./ct_report/coverage/mongoose_instrument.COVER.html

1 -module(mongoose_instrument).
2
3 -behaviour(gen_server).
4
5 %% API
6 -export([config_spec/0,
7 start_link/0, persist/0,
8 set_up/1, set_up/3,
9 tear_down/1, tear_down/2,
10 span/4, span/5,
11 execute/3]).
12
13 %% gen_server callbacks
14 -export([init/1, handle_call/3, handle_cast/2, code_change/3, handle_info/2, terminate/2]).
15
16 -ignore_xref([start_link/0, set_up/3, tear_down/2, span/4, span/5, execute/3]).
17
18 -include("mongoose.hrl").
19 -include("mongoose_config_spec.hrl").
20
21 -type event_name() :: atom().
22 -type labels() :: #{host_type => mongooseim:host_type()}. % to be extended
23 -type metrics() :: #{atom() => spiral | histogram}. % to be extended
24 -type measurements() :: #{atom() => integer() | atom() | binary()}.
25 -type spec() :: {event_name(), labels(), config()}.
26 -type config() :: #{metrics => metrics()}. % to be extended
27 -type handler_fun() :: fun((event_name(), labels(), config(), measurements()) -> any()).
28 -type handlers() :: {[handler_fun()], config()}.
29 -type execution_time() :: integer().
30 -type measure_fun(Result) :: fun((execution_time(), Result) -> measurements()).
31
32 -callback config_spec() -> mongoose_config_spec:config_section().
33 -callback set_up(event_name(), labels(), config()) -> boolean().
34 -callback handle_event(event_name(), labels(), config(), measurements()) -> any().
35
36 -optional_callbacks([config_spec/0]).
37
38 -export_type([event_name/0, labels/0, config/0, measurements/0, spec/0, handlers/0]).
39
40 %% API
41
42 %% @doc Specifies the configuration of the instrumentation section
43 -spec config_spec() -> mongoose_config_spec:config_section().
44 config_spec() ->
45 53 Items = maps:from_list([{atom_to_binary(Key), config_spec(Key)} || Key <- all_handlers()]),
46 53 #section{items = Items, wrap = global_config, include = always}.
47
48 -spec start_link() -> gen_server:start_ret().
49 start_link() ->
50 53 gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
51
52 %% @doc Saves the state to a persistent term, improving performance of `execute' and `span'.
53 %% On the other hand, future calls to `set_up' or `tear_down' will update the persistent term,
54 %% which makes them less performant.
55 %% You should call this function only once - after the initial setup, but before handling any load.
56 -spec persist() -> ok.
57 persist() ->
58 53 gen_server:call(?MODULE, persist).
59
60 %% @doc Sets up instrumentation for multiple events.
61 %% @see set_up/3
62 -spec set_up([spec()]) -> ok.
63 set_up(Specs) ->
64 
:-(
 lists:foreach(fun({EventName, Labels, Config}) -> set_up(EventName, Labels, Config) end, Specs).
65
66 %% @doc Tears down instrumentation for multiple events.
67 %% @see tear_down/2
68 -spec tear_down([spec()]) -> ok.
69 tear_down(Specs) ->
70 
:-(
 lists:foreach(fun({EventName, Labels, _Config}) -> tear_down(EventName, Labels) end, Specs).
71
72 %% @doc Sets up instrumentation for an event identified by `EventName' and `Labels'
73 %% according to `Config'. Fails if the event is already registered, or if the keys of `Labels'
74 %% are different than for already registered events with `EventName'.
75 -spec set_up(event_name(), labels(), config()) -> ok.
76 set_up(EventName, Labels, Config) ->
77 
:-(
 case gen_server:call(?MODULE, {set_up, EventName, Labels, Config}) of
78 
:-(
 ok -> ok;
79 
:-(
 {error, ErrorMap} -> error(ErrorMap)
80 end.
81
82 %% @doc Tears down instrumentation for an event identified by `EventName' and `Labels'.
83 %% This operation is idempotent.
84 -spec tear_down(event_name(), labels()) -> ok.
85 tear_down(EventName, Labels) ->
86 
:-(
 gen_server:call(?MODULE, {tear_down, EventName, Labels}).
87
88 %% @doc Calls `F', measuring its result with `MeasureF', and calls attached event handlers.
89 %% @see span/5
90 -spec span(event_name(), labels(), fun(() -> Result), measure_fun(Result)) -> Result.
91 span(EventName, Labels, F, MeasureF) ->
92 
:-(
 span(EventName, Labels, F, [], MeasureF).
