logger: Rework configuration of logger

Most logger configuration that was possible through
kernel application variables have been moved into a
common 'logger' application environment in kernel.

Now all the configuration possible through the logger
API can be done as sys config.

The handler started by kernel has been renamed to 'default'
instead of logger_std_h.

There is a new logger:setup_handlers/1 function that given an
application name can be used to setup handlers in other applications.

8 files changed, 217 insertions, 172 deletions

diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 57d8fc7a15..1d4e37196c 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -69,7 +69,7 @@
 
 %% Types that can be used from other modules -- alphabetically ordered.
 -export_type([date_time/0, fd/0, file_info/0, filename/0, filename_all/0,
-              io_device/0, name/0, name_all/0, posix/0]).
+              io_device/0, mode/0, name/0, name_all/0, posix/0]).
 
 %%% Includes and defines
 -include("file_int.hrl").
diff --git a/lib/kernel/src/kernel.app.src b/lib/kernel/src/kernel.app.src
index afffcd156e..23ac5b3444 100644
--- a/lib/kernel/src/kernel.app.src
+++ b/lib/kernel/src/kernel.app.src
@@ -140,7 +140,10 @@
                 inet_db,
                 pg2]},
   {applications, []},
-  {env, []},
+  {env, [{logger_level, info},
+         {logger_sasl_compatible, false},
+         {logger_log_progress, false}
+        ]},
   {mod, {kernel, []}},
   {runtime_dependencies, ["erts-10.0", "stdlib-3.5", "sasl-3.0"]}
  ]
diff --git a/lib/kernel/src/kernel.erl b/lib/kernel/src/kernel.erl
index ae982c1741..b0e8c00bbf 100644
--- a/lib/kernel/src/kernel.erl
+++ b/lib/kernel/src/kernel.erl
@@ -30,17 +30,13 @@
 %%% Callback functions for the kernel application.
 %%%-----------------------------------------------------------------
 start(_, []) ->
+    %% Setup the logger and configure the kernel logger environment
+    ok = logger:internal_init_logger(),
     case supervisor:start_link({local, kernel_sup}, kernel, []) of
 	{ok, Pid} ->
             ok = erl_signal_handler:start(),
-            %% add error handler
-            case logger:setup_standard_handler() of
-                ok -> {ok, Pid, []};
-                Error ->
-                    %% Not necessary since the node will crash anyway:
-                    exit(Pid, shutdown),
-                    Error
-            end;
+            ok = logger:add_handlers(kernel),
+            {ok, Pid, []};
 	Error -> Error
     end.
 
@@ -147,7 +143,7 @@ init([]) ->
     case init:get_argument(mode) of
         {ok, [["minimal"]]} ->
             {ok, {SupFlags,
-                  [Code, File, StdError, User, Config, RefC, SafeSup, LoggerSup]}};
+                  [Code, File, StdError, User, LoggerSup, Config, RefC, SafeSup]}};
         _ ->
             Rpc = #{id => rex,
                     start => {rpc, start_link, []},
diff --git a/lib/kernel/src/logger.erl b/lib/kernel/src/logger.erl
index 98a9937111..9a6719923e 100644
--- a/lib/kernel/src/logger.erl
+++ b/lib/kernel/src/logger.erl
@@ -40,14 +40,17 @@
          set_module_level/2, reset_module_level/1,
          set_logger_config/1, set_logger_config/2,
          set_handler_config/2, set_handler_config/3,
-         get_logger_config/0, get_handler_config/1]).
+         get_logger_config/0, get_handler_config/1,
+         add_handlers/1]).
+
+%% Private configuration
+-export([internal_init_logger/0]).
 
 %% Misc
 -export([compare_levels/2]).
 -export([set_process_metadata/1, update_process_metadata/1,
          unset_process_metadata/0, get_process_metadata/0]).
 -export([i/0, i/1]).
--export([setup_standard_handler/0, replace_simple_handler/3]).
 -export([limit_term/1, get_format_depth/0, get_max_size/0, get_utc_config/0]).
 
