[logger] Add handler callback filter_config/1

This function is called when a logger API function for fetching
handler configuration is called. The point is to allow the handler to
remove internal data fields that it might have stored in the
configuration database, before returning the handler configuration to
the caller.

An example of such internal data are the 'handler_pid' and 'mode_tab'
fields that logger_std_h and logger_disk_log_h store in their
configuration maps.

4 files changed, 26 insertions, 4 deletions

diff --git a/lib/kernel/src/logger.erl b/lib/kernel/src/logger.erl
index 3ffa8a0c4e..6762998d4f 100644
--- a/lib/kernel/src/logger.erl
+++ b/lib/kernel/src/logger.erl
@@ -463,7 +463,14 @@ get_primary_config() ->
       HandlerId :: handler_id(),
       Config :: handler_config().
 get_handler_config(HandlerId) ->
-    logger_config:get(?LOGGER_TABLE,HandlerId).
+    case logger_config:get(?LOGGER_TABLE,HandlerId) of
+        {ok,#{module:=Module}=Config} ->
+            {ok,try Module:filter_config(Config)
+                catch _:_ -> Config
+                end};
+        Error ->
+            Error
+    end.
 
 -spec get_handler_config() -> [Config] when
       Config :: handler_config().
diff --git a/lib/kernel/src/logger_disk_log_h.erl b/lib/kernel/src/logger_disk_log_h.erl
index bb8b9f08a4..2a81458ec8 100644
--- a/lib/kernel/src/logger_disk_log_h.erl
+++ b/lib/kernel/src/logger_disk_log_h.erl
@@ -33,7 +33,8 @@
          terminate/2, code_change/3]).
 
 %% logger callbacks
--export([log/2, adding_handler/1, removing_handler/1, changing_config/3]).
+-export([log/2, adding_handler/1, removing_handler/1, changing_config/3,
+         filter_config/1]).
 
 %% handler internal
 -export([log_handler_info/4]).
@@ -247,6 +248,11 @@ log(LogEvent, Config = #{id := Name,
     Bin = logger_h_common:log_to_binary(LogEvent, Config),
     logger_h_common:call_cast_or_drop(Name, HPid, ModeTab, Bin).
 
+%%%-----------------------------------------------------------------
+%%% Remove internal fields from configuration
+filter_config(#{config:=HConfig}=Config) ->
+    Config#{config=>maps:without([handler_pid,mode_tab],HConfig)}.
+
 %%%===================================================================
 %%% gen_server callbacks
 %%%===================================================================
diff --git a/lib/kernel/src/logger_h_common.erl b/lib/kernel/src/logger_h_common.erl
index 38ac7d8ffc..94c640cb92 100644
--- a/lib/kernel/src/logger_h_common.erl
+++ b/lib/kernel/src/logger_h_common.erl
@@ -306,8 +306,11 @@ stop_or_restart(Name, {shutdown,Reason={overloaded,_Name,_QLen,_Mem}},
                         exit(HandlerPid, kill)
                 end,
                 case ConfigResult of
-                    {ok,#{module:=HMod}=HConfig} when is_integer(RestartAfter) ->
+                    {ok,#{module:=HMod}=HConfig0} when is_integer(RestartAfter) ->
                         _ = logger:remove_handler(Name),
+                        HConfig = try HMod:filter_config(HConfig0)
+                                  catch _:_ -> HConfig0
+                                  end,
                         _ = timer:apply_after(RestartAfter, logger, add_handler,
                                               [Name,HMod,HConfig]);
                     {ok,_} ->
diff --git a/lib/kernel/src/logger_std_h.erl b/lib/kernel/src/logger_std_h.erl
index 6bbf75e0ab..42e0f5caf4 100644
--- a/lib/kernel/src/logger_std_h.erl
+++ b/lib/kernel/src/logger_std_h.erl
@@ -35,7 +35,8 @@
          terminate/2, code_change/3]).
 
 %% logger callbacks
--export([log/2, adding_handler/1, removing_handler/1, changing_config/3]).
+-export([log/2, adding_handler/1, removing_handler/1, changing_config/3,
+         filter_config/1]).
 
 %% handler internal
 -export([log_handler_info/4]).
@@ -230,6 +231,11 @@ log(LogEvent, Config = #{id := Name,
     Bin = logger_h_common:log_to_binary(LogEvent, Config),
     logger_h_common:call_cast_or_drop(Name, HPid, ModeTab, Bin).
 
+%%%-----------------------------------------------------------------
+%%% Remove internal fields from configuration
+filter_config(#{config:=HConfig}=Config) ->
+    Config#{config=>maps:without([handler_pid,mode_tab],HConfig)}.
+
 %%%===================================================================
 %%% gen_server callbacks
 %%%===================================================================