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path: root/src/couch_log/src/couch_log_monitor.erl
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% 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(couch_log_monitor).

-behaviour(gen_server).
-vsn(1).

-export([
    start_link/0
]).

-export([
    init/1,
    terminate/2,
    handle_call/3,
    handle_cast/2,
    handle_info/2,
    code_change/3
]).

-define(HANDLER_MOD, couch_log_error_logger_h).

start_link() ->
    gen_server:start_link(?MODULE, [], []).

% OTP_RELEASE defined in OTP >= 21 only
-ifdef(OTP_RELEASE).

init(_) ->
    % see https://erlang.org/doc/man/error_logger.html#add_report_handler-1
    ok = error_logger:add_report_handler(?HANDLER_MOD),
    ok = gen_event:add_sup_handler(error_logger, ?HANDLER_MOD, []),
    {ok, nil}.

-else.

init(_) ->
    error_logger:start(),
    ok = gen_event:add_sup_handler(error_logger, ?HANDLER_MOD, []),
    {ok, nil}.

-endif.

terminate(_, _) ->
    ok.

handle_call(_Msg, _From, St) ->
    {reply, ignored, St}.

handle_cast(_Msg, St) ->
    {noreply, St}.

handle_info({gen_event_EXIT, ?HANDLER_MOD, Reason}, St) ->
    {stop, Reason, St};
handle_info(_Msg, St) ->
    {noreply, St}.

code_change(_, State, _) ->
    {ok, State}.