Example

int getMasterAddr(char *pntIpStr, char *pntPortStr)
{
    //    char ip[512];
    //    char port[10];
    char masterName[512];

    redisContext *redisSentinelContext = NULL, *redisMasterContext = NULL;
    redisReply *reply, **pElement;
    int element;
    int nSent;
    struct timeval tv;
    int masterFound;
    static int esistePrioritario = 0;
    static int primaChiamata = 1;
    static SENTINELLOCAL sentinelList[NUM_OF_SENTINEL];
    DBMANAGERINFO dbfileInfo;

    /*
     * recupera valore property da file dbconf.properties
     * il settaggio dei sentinel a non prioritari avviene solo alla prima
     * chiamata della routine
     */

    if (getInfoFromFile(PROPERTY_FILE, &dbfileInfo) == -1)
        return -1;
    if (getMasterName(&dbfileInfo, masterName) == -1)
        return -1;
    if (getSentinelInfo(LOCAL_SENTINEL, &dbfileInfo, sentinelList[0].ip, &(sentinelList[0].port)) == -1)
        return -1;

    if (getSentinelInfo(MASTER_SENTINEL, &dbfileInfo, sentinelList[1].ip, &(sentinelList[1].port)) == -1)
        return -1;
    if (getSentinelInfo(SLAVE_SENTINEL, &dbfileInfo, sentinelList[2].ip, &(sentinelList[2].port)) == -1)
        return -1;

    /*
     * Parto impostando come sentinel prioritario quello locale
     */

    if (primaChiamata) {
        sentinelList[0].prioritario = 1;
        esistePrioritario = 1;
        sentinelList[1].prioritario = 0;
        sentinelList[2].prioritario = 0;
        primaChiamata = 0;
    }

    /*
     * chiede ai sentinel quale sia il master (se rispondono in modo corretto
     * il loro stato prioritario e' posto a 1 altrimenti viene settato a 0).
     */

    tv.tv_sec = 0;
    tv.tv_usec = TIMEOUT_CONNECTION_IN_MS;
    masterFound = 0;
#ifdef CONNECTION_DEBUG
    fprintf(f, "getMasterAddr ---------------------------------------------------------------------\n");
    fflush(f);
#endif
    for (nSent = 0; nSent < NUM_OF_SENTINEL; nSent++) {
        if (!sentinelList[nSent].prioritario && esistePrioritario) {
#ifdef CONNECTION_DEBUG
            fprintf(f, "getMasterAddr Sentinel n. %d (%s:%d) non prioritario. Passo al successivo.\n", nSent,
                    sentinelList[nSent].ip, sentinelList[nSent].port);
            fflush(f);
#endif
            continue;
        }
#ifdef CONNECTION_DEBUG
        fprintf(f, "getMasterAddr ---------------------------------------------------------------------\n");
        fprintf(f, "getMasterAddr Connessione a sentinel n. %d (%s:%d) \n", nSent, sentinelList[nSent].ip,
                sentinelList[nSent].port);
        fflush(f);
#endif
        redisSentinelContext = redisConnectWithTimeout(sentinelList[nSent].ip, sentinelList[nSent].port, tv);

        if (redisSentinelContext->err) {
#ifdef CONNECTION_DEBUG
            fprintf(f, "getMasterAddr Errore connessione sentinel n. %d (%s:%d): %s\n", nSent, sentinelList[nSent].ip,
                    sentinelList[nSent].port, redisSentinelContext->errstr);
            fflush(f);
#endif
            sentinelList[nSent].prioritario = 0;
            esistePrioritario = 0;
            /*
            if(redisSentinelContext != NULL)
                    redisFree(redisSentinelContext);
            */
            continue;
        } else {
#ifdef CONNECTION_DEBUG
            fprintf(f, "getMasterAddr Connessione riuscita\n");
            fflush(f);
#endif
            reply = redisCommand(redisSentinelContext, "sentinel get-master-addr-by-name %s ", masterName);

            if (reply == NULL || reply->type == REDIS_REPLY_ERROR) {
                printf("getMasterAddr Errore exec cmd sentinel get-master-addr-by-name %s", masterName);
                sentinelList[nSent].prioritario = 0;
                esistePrioritario = 0;
                /*
                if(reply != NULL)
                        freeReplyObject(reply);
 if(redisSentinelContext != NULL)
                        redisFree(redisSentinelContext);
                */
                continue;
            } else if (reply->type == REDIS_REPLY_ARRAY) {
                pElement = reply->element;
                for (element = 0; element < (int)reply->elements; element++) {
                    if (element == 0)
                        strcpy(pntIpStr, (*pElement)->str);
                    else if (element == 1)
                        strcpy(pntPortStr, (*pElement)->str);

                    pElement++;
                }

                if (reply != NULL)
                    freeReplyObject(reply);
                if (redisSentinelContext != NULL)
                    redisFree(redisSentinelContext);

