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1 | // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- |
2 | // vim: ts=8 sw=2 smarttab | |
3 | /* | |
4 | * Ceph - scalable distributed file system | |
5 | * | |
6 | * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net> | |
7 | * | |
8 | * This is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License version 2.1, as published by the Free Software | |
11 | * Foundation. See file COPYING. | |
12 | * | |
13 | */ | |
14 | ||
15 | #ifndef CEPH_DECAYCOUNTER_H | |
16 | #define CEPH_DECAYCOUNTER_H | |
17 | ||
18 | #include "include/utime.h" | |
19 | ||
7c673cae FG |
20 | /** |
21 | * | |
22 | * TODO: normalize value based on some fucntion of half_life, | |
23 | * so that it can be interpreted as an approximation of a | |
24 | * moving average of N seconds. currently, changing half-life | |
25 | * skews the scale of the value, even at steady state. | |
26 | * | |
27 | */ | |
28 | ||
29 | class DecayRate { | |
30 | double k; // k = ln(.5)/half_life | |
31 | ||
32 | friend class DecayCounter; | |
33 | ||
34 | public: | |
35 | DecayRate() : k(0) {} | |
36 | DecayRate(const DecayRate &dr) : k(dr.k) {} | |
37 | ||
38 | // cppcheck-suppress noExplicitConstructor | |
39 | DecayRate(double hl) { set_halflife(hl); } | |
40 | void set_halflife(double hl) { | |
41 | k = ::log(.5) / hl; | |
42 | } | |
43 | }; | |
44 | ||
45 | class DecayCounter { | |
46 | public: | |
47 | double val; // value | |
48 | double delta; // delta since last decay | |
49 | double vel; // recent velocity | |
50 | utime_t last_decay; // time of last decay | |
51 | DecayRate rate; | |
52 | ||
53 | void encode(bufferlist& bl) const; | |
54 | void decode(const utime_t &t, bufferlist::iterator& p); | |
55 | void dump(Formatter *f) const; | |
56 | static void generate_test_instances(list<DecayCounter*>& ls); | |
57 | ||
58 | explicit DecayCounter(const utime_t &now) | |
59 | : val(0), delta(0), vel(0), last_decay(now) | |
60 | { | |
61 | } | |
62 | ||
63 | explicit DecayCounter(const utime_t &now, const DecayRate &rate) | |
64 | : val(0), delta(0), vel(0), last_decay(now), rate(rate) | |
65 | { | |
66 | } | |
67 | ||
68 | // these two functions are for the use of our dencoder testing infrastructure | |
69 | DecayCounter() : val(0), delta(0), vel(0), last_decay() {} | |
70 | ||
71 | void decode(bufferlist::iterator& p) { | |
72 | utime_t fake_time; | |
73 | decode(fake_time, p); | |
74 | } | |
75 | ||
76 | /** | |
77 | * reading | |
78 | */ | |
79 | ||
80 | double get(utime_t now, const DecayRate& rate) { | |
81 | decay(now, rate); | |
82 | return val+delta; | |
83 | } | |
84 | double get(utime_t now) { | |
85 | decay(now, rate); | |
86 | return val+delta; | |
87 | } | |
88 | ||
89 | double get_last() { | |
90 | return val; | |
91 | } | |
92 | ||
93 | double get_last_vel() { | |
94 | return vel; | |
95 | } | |
96 | ||
97 | utime_t get_last_decay() { | |
98 | return last_decay; | |
99 | } | |
100 | ||
101 | /** | |
102 | * adjusting | |
103 | */ | |
104 | ||
105 | double hit(utime_t now, const DecayRate& rate, double v = 1.0) { | |
106 | decay(now, rate); | |
107 | delta += v; | |
108 | return val+delta; | |
109 | } | |
110 | double hit(utime_t now, double v = 1.0) { | |
111 | decay(now, rate); | |
112 | delta += v; | |
113 | return val+delta; | |
114 | } | |
115 | ||
116 | void adjust(double a) { | |
117 | val += a; | |
118 | } | |
119 | void adjust(utime_t now, const DecayRate& rate, double a) { | |
120 | decay(now, rate); | |
121 | val += a; | |
122 | } | |
123 | void scale(double f) { | |
124 | val *= f; | |
125 | delta *= f; | |
126 | vel *= f; | |
127 | } | |
128 | ||
129 | /** | |
130 | * decay etc. | |
131 | */ | |
132 | ||
133 | void reset(utime_t now) { | |
134 | last_decay = now; | |
135 | val = delta = 0; | |
136 | } | |
137 | ||
138 | void decay(utime_t now, const DecayRate &rate); | |
139 | }; | |
140 | ||
141 | inline void encode(const DecayCounter &c, bufferlist &bl) { c.encode(bl); } | |
142 | inline void decode(DecayCounter &c, const utime_t &t, bufferlist::iterator &p) { | |
143 | c.decode(t, p); | |
144 | } | |
145 | // for dencoder | |
146 | inline void decode(DecayCounter &c, bufferlist::iterator &p) { | |
147 | utime_t t; | |
148 | c.decode(t, p); | |
149 | } | |
150 | ||
151 | ||
152 | #endif |