Add builtin chomping to lager_format

src/lager.erl

@@ -56,7 +56,7 @@ log(Level, Module, Function, Line, Pid, Time, Message) ->
     Timestamp = lager_util:format_time(Time),
     Msg = [["[", atom_to_list(Level), "] "],
            io_lib:format("~p@~p:~p:~p ", [Pid, Module, Function, Line]),
-           safe_format_chop("~s", [Message], 4096)],
+           safe_format_chop(Message, [], 4096)],
     safe_notify(lager_util:level_to_num(Level), Timestamp, Msg).
 
 %% @private
@@ -74,7 +74,7 @@ log(Level, Module, Function, Line, Pid, Time, Format, Args) ->
 log(Level, Pid, Message) ->
     Timestamp = lager_util:format_time(),
     Msg = [["[", atom_to_list(Level), "] "], io_lib:format("~p ", [Pid]),
-           safe_format_chop("~s", [Message], 4096)],
+           safe_format_chop(Message, [], 4096)],
     safe_notify(lager_util:level_to_num(Level), Timestamp, Msg).
 
 %% @doc Manually log a message into lager without using the parse transform.
@@ -147,7 +147,10 @@ safe_notify(Level, Timestamp, Msg) ->
 %% arguments. The caller is NOT crashed.
 
 safe_format(Fmt, Args, Limit) ->
-    try lager_trunc_io:format(Fmt, Args, Limit) of
+    safe_format(Fmt, Args, Limit, []).
+
+safe_format(Fmt, Args, Limit, Options) ->
+    try lager_trunc_io:format(Fmt, Args, Limit, Options) of
         Result -> Result
     catch
         _:_ -> lager_trunc_io:format("FORMAT ERROR: ~p ~p", [Fmt, Args], Limit)
@@ -155,4 +158,4 @@ safe_format(Fmt, Args, Limit) ->
 
 %% @private
 safe_format_chop(Fmt, Args, Limit) ->
-    re:replace(safe_format(Fmt, Args, Limit), "\n$", "", [{return, list}]).
+    safe_format(Fmt, Args, Limit, [{chomp, true}]).

src/lager_format.erl

@@ -20,19 +20,27 @@
 
 %% fork of io_lib_format that uses trunc_io to protect against large terms
 
--export([format/3]).
+-export([format/3, format/4]).
+
+-record(options, {
+        chomp = false
+    }).
 
 format(FmtStr, Args, MaxLen) ->
+    format(FmtStr, Args, MaxLen, []).
+
+format(FmtStr, Args, MaxLen, Opts) ->
+    Options = make_options(Opts, #options{}),
     Cs = collect(FmtStr, Args),
-    {Cs2, MaxLen2} = build(Cs, [], MaxLen),
+    {Cs2, MaxLen2} = build(Cs, [], MaxLen, Options),
     %% count how many terms remain
-    Count = lists:foldl(
-        fun({_C, _As, _F, _Adj, _P, _Pad, _Enc}, Acc) ->
-                Acc + 1;
-            (_, Acc) ->
-                Acc
-        end, 0, Cs2),
-    build2(Cs2, Count, MaxLen2).
+    {Count, StrLen} = lists:foldl(
+        fun({_C, _As, _F, _Adj, _P, _Pad, _Enc}, {Terms, Chars}) ->
+                {Terms + 1, Chars};
+            (_, {Terms, Chars}) ->
+                {Terms, Chars + 1}
+        end, {0, 0}, Cs2),
+    build2(Cs2, Count, MaxLen2 - StrLen).
 
 collect([$~|Fmt0], Args0) ->
     {C,Fmt1,Args1} = collect_cseq(Fmt0, Args0),
@@ -117,16 +125,22 @@ collect_cc([$i|Fmt], [A|Args]) -> {$i,[A],Fmt,Args}.
 %%  remaining and only calculate indentation when necessary. Must also
 %%  be smart when calculating indentation for characters in format.
 