93
94 %% @doc Calls `F' with `Args', measuring its execution time.
95 %% The time and the result are passed to `MeasureF', which returns measurements.
96 %% The measurements are then passed to all handlers attached to
97 %% the event identified by `EventName' and `Labels'.
98 %% Fails without calling `F' if the event is not registered.
99 -spec span(event_name(), labels(), fun((...) -> Result), list(), measure_fun(Result)) -> Result.
100 span(EventName, Labels, F, Args, MeasureF) ->
101 
:-(
 Handlers = get_handlers(EventName, Labels),
102 
:-(
 {Time, Result} = timer:tc(F, Args),
103 
:-(
 handle_event(EventName, Labels, MeasureF(Time, Result), Handlers),
104 
:-(
 Result.
105
106 %% @doc Executes all handlers attached to the event identified by `EventName' and `Labels',
107 %% passing `Measurements' to them. Fails if the event is not registered.
108 -spec execute(event_name(), labels(), measurements()) -> ok.
109 execute(EventName, Labels, Measurements) ->
110 
:-(
 Handlers = get_handlers(EventName, Labels),
111 
:-(
 handle_event(EventName, Labels, Measurements, Handlers).
112
113 %% gen_server callbacks
114
115 -type state() :: #{event_name() => #{labels() => handlers()}}.
116
117 -spec init([]) -> {ok, state()}.
118 init([]) ->
119 53 erlang:process_flag(trap_exit, true), % Make sure that terminate is called
120 53 persistent_term:erase(?MODULE), % Prevent inconsistency when restarted after a kill
121 53 {ok, #{}}.
122
123 -spec handle_call(any(), gen_server:from(), state()) ->
124 {reply, ok | {ok, handlers()} | {error, map()}, state()}.
125 handle_call({set_up, EventName, Labels, Config}, _From, State) ->
126 
:-(
 case set_up_and_register(EventName, Labels, Config, State) of
127 {error, _} = Error ->
128 
:-(
 {reply, Error, State};
129 NewState = #{} ->
130 
:-(
 update_if_persisted(State, NewState),
131 
:-(
 {reply, ok, NewState}
132 end;
133 handle_call({tear_down, EventName, Labels}, _From, State) ->
134 
:-(
 NewState = deregister(EventName, Labels, State),
135 
:-(
 update_if_persisted(State, NewState),
136 
:-(
 {reply, ok, NewState};
137 handle_call(persist, _From, State) ->
138 53 persistent_term:put(?MODULE, State),
139 53 {reply, ok, State};
140 handle_call({lookup, EventName, Labels}, _From, State) ->
141 
:-(
 {reply, lookup(EventName, Labels, State), State};
142 handle_call(Request, From, State) ->
143 
:-(
 ?UNEXPECTED_CALL(Request, From),
144 
:-(
 {reply, {error, #{what => unexpected_call, request => Request}}, State}.
145
146 -spec handle_cast(any(), state()) -> {noreply, state()}.
147 handle_cast(Msg, State) ->
148 
:-(
 ?UNEXPECTED_CAST(Msg),
149 
:-(
 {noreply, State}.
150
151 -spec handle_info(any(), state()) -> {noreply, state()}.
152 handle_info(Info, State) ->
153 
:-(
 ?UNEXPECTED_INFO(Info),
154 
:-(
 {noreply, State}.
155
156 -spec terminate(any(), state()) -> ok.
157 terminate(_Reason, _State) ->
158 54 persistent_term:erase(?MODULE),
159 54 ok.
160
161 -spec code_change(any(), state(), any()) -> {ok, state()}.
162 code_change(_OldVsn, State, _Extra) ->
163 
:-(
 {ok, State}.
164
165 %% Internal functions
166
167 -spec update_if_persisted(state(), state()) -> ok.
168 update_if_persisted(State, NewState) ->
169 
:-(
 try persistent_term:get(?MODULE) of
170 
:-(
 State -> persistent_term:put(?MODULE, NewState)
171 catch
172 
:-(
 error:badarg -> ok
173 end.
174
175 -spec set_up_and_register(event_name(), labels(), config(), state()) -> state() | {error, map()}.
