My code is timing out on the serverHandshake(connection) call.

Question about the task

Chat (part 11)

Java Multithreading, Level 6, Lesson 15

Resolved

I can't get past the timeout when calling

userName = serverHandshake(connection);

I commented that line out so I could fail the test and post my code but I usually run it without comments. I'm also not sure where the removal of the user from map should be. Catch block, finally block or after the try-catch block entirely?

It's time to write the main method of the Handler class, which will call all
the helper methods we wrote earlier. Implement the void run() method in the Handler class.

It must:
1) Display a message indicating that a new connection was established with a remote
address that can be obtained using the getRemoteSocketAddress() method.
2) Create a Connection object using the socket field.
3) Call the method that implements the handshake with the client, and store the name of the new client.
4) Send the name of the new participant (USER_ADDED message) to all chat participants.
Think about which method is most suitable for this.
5) Inform the new participant about the existing participants.
6) Start the server's main message-processing loop.
7) Be sure that the connection is closed if an exception occurs.
8) If any IOExceptions or ClassNotFoundExceptions occur, catch them and display a message indicating
that an error occurred while communicating with the remote address. 9) After handling any exceptions, if step 11.3 has finished and returned a name, we need to remove
from connectionMap the entry for that name and send a USER_REMOVED message containing the name to all other participants.
10) The last thing we need to do in the run() method is display a message
indicating that the connection with the remote address is closed.

Our server is completely ready. Try running it.

Requirements:

The run() method should display a message indicating that a connection has been established with the remote address (use the getRemoteSocketAddress() method).
The run() method should create a new connection using the socket field as an argument.
The run() method should call the serverHandshake() method using the newly created connection as an argument; the return value will be the username (userName).
The run() method should call the sendBroadcastMessage() method using a new message as an argument (MessageType.USER_ADDED, userName).
The run() method should call the notifyUsers() method using connection and userName as arguments.
The run() method should call the serverMainLoop() method using connection and userName as arguments.
Before completing, the run() method must remove from connectionMap the entry that corresponds to userName, and send a message to all chat participants that the current user has been removed.
The run() method should correctly handle IOExceptions and ClassNotFoundExceptions.

package com.codegym.task.task30.task3008; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; public class Server { private static Map<String, Connection> connectionMap = new ConcurrentHashMap<>(); public static void main (String[] args) { try (ServerSocket serverSocket = new ServerSocket(ConsoleHelper.readInt())) { ConsoleHelper.writeMessage("Server is running"); while (true) { try (Socket socket = serverSocket.accept()) { new Handler(socket).start(); } catch (Exception e) { System.out.println(e.getMessage()); } } } catch (Exception e) { e.getMessage(); } } public static void sendBroadcastMessage (Message message) { try { for (Map.Entry<String, Connection> entry : connectionMap.entrySet()) { Connection connection = entry.getValue(); connection.send(message); } } catch (IOException e) { ConsoleHelper.writeMessage("Message couldn't be sent."); } } private static class Handler extends Thread { private Socket socket; public Handler (Socket socket) { this.socket = socket; } @Override public void run() { String userName = null; ConsoleHelper.writeMessage("A connection has been established with " + socket.getRemoteSocketAddress()); try (Connection connection = new Connection(socket)) { // userName = serverHandshake(connection); sendBroadcastMessage(new Message(MessageType.USER_ADDED, userName)); notifyUsers(connection, userName); serverMainLoop(connection, userName); } catch (Exception e) { ConsoleHelper.writeMessage("An error occurred while communicating with the remote address."); } finally { if (userName != null) connectionMap.remove(userName); sendBroadcastMessage(new Message(MessageType.USER_REMOVED, userName)); } ConsoleHelper.writeMessage("Connection with " + socket.getRemoteSocketAddress() + " closed."); } private String serverHandshake (Connection connection) throws IOException, ClassNotFoundException { Message nameRequest = new Message(MessageType.NAME_REQUEST); Message response; do { connection.send(nameRequest); response = connection.receive(); } while (response == null || response.getType() != MessageType.USER_NAME || response.getData() == null || response.getData().isEmpty() || connectionMap.containsKey(response.getData())); connectionMap.put(response.getData(), connection); connection.send(new Message (MessageType.NAME_ACCEPTED)); return response.getData(); } private void notifyUsers (Connection connection, String userName) throws IOException { for (Map.Entry<String, Connection> entry : connectionMap.entrySet()) { if (!entry.getKey().equals(userName)) { connection.send(new Message(MessageType.USER_ADDED, entry.getKey())); } } } private void serverMainLoop (Connection connection, String userName) throws IOException, ClassNotFoundException { while (true) { Message received = connection.receive(); if (received.getType() == MessageType.TEXT) { sendBroadcastMessage(new Message (received.getType(), userName + ": " + received.getData())); } else { ConsoleHelper.writeMessage("Error. Message type is not \"TEXT\"."); } } } } }

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Andrew

Level 29 , Seattle, United States

22 May 2019, 18:20

solution

Solution was to rework the handshake method, even though it passed previous testing. Thanks Guadalupe for the example to work from. Instead of including all the tests in the while() clause, put them in an if() test within a while(true) loop. I would love if someone could tell me why doing it the while(true) way doesn't timeout when the do-while() does. I just took all the tests and put them inside while(true) like this:

if(tests){
    connection.send(nameRequest);
    continue;
}

allthemore

Level 41

5 February 2021, 11:24

Thanks a lot for your thorough investigation! Had exactly the same problem. No way would I have guessed that tests were failing (had timeout error too) because of the other method which previously passed the testing. Your fix works for me as well! Appreciate your help!

Guadalupe Gagnon

Level 37 , Tampa, United States

22 May 2019, 16:49

messaged you

Andrew

Level 29 , Seattle, United States

22 May 2019, 16:57

Tks, replied.