Initial import

LICENSE

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+
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+

Makefile

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+all:
+	./rebar compile
+
+clean:
+	./rebar clean
+
+test: all
+	./rebar eunit

README.org

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+* Overview
+  Lager (pronounced lAAger) is a logging framework for Erlang. Its purpose is
+  to provide a more traditional way to perform logging in an erlang application
+  that plays nicely with traditional UNIX logging tools like logrotate and
+  syslog.
+
+  Features
+    - Finer grained log levels (debug, info, notice, warning, error, critical,
+      alert, emergency)
+    - Logger calls are transformed using a parse transform to allow capturing
+      Module/Function/Line/Pid information
+    - When no handler is consuming a log level (eg. debug) no event is even sent
+      to the log handler
+    - Supports multiple backends, including console, file and syslog.
+
+* Usage
+  To use lager in your application, you need to define it as a rebar dep or have
+  some other way of including it in erlang's path. You can then add the
+  following option to the erlang compiler flags
+
+  {parse_transform, lager_transform}
+
+  Alternately, you can add it to the module you which to compile with logging
+  enabled:
+
+  -compile([{parse_transform, lager_transform}]).
+
+  Once you have built your code with lager, you can then generate log messages
+  by doing the following:
+
+  lager:error("Some message")
+
+  Or:
+
+  lager:warning("Some message with a term: ~p", [Term])
+
+  The general form is lager:Severity() where Severity is one of the log levels
+  mentioned above.
+
+* Configuration
+  TODO

rebar.config

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+
+{erl_opts, [debug_info, fail_on_warning]}.

src/lager.app.src

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+%% -*- tab-width: 4;erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+{application, lager,
+ [
+  {description, "Custom error handler"},
+  {vsn, "1.0.0"},
+  {modules, [
+            ]},
+  {applications, [
+                  kernel,
+                  stdlib,
+                  sasl
+                 ]},
+  {registered, []},
+  {mod, {riak_err_app, []}},
+  {env, [
+        ]}
+ ]}.

src/lager.erl

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+%% Copyright (c) 2011 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.
+
+-module(lager).
+
+-behaviour(gen_server).
+
+-export([start_link/0,start/0,sasl_log/3, log/7, log/8]).
+
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
+        code_change/3]).
+
+-record(state, {event_pid, handler_loglevels}).
+
+%% API
+
+start_link() ->
+    %application:start(sasl),
+    %application:set_env(riak_err, print_fun, {lager, sasl_log}),
+    %application:start(riak_err),
+    Handlers = case application:get_env(lager, handlers) of
+        undefined ->
+            [{lager_console_backend, [info]}];
+        Val ->
+            Val
+    end,
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [Handlers], []).
+
+start() ->
+    Handlers = case application:get_env(lager, handlers) of
+        undefined ->
+            [{lager_console_backend, [info]},
+                {lager_file_backend, [{"error.log", error}, {"console.log", info}]}];
+        Val ->
+            Val
+    end,
+    gen_server:start({local, ?MODULE}, ?MODULE, [Handlers], []).
+
+sasl_log(ReportStr, Pid, Message) ->
+    %Level = reportstr_to_level(ReportStr),
+    {{Y, M, D}, {H, Mi, S}} = riak_err_stdlib:maybe_utc(erlang:localtime()),
+    Msg = re:replace(binary:replace(Message, [<<"\r">>, <<"\n">>], <<>>,
+            [global]), " +", " ", [global, {return, binary}]),
+    io:format("~b-~b-~b ~b:~b:~b ~p ~s ~s~n", [Y, M,
+            D, H, Mi, S, Pid, ReportStr, Msg]).
+
+log(Level, Module, Function, Line, Pid, {{Y, M, D}, {H, Mi, S}}, Message) ->
+    Time = io_lib:format("~b-~b-~b ~b:~b:~b", [Y, M, D, H, Mi, S]),
+    Msg = io_lib:format("[~p] ~p@~p:~p:~p ~s", [Level, Pid, Module,
+            Function, Line, Message]),
+    gen_event:notify(lager_event, {log, lager_util:level_to_num(Level), Time, Msg}).
+
+log(Level, Module, Function, Line, Pid, {{Y, M, D}, {H, Mi, S}}, Format, Args) ->
+    Time = io_lib:format("~b-~b-~b ~b:~b:~b", [Y, M, D, H, Mi, S]),
+    Msg = io_lib:format("[~p] ~p@~p:~p:~p ~s", [Level, Pid, Module,
+            Function, Line, io_lib:format(Format, Args)]),
+    gen_event:notify(lager_event, {log, lager_util:level_to_num(Level), Time, Msg}).
+
+%% gen_server callbacks
+
+init([Handlers]) ->
+    %% start a gen_event linked to this process
+    gen_event:start_link({local, lager_event}),
+    %% spin up all the defined handlers
+    [gen_event:add_sup_handler(lager_event, Module, Args) || {Module, Args} <- Handlers],
+    MinLog = minimum_log_level(get_log_levels()),
+    lager_mochiglobal:put(loglevel, MinLog),
+    {ok, #state{}}.
+
+handle_call(_Request, _From, State) ->
+    {reply, ok, State}.
+
+handle_cast(_Request, State) ->
+    {noreply, State}.
+
+handle_info(Info, State) ->
+    io:format("got info ~p~n", [Info]),
+    {noreply, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+
+%% internal functions
+
+get_log_levels() ->
+    [gen_event:call(lager_event, Handler, get_loglevel) ||
+        Handler <- gen_event:which_handlers(lager_event)].
+
+minimum_log_level([]) ->
+    9; %% higher than any log level, logging off
+minimum_log_level(Levels) ->
+    erlang:hd(lists:sort(lists:map(fun(Level) -> lager_util:level_to_num(Level) end, Levels))).

