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/*
* Copyright 1996-2001 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package sun.rmi.transport.tcp;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketException;
import java.rmi.*;
import java.rmi.server.RMISocketFactory;
import sun.rmi.runtime.Log;
import sun.rmi.transport.*;
import sun.rmi.transport.proxy.*;
public class TCPConnection implements Connection {
private Socket socket;
private Channel channel;
private InputStream in = null;
private OutputStream out = null;
private long expiration = Long.MAX_VALUE;
private long lastuse = Long.MIN_VALUE;
private long roundtrip = 5; // round-trip time for ping
/**
* Constructor used for creating a connection to accept call
* (an input connection)
*/
TCPConnection(TCPChannel ch, Socket s, InputStream in, OutputStream out)
{
socket = s;
channel = ch;
this.in = in;
this.out = out;
}
/**
* Constructor used by subclass when underlying input and output streams
* are already available.
*/
TCPConnection(TCPChannel ch, InputStream in, OutputStream out)
{
this(ch, null, in, out);
}
/**
* Constructor used when socket is available, but not underlying
* streams.
*/
TCPConnection(TCPChannel ch, Socket s)
{
this(ch, s, null, null);
}
/**
* Gets the output stream for this connection
*/
public OutputStream getOutputStream() throws IOException
{
if (out == null)
out = new BufferedOutputStream(socket.getOutputStream());
return out;
}
/**
* Release the output stream for this connection.
*/
public void releaseOutputStream() throws IOException
{
if (out != null)
out.flush();
}
/**
* Gets the input stream for this connection.
*/
public InputStream getInputStream() throws IOException
{
if (in == null)
in = new BufferedInputStream(socket.getInputStream());
return in;
}
/**
* Release the input stream for this connection.
*/
public void releaseInputStream()
{
}
/**
* Determine if this connection can be used for multiple operations.
* If the socket implements RMISocketInfo, then we can query it about
* this; otherwise, assume that it does provide a full-duplex
* persistent connection like java.net.Socket.
*/
public boolean isReusable()
{
if ((socket != null) && (socket instanceof RMISocketInfo))
return ((RMISocketInfo) socket).isReusable();
else
return true;
}
/**
* Set the expiration time of this connection.
* @param time The time at which the time out expires.
*/
void setExpiration(long time)
{
expiration = time;
}
/**
* Set the timestamp at which this connection was last used successfully.
* The connection will be pinged for liveness if reused long after
* this time.
* @param time The time at which the connection was last active.
*/
void setLastUseTime(long time)
{
lastuse = time;
}
/**
* Returns true if the timeout has expired on this connection;
* otherwise returns false.
* @param time The current time.
*/
boolean expired(long time)
{
return expiration <= time;
}
/**
* Probes the connection to see if it still alive and connected to
* a responsive server. If the connection has been idle for too
* long, the server is pinged. ``Too long'' means ``longer than the
* last ping round-trip time''.
* <P>
* This method may misdiagnose a dead connection as live, but it
* will never misdiagnose a live connection as dead.
* @return true if the connection and server are recently alive
*/
public boolean isDead()
{
InputStream i;
OutputStream o;
// skip ping if recently used within 1 RTT
long start = System.currentTimeMillis();
if ((roundtrip > 0) && (start < lastuse + roundtrip))
return (false); // still alive and warm
// Get the streams
try {
i = getInputStream();
o = getOutputStream();
} catch (IOException e) {
return (true); // can't even get a stream, must be very dead
}
// Write the ping byte and read the reply byte
int response = 0;
try {
o.write(TransportConstants.Ping);
o.flush();
response = i.read();
} catch (IOException ex) {
TCPTransport.tcpLog.log(Log.VERBOSE, "exception: ", ex);
TCPTransport.tcpLog.log(Log.BRIEF, "server ping failed");
return (true); // server failed the ping test
}
if (response == TransportConstants.PingAck) {
// save most recent RTT for future use
roundtrip = (System.currentTimeMillis() - start) * 2;
// clock-correction may make roundtrip < 0; doesn't matter
return (false); // it's alive and 5-by-5
}
if (TCPTransport.tcpLog.isLoggable(Log.BRIEF)) {
TCPTransport.tcpLog.log(Log.BRIEF,
(response == -1 ? "server has been deactivated" :
"server protocol error: ping response = " + response));
}
return (true);
}
/**
* Close the connection. */
public void close() throws IOException
{
TCPTransport.tcpLog.log(Log.BRIEF, "close connection");
if (socket != null)
socket.close();
else {
in.close();
out.close();
}
}
/**
* Returns the channel for this connection.
*/
public Channel getChannel()
{
return channel;
}
}
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