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/* * Copyright (c) 1996, 2001, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.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;    }}