 %% Basic report formatting
@@ -93,8 +96,10 @@
                     term() => term()}.
 -type timestamp() :: integer().
 
+-type config_handler() :: {handler, handler_id(), module(), config()}.
+
 -export_type([log/0,level/0,report/0,msg_fun/0,metadata/0,config/0,handler_id/0,
-              filter_id/0,filter/0,filter_arg/0,filter_return/0]).
+              filter_id/0,filter/0,filter_arg/0,filter_return/0, config_handler/0]).
 
 %%%-----------------------------------------------------------------
 %%% API
@@ -504,118 +509,184 @@ print_module_levels({Module,Level}) ->
 print_module_levels(ModuleLevels) ->
     lists:map(fun print_module_levels/1, ModuleLevels).
 
--spec setup_standard_handler() -> ok | {error,term()}.
-setup_standard_handler() ->
-    case get_logger_type() of
-        {ok,silent} ->
-            Level = get_logger_level(),
-            ok = set_logger_config(level,Level),
-            remove_handler(logger_simple);
-        {ok,Type} ->
-            Level = get_logger_level(),
-            ok = set_logger_config(level,Level),
-            Filters = get_logger_filters(),
-            setup_standard_handler(Type,#{level=>Level,
-                                          filter_default=>stop,
-                                          filters=>Filters});
-        Error ->
-            Error
+-spec internal_init_logger() -> ok | {error,term()}.
+%% This function is responsible for config of the logger
+%% This is done before add_handlers because we want the
+%% logger settings to take effect before the kernel supervisor
+%% tree is started.
+internal_init_logger() ->
+    try
+        ok = logger:set_logger_config(level, get_logger_level()),
+        ok = logger:set_logger_config(filter_default, get_logger_filter_default()),
+
+        [case logger:add_logger_filter(Id, Filter) of
+             ok -> ok;
+             {error, Reason} -> throw(Reason)
+         end || {Id, Filter} <- get_logger_filters()],
+
+        _ = [[case logger:set_module_level(Module, Level) of
+                  ok -> ok;
+                  {error, Reason} -> throw(Reason)
+              end || Module <- Modules]
+             || {module_level, Level, Modules} <- get_logger_env()],
+
+        case logger:set_handler_config(logger_simple,filters,
+                                       get_default_handler_filters()) of
+            ok -> ok;
+            {error,{not_found,logger_simple}} -> ok
+        end,
+
+        init_kernel_handlers()
+    catch throw:Reason ->
+            ?LOG_ERROR("Invalid logger config: ~p", [Reason]),
+            {error, {bad_config, {kernel, Reason}}}
     end.
 
--spec setup_standard_handler(Type,Config) -> ok | {error,term()} when
-      Type :: tty | standard_io | standard_error | {file,File} |
-              {file,File,Modes} | {disk_log,LogOpts} | false,
-      File :: file:filename(),
-      Modes :: [term()], % [file:mode()], or more specific?
-      Config :: config(),
-      LogOpts :: map().
-setup_standard_handler(false,#{level:=Level,filters:=Filters}) ->
-    case set_handler_config(logger_simple,level,Level) of
-        ok ->
-            set_handler_config(logger_simple,filters,Filters);
-        Error ->
-            Error
-    end;
-setup_standard_handler(Type,Config) ->
-    {Module,TypeConfig} = get_type_config(Type),
-    replace_simple_handler(?STANDARD_HANDLER,
-                           Module,
-                           maps:merge(Config,TypeConfig)).
-
--spec replace_simple_handler(Id,Module,Config) -> ok | {error,term()} when
-      Id :: handler_id(),
-      Module :: module(),
-      Config :: config().
-replace_simple_handler(Id,Module,Config) ->
-    _ = code:ensure_loaded(Module),
-    DoBuffer = erlang:function_exported(Module,swap_buffer,2),
-    case add_handler(Id,Module,Config#{wait_for_buffer=>DoBuffer}) of
-        ok ->
-            if DoBuffer ->
-                    {ok,Buffered} = logger_simple:get_buffer(),
-                    _ = remove_handler(logger_simple),
-                    Module:swap_buffer(?STANDARD_HANDLER,Buffered);
-               true ->
-                    _ = remove_handler(logger_simple),
-                    ok
-            end,
-            ok;
-        Error ->
-            Error
+-spec init_kernel_handlers() -> ok | {error,term()}.
+%% Setup the kernel environment variables to be correct
+%% The actual handlers are started by a call to add_handlers.
+init_kernel_handlers() ->
+    try
+        case get_logger_type() of
+            {ok,silent} ->
+                ok = logger:remove_handler(logger_simple);
+            {ok,false} ->
+                ok;
+            {ok,Type} ->
+                init_default_config(Type)
+        end
+    catch throw:Reason ->
+            ?LOG_ERROR("Invalid default handler config: ~p", [Reason]),
+            {error, {bad_config, {kernel, Reason}}}
     end.
 
