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b2c364fd SK |
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 | |
12 | ]). | |
13 | ||
14 | -record(?MODULE, | |
15 | { erlang_statistics :: ets:tid() | |
16 | }). | |
17 | ||
18 | -define(T, #?MODULE). | |
19 | ||
20 | -opaque t() :: | |
21 | ?T{}. | |
22 | ||
23 | -spec start() -> | |
24 | t(). | |
25 | start() -> | |
26 | Options = | |
27 | [ set | |
28 | , public | |
29 | ], | |
30 | ?T | |
31 | { erlang_statistics = ets:new(beam_stats_delta_erlang_statistics, Options) | |
32 | }. | |
33 | ||
34 | -spec stop(t()) -> | |
35 | {}. | |
36 | stop(?T | |
37 | { erlang_statistics = TidErlangStatistics | |
38 | } | |
39 | ) -> | |
40 | true = ets:delete(TidErlangStatistics), | |
41 | {}. | |
42 | ||
43 | -spec of_context_switches(t()) -> | |
44 | non_neg_integer(). | |
45 | of_context_switches(?T{erlang_statistics=Table}) -> | |
46 | Key = context_switches, | |
47 | {Current, 0} = beam_stats_source:erlang_statistics(Key), | |
48 | delta(Table, Key, Current). | |
49 | ||
50 | -spec of_io(t()) -> | |
51 | { {io_bytes_in , non_neg_integer()} | |
52 | , {io_bytes_out , non_neg_integer()} | |
53 | }. | |
54 | of_io(?T{erlang_statistics=Table}) -> | |
55 | Key = io, | |
56 | { {input , CurrentIn} | |
57 | , {output , CurrentOut} | |
58 | } = beam_stats_source:erlang_statistics(Key), | |
59 | DeltaIn = delta(Table, io_bytes_in , CurrentIn), | |
60 | DeltaOut = delta(Table, io_bytes_out, CurrentOut), | |
61 | { {io_bytes_in , DeltaIn} | |
62 | , {io_bytes_out , DeltaOut} | |
63 | }. | |
64 | ||
65 | -spec delta(ets:tid(), atom(), non_neg_integer()) -> | |
66 | non_neg_integer(). | |
67 | delta(Table, Key, CurrentTotal) -> | |
68 | PreviousTotalOpt = find(Table, Key), | |
69 | PreviousTotal = hope_option:get(PreviousTotalOpt, 0), | |
70 | save(Table, Key, CurrentTotal), | |
71 | CurrentTotal - PreviousTotal. | |
72 | ||
73 | -spec find(ets:tid(), term()) -> | |
74 | hope_option:t(term()). | |
75 | find(Table, K) -> | |
76 | case ets:lookup(Table, K) | |
77 | of [] -> none | |
78 | ; [{K, V}] -> {some, V} | |
79 | end. | |
80 | ||
81 | -spec save(ets:tid(), term(), term()) -> | |
82 | {}. | |
83 | save(Table, K, V) -> | |
84 | true = ets:insert(Table, {K, V}), | |
85 | {}. |