Redis CLIENT LIST

/* With multiplexing we need to take per-client state.
 * Clients are taken in a linked list. */
typedef struct redisClient {
    uint64_t id;            /* Client incremental unique ID. */
    int fd;
    redisDb *db;
    int dictid;
    robj *name;             /* As set by CLIENT SETNAME */
    sds querybuf;
    size_t querybuf_peak;   /* Recent (100ms or more) peak of querybuf size */
    int argc;
    robj **argv;
    struct redisCommand *cmd, *lastcmd;
    int reqtype;
    int multibulklen;       /* number of multi bulk arguments left to read */
    long bulklen;           /* length of bulk argument in multi bulk request */
    list *reply;
    unsigned long reply_bytes; /* Tot bytes of objects in reply list */
    int sentlen;            /* Amount of bytes already sent in the current
                               buffer or object being sent. */
    time_t ctime;           /* Client creation time */
    time_t lastinteraction; /* time of the last interaction, used for timeout */
    time_t obuf_soft_limit_reached_time;
    int flags;              /* REDIS_SLAVE | REDIS_MONITOR | REDIS_MULTI ... */
    int authenticated;      /* when requirepass is non-NULL */
    int replstate;          /* replication state if this is a slave */
    int repl_put_online_on_ack; /* Install slave write handler on ACK. */
    int repldbfd;           /* replication DB file descriptor */
    off_t repldboff;        /* replication DB file offset */
    off_t repldbsize;       /* replication DB file size */
    sds replpreamble;       /* replication DB preamble. */
    long long reploff;      /* replication offset if this is our master */
    long long repl_ack_off; /* replication ack offset, if this is a slave */
    long long repl_ack_time;/* replication ack time, if this is a slave */
    char replrunid[REDIS_RUN_ID_SIZE+1]; /* master run id if this is a master */
    int slave_listening_port; /* As configured with: SLAVECONF listening-port */
    multiState mstate;      /* MULTI/EXEC state */
    int btype;              /* Type of blocking op if REDIS_BLOCKED. */
    blockingState bpop;     /* blocking state */
    long long woff;         /* Last write global replication offset. */
    list *watched_keys;     /* Keys WATCHED for MULTI/EXEC CAS */
    dict *pubsub_channels;  /* channels a client is interested in (SUBSCRIBE) */
    list *pubsub_patterns;  /* patterns a client is interested in (SUBSCRIBE) */
    sds peerid;             /* Cached peer ID. */

    /* Response buffer */
    int bufpos;
    char buf[REDIS_REPLY_CHUNK_BYTES];
} redisClient;

void clientCommand(redisClient *c) {
    if (!strcasecmp(c->argv[1]->ptr,"list") && c->argc == 2) {
        /* CLIENT LIST */
        sds o = getAllClientsInfoString();
        addReplyBulkCBuffer(c,o,sdslen(o));
        sdsfree(o);
    }
}

sds getAllClientsInfoString(void) {
    listNode *ln;
    listIter li;
    redisClient *client;
    sds o = sdsempty();

    o = sdsMakeRoomFor(o,200*listLength(server.clients));
    listRewind(server.clients,&li);
    while ((ln = listNext(&li)) != NULL) {
        client = listNodeValue(ln);
        o = catClientInfoString(o,client);
        o = sdscatlen(o,"\n",1);
    }
    return o;
}

adlist.c

/* Create an iterator in the list private iterator structure */
void listRewind(list *list, listIter *li) {
    li->next = list->head;
    li->direction = AL_START_HEAD;
}

networking.c

/* Concatenate a string representing the state of a client in an human
 * readable format, into the sds string 's'. */
sds catClientInfoString(sds s, redisClient *client) {
    char flags[16], events[3], *p;
    int emask;

    p = flags;
    if (client->flags & REDIS_SLAVE) {
        if (client->flags & REDIS_MONITOR)
            *p++ = 'O';
        else
            *p++ = 'S';
    }
    if (client->flags & REDIS_MASTER) *p++ = 'M';
    if (client->flags & REDIS_MULTI) *p++ = 'x';
    if (client->flags & REDIS_BLOCKED) *p++ = 'b';
    if (client->flags & REDIS_DIRTY_CAS) *p++ = 'd';
    if (client->flags & REDIS_CLOSE_AFTER_REPLY) *p++ = 'c';
    if (client->flags & REDIS_UNBLOCKED) *p++ = 'u';
    if (client->flags & REDIS_CLOSE_ASAP) *p++ = 'A';
    if (client->flags & REDIS_UNIX_SOCKET) *p++ = 'U';
    if (client->flags & REDIS_READONLY) *p++ = 'r';
    if (p == flags) *p++ = 'N';
    *p++ = '\0';

    emask = client->fd == -1 ? 0 : aeGetFileEvents(server.el,client->fd);
    p = events;
    if (emask & AE_READABLE) *p++ = 'r';
    if (emask & AE_WRITABLE) *p++ = 'w';
    *p = '\0';
    return sdscatfmt(s,
        "id=%U addr=%s fd=%i name=%s age=%I idle=%I flags=%s db=%i sub=%i psub=%i multi=%i
				qbuf=%U qbuf-free=%U obl=%U oll=%U omem=%U events=%s cmd=%s",
        (unsigned long long) client->id,
        getClientPeerId(client),
        client->fd,
        client->name ? (char*)client->name->ptr : "",
        (long long)(server.unixtime - client->ctime),
        (long long)(server.unixtime - client->lastinteraction),
        flags,
        client->db->id,
        (int) dictSize(client->pubsub_channels),
        (int) listLength(client->pubsub_patterns),
        (client->flags & REDIS_MULTI) ? client->mstate.count : -1,
        (unsigned long long) sdslen(client->querybuf),
        (unsigned long long) sdsavail(client->querybuf),
        (unsigned long long) client->bufpos,
        (unsigned long long) listLength(client->reply),
        (unsigned long long) getClientOutputBufferMemoryUsage(client),
        events,
        client->lastcmd ? client->lastcmd->name : "NULL");
}

/* This function returns the client peer id, by creating and caching it
 * if client->peerid is NULL, otherwise returning the cached value.
 * The Peer ID never changes during the life of the client, however it
 * is expensive to compute. */
char *getClientPeerId(redisClient *c) {
    char peerid[REDIS_PEER_ID_LEN];

    if (c->peerid == NULL) {
        genClientPeerId(c,peerid,sizeof(peerid));
        c->peerid = sdsnew(peerid);
    }
    return c->peerid;
}