Tiny example using libevent and hiredis

example.c

// cc -Wall -ggdb3 -O0 -o example example.c -lhiredis -levent -lpthread -levent_pthreads

#define _POSIX_C_SOURCE 200809L
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <pthread.h>
#include <hiredis/async.h>
#include <hiredis/adapters/libevent.h>
#include <event2/thread.h>

static redisAsyncContext *ac;
static char *message;
struct event_base *base;

void setCallback(redisAsyncContext *ac, void *r, void *privdata) {
    redisReply *reply = r;
    if (reply == NULL) {
        if (ac->errstr) {
            printf("errstr: %s\n", ac->errstr);
        }
        return;
    }
    assert(reply->type == REDIS_REPLY_STATUS);
    printf("SET result: %s\n", reply->str);
    free(privdata);
}

void connectCallback(const redisAsyncContext *c, int status) {
    if (status != REDIS_OK) {
        printf("Error: %s\n", c->errstr);
        return;
    }
    printf("Connected...\n");
}

void *eventThread(void *arg) {
    struct event_base *base = arg;

    event_base_dispatch(base);

    return NULL;
}

void sigCb(evutil_socket_t fd, short what, void *arg) {
    if (message != NULL) {
        printf("sigCb:  Executing SET foo %s\n", message);
        redisAsyncCommand(ac, setCallback, message, "SET foo %s", message);
    } else {
        printf("sigCb:  NULL payload, exiting loop\n");
        event_base_loopbreak(base);
    }
}

int main(void) {
    pthread_t thread;
    struct event *ev_signal;
    redisOptions options = {0};
    char buffer[255], *newline;

    REDIS_OPTIONS_SET_TCP(&options, "127.0.0.1", 6379);

    ac = redisAsyncConnectWithOptions(&options);
    assert(ac != NULL && !ac->err);

    base = event_base_new();

    evthread_use_pthreads();
    if (evthread_make_base_notifiable(base)<0) {
        printf("Couldn't make base notifiable!");
        return 1;
    }

    /* Let's add our own event so we can signal the loop */
    ev_signal = event_new(base, -1, EV_PERSIST, sigCb, "SET event");

    redisLibeventAttach(ac, base);
    redisAsyncSetConnectCallback(ac, connectCallback);

    assert(pthread_create(&thread, NULL, eventThread, base) == 0);

    while (fgets(buffer, sizeof(buffer), stdin) != NULL) {
        assert((newline = strchr(buffer, '\n')) != NULL);
        *newline = '\0';

        if (!strcmp(buffer, "quit")) {
            message = NULL;
            printf("Exiting loop...\n");
            event_active(ev_signal, 0, 0);
            break;
        }

        /* NOTE:  This is completely unsafe, you would want to use some
                  kind of thread-safe queue to pass the message payload */
        message = strdup(buffer);
        event_active(ev_signal, 0, 0);
    }

    assert(pthread_join(thread, NULL) == 0);

    return 0;
}