1 files changed, 113 insertions, 0 deletions
diff --git a/lib/kernel/src/logger_handler_watcher.erl b/lib/kernel/src/logger_handler_watcher.erl
new file mode 100644
index 0000000000..b75c74c643
--- /dev/null
+++ b/lib/kernel/src/logger_handler_watcher.erl
@@ -0,0 +1,113 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2018. All Rights Reserved.
+%%
+%% 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.
+%%
+%% %CopyrightEnd%
+%%
+-module(logger_handler_watcher).
+
+-behaviour(gen_server).
+
+%% API
+-export([start_link/0]).
+-export([register_handler/2]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
+
+-define(SERVER, ?MODULE).
+
+-record(state, {handlers}).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+
+-spec start_link() -> {ok, Pid :: pid()} |
+                      {error, Error :: {already_started, pid()}} |
+                      {error, Error :: term()} |
+                      ignore.
+start_link() ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
+
+-spec register_handler(Id::logger:handler_id(),Pid::pid()) -> ok.
+register_handler(Id,Pid) ->
+    gen_server:call(?SERVER,{register,Id,Pid}).
+
+%%%===================================================================
+%%% gen_server callbacks
+%%%===================================================================
+
+-spec init(Args :: term()) -> {ok, State :: term()} |
+                              {ok, State :: term(), Timeout :: timeout()} |
+                              {ok, State :: term(), hibernate} |
+                              {stop, Reason :: term()} |
+                              ignore.
+init([]) ->
+    process_flag(trap_exit, true),
+    {ok, #state{handlers=[]}}.
+
+-spec handle_call(Request :: term(), From :: {pid(), term()}, State :: term()) ->
+                         {reply, Reply :: term(), NewState :: term()} |
+                         {reply, Reply :: term(), NewState :: term(), Timeout :: timeout()} |
+                         {reply, Reply :: term(), NewState :: term(), hibernate} |
+                         {noreply, NewState :: term()} |
+                         {noreply, NewState :: term(), Timeout :: timeout()} |
+                         {noreply, NewState :: term(), hibernate} |
+                         {stop, Reason :: term(), Reply :: term(), NewState :: term()} |
+                         {stop, Reason :: term(), NewState :: term()}.
+handle_call({register,Id,Pid}, _From, #state{handlers=Hs}=State) ->
+    Ref = erlang:monitor(process,Pid),
+    Hs1 = lists:keystore(Id,1,Hs,{Id,Ref}),
+    {reply, ok, State#state{handlers=Hs1}}.
+
+-spec handle_cast(Request :: term(), State :: term()) ->
+                         {noreply, NewState :: term()} |
+                         {noreply, NewState :: term(), Timeout :: timeout()} |
+                         {noreply, NewState :: term(), hibernate} |
+                         {stop, Reason :: term(), NewState :: term()}.
+handle_cast(_Request, State) ->
+    {noreply, State}.
+
+-spec handle_info(Info :: timeout() | term(), State :: term()) ->
+                         {noreply, NewState :: term()} |
+                         {noreply, NewState :: term(), Timeout :: timeout()} |
+                         {noreply, NewState :: term(), hibernate} |
+                         {stop, Reason :: normal | term(), NewState :: term()}.
+handle_info({'DOWN',Ref,process,_,shutdown}, #state{handlers=Hs}=State) ->
+    case lists:keytake(Ref,2,Hs) of
+        {value,{Id,Ref},Hs1} ->
+            %% Probably terminated by supervisor. Remove the handler to avoid
+            %% error printouts due to failing handler.
+            _ = case logger:get_handler_config(Id) of
+                    {ok,_} ->
+                        logger:remove_handler(Id);
+                    _ ->
+                        ok
+                end,
+            {noreply,State#state{handlers=Hs1}};
+        false ->
+            {noreply, State}
+    end;
+handle_info({'DOWN',Ref,process,_,_OtherReason}, #state{handlers=Hs}=State) ->
+    {noreply,State#state{handlers=lists:keydelete(Ref,2,Hs)}};
+handle_info(_Other,State) ->
+    {noreply,State}.
+
+-spec terminate(Reason :: normal | shutdown | {shutdown, term()} | term(),
+                State :: term()) -> any().
+terminate(_Reason, _State) ->
+    ok.