Function migrateGetSocket

src/cluster.cpp:5393–5437

Return a migrateCachedSocket containing a TCP socket connected with the * target instance, possibly returning a cached one. * * This function is responsible of sending errors to the client if a * connection can't be established. In this case -1 is returned. * Otherwise on success the socket is returned, and the caller should not * attempt to free it after usage. * * If the caller detects a

 * should be called so that the connection will be created from scratch
 * the next time. */
migrateCachedSocket* migrateGetSocket(client *c, robj *host, robj *port, long timeout) {
    connection *conn;
    sds name = sdsempty();
    migrateCachedSocket *cs;

    /* Check if we have an already cached socket for this ip:port pair. */
    name = sdscatlen(name,ptrFromObj(host),sdslen(szFromObj(host)));
    name = sdscatlen(name,":",1);
    name = sdscatlen(name,ptrFromObj(port),sdslen(szFromObj(port)));
    cs = (migrateCachedSocket*)dictFetchValue(g_pserver->migrate_cached_sockets,name);
    if (cs) {
        sdsfree(name);
        cs->last_use_time = g_pserver->unixtime;
        return cs;
    }

    /* No cached socket, create one. */
    if (dictSize(g_pserver->migrate_cached_sockets) == MIGRATE_SOCKET_CACHE_ITEMS) {
        /* Too many items, drop one at random. */
        dictEntry *de = dictGetRandomKey(g_pserver->migrate_cached_sockets);
        cs = (migrateCachedSocket*)dictGetVal(de);
        connClose(cs->conn);
        zfree(cs);
        dictDelete(g_pserver->migrate_cached_sockets,dictGetKey(de));
    }

    /* Create the socket */
    conn = g_pserver->tls_cluster ? connCreateTLS() : connCreateSocket();
    if (connBlockingConnect(conn, szFromObj(c->argv[1]), atoi(szFromObj(c->argv[2])), timeout)
            != C_OK) {
        addReplyError(c,"-IOERR error or timeout connecting to the client");
        connClose(conn);
        sdsfree(name);
        return NULL;
    }
    connEnableTcpNoDelay(conn);

    /* Add to the cache and return it to the caller. */
    cs = (migrateCachedSocket*)zmalloc(sizeof(*cs), MALLOC_LOCAL);
    cs->conn = conn;
    cs->last_dbid = -1;
    cs->last_use_time = g_pserver->unixtime;
    dictAdd(g_pserver->migrate_cached_sockets,name,cs);
    return cs;
}

/* Free a migrate cached connection. */
void migrateCloseSocket(robj *host, robj *port) {