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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
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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  }