176 set_up_and_register(EventName, Labels, Config, State) ->
177 
:-(
 LabelKeys = label_keys(Labels),
178 
:-(
 case State of
179 #{EventName := #{Labels := _}} ->
180 
:-(
 {error, #{what => event_already_registered,
181 event_name => EventName, labels => Labels}};
182 #{EventName := HandlerMap} ->
183 
:-(
 {ExistingLabels, _, _} = maps:next(maps:iterator(HandlerMap)),
184 
:-(
 case label_keys(ExistingLabels) of
185 LabelKeys ->
186 
:-(
 Handlers = do_set_up(EventName, Labels, Config),
187 
:-(
 State#{EventName := HandlerMap#{Labels => Handlers}};
188 ExistingKeys ->
189 
:-(
 {error, #{what => inconsistent_labels,
190 event_name => EventName, labels => Labels,
191 existing_label_keys => ExistingKeys}}
192 end;
193 #{} ->
194 
:-(
 Handlers = do_set_up(EventName, Labels, Config),
195 
:-(
 State#{EventName => #{Labels => Handlers}}
196 end.
197
198 -spec do_set_up(event_name(), labels(), config()) -> handlers().
199 do_set_up(EventName, Labels, Config) ->
200 
:-(
 AllModules = handler_modules(),
201 
:-(
 UsedModules = lists:filter(fun(Mod) -> Mod:set_up(EventName, Labels, Config) end, AllModules),
202 
:-(
 {[fun Mod:handle_event/4 || Mod <- UsedModules], Config}.
203
204 -spec deregister(event_name(), labels(), state()) -> state().
205 deregister(EventName, Labels, State) ->
206 
:-(
 case State of
207 #{EventName := HandlerMap} ->
208 
:-(
 case maps:remove(Labels, HandlerMap) of
209 Empty when Empty =:= #{} ->
210 
:-(
 maps:remove(EventName, State);
211 NewHandlerMap ->
212 
:-(
 State#{EventName := NewHandlerMap}
213 end;
214 #{} ->
215 
:-(
 State
216 end.
217
218 -spec lookup(event_name(), labels()) -> {ok, handlers()} | {error, map()}.
219 lookup(EventName, Labels) ->
220 
:-(
 try persistent_term:get(?MODULE) of
221 State ->
222 
:-(
 lookup(EventName, Labels, State)
223 catch
224 %% Although persist/0 should be called before handling traffic,
225 %% some instrumented events might happen before that, and they shouldn't fail.
226 error:badarg ->
227 
:-(
 ?LOG_INFO(#{what => mongoose_instrument_lookup_without_persistent_term,
228 
:-(
 event_name => EventName, labels => Labels}),
229 
:-(
 gen_server:call(?MODULE, {lookup, EventName, Labels})
230 end.
231
232 -spec lookup(event_name(), labels(), state()) -> {ok, handlers()} | {error, map()}.
233 lookup(EventName, Labels, State) ->
234 
:-(
 case State of
235 #{EventName := #{Labels := Handlers}} ->
236 
:-(
 {ok, Handlers};
237 #{} ->
238 
:-(
 {error, #{what => event_not_registered, event_name => EventName, labels => Labels}}
239 end.
240
241 -spec label_keys(labels()) -> [atom()].
242 label_keys(Labels) ->
243 
:-(
 lists:sort(maps:keys(Labels)).
244
245 -spec get_handlers(event_name(), labels()) -> handlers().
246 get_handlers(EventName, Labels) ->
247 
:-(
 case lookup(EventName, Labels) of
248 
:-(
 {ok, Handlers} -> Handlers;
249 
:-(
 {error, ErrorMap} -> error(ErrorMap)
250 end.
251
252 -spec handle_event(event_name(), labels(), measurements(), handlers()) -> ok.
253 handle_event(Event, Labels, Measurements, {EventHandlers, Config}) ->
254 
:-(
 lists:foreach(fun(Handler) -> Handler(Event, Labels, Config, Measurements) end, EventHandlers).
255
256 -spec handler_modules() -> [module()].
257 handler_modules() ->
258 
:-(
 [handler_module(Key) || Key <- maps:keys(mongoose_config:get_opt(instrumentation))].
259
260 -spec handler_module(atom()) -> binary().
261 handler_module(Key) ->
262 159 list_to_existing_atom("mongoose_instrument_" ++ atom_to_list(Key)).
263
264 -spec config_spec(atom()) -> mongoose_config_spec:config_section().
265 config_spec(Key) ->
266 159 Module = handler_module(Key),
267 159 case mongoose_lib:is_exported(Module, config_spec, 0) of
268 53 true -> Module:config_spec();
269 106 false -> #section{}
270 end.
271
272 all_handlers() ->
273 53 [prometheus, exometer, log].
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