/*
    * 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.giraph.utils;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintStream;
  import java.lang.management.ManagementFactory;
  import java.nio.charset.Charset;
  import java.util.Date;
  
  /**
   * Helper to run jmap and print the output
   */
  public class JMap {
    /** Arguments to pass in to command */
    public static final String ARGS = " -histo ";
    /** This option will print out onlu live objects */
    private static String LIVE_HISTO_OPTION = " -histo:live ";
  
    /** Do not construct */
    protected JMap() { }
  
    /**
     * Get the process ID of the current running process
     *
     * @return Integer process ID
     */
    public static int getProcessId() {
      String processId = ManagementFactory.getRuntimeMXBean().getName();
      if (processId.contains("@")) {
        processId = processId.substring(0, processId.indexOf("@"));
      }
      return Integer.parseInt(processId);
    }
  
    /**
     * Run jmap, print numLines of output from it to stderr.
     *
     * @param numLines Number of lines to print
     * @param liveObjectsOnly Should we only print non GC-able objects?
     * @param jmapPath Path to jmap binary
     */
    public static void heapHistogramDump(int numLines,
                                         boolean liveObjectsOnly,
                                         String jmapPath) {
      heapHistogramDump(numLines, liveObjectsOnly, System.err, jmapPath);
    }
  
    /**
     * Run jmap, print numLines of output from it to stderr.
     *
     * @param numLines Number of lines to print
     * @param jmapPath Path to jmap binary
     */
    public static void heapHistogramDump(int numLines, String jmapPath) {
      heapHistogramDump(numLines, System.err, jmapPath);
    }
  
    /**
     * Run jmap, print numLines of output from it to stream passed in.
     *
     * @param numLines Number of lines to print
     * @param printStream Stream to print to
     * @param jmapPath Path to jmap binary
     */
    public static void heapHistogramDump(int numLines, PrintStream printStream,
                                         String jmapPath) {
      heapHistogramDump(numLines, false, printStream, jmapPath);
    }
  
    /**
     * Run jmap, print numLines of output from it to stream passed in.
     *
     * @param numLines Number of lines to print
     * @param liveObjectsOnly Should we only print non GC-able objects?
     * @param printStream Stream to print to
     * @param jmapPath Path to jmap binary
     */
    private static void heapHistogramDump(int numLines,
                                          boolean liveObjectsOnly,
                                          PrintStream printStream,
                                         String jmapPath) {
     try {
       String args = liveObjectsOnly ? LIVE_HISTO_OPTION : ARGS;
       Process p = Runtime.getRuntime().exec(jmapPath + args + getProcessId());
       BufferedReader in = new BufferedReader(
           new InputStreamReader(p.getInputStream(), Charset.defaultCharset()));
       printStream.println("JMap " +
           (liveObjectsOnly ? "histo:live" : "histo") +
           " dump at " + new Date());
       String line = in.readLine();
       for (int i = 0; i < numLines && line != null; ++i) {
         printStream.println("--\t" + line);
         line = in.readLine();
       }
       in.close();
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
 }