embeded-gateway/document/markdown/Redis.md

C client of redis hiredis

implementation of deque

#include <stdio.h>
#include <stdlib.h>
#include <hiredis/hiredis.h>

int main(void) {
    // Connect to Redis server
    redisContext *ctx = redisConnect("127.0.0.1", 6379);
    if (ctx == NULL || ctx->err) {
        if (ctx) {
            printf("Error: %s\n", ctx->errstr);
            redisFree(ctx);
        } else {
            printf("Error: Can't allocate redis context\n");
        }
        exit(1);
    }

    // Push items from top and bottom of the deque
    redisReply *reply;
    reply = redisCommand(ctx, "LPUSH mydeque item1"); // Push at the front
    freeReplyObject(reply);
    reply = redisCommand(ctx, "RPUSH mydeque item2"); // Push at the back
    freeReplyObject(reply);

    // Pop items from top and bottom of the deque
    reply = redisCommand(ctx, "LPOP mydeque"); // Pop from the front
    if (reply && reply->type == REDIS_REPLY_STRING) {
        printf("Popped item from the front: %s\n", reply->str);
    }
    freeReplyObject(reply);

    reply = redisCommand(ctx, "RPOP mydeque"); // Pop from the back
    if (reply && reply->type == REDIS_REPLY_STRING) {
        printf("Popped item from the back: %s\n", reply->str);
    }
    freeReplyObject(reply);

    // Free the Redis context
    redisFree(ctx);

    return 0;
}

/* Set some keys and then read them back.  Once we do that, Redis will deliver
 * invalidation push messages whenever the key is modified */
for (j = 0; j < KEY_COUNT; j++) {
    reply = redisCommand(c, "SET key:%d initial:%d", j, j);
    assertReplyAndFree(c, reply, REDIS_REPLY_STATUS);

    reply = redisCommand(c, "GET key:%d", j);
    assertReplyAndFree(c, reply, REDIS_REPLY_STRING);
}

/* Trigger invalidation messages by updating keys we just read */
for (j = 0; j < KEY_COUNT; j++) {
    printf("            main(): SET key:%d update:%d\n", j, j);
    reply = redisCommand(c, "SET key:%d update:%d", j, j);
    assertReplyAndFree(c, reply, REDIS_REPLY_STATUS);
    printf("            main(): SET REPLY OK\n");
}

```