-build([{C,As,F,Ad,P,Pad,Enc}|Cs], Acc, MaxLen) ->
+build([{$n, _, _, _, _, _, _}], Acc, MaxLen, #options{chomp=true}) ->
+    %% trailing ~n, ignore
+    {lists:reverse(Acc), MaxLen};
+build([{C,As,F,Ad,P,Pad,Enc}|Cs], Acc, MaxLen, O) ->
     {S, MaxLen2} = control(C, As, F, Ad, P, Pad, Enc, MaxLen),
-    build(Cs, [S|Acc], MaxLen2);
-build([$\n|Cs], Acc, MaxLen) ->
-    build(Cs, [$\n|Acc], MaxLen - 1);
-build([$\t|Cs], Acc, MaxLen) ->
-    build(Cs, [$\t|Acc], MaxLen - 1);
-build([C|Cs], Acc, MaxLen) ->
-    build(Cs, [C|Acc], MaxLen - 1);
-build([], Acc, MaxLen) ->
+    build(Cs, [S|Acc], MaxLen2, O);
+build([$\n], Acc, MaxLen, #options{chomp=true}) ->
+    %% trailing \n, ignore
+    {lists:reverse(Acc), MaxLen};
+build([$\n|Cs], Acc, MaxLen, O) ->
+    build(Cs, [$\n|Acc], MaxLen - 1, O);
+build([$\t|Cs], Acc, MaxLen, O) ->
+    build(Cs, [$\t|Acc], MaxLen - 1, O);
+build([C|Cs], Acc, MaxLen, O) ->
+    build(Cs, [C|Acc], MaxLen - 1, O);
+build([], Acc, MaxLen, _O) ->
     {lists:reverse(Acc), MaxLen}.
 
 build2([{C,As,F,Ad,P,Pad,Enc}|Cs], Count, MaxLen) ->
@@ -234,6 +248,11 @@ maybe_flatten(X) when is_list(X) ->
 maybe_flatten(X) ->
     X.
 
+make_options([], Options) ->
+    Options;
+make_options([{chomp, Bool}|T], Options) when is_boolean(Bool) ->
+    make_options(T, Options#options{chomp=Bool}).
+
 -ifdef(UNICODE_AS_BINARIES).
 uniconv(C) ->
     unicode:characters_to_binary(C,unicode).

src/lager_handler_watcher.erl

@@ -110,7 +110,7 @@ reinstall_on_initial_failure_test_() ->
                     try
                       ?assertEqual(1, lager_test_backend:count()),
                       {_Level, _Time, [_, _, Message]} = lager_test_backend:pop(),
-                      ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, Message),
+                      ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, lists:flatten(Message)),
                       ?assertEqual(0, lager_test_backend:count()),
                       timer:sleep(6000),
                       ?assertEqual(0, lager_test_backend:count()),
@@ -139,9 +139,9 @@ reinstall_on_runtime_failure_test_() ->
                         timer:sleep(6000),
                         ?assertEqual(2, lager_test_backend:count()),
                         {_Level, _Time, [_, _, Message]} = lager_test_backend:pop(),
-                        ?assertEqual("Lager event handler lager_crash_backend exited with reason crash", Message),
+                        ?assertEqual("Lager event handler lager_crash_backend exited with reason crash", lists:flatten(Message)),
                         {_Level2, _Time2, [_, _, Message2]} = lager_test_backend:pop(),
-                        ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, Message2),
+                        ?assertMatch("Lager failed to install handler lager_crash_backend into lager_event, retrying later :"++_, lists:flatten(Message2)),
                         ?assertEqual(false, lists:member(lager_crash_backend, gen_event:which_handlers(lager_event)))
                     after
                        application:stop(lager),

src/lager_trunc_io.erl

@@ -33,7 +33,7 @@
 -module(lager_trunc_io).
 -author('matthias@corelatus.se').
 %% And thanks to Chris Newcombe for a bug fix 
--export([format/3, print/2, print/3, fprint/2, fprint/3, safe/2]). % interface functions
+-export([format/3, format/4, print/2, print/3, fprint/2, fprint/3, safe/2]). % interface functions
 -version("$Id: trunc_io.erl,v 1.11 2009-02-23 12:01:06 matthias Exp $").
 
 -ifdef(TEST).
@@ -52,7 +52,10 @@
     }).
 
 format(Fmt, Args, Max) ->
-    try lager_format:format(Fmt, Args, Max) of
+    format(Fmt, Args, Max, []).
+
+format(Fmt, Args, Max, Options) ->
+    try lager_format:format(Fmt, Args, Max, Options) of
         Result -> Result
     catch
         _:_ ->