Function sortCommand

app/redis-6.2.6/src/sort.c:192–597

The SORT command is the most complex command in Redis. Warning: this code * is optimized for speed and a bit less for readability */

/* The SORT command is the most complex command in Redis. Warning: this code
 * is optimized for speed and a bit less for readability */
void sortCommand(client *c) {
    list *operations;
    unsigned int outputlen = 0;
    int desc = 0, alpha = 0;
    long limit_start = 0, limit_count = -1, start, end;
    int j, dontsort = 0, vectorlen;
    int getop = 0; /* GET operation counter */
    int int_conversion_error = 0;
    int syntax_error = 0;
    robj *sortval, *sortby = NULL, *storekey = NULL;
    redisSortObject *vector; /* Resulting vector to sort */

    /* Create a list of operations to perform for every sorted element.
     * Operations can be GET */
    operations = listCreate();
    listSetFreeMethod(operations,zfree);
    j = 2; /* options start at argv[2] */

    /* The SORT command has an SQL-alike syntax, parse it */
    while(j < c->argc) {
        int leftargs = c->argc-j-1;
        if (!strcasecmp(c->argv[j]->ptr,"asc")) {
            desc = 0;
        } else if (!strcasecmp(c->argv[j]->ptr,"desc")) {
            desc = 1;
        } else if (!strcasecmp(c->argv[j]->ptr,"alpha")) {
            alpha = 1;
        } else if (!strcasecmp(c->argv[j]->ptr,"limit") && leftargs >= 2) {
            if ((getLongFromObjectOrReply(c, c->argv[j+1], &limit_start, NULL)
                 != C_OK) ||
                (getLongFromObjectOrReply(c, c->argv[j+2], &limit_count, NULL)
                 != C_OK))
            {
                syntax_error++;
                break;
            }
            j+=2;
        } else if (!strcasecmp(c->argv[j]->ptr,"store") && leftargs >= 1) {
            storekey = c->argv[j+1];
            j++;
        } else if (!strcasecmp(c->argv[j]->ptr,"by") && leftargs >= 1) {
            sortby = c->argv[j+1];
            /* If the BY pattern does not contain '*', i.e. it is constant,
             * we don't need to sort nor to lookup the weight keys. */
            if (strchr(c->argv[j+1]->ptr,'*') == NULL) {
                dontsort = 1;
            } else {
                /* If BY is specified with a real patter, we can't accept
                 * it in cluster mode. */
                if (server.cluster_enabled) {
                    addReplyError(c,"BY option of SORT denied in Cluster mode.");
                    syntax_error++;
                    break;
                }
            }
            j++;
        } else if (!strcasecmp(c->argv[j]->ptr,"get") && leftargs >= 1) {
            if (server.cluster_enabled) {