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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.
%
% @doc Modules wishing to handle writing log
% messages should implement this behavior.
-module(couch_log_writer).
-export([
init/0,
terminate/2,
write/2
]).
-include("couch_log.hrl").
-define(DEFAULT_WRITER, couch_log_writer_stderr).
-callback init() -> {ok, State::term()}.
-callback terminate(Reason::term(), State::term()) -> ok.
-callback write(LogEntry::#log_entry{}, State::term()) ->
{ok, NewState::term()}.
-spec init() -> {atom(), term()}.
init() ->
Writer = get_writer_mod(),
{ok, St} = Writer:init(),
{Writer, St}.
-spec terminate(term(), {atom(), term()}) -> ok.
terminate(Reason, {Writer, St}) ->
ok = Writer:terminate(Reason, St).
-spec write(#log_entry{}, {atom(), term()}) -> {atom(), term()}.
write(Entry, {Writer, St}) ->
{ok, NewSt} = Writer:write(Entry, St),
{Writer, NewSt}.
get_writer_mod() ->
WriterStr = config:get("log", "writer", "stderr"),
ModName1 = to_atom("couch_log_writer_" ++ WriterStr),
case mod_exists(ModName1) of
true ->
ModName1;
false ->
ModName2 = to_atom(WriterStr),
case mod_exists(ModName2) of
true ->
ModName2;
false ->
?DEFAULT_WRITER
end
end.
to_atom(Str) ->
try list_to_existing_atom(Str) of
Atom -> Atom
catch _:_ ->
undefined
end.
mod_exists(ModName) ->
code:which(ModName) /= non_existing.
|
