path: root/gnu/java/rmi/server/UnicastConnectionManager.java

/* UnicastConnectionManager.java --
   Copyright (c) 1996, 1997, 1998, 1999, 2002, 2004
   Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
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exception statement from your version. */


package gnu.java.rmi.server;

import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.rmi.RemoteException;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RMIServerSocketFactory;
import java.rmi.server.RMISocketFactory;
import java.util.ArrayList;
import java.util.ConcurrentModificationException;
import java.util.Hashtable;
import java.util.Iterator;

public class UnicastConnectionManager
	implements Runnable, ProtocolConstants {

private static String localhost;
// use different maps for server/client type UnicastConnectionManager
private static Hashtable servers = new Hashtable();
// Package-private to avoid trampolines.
static Hashtable clients = new Hashtable();
ArrayList connections; //client connection pool

// make serverThread volatile for poll
private volatile Thread serverThread;
private ServerSocket ssock;
String serverName;
int serverPort;

// Package-private to avoid a trampoline.
static Thread scavenger;

// If client and server are in the same VM, serverobj represents server
Object serverobj;

private static RMISocketFactory defaultSocketFactory = RMISocketFactory.getSocketFactory();
private RMIServerSocketFactory serverFactory;
private RMIClientSocketFactory clientFactory;

// The following is for debug
private static int ncsock = 0;    //count of client socket
private static int nssock = 0;    //count of server socket
private static int ncmanager = 0; //count of client manager
private static int nsmanager = 0; //count of server manager

private static final boolean debug = false;

private static final Object GLOBAL_LOCK = new Object();

static {
        try {
                //Use host address instead of host name to avoid name resolving issues
                //localhost = InetAddress.getLocalHost().getHostName();
                localhost = InetAddress.getLocalHost().getHostAddress();
        }
        catch (UnknownHostException _) {
                localhost = "localhost";
        }
        
        
}

//Only one scavenger thread running globally
private static void startScavenger(){
    scavenger = new Thread(new Runnable(){
        public void run(){
            if (debug) System.out.println("************* start scavenger.");
            boolean liveon = true;
            while (liveon){
                // Sleep for the expire timeout
                try{
                    Thread.sleep(UnicastConnection.CONNECTION_TIMEOUT);
                }catch(InterruptedException _ie){
                    break;
                }
                liveon = false;
                // Scavenge all clients' connections that're expired
                Iterator iter = clients.values().iterator();
                long l = System.currentTimeMillis();
                try{
                    while(iter.hasNext()){
                        UnicastConnectionManager man = (UnicastConnectionManager)iter.next();
                        ArrayList conns = man.connections;
                        synchronized(conns) { // is the lock a little coarser?
                            for (int last = conns.size() - 1;
                                 last >= 0;
                                 --last)
                            {
                                UnicastConnection conn = (UnicastConnection)conns.get(last);
                                if (UnicastConnection.isExpired(conn, l)){
                                    conns.remove(last);
                                    conn.disconnect();
                                    conn = null;   
                                }else
                                    liveon = true; //there're still live connections
                            }
                        }
                    }
                }catch(ConcurrentModificationException cme) {
                    // handle it lazily
                    liveon = true;
                }
            }
            scavenger = null;
            if (debug) System.out.println("************* exit scavenger.");
        }
    });
    // As it is used for client connection, we may put this thread
    // in daemon state to prevent the VM from blocking when exiting.
    scavenger.setDaemon(true);
    scavenger.start();
}

/**
  * Client UnicastConnectionManager constructor
  */
private UnicastConnectionManager(String host, int port, RMIClientSocketFactory csf) {
	ssock = null;
	serverName = host;
	serverPort = port;
	serverFactory = null;
	clientFactory = csf;
    connections = new ArrayList();
}

/**
  * Server UnicastConnectionManager constructor
  */
private UnicastConnectionManager(int port, RMIServerSocketFactory ssf) throws RemoteException {

	try {
		ssock = ssf.createServerSocket(port);
		serverPort = ssock.getLocalPort();
	}
	catch (IOException ioex) {
		ssock = null;
		serverPort = 0;
		throw new java.rmi.server.ExportException("can not create Server Socket on port " + port,ioex);
	}
	serverName = localhost;
	serverFactory = ssf;
	clientFactory = null;
}

/**
 * Return a client connection manager which will connect to the given
 * host/port.
 */
public static synchronized UnicastConnectionManager getInstance(String host, int port, RMIClientSocketFactory csf) {
//System.out.println("getInstance: " + host + "," + port + "," + csf);
	if (csf == null) {
        csf = defaultSocketFactory;
	}
	// change host name to host address to avoid name resolving issues
	try{
    	host = InetAddress.getByName(host).getHostAddress();
    }catch(Exception _){}
    
	TripleKey key = new TripleKey(host, port, csf);
	UnicastConnectionManager man = (UnicastConnectionManager)clients.get(key);
	if (man == null) {
		man = new UnicastConnectionManager(host, port, csf);
        if (debug) {
            ncmanager++;
            System.out.println("\n\n ====== " + ncmanager + " client managers.\n\n");
        }
		clients.put(key, man);
        
        // Detect if client and server are in the same VM, i.e., their keys are equal
        UnicastConnectionManager svrman = (UnicastConnectionManager)servers.get(key);
        if(svrman != null){ // server and client are in the same VM
            man.serverobj = svrman.serverobj;
        }
	}
	return (man);
}

