Support module level logger header

include/logger.hrl

@@ -14,6 +14,8 @@
 
 %% debug | info | notice | warning | error | critical | alert | emergency
 
+-compile({parse_transform, emqx_logger}).
+
 -define(DEBUG(Format), ?LOG(debug, Format, [])).
 -define(DEBUG(Format, Args), ?LOG(debug, Format, Args)).
 
@@ -39,5 +41,5 @@
 
 -define(LOG(Level, Format, Args),
         begin
-          (logger:log(Level,#{},#{report_cb => fun(_) -> {(Format), (Args)} end}))
+          (logger:log(Level,#{},#{report_cb => fun(_) -> {'$logger_header'()++(Format), (Args)} end}))
         end).

src/emqx_logger.erl

@@ -48,6 +48,8 @@
         , get_log_handler/1
         ]).
 
+-export([parse_transform/2]).
+
 %%------------------------------------------------------------------------------
 %% APIs
 %%------------------------------------------------------------------------------
@@ -120,6 +122,9 @@ set_log_level(Level) ->
         {error, Error} -> {error, {primary_logger_level, Error}}
     end.
 
+parse_transform(AST, _Opts) ->
+    trans(AST, "", []).
+
 %%------------------------------------------------------------------------------
 %% Internal Functions
 %%------------------------------------------------------------------------------
@@ -160,3 +165,26 @@ rollback([{ID, Level} | List]) ->
     rollback(List);
 rollback([]) -> ok.
 
+%% Generate a function '$logger_header'/0 into the source code
+trans([], LogHeader, ResAST) ->
+    lists:reverse([header_fun(LogHeader) | ResAST]);
+trans([{eof, L} | AST], LogHeader, ResAST) ->
+    lists:reverse([{eof, L}, header_fun(LogHeader) | ResAST]) ++ AST;
+trans([{attribute, _, module, _Mod} = M | AST], Header, ResAST) ->
+    trans(AST, Header, [export_header_fun(), M | ResAST]);
+trans([{attribute, _, logger_header, Header} | AST], _, ResAST) ->
+    trans(AST, Header, ResAST);
+trans([F | AST], LogHeader, ResAST) ->
+    trans(AST, LogHeader, [F | ResAST]).
+
+export_header_fun() ->
+    {attribute,erl_anno:new(0),export,[{'$logger_header',0}]}.
+
+header_fun(LogHeader) ->
+    L = erl_anno:new(0),
+    {function,L,'$logger_header',0,
+         [{clause,L,
+             [], [], [{string,L,pad(LogHeader)}]}]}.
+
+pad("") -> "";
+pad(Str) -> Str ++ " ".