From 683974e1c855797c0f6aa02a4bf9d9385b8a6c5b Mon Sep 17 00:00:00 2001
From: Zaiming Shi <zmstone@gmail.com>
Date: Sat, 31 Jul 2021 21:25:00 +0200
Subject: [PATCH] refactor(log/textfmt): print mfa metadata in text formatter

---
 apps/emqx/include/logger.hrl          |  9 ++++---
 apps/emqx/src/emqx_logger_jsonfmt.erl |  2 +-
 apps/emqx/src/emqx_logger_textfmt.erl | 36 +++++++++++++--------------
 3 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/apps/emqx/include/logger.hrl b/apps/emqx/include/logger.hrl
index 80799179f..2c5bea89f 100644
--- a/apps/emqx/include/logger.hrl
+++ b/apps/emqx/include/logger.hrl
@@ -47,9 +47,7 @@
         case logger:allow(Level, ?MODULE) of
             true ->
                 logger:log(Level, (Format), (Args),
-                           (Meta)#{ mfa => <<(atom_to_binary(?MODULE, utf8))/binary, $:,
-                                             (atom_to_binary(?FUNCTION_NAME, utf8))/binary, $/,
-                                             (integer_to_binary(?FUNCTION_ARITY))/binary>>
+                           (Meta)#{ mfa => {?MODULE, ?FUNCTION_NAME, ?FUNCTION_ARITY}
                                   , line => ?LINE
                                   });
             false ->
@@ -58,4 +56,9 @@
 
 -define(LOG(Level, Format, Args), ?LOG(Level, Format, Args, #{})).
 
+%% structured logging
+-define(SLOG(Level, Data),
+        logger:log(Level, Data, #{ mfa => {?MODULE, ?FUNCTION_NAME, ?FUNCTION_ARITY}
+                                 , line => ?LINE})).
+
 -endif.
diff --git a/apps/emqx/src/emqx_logger_jsonfmt.erl b/apps/emqx/src/emqx_logger_jsonfmt.erl
index 5d9094c51..387c9b4c3 100644
--- a/apps/emqx/src/emqx_logger_jsonfmt.erl
+++ b/apps/emqx/src/emqx_logger_jsonfmt.erl
@@ -219,7 +219,7 @@ json_obj(Data, Config) ->
                       json_kv(K, V, D, Config)
               end, maps:new(), Data).
 
-json_kv(mfa, {M, F, A}, Data, _Config) -> %% snabbkaffe
+json_kv(mfa, {M, F, A}, Data, _Config) ->
     maps:put(mfa, <<(atom_to_binary(M, utf8))/binary, $:,
                     (atom_to_binary(F, utf8))/binary, $/,
                     (integer_to_binary(A))/binary>>, Data);
diff --git a/apps/emqx/src/emqx_logger_textfmt.erl b/apps/emqx/src/emqx_logger_textfmt.erl
index eae637e4d..97862a72a 100644
--- a/apps/emqx/src/emqx_logger_textfmt.erl
+++ b/apps/emqx/src/emqx_logger_textfmt.erl
@@ -19,26 +19,24 @@
 -export([format/2]).
 -export([check_config/1]).
 
-%% metadata fields which we do not wish to merge into log data
--define(WITHOUT_MERGE,
-        [ report_cb % just a callback
-        , time      % formatted as a part of templated message
-        , peername  % formatted as a part of templated message
-        , clientid  % formatted as a part of templated message
-        , gl        % not interesting
-        , file
-        ]).
-
 check_config(X) -> logger_formatter:check_config(X).
 
-format(#{msg := Msg0, meta := Meta} = Event, Config) ->
-    Msg = maybe_merge(Msg0, Meta),
-    logger_formatter:format(Event#{msg := Msg}, Config).
+format(#{msg := {report, Report}, meta := Meta} = Event, Config) when is_map(Report) ->
+    logger_formatter:format(Event#{msg := {report, enrich(Report, Meta)}}, Config);
+format(#{msg := {Fmt, Args}, meta := Meta} = Event, Config) when is_list(Fmt) ->
+    {NewFmt, NewArgs} = enrich_fmt(Fmt, Args, Meta),
+    logger_formatter:format(Event#{msg := {NewFmt, NewArgs}}, Config).
 
-maybe_merge({report, Report}, Meta) when is_map(Report) ->
-    {report, maps:merge(Report, filter(Meta))};
-maybe_merge(Report, _Meta) ->
-    Report.
+enrich(Report, #{mfa := Mfa, line := Line}) ->
+    Report#{mfa => mfa(Mfa), line => Line};
+enrich(Report, _) -> Report.
 
-filter(Meta) ->
-    maps:without(?WITHOUT_MERGE, Meta).
+enrich_fmt(Fmt, Args, #{mfa := Mfa, line := Line}) ->
+    {Fmt ++ " mfa: ~s line: ~w", Args ++ [mfa(Mfa), Line]};
+enrich_fmt(Fmt, Args, _) ->
+    {Fmt, Args}.
+
+mfa({M, F, A}) ->
+    <<(atom_to_binary(M, utf8))/binary, $:,
+      (atom_to_binary(F, utf8))/binary, $/,
+      (integer_to_binary(A))/binary>>.