| % 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(config_notifier). |
| |
| -behaviour(gen_event). |
| -vsn(1). |
| |
| %% Public interface |
| -export([subscribe/1]). |
| -export([subscribe/2]). |
| |
| %% gen_event interface |
| -export([ |
| init/1, |
| handle_event/2, |
| handle_call/2, |
| handle_info/2, |
| terminate/2, |
| code_change/3 |
| ]). |
| |
| subscribe(Subscription) -> |
| subscribe(self(), Subscription). |
| |
| subscribe(Subscriber, Subscription) -> |
| case lists:member(Subscriber, handlers()) of |
| true -> |
| ok; |
| false -> |
| gen_event:add_sup_handler( |
| config_event, {?MODULE, Subscriber}, {Subscriber, Subscription}) |
| end. |
| |
| init({Subscriber, Subscription}) -> |
| {ok, {Subscriber, Subscription}}. |
| |
| handle_event({config_change, _, _, _, _} = Event, {Subscriber, Subscription}) -> |
| maybe_notify(Event, Subscriber, Subscription), |
| {ok, {Subscriber, Subscription}}. |
| |
| handle_call(_Request, St) -> |
| {ok, ignored, St}. |
| |
| handle_info(_Info, St) -> |
| {ok, St}. |
| |
| terminate(_Reason, {_Subscriber, _Subscription}) -> |
| ok. |
| |
| code_change(_OldVsn, St, _Extra) -> |
| {ok, St}. |
| |
| maybe_notify(Event, Subscriber, all) -> |
| Subscriber ! Event; |
| maybe_notify({config_change, Sec, Key, _, _} = Event, Subscriber, Subscription) -> |
| case should_notify(Sec, Key, Subscription) of |
| true -> |
| Subscriber ! Event; |
| false -> |
| ok |
| end. |
| |
| should_notify(Sec, Key, Subscription) -> |
| lists:any(fun(S) -> S =:= Sec orelse S =:= {Sec, Key} end, Subscription). |
| |
| handlers() -> |
| AllHandlers = gen_event:which_handlers(config_event), |
| [Id || {?MODULE, Id} <- AllHandlers]. |