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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 | |
39ff67a6 SK |
35 | { erlang_statistics = |
36 | ets:new(beam_stats_delta_erlang_statistics, Options) | |
7dbc59b6 SK |
37 | , erlang_process_info_reductions = |
38 | ets:new(beam_stats_delta_erlang_process_info_reductions, Options) | |
b2c364fd SK |
39 | }. |
40 | ||
41 | -spec stop(t()) -> | |
42 | {}. | |
43 | stop(?T | |
39ff67a6 | 44 | { erlang_statistics = TidErlangStatistics |
7dbc59b6 | 45 | , erlang_process_info_reductions = TidErlangProcessInfoReductions |
b2c364fd SK |
46 | } |
47 | ) -> | |
48 | true = ets:delete(TidErlangStatistics), | |
7dbc59b6 | 49 | true = ets:delete(TidErlangProcessInfoReductions), |
b2c364fd SK |
50 | {}. |
51 | ||
140077ce SK |
52 | -spec gc(t()) -> |
53 | {}. | |
54 | gc(?T{erlang_process_info_reductions=Table}=T) -> | |
55 | case ets:first(Table) | |
56 | of '$end_of_table' -> | |
57 | {} | |
58 | ; FirstPid when is_pid(FirstPid) -> | |
59 | gc(T, FirstPid) | |
60 | end. | |
61 | ||
62 | -spec gc(t(), pid()) -> | |
63 | {}. | |
64 | gc(?T{erlang_process_info_reductions=Table}=T, Pid) -> | |
9b2aef83 | 65 | Next = ets:next(Table, Pid), |
140077ce SK |
66 | case beam_stats_source:erlang_is_process_alive(Pid) |
67 | of true -> true | |
68 | ; false -> ets:delete(Table, Pid) | |
69 | end, | |
9b2aef83 | 70 | case Next |
140077ce SK |
71 | of '$end_of_table' -> |
72 | {} | |
73 | ; NextPid when is_pid(NextPid) -> | |
74 | gc(T, NextPid) | |
75 | end. | |
76 | ||
b2c364fd SK |
77 | -spec of_context_switches(t()) -> |
78 | non_neg_integer(). | |
79 | of_context_switches(?T{erlang_statistics=Table}) -> | |
80 | Key = context_switches, | |
81 | {Current, 0} = beam_stats_source:erlang_statistics(Key), | |
82 | delta(Table, Key, Current). | |
83 | ||
84 | -spec of_io(t()) -> | |
85 | { {io_bytes_in , non_neg_integer()} | |
86 | , {io_bytes_out , non_neg_integer()} | |
87 | }. | |
88 | of_io(?T{erlang_statistics=Table}) -> | |
89 | Key = io, | |
90 | { {input , CurrentIn} | |
91 | , {output , CurrentOut} | |
92 | } = beam_stats_source:erlang_statistics(Key), | |
93 | DeltaIn = delta(Table, io_bytes_in , CurrentIn), | |
94 | DeltaOut = delta(Table, io_bytes_out, CurrentOut), | |
95 | { {io_bytes_in , DeltaIn} | |
96 | , {io_bytes_out , DeltaOut} | |
97 | }. | |
98 | ||
11e1cb97 SK |
99 | % We can get between-calls-delta directly from erlang:statistics(reductions), |
100 | % but then if some other process also calls it - we'll get incorrect data on | |
101 | % the next call. | |
102 | % Managing deltas ourselves here, will at least reduce the possible callers to | |
103 | % only those with knowledge of our table ID. | |
104 | -spec of_reductions(t()) -> | |
105 | non_neg_integer(). | |
106 | of_reductions(?T{erlang_statistics=Table}) -> | |
107 | Key = reductions, | |
108 | {Current, _} = beam_stats_source:erlang_statistics(Key), | |
109 | delta(Table, Key, Current). | |
110 | ||
7dbc59b6 SK |
111 | -spec of_process_info_reductions(t(), pid()) -> |
112 | hope_option:t(non_neg_integer()). | |
113 | of_process_info_reductions(?T{erlang_process_info_reductions=Table}, Pid) -> | |
114 | case beam_stats_source:erlang_process_info(Pid, reductions) | |
115 | of undefined -> | |
116 | none | |
117 | ; {reductions, Current} -> | |
118 | Delta = delta(Table, Pid, Current), | |
119 | {some, Delta} | |
120 | end. | |
121 | ||
122 | -spec delta(ets:tid(), Key, non_neg_integer()) -> | |
123 | non_neg_integer() | |
124 | when Key :: atom() | pid(). | |
b2c364fd SK |
125 | delta(Table, Key, CurrentTotal) -> |
126 | PreviousTotalOpt = find(Table, Key), | |
127 | PreviousTotal = hope_option:get(PreviousTotalOpt, 0), | |
128 | save(Table, Key, CurrentTotal), | |
129 | CurrentTotal - PreviousTotal. | |
130 | ||
131 | -spec find(ets:tid(), term()) -> | |
132 | hope_option:t(term()). | |
133 | find(Table, K) -> | |
134 | case ets:lookup(Table, K) | |
135 | of [] -> none | |
136 | ; [{K, V}] -> {some, V} | |
137 | end. | |
138 | ||
139 | -spec save(ets:tid(), term(), term()) -> | |
140 | {}. | |
141 | save(Table, K, V) -> | |
142 | true = ets:insert(Table, {K, V}), | |
143 | {}. |