intHisto.hpp revision 1472:c18cbe5936b8 
1254885Sdumbbell/*
2254885Sdumbbell * Copyright (c) 2001, 2007, Oracle and/or its affiliates. All rights reserved.
3254885Sdumbbell * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4254885Sdumbbell *
5254885Sdumbbell * This code is free software; you can redistribute it and/or modify it
6254885Sdumbbell * 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// This class implements a simple histogram.
26
27// A histogram summarizes a series of "measurements", each of which is
28// assumed (required in this implementation) to have an outcome that is a
29// non-negative integer.  The histogram efficiently maps measurement outcomes
30// to the number of measurements had that outcome.
31
32// To print the results, invoke print() on your Histogram*.
33
34// Note: there is already an existing "Histogram" class, in file
35// histogram.{hpp,cpp}, but to my mind that's not a histogram, it's a table
36// mapping strings to counts.  To be a histogram (IMHO) it needs to map
37// numbers (in fact, integers) to number of occurrences of that number.
38
39// ysr: (i am not sure i agree with the above note.) i suspect we want to have a
40// histogram template that will map an arbitrary type (with a defined order
41// relation) to a count.
42
43
44class IntHistogram : public CHeapObj {
45 protected:
46  int _max;
47  int _tot;
48  GrowableArray<int>* _elements;
49
50public:
51  // Create a new, empty table.  "est" is an estimate of the maximum outcome
52  // that will be added, and "max" is an outcome such that all outcomes at
53  // least that large will be bundled with it.
54  IntHistogram(int est, int max);
55  // Add a measurement with the given outcome to the sequence.
56  void add_entry(int outcome);
57  // Return the number of entries recorded so far with the given outcome.
58  int  entries_for_outcome(int outcome);
59  // Return the total number of entries recorded so far.
60  int  total_entries() { return _tot; }
61  // Return the number of entries recorded so far with the given outcome as
62  // a fraction of the total number recorded so far.
63  double fraction_for_outcome(int outcome) {
64    return
65      (double)entries_for_outcome(outcome)/
66      (double)total_entries();
67  }
68  // Print the histogram on the given output stream.
69  void print_on(outputStream* st) const;
70};
71