/**
 * Return a server connection manager which will accept connection on the
 * given port.
 */
public static synchronized UnicastConnectionManager getInstance(int port, RMIServerSocketFactory ssf) throws RemoteException {
//System.out.println("getInstance: " + port + "," + ssf);
	if (ssf == null) {
        ssf = defaultSocketFactory;
	}
	TripleKey key = new TripleKey(localhost, port, ssf);
	UnicastConnectionManager man = (UnicastConnectionManager)servers.get(key);
	if (man == null) {
		man = new UnicastConnectionManager(port, ssf);
        if (debug) {
            nsmanager++;
            System.out.println("\n\n ****** " + nsmanager + " server managers.\n\n");
        }
		// The provided port might not be the set port.
		key.port = man.serverPort;
		servers.put(key, man);
	}
	return (man);
}

/**
 * Get a connection from this manager.
 */
public UnicastConnection getConnection() throws IOException {
	if (ssock == null) {
		return (getClientConnection());
	}
	else {
		return (getServerConnection());
	}
}

/**
 * Accept a connection to this server.
 */
private UnicastConnection getServerConnection() throws IOException {
	Socket sock = ssock.accept();
    sock.setTcpNoDelay(true); //??
	UnicastConnection conn = new UnicastConnection(this, sock);
	conn.acceptConnection();
    if (debug){
        nssock++;
        System.out.println("\n\n ****** " + nssock + " server socks.\n\n");
    }
    //System.out.println("Server connection " + sock);
	return (conn);
}

/**
 * Make a conection from this client to the server.
 */
private UnicastConnection getClientConnection() throws IOException {
    ArrayList conns = connections;
    UnicastConnection conn;
    
    synchronized(conns) {
        int nconn = conns.size() - 1;
    
        // if there're free connections in connection pool
        if(nconn >= 0) {
            conn = (UnicastConnection)conns.get(nconn);
            //Should we check if conn is alive using Ping??
            conns.remove(nconn);
            
            // Check if the connection is already expired
            long l = System.currentTimeMillis();
            if (!UnicastConnection.isExpired(conn, l)){
                return conn;
            }else {
                conn.disconnect();
                conn = null;   
            }
        }
    }
    
	Socket sock = clientFactory.createSocket(serverName, serverPort);
    conn = new UnicastConnection(this, sock);
	conn.makeConnection(DEFAULT_PROTOCOL);
    
    if (debug) {
        ncsock++;
        System.out.println("\n\n ====== " + ncsock + " client socks.\n\n");
    }

	return (conn);
}

/**
 * Discard a connection when we're done with it - maybe it can be
 * recycled.
 */
public void discardConnection(UnicastConnection conn) {
//System.out.println("Discarding connection " + conn);
    //conn.disconnect();
    if (ssock != null) //server connection
	conn.disconnect();
    else {
        // To client connection, we'd like to return back to pool
        UnicastConnection.resetTime(conn);
        //Ensure there're only one scavenger globally
        synchronized(GLOBAL_LOCK) {
            connections.add(conn); //borrow this lock to garantee thread safety 
            if (scavenger == null)
                startScavenger();
        }
    }
}

/**
 * Start a server on this manager if it's a server socket and we've not
 * already got one running.
 */
public void startServer() {
	synchronized(this) {
		if (ssock == null || serverThread != null) {
			return;
		}
		serverThread = new Thread(this);
        // The following is not necessary when java.lang.Thread's constructor do this.
        // serverThread.setContextClassLoader(Thread.currentThread().getContextClassLoader());
	}
	serverThread.start();
}

/**
 * Stop a server on this manager
 */
public void stopServer() {
    synchronized(this) {
    	if(serverThread != null){
    	    serverThread = null;
    	    try{
    	        ssock.close();
    	    }catch(Exception _){}
    	}
    }
}

/**
 * Server thread for connection manager.
 */
public void run() {
	for (;serverThread != null;) { // if serverThread==null, then exit thread
		try {
//System.out.println("Waiting for connection on " + serverPort);
			UnicastConnection conn = getServerConnection();

			// get address of remote host for the RMIIncomingThread object
			String remoteHost = null;
			if (conn.sock != null) {
				remoteHost = conn.sock.getInetAddress().getHostAddress();			
			}

			// use a thread pool to improve performance
            //ConnectionRunnerPool.dispatchConnection(conn);
            (new RMIIncomingThread(conn, remoteHost)).start();
//	   (new Thread(conn)).start();
		}
		catch (Exception e) {
            e.printStackTrace();
		}
	}
}

/**
 * Serialization routine.
 */
void write(ObjectOutput out) throws IOException {
        out.writeUTF(serverName);
        out.writeInt(serverPort);
}

/**
 * Serialization routine.
 */
static UnicastConnectionManager read(ObjectInput in) throws IOException {
        String host = in.readUTF();
        int port = in.readInt();
        //RMIClientSocketFactory csf = ((RMIObjectInputStream)in).manager.clientFactory;
        //return (getInstance(host, port, csf));
        return (getInstance(host, port, null));
}

}

/**
 * This is use as the hashkey for the client/server connections.
 */
class TripleKey {

String host;
int port;
Object other;

TripleKey(String host, int port, Object other) {
	this.host = host;
	this.port = port;
	this.other = other;
}

/**
 * Hash code just include the host and other - we ignore the port since
 * this has unusual matching behaviour.
 */
public int hashCode() {
	return (host.hashCode() ^ other.hashCode());
}

public boolean equals(Object obj) {
	if (obj instanceof TripleKey) {
		TripleKey other = (TripleKey)obj;
		if (this.host.equals(other.host) &&
		    this.other == other.other &&
            (this.port == other.port /* || this.port == 0 || other.port == 0*/)) {
			return (true);
		}
	}
	return (false);
}

}