1/*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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24
25#ifndef SHARE_VM_UTILITIES_NUMBERSEQ_HPP
26#define SHARE_VM_UTILITIES_NUMBERSEQ_HPP
27
28#include "memory/allocation.hpp"
29
30/**
31 **  This file contains a few classes that represent number sequence,
32 **  x1, x2, x3, ..., xN, and can calculate their avg, max, and sd.
33 **
34 **  Here's a quick description of the classes:
35 **
36 **    AbsSeq: abstract superclass
37 **    NumberSeq: the sequence is assumed to be very long and the
38 **      maximum, avg, sd, davg, and dsd are calculated over all its elements
39 **    TruncatedSeq: this class keeps track of the last L elements
40 **      of the sequence and calculates avg, max, and sd only over them
41 **/
42
43#define DEFAULT_ALPHA_VALUE 0.7
44
45class AbsSeq: public CHeapObj<mtInternal> {
46private:
47  void init(double alpha);
48
49protected:
50  int    _num; // the number of elements in the sequence
51  double _sum; // the sum of the elements in the sequence
52  double _sum_of_squares; // the sum of squares of the elements in the sequence
53
54  double _davg; // decaying average
55  double _dvariance; // decaying variance
56  double _alpha; // factor for the decaying average / variance
57
58  // This is what we divide with to get the average. In a standard
59  // number sequence, this should just be the number of elements in it.
60  virtual double total() const { return (double) _num; };
61
62public:
63  AbsSeq(double alpha = DEFAULT_ALPHA_VALUE);
64
65  virtual void add(double val); // adds a new element to the sequence
66  void add(unsigned val) { add((double) val); }
67  virtual double maximum() const = 0; // maximum element in the sequence
68  virtual double last() const = 0; // last element added in the sequence
69
70  // the number of elements in the sequence
71  int num() const { return _num; }
72  // the sum of the elements in the sequence
73  double sum() const { return _sum; }
74
75  double avg() const; // the average of the sequence
76  double variance() const; // the variance of the sequence
77  double sd() const; // the standard deviation of the sequence
78
79  double davg() const; // decaying average
80  double dvariance() const; // decaying variance
81  double dsd() const; // decaying "standard deviation"
82
83  // Debugging/Printing
84  virtual void dump();
85  virtual void dump_on(outputStream* s);
86};
87
88class NumberSeq: public AbsSeq {
89private:
90  bool check_nums(NumberSeq* total, int n, NumberSeq** parts);
91
92protected:
93  double _last;
94  double _maximum; // keep track of maximum value
95
96public:
97  NumberSeq(double alpha = DEFAULT_ALPHA_VALUE);
98
99  virtual void add(double val);
100  virtual double maximum() const { return _maximum; }
101  virtual double last() const { return _last; }
102
103  // Debugging/Printing
104  virtual void dump_on(outputStream* s);
105};
106
107class TruncatedSeq: public AbsSeq {
108private:
109  enum PrivateConstants {
110    DefaultSeqLength = 10
111  };
112  void init();
113protected:
114  double *_sequence; // buffers the last L elements in the sequence
115  int     _length; // this is L
116  int     _next;   // oldest slot in the array, i.e. next to be overwritten
117
118public:
119  // accepts a value for L
120  TruncatedSeq(int length = DefaultSeqLength,
121               double alpha = DEFAULT_ALPHA_VALUE);
122  ~TruncatedSeq();
123  virtual void add(double val);
124  virtual double maximum() const;
125  virtual double last() const; // the last value added to the sequence
126
127  double oldest() const; // the oldest valid value in the sequence
128  double predict_next() const; // prediction based on linear regression
129
130  // Debugging/Printing
131  virtual void dump_on(outputStream* s);
132};
133
134#endif // SHARE_VM_UTILITIES_NUMBERSEQ_HPP
135