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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 | |
140077ce | 10 | , gc/1 |
b2c364fd SK |
11 | , of_context_switches/1 |
12 | , of_io/1 | |
11e1cb97 | 13 | , of_reductions/1 |
7dbc59b6 | 14 | , of_process_info_reductions/2 |
b2c364fd SK |
15 | ]). |
16 | ||
17 | -record(?MODULE, | |
18 | { erlang_statistics :: ets:tid() | |
7dbc59b6 | 19 | , erlang_process_info_reductions :: ets:tid() |
b2c364fd SK |
20 | }). |
21 | ||
22 | -define(T, #?MODULE). | |
23 | ||
24 | -opaque t() :: | |
25 | ?T{}. | |
26 | ||
27 | -spec start() -> | |
28 | t(). | |
29 | start() -> | |
30 | Options = | |
31 | [ set | |
32 | , public | |
33 | ], | |
34 | ?T | |
35 | { erlang_statistics = ets:new(beam_stats_delta_erlang_statistics, Options) | |
7dbc59b6 SK |
36 | , erlang_process_info_reductions = |
37 | ets:new(beam_stats_delta_erlang_process_info_reductions, Options) | |
b2c364fd SK |
38 | }. |
39 | ||
40 | -spec stop(t()) -> | |
41 | {}. | |
42 | stop(?T | |
43 | { erlang_statistics = TidErlangStatistics | |
7dbc59b6 | 44 | , erlang_process_info_reductions = TidErlangProcessInfoReductions |
b2c364fd SK |
45 | } |
46 | ) -> | |
47 | true = ets:delete(TidErlangStatistics), | |
7dbc59b6 | 48 | true = ets:delete(TidErlangProcessInfoReductions), |
b2c364fd SK |
49 | {}. |
50 | ||
140077ce SK |
51 | -spec gc(t()) -> |
52 | {}. | |
53 | gc(?T{erlang_process_info_reductions=Table}=T) -> | |
54 | case ets:first(Table) | |
55 | of '$end_of_table' -> | |
56 | {} | |
57 | ; FirstPid when is_pid(FirstPid) -> | |
58 | gc(T, FirstPid) | |
59 | end. | |
60 | ||
61 | -spec gc(t(), pid()) -> | |
62 | {}. | |
63 | gc(?T{erlang_process_info_reductions=Table}=T, Pid) -> | |
9b2aef83 | 64 | Next = ets:next(Table, Pid), |
140077ce SK |
65 | case beam_stats_source:erlang_is_process_alive(Pid) |
66 | of true -> true | |
67 | ; false -> ets:delete(Table, Pid) | |
68 | end, | |
9b2aef83 | 69 | case Next |
140077ce SK |
70 | of '$end_of_table' -> |
71 | {} | |
72 | ; NextPid when is_pid(NextPid) -> | |
73 | gc(T, NextPid) | |
74 | end. | |
75 | ||
b2c364fd SK |
76 | -spec of_context_switches(t()) -> |
77 | non_neg_integer(). | |
78 | of_context_switches(?T{erlang_statistics=Table}) -> | |
79 | Key = context_switches, | |
80 | {Current, 0} = beam_stats_source:erlang_statistics(Key), | |
81 | delta(Table, Key, Current). | |
82 | ||
83 | -spec of_io(t()) -> | |
84 | { {io_bytes_in , non_neg_integer()} | |
85 | , {io_bytes_out , non_neg_integer()} | |
86 | }. | |
87 | of_io(?T{erlang_statistics=Table}) -> | |
88 | Key = io, | |
89 | { {input , CurrentIn} | |
90 | , {output , CurrentOut} | |
91 | } = beam_stats_source:erlang_statistics(Key), | |
92 | DeltaIn = delta(Table, io_bytes_in , CurrentIn), | |
93 | DeltaOut = delta(Table, io_bytes_out, CurrentOut), | |
94 | { {io_bytes_in , DeltaIn} | |
95 | , {io_bytes_out , DeltaOut} | |
96 | }. | |
97 | ||
11e1cb97 SK |
98 | % We can get between-calls-delta directly from erlang:statistics(reductions), |
99 | % but then if some other process also calls it - we'll get incorrect data on | |
100 | % the next call. | |
101 | % Managing deltas ourselves here, will at least reduce the possible callers to | |
102 | % only those with knowledge of our table ID. | |
103 | -spec of_reductions(t()) -> | |
104 | non_neg_integer(). | |
105 | of_reductions(?T{erlang_statistics=Table}) -> | |
106 | Key = reductions, | |
107 | {Current, _} = beam_stats_source:erlang_statistics(Key), | |
108 | delta(Table, Key, Current). | |
109 | ||
7dbc59b6 SK |
110 | -spec of_process_info_reductions(t(), pid()) -> |
111 | hope_option:t(non_neg_integer()). | |
112 | of_process_info_reductions(?T{erlang_process_info_reductions=Table}, Pid) -> | |
113 | case beam_stats_source:erlang_process_info(Pid, reductions) | |
114 | of undefined -> | |
115 | none | |
116 | ; {reductions, Current} -> | |
117 | Delta = delta(Table, Pid, Current), | |
118 | {some, Delta} | |
119 | end. | |
120 | ||
121 | -spec delta(ets:tid(), Key, non_neg_integer()) -> | |
122 | non_neg_integer() | |
123 | when Key :: atom() | pid(). | |
b2c364fd SK |
124 | delta(Table, Key, CurrentTotal) -> |
125 | PreviousTotalOpt = find(Table, Key), | |
126 | PreviousTotal = hope_option:get(PreviousTotalOpt, 0), | |
127 | save(Table, Key, CurrentTotal), | |
128 | CurrentTotal - PreviousTotal. | |
129 | ||
130 | -spec find(ets:tid(), term()) -> | |
131 | hope_option:t(term()). | |
132 | find(Table, K) -> | |
133 | case ets:lookup(Table, K) | |
134 | of [] -> none | |
135 | ; [{K, V}] -> {some, V} | |
136 | end. | |
137 | ||
138 | -spec save(ets:tid(), term(), term()) -> | |
139 | {}. | |
140 | save(Table, K, V) -> | |
141 | true = ets:insert(Table, {K, V}), | |
142 | {}. |