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 
ProgressiveHeapVisitor(HeapVisitor userHeapVisitor, HeapProgressThunk thunk)43   public ProgressiveHeapVisitor(HeapVisitor userHeapVisitor,
44                                 HeapProgressThunk thunk) {
45     this.userHeapVisitor = userHeapVisitor;
46     this.thunk = thunk;
47   }
48 
prologue(long usedSize)49   public void prologue(long usedSize) {
50     this.usedSize = usedSize;
51     visitedSize = 0;
52     userHeapVisitor.prologue(usedSize);
53   }
54 
doObj(Oop obj)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 
epilogue()66   public void epilogue() {
67     userHeapVisitor.epilogue();
68     thunk.heapIterationComplete();
69   }
70 }
71