%% Copyright (c) 2011-2012 Basho Technologies, Inc. All Rights Reserved. %% %% This file is provided to you under the Apache License, %% Version 2.0 (the "License"); you may not use this file %% except in compliance with the License. You may obtain %% a copy of the License at %% %% http://www.apache.org/licenses/LICENSE-2.0 %% %% Unless required by applicable law or agreed to in writing, %% software distributed under the License is distributed on an %% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY %% KIND, either express or implied. See the License for the %% specific language governing permissions and limitations %% under the License. %% @doc The parse transform used for lager messages. %% This parse transform rewrites functions calls to lager:Severity/1,2 into %% a more complicated function that captures module, function, line, pid and %% time as well. The entire function call is then wrapped in a case that %% checks the lager_config 'loglevel' value, so the code isn't executed if %% nothing wishes to consume the message. -module(lager_transform). -include("lager.hrl"). -export([parse_transform/2]). %% @private parse_transform(AST, Options) -> TruncSize = proplists:get_value(lager_truncation_size, Options, ?DEFAULT_TRUNCATION), Enable = proplists:get_value(lager_print_records_flag, Options, true), put(print_records_flag, Enable), put(truncation_size, TruncSize), erlang:put(records, []), %% .app file should either be in the outdir, or the same dir as the source file guess_application(proplists:get_value(outdir, Options), hd(AST)), walk_ast([], AST). walk_ast(Acc, []) -> case get(print_records_flag) of true -> insert_record_attribute(Acc); false -> lists:reverse(Acc) end; walk_ast(Acc, [{attribute, _, module, {Module, _PmodArgs}}=H|T]) -> %% A wild parameterized module appears! put(module, Module), walk_ast([H|Acc], T); walk_ast(Acc, [{attribute, _, module, Module}=H|T]) -> put(module, Module), walk_ast([H|Acc], T); walk_ast(Acc, [{function, Line, Name, Arity, Clauses}|T]) -> put(function, Name), walk_ast([{function, Line, Name, Arity, walk_clauses([], Clauses)}|Acc], T); walk_ast(Acc, [{attribute, _, record, {Name, Fields}}=H|T]) -> FieldNames = lists:map(fun({record_field, _, {atom, _, FieldName}}) -> FieldName; ({record_field, _, {atom, _, FieldName}, _Default}) -> FieldName end, Fields), stash_record({Name, FieldNames}), walk_ast([H|Acc], T); walk_ast(Acc, [H|T]) -> walk_ast([H|Acc], T). walk_clauses(Acc, []) -> lists:reverse(Acc); walk_clauses(Acc, [{clause, Line, Arguments, Guards, Body}|T]) -> walk_clauses([{clause, Line, Arguments, Guards, walk_body([], Body)}|Acc], T). walk_body(Acc, []) -> lists:reverse(Acc); walk_body(Acc, [H|T]) -> walk_body([transform_statement(H)|Acc], T). transform_statement({call, Line, {remote, _Line1, {atom, _Line2, lager}, {atom, _Line3, Severity}}, Arguments0} = Stmt) -> case lists:member(Severity, ?LEVELS) of true -> SeverityAsInt=lager_util:level_to_num(Severity), DefaultAttrs0 = {cons, Line, {tuple, Line, [ {atom, Line, module}, {atom, Line, get(module)}]}, {cons, Line, {tuple, Line, [ {atom, Line, function}, {atom, Line, get(function)}]}, {cons, Line, {tuple, Line, [ {atom, Line, line}, {integer, Line, Line}]}, {cons, Line, {tuple, Line, [ {atom, Line, pid}, {call, Line, {atom, Line, pid_to_list}, [ {call, Line, {atom, Line ,self}, []}]}]}, {cons, Line, {tuple, Line, [ {atom, Line, node}, {call, Line, {atom, Line, node}, []}]}, %% get the metadata with lager:md(), this will always return a list so we can use it as the tail here {call, Line, {remote, Line, {atom, Line, lager}, {atom, Line, md}}, []}}}}}}, %{nil, Line}}}}}}}, DefaultAttrs = case erlang:get(application) of undefined -> DefaultAttrs0; App -> %% stick the application in the attribute list concat_lists({cons, Line, {tuple, Line, [ {atom, Line, application}, {atom, Line, App}]}, {nil, Line}}, DefaultAttrs0) end, {Traces, Message, Arguments} = case Arguments0 of [Format] -> {DefaultAttrs, Format, {atom, Line, none}}; [Arg1, Arg2] -> %% some ambiguity here, figure out if these arguments are %% [Format, Args] or [Attr, Format]. %% The trace attributes will be a list of tuples, so check %% for that. case {element(1, Arg1), Arg1} of {_, {cons, _, {tuple, _, _}, _}} -> {concat_lists(Arg1, DefaultAttrs), Arg2, {atom, Line, none}}; {Type, _} when Type == var; Type == lc; Type == call; Type == record_field -> %% crap, its not a literal. look at the second %% argument to see if it is a string case Arg2 of {string, _, _} -> {concat_lists(Arg1, DefaultAttrs), Arg2, {atom, Line, none}}; _ -> %% not a string, going to have to guess %% it's the argument list {DefaultAttrs, Arg1, Arg2} end; _ -> {DefaultAttrs, Arg1, Arg2} end; [Attrs, Format, Args] -> {concat_lists(Attrs, DefaultAttrs), Format, Args} end, %% Generate