src/lager_console_backend.erl

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+%% Copyright (c) 2011 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.
+
+-module(lager_console_backend).
+
+-behaviour(gen_event).
+
+-export([init/1, handle_call/2, handle_event/2, handle_info/2, terminate/2,
+        code_change/3]).
+
+-record(state, {level, nlevel}).
+
+init([Level]) ->
+    {ok, #state{level=Level, nlevel=lager_util:level_to_num(Level)}}.
+
+handle_call(get_loglevel, #state{level=Level} = State) ->
+    {ok, Level, State};
+handle_call(_Request, State) ->
+    {ok, ok, State}.
+
+handle_event({log, Level, Time, Message}, #state{nlevel=LogLevel} = State) when Level >= LogLevel ->
+    io:put_chars([Time, " ", Message, "\n"]),
+    {ok, State};
+handle_event(_Event, State) ->
+    {ok, State}.
+
+handle_info(_Info, State) ->
+    {ok, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.

src/lager_file_backend.erl

@@ -0,0 +1,165 @@
+%% Copyright (c) 2011 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.
+
+-module(lager_file_backend).
+
+-behaviour(gen_event).
+
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+-endif.
+
+-include_lib("kernel/include/file.hrl").
+
+-compile([{parse_transform, lager_transform}]).
+
+-export([init/1, handle_call/2, handle_event/2, handle_info/2, terminate/2,
+        code_change/3]).
+
+-record(state, {files}).
+
+init(LogFiles) ->
+    Files = [begin
+                case open(Name) of
+                    {ok, {FD, Inode}} ->
+                        {Name, lager_util:level_to_num(Level), FD, Inode};
+                    Error ->
+                        lager:error("Failed to open log file ~s with error ~p",
+                            [Name, Error]),
+                        undefined
+                end
+            end ||
+        {Name, Level} <- LogFiles],
+    {ok, #state{files=Files}}.
+
+handle_call(get_loglevel, #state{files=Files} = State) ->
+    Result = lists:foldl(fun({_, Level, _, _}, L) -> erlang:min(Level, L);
+            (_, L) -> L end, 9,
+        Files),
+    {ok, Result, State};
+handle_call(_Request, State) ->
+    {ok, ok, State}.
+
+handle_event({log, Level, Time, Message}, #state{files=Files} = State) ->
+    NewFiles = lists:map(
+        fun({_, L, _, _} = File) when Level >= L ->
+                write(File, Level, [Time, " ", Message, "\n"]);
+            (File) ->
+                File
+        end, Files),
+    {ok, State#state{files=NewFiles}};
+handle_event(_Event, State) ->
+    {ok, State}.
+
+handle_info(_Info, State) ->
+    {ok, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+open(Name) ->
+    case file:open(Name, [append, delayed_write, raw]) of
+        {ok, FD} ->
+            case file:read_file_info(Name) of
+                {ok, FInfo} ->
+                    Inode = FInfo#file_info.inode,
+                    {ok, {FD, Inode}};
+                X -> X
+            end;
+        Y -> Y
+    end.
+
+write({Name, L, FD, Inode}, Level, Msg) ->
+    Result = case file:read_file_info(Name) of
+        {ok, FInfo} ->
+            Inode2 = FInfo#file_info.inode,
+            case Inode == Inode2 of
+                true ->
+                    {FD, Inode};
+                false ->
+                    case open(Name) of
+                        {ok, {FD2, Inode3}} ->
+                            %% inode changed, file was probably moved and
+                            %% recreated
+                            {FD2, Inode3};
+                        Error ->
+                            lager:error("Failed to reopen file ~s with error ~p",
+                                [Name, Error]),
+                            undefined
+                    end
+            end;
+        _ ->
+            case open(Name) of
+                {ok, {FD2, Inode3}} ->
+                    %% file was removed
+                    {FD2, Inode3};
+                Error ->
+                    lager:error("Failed to reopen file ~s with error ~p",
+                        [Name, Error]),
+                    undefined
+            end
+    end,
+    case Result of
+        {NewFD, NewInode} ->
+            file:write(NewFD, Msg),
+            case Level of
+                _ when Level >= 4 ->
+                    %% force a sync on any message at error severity or above
+                    file:datasync(NewFD);
+                _ -> ok
+            end,
+            {Name, L, NewFD, NewInode};
+        _ ->
+            undefined
+    end.
+
+
+-ifdef(TEST).
+
+get_loglevel_test() ->
+    {ok, Level, _} = handle_call(get_loglevel,
+        #state{files=[
+                {"foo", lager_util:level_to_num(warning), 0, 0},
+                {"bar", lager_util:level_to_num(info), 0, 0}]}),
+    ?assertEqual(Level, lager_util:level_to_num(info)),
+    {ok, Level2, _} = handle_call(get_loglevel,
+        #state{files=[
+                {"foo", lager_util:level_to_num(warning), 0, 0},
+                {"foo", lager_util:level_to_num(critical), 0, 0},
+                {"bar", lager_util:level_to_num(error), 0, 0}]}),
+    ?assertEqual(Level2, lager_util:level_to_num(warning)).
+
+rotation_test() ->
+    {ok, {FD, Inode}} = open("test.log"),
+    ?assertEqual({"test.log", 0, FD, Inode},
+        write({"test.log", 0, FD, Inode}, 0, "hello world")),
+    file:delete("test.log"),
+    Result = write({"test.log", 0, FD, Inode}, 0, "hello world"),
+    %% assert file has changed
+    ?assert({"test.log", 0, FD, Inode} =/= Result),
+    ?assertMatch({"test.log", 0, _, _}, Result),
+    file:rename("test.log", "test.log.1"),
+    Result2 = write(Result, 0, "hello world"),
+    %% assert file has changed
+    ?assert(Result =/= Result2),
+    ?assertMatch({"test.log", 0, _, _}, Result2),
+    ok.
+
+-endif.
+

