protected void doConnect()

in dubbo-remoting/dubbo-remoting-netty/src/main/java/org/apache/dubbo/remoting/transport/netty/NettyClient.java [89:191]
90 lines of code
12 McCabe index (conditional complexity)

    protected void doConnect() throws Throwable {
        long start = System.currentTimeMillis();
        InetSocketAddress connectAddress = getConnectAddress();
        ChannelFuture future = bootstrap.connect(connectAddress);
        long connectTimeout = getConnectTimeout();
        long deadline = start + connectTimeout;
        try {
            while (true) {
                boolean ret = future.awaitUninterruptibly(connectTimeout, TimeUnit.MILLISECONDS);

                if (ret && future.isSuccess()) {
                    Channel newChannel = future.getChannel();
                    newChannel.setInterestOps(Channel.OP_READ_WRITE);
                    try {
                        // copy reference
                        Channel oldChannel = NettyClient.this.channel;
                        if (oldChannel != null) {
                            try {
                                if (logger.isInfoEnabled()) {
                                    logger.info("Close old netty channel " + oldChannel
                                            + " on create new netty channel " + newChannel);
                                }
                                // Close old channel
                                oldChannel.close();
                            } finally {
                                NettyChannel.removeChannelIfDisconnected(oldChannel);
                            }
                        }
                    } finally {
                        if (NettyClient.this.isClosed()) {
                            try {
                                if (logger.isInfoEnabled()) {
                                    logger.info(
                                            "Close new netty channel " + newChannel + ", because the client closed.");
                                }
                                newChannel.close();
                            } finally {
                                NettyClient.this.channel = null;
                                NettyChannel.removeChannelIfDisconnected(newChannel);
                            }
                        } else {
                            NettyClient.this.channel = newChannel;
                        }
                    }
                    break;
                } else if (future.getCause() != null) {
                    Throwable cause = future.getCause();

                    if (cause instanceof ClosedChannelException) {
                        // Netty3.2.10 ClosedChannelException issue, see https://github.com/netty/netty/issues/138
                        connectTimeout = deadline - System.currentTimeMillis();
                        if (connectTimeout > 0) {
                            // 6-1 - Retry connect to provider server by Netty3.2.10 ClosedChannelException issue#138.
                            logger.warn(
                                    TRANSPORT_FAILED_CONNECT_PROVIDER,
                                    "Netty3.2.10 ClosedChannelException issue#138",
                                    "",
                                    "Retry connect to provider server.");
                            future = bootstrap.connect(connectAddress);
                            continue;
                        }
                    }
                    RemotingException remotingException = new RemotingException(
                            this,
                            "client(url: " + getUrl() + ") failed to connect to server " + getRemoteAddress()
                                    + ", error message is:" + cause.getMessage(),
                            cause);

                    // 6-1 - Failed to connect to provider server by other reason.
                    logger.error(
                            TRANSPORT_FAILED_CONNECT_PROVIDER,
                            "network disconnected",
                            "",
                            "Failed to connect to provider server by other reason.",
                            cause);

                    throw remotingException;
                } else {

                    RemotingException remotingException = new RemotingException(
                            this,
                            "client(url: " + getUrl() + ") failed to connect to server " + getRemoteAddress()
                                    + " client-side timeout " + getConnectTimeout() + "ms (elapsed: "
                                    + (System.currentTimeMillis() - start) + "ms) from netty client "
                                    + NetUtils.getLocalHost() + " using dubbo version " + Version.getVersion());

                    // 6-2 - Client-side timeout.
                    logger.error(
                            TRANSPORT_CLIENT_CONNECT_TIMEOUT,
                            "provider crash",
                            "",
                            "Client-side timeout.",
                            remotingException);

                    throw remotingException;
                }
            }
        } finally {
            if (!isConnected()) {
                future.cancel();
            }
        }
    }