prosody
0e29c05c3503
util/statistics.lua

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util/statistics.lua @ 6553:0e29c05c3503

util.statistics: New library for gathering various kinds of statistics
author Matthew Wild <mwild1@gmail.com>
date Tue, 20 Jan 2015 12:31:32 +0000
child 6555:7b2d16c14659
comparison
equal deleted inserted replaced
6552:bcb834728ee5 6553:0e29c05c3503
1 local t_sort = table.sort
2 local m_floor = math.floor;
3 local time = require "socket".gettime;
4
5 local function nop_function() end
6
7 local function percentile(arr, length, pc)
8 local n = pc/100 * (length + 1);
9 local k, d = m_floor(n), n%1;
10 if k == 0 then
11 return arr[1];
12 elseif k >= length then
13 return arr[length];
14 end
15 return arr[k] + d*(arr[k+1] - arr[k]);
16 end
17
18 local function new_registry(config)
19 config = config or {};
20 local duration_sample_interval = config.duration_sample_interval or 5;
21 local duration_max_samples = config.duration_max_stored_samples or 5000;
22
23 local registry = {};
24 local methods;
25 methods = {
26 amount = function (name, initial)
27 local v = initial or 0;
28 registry[name] = function () return "amount", v; end
29 return function (new_v) v = new_v; end
30 end;
31 counter = function (name, initial)
32 local v = initial or 0;
33 registry[name] = function () return "amount", v; end
34 return function (delta)
35 v = v + delta;
36 end;
37 end;
38 rate = function (name)
39 local since, n = time(), 0;
40 registry[name] = function ()
41 local t = time();
42 local stats = {
43 rate = n/(t-since);
44 count = n;
45 };
46 since, n = t, 0;
47 return "rate", stats.rate, stats;
48 end;
49 return function ()
50 n = n + 1;
51 end;
52 end;
53 duration = function (name)
54 local events, last_event = {}, 0;
55 local n_actual_events = 0;
56 local since = time();
57
58 registry[name] = function ()
59 local n_stored_events = #events;
60 t_sort(events);
61 local sum = 0;
62 for i = 1, n_stored_events do
63 sum = sum + events[i];
64 end
65
66 local new_time = time();
67
68 local stats = {
69 samples = events;
70 sample_count = n_stored_events;
71 count = n_actual_events,
72 rate = n_actual_events/(new_time-since);
73 average = n_stored_events > 0 and sum/n_stored_events or 0,
74 min = events[1],
75 max = events[n_stored_events],
76 };
77
78 events, last_event = {}, 0;
79 n_actual_events = 0;
80 since = new_time;
81
82 return "duration", stats.average, stats;
83 end;
84
85 return function ()
86 n_actual_events = n_actual_events + 1;
87 if n_actual_events%duration_sample_interval > 0 then
88 return nop_function;
89 end
90
91 local start_time = time();
92 return function ()
93 local end_time = time();
94 local duration = end_time - start_time;
95 last_event = (last_event%duration_max_samples) + 1;
96 events[last_event] = duration;
97 end
98 end;
99 end;
100
101 get_stats = function ()
102 return registry;
103 end;
104 };
105 return methods;
106 end
107
108 return {
109 new = new_registry;
110 get_histogram = function (duration, n_buckets)
111 n_buckets = n_buckets or 100;
112 local events, n_events = duration.samples, duration.sample_count;
113 if not (events and n_events) then
114 return nil, "not a valid duration stat";
115 end
116 local histogram = {};
117
118 for i = 1, 100, 100/n_buckets do
119 histogram[i] = percentile(events, n_events, i);
120 end
121 return histogram;
122 end;
123
124 get_percentile = function (duration, pc)
125 local events, n_events = duration.samples, duration.sample_count;
126 if not (events and n_events) then
127 return nil, "not a valid duration stat";
128 end
129 return percentile(events, n_events, pc);
130 end;
131 }