/*

 * Copyright (c) 2000, 2006, 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.utilities;

import sun.jvm.hotspot.memory.*;

import sun.jvm.hotspot.oops.*;

/** This class wraps a user's chosen HeapVisitor with the

    functionality that a chosen "thunk" is called periodically during

    the heap traversal. This allows a progress bar to be displayed

    during long heap scans. */

public class ProgressiveHeapVisitor implements HeapVisitor {

  private HeapVisitor userHeapVisitor;

  private HeapProgressThunk thunk;

  private long usedSize;

  private long visitedSize;

  private double lastNotificationFraction;

  private static double MINIMUM_NOTIFICATION_FRACTION = 0.01;

  public ProgressiveHeapVisitor(HeapVisitor userHeapVisitor,

                                HeapProgressThunk thunk) {

    this.userHeapVisitor = userHeapVisitor;

    this.thunk = thunk;

  }

  public void prologue(long usedSize) {

    this.usedSize = usedSize;

    visitedSize = 0;

    userHeapVisitor.prologue(usedSize);

  }

  public boolean doObj(Oop obj) {

    userHeapVisitor.doObj(obj);

    visitedSize += obj.getObjectSize();

    double curFrac = (double) visitedSize / (double) usedSize;

    if (curFrac > lastNotificationFraction + MINIMUM_NOTIFICATION_FRACTION) {

      thunk.heapIterationFractionUpdate(curFrac);

      lastNotificationFraction = curFrac;

    }

    return false;

  }

  public void epilogue() {

    userHeapVisitor.epilogue();

    thunk.heapIterationComplete();

  }

}