1 /*

     2  * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 package sun.jvm.hotspot.utilities;

    26 

    27 import sun.jvm.hotspot.memory.*;

    28 import sun.jvm.hotspot.oops.*;

    29 

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

    31     functionality that a chosen "thunk" is called periodically during

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

    33     during long heap scans. */

    34 

    35 public class ProgressiveHeapVisitor implements HeapVisitor {

    36   private HeapVisitor userHeapVisitor;

    37   private HeapProgressThunk thunk;

    38   private long usedSize;

    39   private long visitedSize;

    40   private double lastNotificationFraction;

    41   private static double MINIMUM_NOTIFICATION_FRACTION = 0.01;

    42 

    43   public ProgressiveHeapVisitor(HeapVisitor userHeapVisitor,

    44                                 HeapProgressThunk thunk) {

    45     this.userHeapVisitor = userHeapVisitor;

    46     this.thunk = thunk;

    47   }

    48 

    49   public void prologue(long usedSize) {

    50     this.usedSize = usedSize;

    51     visitedSize = 0;

    52     userHeapVisitor.prologue(usedSize);

    53   }

    54 

    55   public boolean doObj(Oop obj) {

    56     userHeapVisitor.doObj(obj);

    57     visitedSize += obj.getObjectSize();

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

    59     if (curFrac > lastNotificationFraction + MINIMUM_NOTIFICATION_FRACTION) {

    60       thunk.heapIterationFractionUpdate(curFrac);

    61       lastNotificationFraction = curFrac;

    62     }

    63     return false;

    64   }

    65 

    66   public void epilogue() {

    67     userHeapVisitor.epilogue();

    68     thunk.heapIterationComplete();

    69   }

    70 }