+-spec add_handlers(Application) -> ok | {error,term()} when
+      Application :: atom();
+                    (HandlerConfig) -> ok | {error,term()} when
+      HandlerConfig :: [config_handler()].
+%% This function is responsible for resolving the handler config
+%% and then starting the correct handlers. This is done after the
+%% kernel supervisor tree has been started as it needs the logger_sup.
+add_handlers(App) when is_atom(App) ->
+    add_handlers(application:get_env(App, logger, []));
+add_handlers(HandlerConfig) ->
+    try
+        check_logger_config(HandlerConfig),
+        DefaultAdded =
+            lists:foldl(
+              fun({handler, default = Id, Module, Config}, _)
+                    when not is_map_key(filters, Config) ->
+                      %% The default handler should have a couple of extra filters
+                      %% set on it by default.
+                      DefConfig = #{ filter_default => stop,
+                                     filters => get_default_handler_filters()},
+                      setup_handler(Id, Module, maps:merge(DefConfig,Config)),
+                      true;
+                 ({handler, Id, Module, Config}, Default) ->
+                      setup_handler(Id, Module, Config),
+                      Default orelse Id == default;
+                 (_, Default) -> Default
+              end, false, HandlerConfig),
+        %% If a default handler was added we try to remove the simple_logger
+        %% If the simple logger exists it will replay its log events
+        %% to the handler(s) added in the fold above.
+        _ = [case logger:remove_handler(logger_simple) of
+                 ok -> ok;
+                 {error,{not_found,logger_simple}} -> ok
+             end || DefaultAdded],
+        ok
+    catch throw:Reason ->
+            ?LOG_ERROR("Invalid logger handler config: ~p", [Reason]),
+            {error, {bad_config, {handler, Reason}}}
+    end.
+
+setup_handler(Id, Module, Config) ->
+    case logger:add_handler(Id, Module, Config) of
+        ok -> ok;
+        {error, Reason} -> throw(Reason)
+    end.
+
+check_logger_config(_) ->
+    ok.
+
+-spec get_logger_type() -> {ok, standard_io | false | silent |
+                            {file, file:name_all()} |
+                            {file, file:name_all(), [file:mode()]}}.
 get_logger_type() ->
-    Type0 =
-        case application:get_env(kernel, logger_dest) of
-            undefined ->
-                application:get_env(kernel, error_logger);
-            T ->
-                T
-        end,
-    case Type0 of
+    case application:get_env(kernel, error_logger) of
         {ok, tty} ->
-            {ok, tty};
+            {ok, standard_io};
         {ok, {file, File}} when is_list(File) ->
             {ok, {file, File}};
         {ok, {file, File, Modes}} when is_list(File), is_list(Modes) ->
             {ok, {file, File, Modes}};
-        {ok, {disk_log, File}} when is_list(File) ->
-            {ok, {disk_log, get_disk_log_config(File)}};
         {ok, false} ->
             {ok, false};
         {ok, silent} ->
             {ok, silent};
         undefined ->
-            {ok, tty}; % default value
+            case lists:member({handler,default,undefined}, get_logger_env()) of
+                true ->
+                    {ok, false};
+                false ->
+                    {ok, standard_io} % default value
+            end;
         {ok, Bad} ->
-            {error,{bad_config, {kernel, {logger_dest, Bad}}}}
+            throw({error_logger, Bad})
     end.
 
