Name: dk106046 Date: 11/27/2003

java version "1.4.2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2-b28)
Java HotSpot(TM) Client VM (build 1.4.2-b28, mixed mode)



/* This testcase illustrates a problem with non-blocking connection to a server.
We start a simple server, listening on port 8765, which just accepts
connections. We then register a non-blocking SocketChannel (the client) with a
selector with interest in OP_CONNECT, so that we can use the selector to notify
us when the channel is ready to finish connecting. We call client.connect and
then selector.select in a loop. The selector fires and with the client channel
in the selected-keys set and we call finishConnect() on the client's channel.
Then the problem occurs: the selector repeatedly fires with no entries in its
selected-keys set, whereas it should block in the next select operation until
there is at least one key in the selected-keys set. */

import java.net.*;
import java.util.Iterator;
import java.nio.channels.*;

public class OpConnectTest {

    public static int PORT = 8765;

    public static void main( String[] args ) {
        new OpConnectTest() . runTest();
    }

    /* Start a server running in a separate thread. Wait for it to start then
    do a non-blocking connect to it. */
    public void runTest() {
        try{
            new Thread( new Runnable() {
                public void run() {
                    new AcceptServer() . startServer();
                }
            } ) . start();
            // Give the server enough time to start up.
            Thread.sleep( 200 );
            connectNonBlockingClient();
            connectFinished = true;
        } catch ( Exception e ) {
            System.out.println( e );
        }
    }

    public static boolean connectFinished = false;

    /* Create a SocketChannel, register it with a Selector for OP_CONNECT, then
    do a non-blocking connect. */
    public void connectNonBlockingClient() throws Exception
    {
        SocketChannel channel = SocketChannel.open( );
        channel.configureBlocking( false );

        Selector selector = Selector.open();
        channel.register( selector, SelectionKey.OP_CONNECT );
        
        channel.connect( new InetSocketAddress( "localhost", PORT ) );

        for ( int j=1; j < 10; j++ ) {
            selector.select();
            System.out.println( "selector.SelectedKeys().size() = "
                               + selector.selectedKeys().size() );
            
            Iterator i = selector.selectedKeys().iterator();
            while ( i.hasNext() ) {
                SelectionKey key = (SelectionKey)i.next();
                i.remove();
                try {
                    if ( ((SocketChannel)key.channel()).finishConnect() )
                        System.out.println( "connected" );
                    else
                        System.out.println( "not connected" );
                } catch ( ConnectException e ) {
                    System.out.println( "encountered problem connecting" );
                    throw e;
                }
                System.out.println( "key.isValid() = " + key.isValid()
                  + ", key.channel().isOpen() = " + key.channel().isOpen() );
            }
        }
    }
}

class AcceptServer {
    public void startServer() {
        try{
            ServerSocketChannel server = ServerSocketChannel.open();
            server.configureBlocking( false );
            System.out.println( "Starting AcceptServer listening on port "
                               + OpConnectTest.PORT );
            server.socket().bind( new InetSocketAddress( OpConnectTest.PORT ) );
            while ( !OpConnectTest.connectFinished ) {
                server.accept(); // Accept connection, then do nothing with it.
            }
        } catch ( Exception e ) {
            System.out.println( e );
        }
    }
}


======================================================================