/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software
* License version 1.1, a copy of which has been included with this
* distribution in the LICENSE.txt file. */
package org.apache.log4j.varia;
import java.io.*;
import java.net.Socket;
import java.net.ServerSocket;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.RollingFileAppender;
import org.apache.log4j.helpers.LogLog;
/**
This appender listens on a socket on the port specified by the
<b>Port</b> property for a "RollOver" message. When such a message
is received, the underlying log file is rolled over and an
acknowledgment message is sent back to the process initiating the
roll over.
<p>This method of triggering roll over has the advantage of being
operating system independent, fast and reliable.
<p>A simple application {@link Roller} is provided to initiate the
roll over.
<p>Note that the initiator is not authenticated. Anyone can trigger
a rollover. In production environments, it is recommended that you
add some form of protection to prevent undesired rollovers.
@author Ceki Gülcü
@since version 0.9.0 */
public class ExternallyRolledFileAppender extends RollingFileAppender {
/**
The string constant sent to initiate a roll over. Current value of
this string constant is <b>RollOver</b>.
*/
static final public String ROLL_OVER = "RollOver";
/**
The string constant sent to acknowledge a roll over. Current value of
this string constant is <b>OK</b>.
*/
static final public String OK = "OK";
int port = 0;
HUP hup;
/**
The default constructor does nothing but calls its super-class
constructor. */
public
ExternallyRolledFileAppender() {
}
/**
The <b>Port</b> [roperty is used for setting the port for
listening to external roll over messages.
*/
public
void setPort(int port) {
this.port = port;
}
/**
Returns value of the <b>Port</b> option.
*/
public
int getPort() {
return port;
}
/**
Start listening on the port specified by a preceding call to
{@link #setPort}. */
public
void activateOptions() {
super.activateOptions();
if(port != 0) {
if(hup != null) {
hup.interrupt();
}
hup = new HUP(this, port);
hup.setDaemon(true);
hup.start();
}
}
}
class HUP extends Thread {
int port;
ExternallyRolledFileAppender er;
HUP(ExternallyRolledFileAppender er, int port) {
this.er = er;
this.port = port;
}
public
void run() {
while(!isInterrupted()) {
try {
ServerSocket serverSocket = new ServerSocket(port);
while(true) {
Socket socket = serverSocket.accept();
LogLog.debug("Connected to client at " + socket.getInetAddress());
new Thread(new HUPNode(socket, er)).start();
}
}
catch(Exception e) {
e.printStackTrace();
}
}
}
}
class HUPNode implements Runnable {
Socket socket;
DataInputStream dis;
DataOutputStream dos;
ExternallyRolledFileAppender er;
public
HUPNode(Socket socket, ExternallyRolledFileAppender er) {
this.socket = socket;
this.er = er;
try {
dis = new DataInputStream(socket.getInputStream());
dos = new DataOutputStream(socket.getOutputStream());
}
catch(Exception e) {
e.printStackTrace();
}
}
public void run() {
try {
String line = dis.readUTF();
LogLog.debug("Got external roll over signal.");
if(ExternallyRolledFileAppender.ROLL_OVER.equals(line)) {
synchronized(er) {
er.rollOver();
}
dos.writeUTF(ExternallyRolledFileAppender.OK);
}
else {
dos.writeUTF("Expecting [RollOver] string.");
}
dos.close();
}
catch(Exception e) {
LogLog.error("Unexpected exception. Exiting HUPNode.", e);
}
}
}
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