ObjectHistogramElement.java

/*
 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package sun.jvm.hotspot.oops;

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;

public class ObjectHistogramElement {

  private Klass klass;
  private long  count; // Number of instances of klass
  private long  size;  // Total size of all these instances

  public ObjectHistogramElement(Klass k) {
     klass = k;
     count = 0;
     size  = 0;
  }

  public void updateWith(Oop obj) {
    count = count + 1;
    size  = size  + obj.getObjectSize();
  }

  public int compare(ObjectHistogramElement other) {
    return (int) (other.size - size);
  }

  /** Klass for this ObjectHistogramElement */
  public Klass getKlass() {
    return klass;
  }

  /** Number of instances of klass */
  public long getCount() {
    return count;
  }

  /** Total size of all these instances */
  public long getSize() {
    return size;
  }

  private String getInternalName(Klass k) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    getKlass().printValueOn(new PrintStream(bos));
    // '*' is used to denote VM internal klasses.
    return "* " + bos.toString();
  }

  /** Human readable description **/
  public String getDescription() {
     Klass k = getKlass();
     if (k instanceof InstanceKlass) {
        return k.getName().asString().replace('/', '.');
     } else if (k instanceof ArrayKlass) {
       ArrayKlass ak = (ArrayKlass) k;
       if (k instanceof TypeArrayKlass) {
          TypeArrayKlass tak = (TypeArrayKlass) ak;
          return tak.getElementTypeName() + "[]";
       } else if (k instanceof ObjArrayKlass) {
          ObjArrayKlass oak = (ObjArrayKlass) ak;
          Klass bottom = oak.getBottomKlass();
          int dim = (int) oak.getDimension();
          StringBuffer buf = new StringBuffer();
          if (bottom instanceof TypeArrayKlass) {
            buf.append(((TypeArrayKlass) bottom).getElementTypeName());
          } else if (bottom instanceof InstanceKlass) {
            buf.append(bottom.getName().asString().replace('/', '.'));
          } else {
            throw new RuntimeException("should not reach here");
          }
          for (int i=0; i < dim; i++) {
            buf.append("[]");
          }
          return buf.toString();
       }
    }
    return getInternalName(k);
  }

  public static void titleOn(PrintStream tty) {
    tty.println("Object Histogram:");
    tty.println();
    tty.println("num " + "\t" + "  #instances" + "\t" + "#bytes" + "\t" + "Class description");
    tty.println("--------------------------------------------------------------------------");
  }

  public void printOn(PrintStream tty) {
    tty.print(count + "\t" + size + "\t");
    tty.print(getDescription());
    tty.println();
  }
}