| % 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. |
| |
| %% The purpose of this module is to allow event handlers to particpate in Erlang |
| %% supervisor trees. It provide a monitorable process that crashes if the event |
| %% handler fails. The process, when shutdown, deregisters the event handler. |
| |
| -module(couch_event_sup). |
| -behaviour(gen_server). |
| -vsn(1). |
| |
| -include_lib("couch/include/couch_db.hrl"). |
| |
| -export([start_link/3,start_link/4, stop/1]). |
| -export([init/1, terminate/2, handle_call/3, handle_cast/2, handle_info/2,code_change/3]). |
| |
| % |
| % Instead calling the |
| % ok = gen_event:add_sup_handler(error_logger, my_log, Args) |
| % |
| % do this: |
| % {ok, LinkedPid} = couch_event_sup:start_link(error_logger, my_log, Args) |
| % |
| % The benefit is the event is now part of the process tree, and can be |
| % started, restarted and shutdown consistently like the rest of the server |
| % components. |
| % |
| % And now if the "event" crashes, the supervisor is notified and can restart |
| % the event handler. |
| % |
| % Use this form to named process: |
| % {ok, LinkedPid} = couch_event_sup:start_link({local, my_log}, error_logger, my_log, Args) |
| % |
| |
| start_link(EventMgr, EventHandler, Args) -> |
| gen_server:start_link(couch_event_sup, {EventMgr, EventHandler, Args}, []). |
| |
| start_link(ServerName, EventMgr, EventHandler, Args) -> |
| gen_server:start_link(ServerName, couch_event_sup, {EventMgr, EventHandler, Args}, []). |
| |
| stop(Pid) -> |
| gen_server:cast(Pid, stop). |
| |
| init({EventMgr, EventHandler, Args}) -> |
| case gen_event:add_sup_handler(EventMgr, EventHandler, Args) of |
| ok -> |
| {ok, {EventMgr, EventHandler}}; |
| {stop, Error} -> |
| {stop, Error} |
| end. |
| |
| terminate(_Reason, _State) -> |
| ok. |
| |
| handle_call(_Whatever, _From, State) -> |
| {ok, State}. |
| |
| handle_cast(stop, State) -> |
| {stop, normal, State}. |
| |
| handle_info({gen_event_EXIT, _Handler, Reason}, State) -> |
| {stop, Reason, State}. |
| |
| code_change(_OldVsn, State, _Extra) -> |
| {ok, State}. |