/*
    * 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.util;
  
  
  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 PidFile extends Thread {
  
    String name;
    private static Log log = LogFactory.getLog(PidFile.class);
    private static FileLock lock = null;
    private static FileOutputStream pidFileOutput = null;
    private static final String DEFAULT_CHUKWA_HOME;
    
    static {
        //use /tmp as a default, only if we can't create tmp files via Java.
      File chukwaHome = new File(System.getProperty("java.io.tmpdir"), "chukwa");
      try {
        File tmpFile = File.createTempFile("chukwa", "discovertmp");
        File tmpDir = tmpFile.getParentFile();
        tmpFile.delete();
        chukwaHome = new File(tmpDir, "chukwa");
        chukwaHome.mkdir();
      } catch(IOException e) {
        log.debug(ExceptionUtil.getStackTrace(e));
      } finally {    
        DEFAULT_CHUKWA_HOME = chukwaHome.getAbsolutePath();
      }
    };
  
    public PidFile(String name) {
      this.name = name;
      try {
        init();
      } catch (IOException ex) {
        clean();
        System.exit(-1);
      }
    }
  
    public void init() throws IOException {
      String pidLong = ManagementFactory.getRuntimeMXBean().getName();
      String[] items = pidLong.split("@");
      String pid = items[0];
      String chukwaPath = System.getProperty("CHUKWA_HOME");
      if(chukwaPath == null) {
        chukwaPath = DEFAULT_CHUKWA_HOME;
      }
      StringBuffer pidFilesb = new StringBuffer();
      String pidDir = System.getenv("CHUKWA_PID_DIR");
      if (pidDir == null) {
        pidDir = chukwaPath + File.separator + "var" + File.separator + "run";
      }
      pidFilesb.append(pidDir).append(File.separator).append(name).append(".pid");
      try {
        File existsFile = new File(pidDir);
        if (!existsFile.exists()) {
          boolean success = (new File(pidDir)).mkdirs();
          if (!success) {
            throw (new IOException());
          }
        }
        File pidFile = new File(pidFilesb.toString());
  
        pidFileOutput = new FileOutputStream(pidFile);
        pidFileOutput.write(pid.getBytes());
        pidFileOutput.flush();
        FileChannel channel = pidFileOutput.getChannel();
        PidFile.lock = channel.tryLock();
        if (PidFile.lock != null) {
          log.debug("Initlization succeeded...");
        } else {
          throw (new IOException("Can not get lock on pid file: " + pidFilesb));
        }
      } catch (IOException ex) {
        System.out.println("Initialization failed: can not write pid file to " + pidFilesb);
        log.error("Initialization failed...");
        log.error(ex.getMessage());
       System.exit(-1);
       throw ex;
 
     }
 
   }
 
   public void clean() {
     String chukwaPath = System.getenv("CHUKWA_HOME");
     if(chukwaPath == null) {
       chukwaPath = DEFAULT_CHUKWA_HOME;
     }
     StringBuffer pidFilesb = new StringBuffer();
     String pidDir = System.getenv("CHUKWA_PID_DIR");
     if (pidDir == null) {
       pidDir = chukwaPath + File.separator + "var" + File.separator + "run";
     }
     pidFilesb.append(pidDir).append(File.separator).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);
     }
   }
 
   public void run() {
     clean();
   }
 }