LoaderServer.java

/*
 * 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.hadoop.chukwa.inputtools.mdl;


import java.io.IOException;
import java.io.File;
import java.io.*;
import java.lang.management.ManagementFactory;
import java.nio.channels.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class LoaderServer {

  String name;
  private static Log log = LogFactory.getLog(LoaderServer.class);
  private static FileLock lock = null;
  private static FileOutputStream pidFileOutput = null;

  public LoaderServer(String name) {
    this.name = name;
  }

  public void init() throws IOException {
    String pidLong = ManagementFactory.getRuntimeMXBean().getName();
    String[] items = pidLong.split("@");
    String pid = items[0];
    String chukwaPath = System.getProperty("CHUKWA_HOME");
    StringBuffer pidFilesb = new StringBuffer();
    pidFilesb.append(chukwaPath).append("/var/run/").append(name)
        .append(".pid");
    try {
      File pidFile = new File(pidFilesb.toString());

      pidFileOutput = new FileOutputStream(pidFile);
      pidFileOutput.write(pid.getBytes());
      pidFileOutput.flush();
      FileChannel channel = pidFileOutput.getChannel();
      LoaderServer.lock = channel.tryLock();
      if (LoaderServer.lock != null) {
        log.info("Initlization succeeded...");
      } else {
        throw (new IOException());
      }
    } catch (IOException ex) {
      System.out.println("Initializaiton failed: can not write pid file.");
      log.error("Initialization failed...");
      log.error(ex.getMessage());
      System.exit(-1);
      throw ex;

    }

  }

  public void clean() {
    String chukwaPath = System.getenv("CHUKWA_HOME");
    StringBuffer pidFilesb = new StringBuffer();
    pidFilesb.append(chukwaPath).append("/var/run/").append(name)
        .append(".pid");
    String pidFileName = pidFilesb.toString();

    File pidFile = new File(pidFileName);
    if (!pidFile.exists()) {
      log.error("Delete pid file, No such file or directory: " + pidFileName);
    } else {
      try {
        lock.release();
        pidFileOutput.close();
      } catch (IOException e) {
        log.error("Unable to release file lock: " + pidFileName);
      }
    }

    boolean result = pidFile.delete();
    if (!result) {
      log.error("Delete pid file failed, " + pidFileName);
    }
  }

}