-get_disk_log_config(File) ->
-    Config1 =
-        case application:get_env(kernel,logger_disk_log_maxfiles) of
-            undefined -> #{};
-            {ok,MF} -> #{max_no_files=>MF}
-        end,
-    Config2 =
-        case application:get_env(kernel,logger_disk_log_maxbytes) of
-            undefined -> Config1;
-            {ok,MB} -> Config1#{max_no_bytes=>MB}
-        end,
-    Config3 =
-        case application:get_env(kernel,logger_disk_log_type) of
-            undefined -> Config2;
-            {ok,T} -> Config1#{type=>T}
-        end,
-    Config3#{file=>File}.
-
 get_logger_level() ->
-    case application:get_env(kernel,logger_level) of
-        undefined -> info;
-        {ok,Level} when ?IS_LEVEL(Level) -> Level
+    case application:get_env(kernel,logger_level,info) of
+        Level when ?IS_LEVEL(Level) ->
+            Level;
+        Level ->
+            throw({logger_level, Level})
+    end.
+
+get_logger_filter_default() ->
+    case lists:keyfind(filters,1,get_logger_env()) of
+        {filters,Default,_} ->
+            Default;
+        false ->
+            log
     end.
 
 get_logger_filters() ->
+    lists:foldl(
+      fun({filters, _, Filters}, _Acc) ->
+              Filters;
+         (_, Acc) ->
+              Acc
+      end, [], get_logger_env()).
+
+%% This function looks at the kernel logger environment
+%% and updates it so that the correct logger is configured
+init_default_config(Type) when Type==standard_io;
+                                Type==standard_error;
+                                element(1,Type)==file ->
+    Env = get_logger_env(),
+    DefaultConfig = #{logger_std_h=>#{type=>Type}},
+    NewLoggerEnv =
+        case lists:keyfind(default, 2, Env) of
+            {handler, default, Module, Config} ->
+                lists:map(
+                  fun({handler, default, logger_std_h, _}) ->
+                          %% Only want to add the logger_std_h config
+                          %% if not configured by user AND the default
+                          %% handler is still the logger_std_h.
+                          {handler, default, Module, maps:merge(DefaultConfig,Config)};
+                     (Other) ->
+                          Other
+                  end, Env);
+            _ ->
+                %% Nothing has been configured, use default
+                [{handler, default, logger_std_h, DefaultConfig} | Env]
+        end,
+    application:set_env(kernel, logger, NewLoggerEnv, [{timeout,infinity}]);
+init_default_config(Type) ->
+    throw({illegal_logger_type,Type}).
+
+get_default_handler_filters() ->
     case application:get_env(kernel, logger_sasl_compatible, false) of
         true ->
             ?DEFAULT_HANDLER_FILTERS([beam,erlang,otp]);
@@ -631,18 +702,8 @@ get_logger_filters() ->
             Extra ++ ?DEFAULT_HANDLER_FILTERS([beam,erlang,otp,sasl])
     end.
 
-get_type_config({disk_log,LogOpts}) ->
-    {logger_disk_log_h,#{disk_log_opts=>LogOpts}};
-get_type_config(tty) ->
-    %% This is only for backwards compatibility with error_logger and
-    %% old kernel and sasl environment variables
-    get_type_config(standard_io);
-get_type_config(Type) when Type==standard_io;
-                           Type==standard_error;
-                           element(1,Type)==file ->
-    {logger_std_h,#{logger_std_h=>#{type=>Type}}};
-get_type_config(Type) ->
-    {error,{illegal_logger_type,Type}}.
+get_logger_env() ->
+    application:get_env(kernel, logger, []).
 