/*
* ottenute dal sentinel le coordinate del master prova a collegarsi a quest'ultimo
* per verificare che sia realmente master
*/
#ifdef CONNECTION_DEBUG
                fprintf(f, "getMasterAddr Sentinel n. %d ha indicato master ip = %s port = %d\n", nSent, pntIpStr,
                        atoi(pntPortStr));
                fflush(f);

#endif
                redisMasterContext = redisConnectWithTimeout(pntIpStr, atoi(pntPortStr), tv);
                if (redisSentinelContext->err) {
                    printf("getMasterAddr Errore connessione master %s: %s\n", masterName,
                           redisSentinelContext->errstr);
                    sentinelList[nSent].prioritario = 0;
                    esistePrioritario = 0;

                    /*
                                       if(reply != NULL)
                                               freeReplyObject(reply);
                                       if(redisMasterContext != NULL)
                                               redisFree(redisMasterContext);
                                       */
                    continue;
                } else {
#ifdef CONNECTION_DEBUG
                    fprintf(f, "getMasterAddr Connessione riuscita\n");
                    fflush(f);
#endif
                    reply = redisCommand(redisMasterContext, "role");

                    if (reply == NULL || reply->type == REDIS_REPLY_ERROR) {
                        printf("getMasterAddr Errore exec cmd role verso master %s ", masterName);
                        sentinelList[nSent].prioritario = 0;
                        esistePrioritario = 0;
                        /*
                        if(reply != NULL)
                                freeReplyObject(reply);
                        if(redisMasterContext != NULL)
                                redisFree(redisMasterContext);
                        */
                        continue;
                    } else if (reply->type == REDIS_REPLY_ARRAY) {
                        pElement = reply->element;
                        if (strcmp((*pElement)->str, "master") == 0) {
#ifdef CONNECTION_DEBUG
                            fprintf(f, "getMasterAddr Sentinel n. %d ha indicato un master corretto\n", nSent);
                            fflush(f);
#endif
                            sentinelList[nSent].prioritario = 1;
                            esistePrioritario = 1;
                            if (reply != NULL)
                                freeReplyObject(reply);
                            masterFound = 1;
                            break;
                        } else {
                            printf("getMasterAddr Sentinel n. %d ha indicato un master errato\n", nSent);
                            sentinelList[nSent].prioritario = 0;
                            esistePrioritario = 0;
                            if (reply != NULL)
                                freeReplyObject(reply);
                            if (redisMasterContext != NULL)
                                redisFree(redisMasterContext);
                            continue;
                        }
                    }
                }
            }
        }
    }
#ifdef CONNECTION_DEBUG_2
    fprintf(f, "getMasterAddr ---------------------------------------------------------------------\n");
    fprintf(f, "getMasterAddr Stato attuale dei sentinel\n");
    fprintf(f, "getMasterAddr esistePrioritario = %d\n", esistePrioritario);
    fprintf(f, "getMasterAddr primaChiamata     = %d\n", primaChiamata);

    for (nSent = 0; nSent < NUM_OF_SENTINEL; nSent++) {
        fprintf(f, "getMasterAddr ---------------------------------------------------------------------\n");
        fprintf(f, "getMasterAddr Sentinel n.%d\n", nSent);
        fprintf(f, "getMasterAddr ip          = %s\n", sentinelList[nSent].ip);
        fprintf(f, "getMasterAddr port        = %d\n", sentinelList[nSent].port);
        fprintf(f, "getMasterAddr prioritario = %d\n", sentinelList[nSent].prioritario);
    }
    fflush(f);

#endif
    if (masterFound) {
#ifdef GETMASTER_DEBUG
        printf("getMasterAddr: Coordinate master (%s:%d) \n", pntIpStr, atoi(pntPortStr));

#endif
        redisFree(redisMasterContext);
        return (0);
    } else
        return (-1);
}