numberSeq.hpp revision 3206:2c0751569716 
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24
25#ifndef SHARE_VM_UTILITIES_NUMBERSEQ_HPP
26#define SHARE_VM_UTILITIES_NUMBERSEQ_HPP
27
28/**
29 **  This file contains a few classes that represent number sequence,
30 **  x1, x2, x3, ..., xN, and can calculate their avg, max, and sd.
31 **
32 **  Here's a quick description of the classes:
33 **
34 **    AbsSeq: abstract superclass
35 **    NumberSeq: the sequence is assumed to be very long and the
36 **      maximum, avg, sd, davg, and dsd are calculated over all its elements
37 **    TruncatedSeq: this class keeps track of the last L elements
38 **      of the sequence and calculates avg, max, and sd only over them
39 **/
40
41#define DEFAULT_ALPHA_VALUE 0.7
42
43class AbsSeq {
44private:
45  void init(double alpha);
46
47protected:
48  int    _num; // the number of elements in the sequence
49  double _sum; // the sum of the elements in the sequence
50  double _sum_of_squares; // the sum of squares of the elements in the sequence
51
52  double _davg; // decaying average
53  double _dvariance; // decaying variance
54  double _alpha; // factor for the decaying average / variance
55
56  // This is what we divide with to get the average. In a standard
57  // number sequence, this should just be the number of elements in it.
58  virtual double total() const { return (double) _num; };
59
60public:
61  AbsSeq(double alpha = DEFAULT_ALPHA_VALUE);
62
63  virtual void add(double val); // adds a new element to the sequence
64  void add(unsigned val) { add((double) val); }
65  virtual double maximum() const = 0; // maximum element in the sequence
66  virtual double last() const = 0; // last element added in the sequence
67
68  // the number of elements in the sequence
69  int num() const { return _num; }
70  // the sum of the elements in the sequence
71  double sum() const { return _sum; }
72
73  double avg() const; // the average of the sequence
74  double variance() const; // the variance of the sequence
75  double sd() const; // the standard deviation of the sequence
76
77  double davg() const; // decaying average
78  double dvariance() const; // decaying variance
79  double dsd() const; // decaying "standard deviation"
80
81  // Debugging/Printing
82  virtual void dump();
83  virtual void dump_on(outputStream* s);
84};
85
86class NumberSeq: public AbsSeq {
87private:
88  bool check_nums(NumberSeq* total, int n, NumberSeq** parts);
89
90protected:
91  double _last;
92  double _maximum; // keep track of maximum value
93
94public:
95  NumberSeq(double alpha = DEFAULT_ALPHA_VALUE);
96  NumberSeq(NumberSeq* total, int n_parts, NumberSeq** parts);
97
98  virtual void add(double val);
99  virtual double maximum() const { return _maximum; }
100  virtual double last() const { return _last; }
101
102  // Debugging/Printing
103  virtual void dump_on(outputStream* s);
104};
105
106class TruncatedSeq: public AbsSeq {
107private:
108  enum PrivateConstants {
109    DefaultSeqLength = 10
110  };
111  void init();
112protected:
113  double *_sequence; // buffers the last L elements in the sequence
114  int     _length; // this is L
115  int     _next;   // oldest slot in the array, i.e. next to be overwritten
116
117public:
118  // accepts a value for L
119  TruncatedSeq(int length = DefaultSeqLength,
120               double alpha = DEFAULT_ALPHA_VALUE);
121  ~TruncatedSeq();
122  virtual void add(double val);
123  virtual double maximum() const;
124  virtual double last() const; // the last value added to the sequence
125
126  double oldest() const; // the oldest valid value in the sequence
127  double predict_next() const; // prediction based on linear regression
128
129  // Debugging/Printing
130  virtual void dump_on(outputStream* s);
131};
132
133#endif // SHARE_VM_UTILITIES_NUMBERSEQ_HPP
134