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1 | -module(beam_stats_delta). |
2 | ||
3 | -export_type( | |
4 | [ t/0 | |
5 | ]). | |
6 | ||
7 | -export( | |
8 | [ start/0 | |
9 | , stop/1 | |
10 | , of_context_switches/1 | |
11 | , of_io/1 | |
11e1cb97 | 12 | , of_reductions/1 |
7dbc59b6 | 13 | , of_process_info_reductions/2 |
b2c364fd SK |
14 | ]). |
15 | ||
16 | -record(?MODULE, | |
17 | { erlang_statistics :: ets:tid() | |
7dbc59b6 | 18 | , erlang_process_info_reductions :: ets:tid() |
b2c364fd SK |
19 | }). |
20 | ||
21 | -define(T, #?MODULE). | |
22 | ||
23 | -opaque t() :: | |
24 | ?T{}. | |
25 | ||
26 | -spec start() -> | |
27 | t(). | |
28 | start() -> | |
29 | Options = | |
30 | [ set | |
31 | , public | |
32 | ], | |
33 | ?T | |
34 | { erlang_statistics = ets:new(beam_stats_delta_erlang_statistics, Options) | |
7dbc59b6 SK |
35 | , erlang_process_info_reductions = |
36 | ets:new(beam_stats_delta_erlang_process_info_reductions, Options) | |
b2c364fd SK |
37 | }. |
38 | ||
39 | -spec stop(t()) -> | |
40 | {}. | |
41 | stop(?T | |
42 | { erlang_statistics = TidErlangStatistics | |
7dbc59b6 | 43 | , erlang_process_info_reductions = TidErlangProcessInfoReductions |
b2c364fd SK |
44 | } |
45 | ) -> | |
46 | true = ets:delete(TidErlangStatistics), | |
7dbc59b6 | 47 | true = ets:delete(TidErlangProcessInfoReductions), |
b2c364fd SK |
48 | {}. |
49 | ||
50 | -spec of_context_switches(t()) -> | |
51 | non_neg_integer(). | |
52 | of_context_switches(?T{erlang_statistics=Table}) -> | |
53 | Key = context_switches, | |
54 | {Current, 0} = beam_stats_source:erlang_statistics(Key), | |
55 | delta(Table, Key, Current). | |
56 | ||
57 | -spec of_io(t()) -> | |
58 | { {io_bytes_in , non_neg_integer()} | |
59 | , {io_bytes_out , non_neg_integer()} | |
60 | }. | |
61 | of_io(?T{erlang_statistics=Table}) -> | |
62 | Key = io, | |
63 | { {input , CurrentIn} | |
64 | , {output , CurrentOut} | |
65 | } = beam_stats_source:erlang_statistics(Key), | |
66 | DeltaIn = delta(Table, io_bytes_in , CurrentIn), | |
67 | DeltaOut = delta(Table, io_bytes_out, CurrentOut), | |
68 | { {io_bytes_in , DeltaIn} | |
69 | , {io_bytes_out , DeltaOut} | |
70 | }. | |
71 | ||
11e1cb97 SK |
72 | % We can get between-calls-delta directly from erlang:statistics(reductions), |
73 | % but then if some other process also calls it - we'll get incorrect data on | |
74 | % the next call. | |
75 | % Managing deltas ourselves here, will at least reduce the possible callers to | |
76 | % only those with knowledge of our table ID. | |
77 | -spec of_reductions(t()) -> | |
78 | non_neg_integer(). | |
79 | of_reductions(?T{erlang_statistics=Table}) -> | |
80 | Key = reductions, | |
81 | {Current, _} = beam_stats_source:erlang_statistics(Key), | |
82 | delta(Table, Key, Current). | |
83 | ||
7dbc59b6 SK |
84 | -spec of_process_info_reductions(t(), pid()) -> |
85 | hope_option:t(non_neg_integer()). | |
86 | of_process_info_reductions(?T{erlang_process_info_reductions=Table}, Pid) -> | |
87 | case beam_stats_source:erlang_process_info(Pid, reductions) | |
88 | of undefined -> | |
89 | none | |
90 | ; {reductions, Current} -> | |
91 | Delta = delta(Table, Pid, Current), | |
92 | {some, Delta} | |
93 | end. | |
94 | ||
95 | -spec delta(ets:tid(), Key, non_neg_integer()) -> | |
96 | non_neg_integer() | |
97 | when Key :: atom() | pid(). | |
b2c364fd SK |
98 | delta(Table, Key, CurrentTotal) -> |
99 | PreviousTotalOpt = find(Table, Key), | |
100 | PreviousTotal = hope_option:get(PreviousTotalOpt, 0), | |
101 | save(Table, Key, CurrentTotal), | |
102 | CurrentTotal - PreviousTotal. | |
103 | ||
104 | -spec find(ets:tid(), term()) -> | |
105 | hope_option:t(term()). | |
106 | find(Table, K) -> | |
107 | case ets:lookup(Table, K) | |
108 | of [] -> none | |
109 | ; [{K, V}] -> {some, V} | |
110 | end. | |
111 | ||
112 | -spec save(ets:tid(), term(), term()) -> | |
113 | {}. | |
114 | save(Table, K, V) -> | |
115 | true = ets:insert(Table, {K, V}), | |
116 | {}. |