/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements.  See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License.  You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.apache.log4j.varia;import org.apache.log4j.RollingFileAppender;import org.apache.log4j.helpers.LogLog;import java.io.DataInputStream;import java.io.DataOutputStream;import java.net.ServerSocket;import java.net.Socket;/**   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 G&uuml;lc&uuml;   @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);    }  }}