migrate oc_stat_exporter to gen_event

Author: hauleth

.editorconfig

@@ -0,0 +1,8 @@
+[*]
+indent_style = space
+
+[*.erl]
+indent_size = 4
+
+[*.yml]
+indent_size = 2

src/oc_internal_timer.erl

@@ -2,7 +2,7 @@
 
 -callback ping() -> ok.
 
--export([start_link/1,
+-export([start_link/2,
          init/1,
          handle_call/3,
          handle_cast/2,
@@ -12,27 +12,25 @@
                 interval :: pos_integer(),
                 module :: module()}).
 
-start_link(Opts) ->
-  gen_server:start_link(?MODULE, Opts, []).
+start_link(Interval, Module) ->
+    gen_server:start_link(?MODULE, {Interval, Module}, []).
 
-init(Opts) ->
-  Interval = proplists:get_value(interval, Opts),
-  Module = proplists:get_value(module, Opts),
-  Ref = erlang:send_after(Interval, self(), ping),
+init({Interval, Module}) ->
+    Ref = erlang:send_after(Interval, self(), ping),
 
-  {ok, #state{timer = Ref,
-              interval = Interval,
-              module = Module}}.
+    {ok, #state{timer = Ref,
+                interval = Interval,
+                module = Module}}.
 
 handle_call(_Msg, _From, State) -> {reply, ok, State}.
 
 handle_cast(_Msg, State) -> {noreply, State}.
 
 handle_info(ping, #state{timer = Ref, interval = Interval, module = Mod}) ->
-  _ = erlang:cancel_timer(Ref),
-  ok = Mod:ping(),
-  NewRef = erlang:send_after(Interval, self(), ping),
+    _ = erlang:cancel_timer(Ref),
+    ok = Mod:ping(),
+    NewRef = erlang:send_after(Interval, self(), ping),
 
-  {noreply, #state{timer = NewRef,
-                   interval = Interval,
-                   module = Mod}}.
+    {noreply, #state{timer = NewRef,
+                     interval = Interval,
+                     module = Mod}}.

src/oc_reporter_pid.erl

@@ -17,13 +17,16 @@
 %%%-----------------------------------------------------------------------
 -module(oc_reporter_pid).
 
--behaviour(oc_reporter).
+-behaviour(gen_event).
 
 -export([init/1,
-         report/2]).
+         handle_call/2,
+         handle_event/2]).
 
 init(Pid) -> Pid.
 
-report(Spans, Pid) ->
+handle_call(_Msg, State) -> {ok, ok, State}.
+
+handle_event(Spans, Pid) ->
     [Pid ! {span, Span} || Span <- Spans],
-    ok.
+    {ok, Pid}.

src/oc_reporter_stdout.erl

@@ -1,3 +1,18 @@
+%%%------------------------------------------------------------------------
+%% Copyright 2017, OpenCensus Authors
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%%------------------------------------------------------------------------
+
 -module(oc_reporter_stdout).
 
 -behaviour(gen_event).

src/oc_stat.erl

@@ -17,10 +17,16 @@
 %%%-----------------------------------------------------------------------
 -module(oc_stat).
 
+-behaviour(gen_server).
+
 -export([record/2,
          record/3,
          export/0]).
 
+-export([add_handler/1,
+         add_handler/2,
+         delete_handler/1]).
+
 -export([start_link/0,
          init/1,
          handle_call/3,
@@ -75,6 +81,29 @@ record(Ctx, Measures) ->
 export() ->
     [oc_stat_view:export(View) || View <- oc_stat_view:all_subscribed_()].
 
+%%--------------------------------------------------------------------
+%% @doc
+%% @equiv add_handler(Handler, []).
+%% @end
+%%--------------------------------------------------------------------
+add_handler(Handler) -> add_handler(Handler, []).
+
+%%--------------------------------------------------------------------
+%% @doc
+%% Add new handler
+%% @end
+%%--------------------------------------------------------------------
+add_handler(Handler, Args) ->
+    gen_event:add_handler(oc_stat_reporter, Handler, Args).
+
+%%--------------------------------------------------------------------
+%% @doc
+%% Delete handler
+%% @end
+%%--------------------------------------------------------------------
+delete_handler(Handler) ->
+    gen_event:delete_handler(oc_stat_reporter, Handler, []).
+
 %% gen_server implementation
 
 %% @private

src/oc_stat_exporter.erl

@@ -1,5 +1,5 @@
 %%%------------------------------------------------------------------------
-%% Copyright 2018, OpenCensus Authors
+%% Copyright 2017, OpenCensus Authors
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
 %% You may obtain a copy of the License at
@@ -11,39 +11,34 @@
 %% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 %% See the License for the specific language governing permissions and
 %% limitations under the License.
-%%
-%% @doc Server with no logic, simply owns the span ets table.
+%%%------------------------------------------------------------------------
+
+%% @doc
+%% Exporter exports the collected records as view data.
 %% @end
-%%%-------------------------------------------------------------------------
--module(oc_server).
+-module(oc_stat_reporter).
 
--export([start_link/0]).
+-behaviour(oc_internal_timer).
 
--export([init/1,
-         handle_call/3,
-         handle_cast/2]).
+-export([start_link/1,
+         ping/0]).
 
 -include("opencensus.hrl").
+-include("oc_logger.hrl").
 
--record(state, {}).
-
-start_link() ->
-    maybe_init_ets(),
-    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+start_link(Handlers) ->
+    case gen_event:start_link({local, ?MODULE}, []) of
+        {ok, Pid} ->
+            [gen_event:add_handler(Pid, Handler, Opts)
+             || {Handler, Opts} <- Handlers],
 
-init([]) ->
-    {ok, #state{}}.
-
-handle_call(_, _From, State) ->
-    {noreply, State}.
+            {ok, Pid};
+        Other -> Other
+    end.
 
-handle_cast(_, State) ->
-    {noreply, State}.
+%% @private
+ping() ->
+    Measurements = oc_stat:export(),
+    gen_event:sync_notify(?MODULE, {stats, Measurements}),
 
-maybe_init_ets() ->
-    case ets:info(?SPAN_TAB, name) of
-        undefined ->
-            ets:new(?SPAN_TAB, [named_table, public, {write_concurrency, true}, {keypos, #span.span_id}]);
-        _ ->
-            ok
-    end.
+    ok.