 %%%-----------------------------------------------------------------
 -spec limit_term(term()) -> term().
diff --git a/lib/kernel/src/logger_config.erl b/lib/kernel/src/logger_config.erl
index 799aea9617..40dc1b1e1b 100644
--- a/lib/kernel/src/logger_config.erl
+++ b/lib/kernel/src/logger_config.erl
@@ -31,7 +31,7 @@
 -include("logger_internal.hrl").
 
 new(Name) ->
-    _ = ets:new(Name,[set,protected,named_table]),
+    _ = ets:new(Name,[set,protected,named_table,{write_concurrency,true}]),
     ets:whereis(Name).
 
 delete(Tid,Id) ->
diff --git a/lib/kernel/src/logger_internal.hrl b/lib/kernel/src/logger_internal.hrl
index 8c0fc2725d..f9377259f3 100644
--- a/lib/kernel/src/logger_internal.hrl
+++ b/lib/kernel/src/logger_internal.hrl
@@ -22,7 +22,7 @@
 -define(LOGGER_KEY,'$logger_config$').
 -define(HANDLER_KEY,'$handler_config$').
 -define(LOGGER_META_KEY,'$logger_metadata$').
--define(STANDARD_HANDLER, logger_std_h).
+-define(STANDARD_HANDLER, default).
 -define(DEFAULT_HANDLER_FILTERS,
         ?DEFAULT_HANDLER_FILTERS([beam,erlang,otp])).
 -define(DEFAULT_HANDLER_FILTERS(Domain),
diff --git a/lib/kernel/src/logger_server.erl b/lib/kernel/src/logger_server.erl
index a7f302ac8f..268fd4f2f3 100644
--- a/lib/kernel/src/logger_server.erl
+++ b/lib/kernel/src/logger_server.erl
@@ -122,8 +122,7 @@ init([]) ->
     logger_config:create(Tid,logger,LoggerConfig),
     SimpleConfig0 = maps:merge(default_config(logger_simple),
                                #{filter_default=>stop,
-                                 filters=>?DEFAULT_HANDLER_FILTERS,
-                                 logger_simple=>#{buffer=>true}}),
+                                 filters=>?DEFAULT_HANDLER_FILTERS}),
     %% If this fails, then the node should crash
     {ok,SimpleConfig} =
         logger_simple:adding_handler(logger_simple,SimpleConfig0),
@@ -139,12 +138,21 @@ handle_call({add_handler,Id,Module,HConfig}, _From, #state{tid=Tid}=State) ->
                 %% inform the handler
                 case call_h(Module,adding_handler,[Id,HConfig],{ok,HConfig}) of
                     {ok,HConfig1} ->
-                        logger_config:create(Tid,Id,Module,HConfig1),
-                        {ok,Config} = do_get_config(Tid,logger),
-                        Handlers = maps:get(handlers,Config,[]),
-                        do_set_config(Tid,logger,
-                                      Config#{handlers=>[Id|Handlers]}),
-                        ok;
+                        %% We know that the call_h would have loaded the module
+                        %% if it existed, so it is safe here to call function_exported
+                        %% to find out if this is a valid handler
+                        case erlang:function_exported(Module, log, 2) of
+                            true ->
+                                logger_config:create(Tid,Id,Module,HConfig1),
+                                {ok,Config} = do_get_config(Tid,logger),
+                                Handlers = maps:get(handlers,Config,[]),
+                                do_set_config(Tid,logger,
+                                              Config#{handlers=>[Id|Handlers]});
+                            false ->
+                                {error,{invalid_handler,
+                                        {function_not_exported,
+                                         {Module,log,2}}}}
+                        end;
                     {error,HReason} ->
                         {error,{handler_not_added,HReason}}
                 end
diff --git a/lib/kernel/src/logger_simple.erl b/lib/kernel/src/logger_simple.erl
index a1b427b96c..5272455a2d 100644
--- a/lib/kernel/src/logger_simple.erl
+++ b/lib/kernel/src/logger_simple.erl
@@ -20,37 +20,18 @@
 -module(logger_simple).
 