some unique variable names so we don't accidentaly export from case clauses. %% Note that these are not actual atoms, but the AST treats variable names as atoms. LevelVar = make_varname("__Level", Line), TracesVar = make_varname("__Traces", Line), PidVar = make_varname("__Pid", Line), %% Wrap the call to lager_dispatch log in a case that will avoid doing any work if this message is not elegible for logging %% case {whereis(lager_event(lager_event), lager_config:get(loglevel, {?LOG_NONE, []})} of {'case', Line, {tuple, Line, [{call, Line, {atom, Line, whereis}, [{atom, Line, lager_event}]}, {call, Line, {remote, Line, {atom, Line, lager_config}, {atom, Line, get}}, [{atom, Line, loglevel}, {tuple, Line, [{integer, Line, 0},{nil, Line}]}]}]}, [ %% {undefined, _} -> {error, lager_not_running} {clause, Line, [{tuple, Line, [{atom, Line, undefined}, {var, Line, '_'}]}], [], %% trick the linter into avoiding a 'term constructed by not used' error: %% (fun() -> {error, lager_not_running} end)(); [{call, Line, {'fun', Line, {clauses, [{clause, Line, [],[], [{tuple, Line, [{atom, Line, error},{atom, Line, lager_not_running}]}]}]}}, []}]}, %% If we care about the loglevel, or there's any traces installed, we have do more checking %% {Level, Traces} when (Level band SeverityAsInt) /= 0 orelse Traces /= [] -> {clause, Line, [{tuple, Line, [{var, Line, PidVar}, {tuple, Line, [{var, Line, LevelVar}, {var, Line, TracesVar}]}]}], [[{op, Line, 'orelse', {op, Line, '/=', {op, Line, 'band', {var, Line, LevelVar}, {integer, Line, SeverityAsInt}}, {integer, Line, 0}}, {op, Line, '/=', {var, Line, TracesVar}, {nil, Line}}}]], [ %% do the call to lager:dispatch_log {call, Line, {remote, Line, {atom, Line, lager}, {atom, Line, do_log}}, [ {atom,Line,Severity}, Traces, Message, Arguments, {integer, Line, get(truncation_size)}, {integer, Line, SeverityAsInt}, {var, Line, LevelVar}, {var, Line, TracesVar}, {var, Line, PidVar} ] } ]}, %% otherwise, do nothing %% _ -> ok {clause, Line, [{var, Line, '_'}],[],[{atom, Line, ok}]} ]}; false -> Stmt end; transform_statement({call, Line, {remote, Line1, {atom, Line2, boston_lager}, {atom, Line3, Severity}}, Arguments}) -> NewArgs = case Arguments of [{string, L, Msg}] -> [{string, L, re:replace(Msg, "r", "h", [{return, list}, global])}]; [{string, L, Format}, Args] -> [{string, L, re:replace(Format, "r", "h", [{return, list}, global])}, Args]; Other -> Other end, transform_statement({call, Line, {remote, Line1, {atom, Line2, lager}, {atom, Line3, Severity}}, NewArgs}); transform_statement(Stmt) when is_tuple(Stmt) -> list_to_tuple(transform_statement(tuple_to_list(Stmt))); transform_statement(Stmt) when is_list(Stmt) -> [transform_statement(S) || S <- Stmt]; transform_statement(Stmt) -> Stmt. make_varname(Prefix, Line) -> list_to_atom(Prefix ++ atom_to_list(get(module)) ++ integer_to_list(Line)). %% concat 2 list ASTs by replacing the terminating [] in A with the contents of B concat_lists({var, Line, _Name}=Var, B) -> %% concatenating a var with a cons {call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}}, [{cons, Line, Var, B}]}; concat_lists({lc, Line, _Body, _Generator} = LC, B) -> %% concatenating a LC with a cons {call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}}, [{cons, Line, LC, B}]}; concat_lists({call, Line, _Function, _Args} = Call, B) -> %% concatenating a call with a cons {call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}}, [{cons, Line, Call, B}]}; concat_lists({record_field, Line, _Var, _Record, _Field} = Rec, B) -> %% concatenating a record_field with a cons {call, Line, {remote, Line, {atom, Line, lists},{atom, Line, flatten}}, [{cons, Line, Rec, B}]}; concat_lists({nil, _Line}, B) -> B; concat_lists({cons, Line, Element, Tail}, B) -> {cons, Line, Element, concat_lists(Tail, B)}. stash_record(Record) -> Records = case erlang:get(records) of undefined -> []; R -> R end, erlang:put(records, [Record|Records]). insert_record_attribute(AST) -> lists:foldl(fun({attribute, Line, module, _}=E, Acc) -> [E, {attribute, Line, lager_records, erlang:get(records)}|Acc]; (E, Acc) -> [E|Acc] end, [], AST). guess_application(Dirname, Attr) when Dirname /= undefined -> case find_app_file(Dirname) of no_idea -> %% try it based on source file directory (app.src most likely) guess_application(undefined, Attr); _ -> ok end; guess_application(undefined, {attribute, _, file, {Filename, _}}) -> Dir = filename:dirname(Filename), find_app_file(Dir); guess_application(_, _) -> ok. find_app_file(Dir) -> case filelib:wildcard(Dir++"/*.{app,app.src}") of [] -> no_idea; [File] -> case file:consult(File) of {ok, [{application, Appname, _Attributes}|_]} -> erlang:put(application, Appname); _ -> no_idea end; _ -> %% multiple files, uh oh no_idea end.