the same time,
                     77:                                 * give up the candidature: it will be the master.
                     78:                                 */
                     79:                                ret = SLAVE;
                     80:                                break;
                     81: 
                     82:                        case TSP_QUIT:
                     83:                        case TSP_REFUSE:
                     84:                                /*
                     85:                                 * Collision: change value of election timer 
                     86:                                 * using exponential backoff.
                     87:                                 * The value of timer will be recomputed (in slave.c)
                     88:                                 * using the original interval when election will 
                     89:                                 * be successfully completed.
                     90:                                 */
                     91:                                backoff *= 2;
                     92:                                delay2 = casual((long)MINTOUT, 
                     93:                                                        (long)(MAXTOUT * backoff));
                     94:                                ret = SLAVE;
                     95:                                break;
                     96: 
                     97:                        case TSP_ELECTION:
                     98:                                /* no master for another round */
                     99:                                msg.tsp_type = TSP_REFUSE;
                    100:                                (void)strcpy(msg.tsp_name, hostname);
                    101:                                server = from;
                    102:                                answer = acksend(&msg, &server, resp->tsp_name,
                    103:                                    TSP_ACK, (struct netinfo *)NULL);
                    104:                                if (answer == NULL) {
                    105:                                        syslog(LOG_ERR, "error in election");
                    106:                                } else {
                    107:                                        (void) addmach(resp->tsp_name, &from);
                    108:                                }
                    109:                                break;
                    110: 
                    111:                        case TSP_SLAVEUP:
                    112:                                (void) addmach(resp->tsp_name, &from);
                    113:                                break;
                    114: 
                    115:                        case TSP_SETDATE:
                    116:                        case TSP_SETDATEREQ:
                    117:                                break;
                    118: 
                    119:                        default:
                    120:                                if (trace) {
                    121:                                        fprintf(fd, "candidate: ");
                    122:                                        print(resp, &from);
                    123:                                }
                    124:                                break;
                    125:                        }
                    126:                } else {
                    127:                        break;
                    128:                }
                    129:        } while (ret == MASTER);
                    130:        return(ret);
                    131: }

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