 -export([adding_handler/2, removing_handler/2, log/2]).
--export([get_buffer/0]).
 
 %% This module implements a simple handler for logger. It is the
 %% default used during system start.
 
 %%%-----------------------------------------------------------------
-%%% API
-get_buffer() ->
-    case whereis(?MODULE) of
-        undefined ->
-            {error,noproc};
-        Pid ->
-            Ref = erlang:monitor(process,Pid),
-            Pid ! {get_buffer,self()},
-            receive
-                {buffer,Buffer} ->
-                    erlang:demonitor(Ref,[flush]),
-                    {ok,Buffer};
-                {'DOWN',Ref,process,Pid,Reason} ->
-                    {error,Reason}
-            end
-    end.
-
-%%%-----------------------------------------------------------------
 %%% Logger callback
 
 adding_handler(?MODULE,Config) ->
     Me = self(),
     case whereis(?MODULE) of
         undefined ->
-            {Pid,Ref} = spawn_opt(fun() -> init(Me,Config) end,
+            {Pid,Ref} = spawn_opt(fun() -> init(Me) end,
                                   [link,monitor,{message_queue_data,off_heap}]),
             receive
                 {'DOWN',Ref,process,Pid,Reason} ->
@@ -102,48 +83,44 @@ log(_,_) ->
 
 %%%-----------------------------------------------------------------
 %%% Process
-init(Starter,Config) ->
+init(Starter) ->
     register(?MODULE,self()),
     Starter ! {self(),started},
-    BufferSize =
-        case Config of
-            #{?MODULE:=#{buffer:=true}} ->
-                10;
-            _ ->
-                infinity
-        end,
-    loop(#{buffer_size=>BufferSize,dropped=>0,buffer=>[]},infinity).
+    loop(#{buffer_size=>10,dropped=>0,buffer=>[]}).
 
-loop(Buffer,Timeout) ->
+loop(Buffer) ->
     receive
         stop ->
-            ok;
-        {get_buffer,From} ->
-            loop(Buffer#{send_to=>From},0);
+            %% We replay the logger messages of there is
+            %% a default handler when the simple handler
+            %% is removed.
+            case logger:get_handler_config(default) of
+                {ok, _} ->
+                    replay_buffer(Buffer);
+                _ ->
+                    ok
+            end;
         {log,#{msg:=_,meta:=#{time:=_}}=Log} ->
             do_log(Log),
-            loop(update_buffer(Buffer,Log),Timeout);
+            loop(update_buffer(Buffer,Log));
         _ ->
             %% Unexpected message - flush it!
-            loop(Buffer,Timeout)
-    after Timeout ->
-            #{dropped:=D,buffer:=B,send_to:=Pid} = Buffer,
-            LogList = lists:reverse(B) ++ drop_msg(D),
-            Pid ! {buffer,LogList},
-            loop(Buffer#{buffer_size=>infinity,
-                         dropped=>0,
-                         buffer=>[],
-                         send_to=>false},
-                 infinity)
+            loop(Buffer)
     end.
 
-update_buffer(#{buffer_size:=infinity}=Buffer,_Log) ->
-    Buffer;
 update_buffer(#{buffer_size:=0,dropped:=D}=Buffer,_Log) ->
     Buffer#{dropped=>D+1};
 update_buffer(#{buffer_size:=S,buffer:=B}=Buffer,Log) ->
     Buffer#{buffer_size=>S-1,buffer=>[Log|B]}.
 
+replay_buffer(#{ dropped := D, buffer := Buffer }) ->
+    lists:foreach(
+      fun F(#{msg := {Tag, Msg}} = L) when Tag =:= string; Tag =:= report ->
+              F(L#{ msg := Msg });
+          F(#{ level := Level, msg := Msg, meta := MD}) ->
+              logger:log(Level, Msg, MD)
+      end, lists:reverse(Buffer, drop_msg(D))).
+
 drop_msg(0) ->
     [];
 drop_msg(N) ->