public synchronized void registerServer()

in src/main/java/com/uber/rss/metadata/ZooKeeperServiceRegistry.java [91:151]
50 lines of code
12 McCabe index (conditional complexity)

    public synchronized void registerServer(String dataCenter, String cluster, String serverId, String runningVersion, String connectionString) {
        if (StringUtils.isBlank(dataCenter)) {
            throw new IllegalArgumentException(String.format("Invalid input: dataCenter=%s", dataCenter));
        }

        if (StringUtils.isBlank(cluster)) {
            throw new IllegalArgumentException(String.format("Invalid input: cluster=%s", cluster));
        }

        if (StringUtils.isBlank(serverId)) {
            throw new IllegalArgumentException(String.format("Invalid input: serverId=%s", serverId));
        }

        if (StringUtils.isBlank(runningVersion)) {
            throw new IllegalArgumentException(String.format("Invalid input: runningVersion=%s", runningVersion));
        }

        if (StringUtils.isBlank(connectionString)) {
            throw new IllegalArgumentException(String.format("Invalid input: connectionString=%s", connectionString));
        }

        final String nodeName = getNodeName(serverId);
        final String nodePath = getNodePath(dataCenter, cluster, nodeName);

        final ZooKeeperServerNodeData nodeData = new ZooKeeperServerNodeData();
        nodeData.setRunningVersion(runningVersion);
        nodeData.setConnectionString(connectionString);
        final byte[] nodeDataBytes = JsonUtils.serialize(nodeData).getBytes(StandardCharsets.UTF_8);
        // Two loops because first loop will only fail in the unlikely situation that the ephemeral node already exists
        // and needs to be deleted before trying again.
        for (int i = 0; i < 2; i++) {
            try {
                zk.create()
                        .creatingParentsIfNeeded()
                        .withMode(CreateMode.EPHEMERAL)
                        .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
                        .forPath(nodePath, nodeDataBytes);
                return;
            } catch (KeeperException.NodeExistsException nee) {
                if (i == 1) {
                    M3Stats.addException(nee, this.getClass().getSimpleName());
                    // This is only a problem on the second attempt
                    throw new RssException("Unable to register ZooKeeper node " + nodePath, nee);
                }
                logger.info("ZooKeeper node already exists: " + nodePath, nee);
                try {
                    // Need to delete it so that the ephemeral node remains tied to the lifetime of this connection
                    zk.delete().forPath(nodePath);
                } catch (KeeperException.NoNodeException nne) {
                    // It's a race condition, but it's fine provided that *somebody* deleted it. Try again.
                } catch (Exception e) {
                    M3Stats.addException(e, this.getClass().getSimpleName());
                    throw new RssException("Unable to delete existing ZooKeeper node " + nodePath, e);
                }
            } catch (Exception e) {
                M3Stats.addException(e, this.getClass().getSimpleName());
                throw new RssException("Unable to create ZooKeeper node " + nodePath, e);
            }
        }
        throw new RssException("Too many failures trying to register the node");
    }