src/lager_mochiglobal.erl

@@ -0,0 +1,107 @@
+%% @author Bob Ippolito <bob@mochimedia.com>
+%% @copyright 2010 Mochi Media, Inc.
+%% @doc Abuse module constant pools as a "read-only shared heap" (since erts 5.6)
+%%      <a href="http://www.erlang.org/pipermail/erlang-questions/2009-March/042503.html">[1]</a>.
+-module(lager_mochiglobal).
+-author("Bob Ippolito <bob@mochimedia.com>").
+-export([get/1, get/2, put/2, delete/1]).
+
+-spec get(atom()) -> any() | undefined.
+%% @equiv get(K, undefined)
+get(K) ->
+    get(K, undefined).
+
+-spec get(atom(), T) -> any() | T.
+%% @doc Get the term for K or return Default.
+get(K, Default) ->
+    get(K, Default, key_to_module(K)).
+
+get(_K, Default, Mod) ->
+    try Mod:term()
+    catch error:undef ->
+            Default
+    end.
+
+-spec put(atom(), any()) -> ok.
+%% @doc Store term V at K, replaces an existing term if present.
+put(K, V) ->
+    put(K, V, key_to_module(K)).
+
+put(_K, V, Mod) ->
+    Bin = compile(Mod, V),
+    code:purge(Mod),
+    {module, Mod} = code:load_binary(Mod, atom_to_list(Mod) ++ ".erl", Bin),
+    ok.
+
+-spec delete(atom()) -> boolean().
+%% @doc Delete term stored at K, no-op if non-existent.
+delete(K) ->
+    delete(K, key_to_module(K)).
+
+delete(_K, Mod) ->
+    code:purge(Mod),
+    code:delete(Mod).
+
+-spec key_to_module(atom()) -> atom().
+key_to_module(K) ->
+    list_to_atom("mochiglobal:" ++ atom_to_list(K)).
+
+-spec compile(atom(), any()) -> binary().
+compile(Module, T) ->
+    {ok, Module, Bin} = compile:forms(forms(Module, T),
+                                      [verbose, report_errors]),
+    Bin.
+
+-spec forms(atom(), any()) -> [erl_syntax:syntaxTree()].
+forms(Module, T) ->
+    [erl_syntax:revert(X) || X <- term_to_abstract(Module, term, T)].
+
+-spec term_to_abstract(atom(), atom(), any()) -> [erl_syntax:syntaxTree()].
+term_to_abstract(Module, Getter, T) ->
+    [%% -module(Module).
+     erl_syntax:attribute(
+       erl_syntax:atom(module),
+       [erl_syntax:atom(Module)]),
+     %% -export([Getter/0]).
+     erl_syntax:attribute(
+       erl_syntax:atom(export),
+       [erl_syntax:list(
+         [erl_syntax:arity_qualifier(
+            erl_syntax:atom(Getter),
+            erl_syntax:integer(0))])]),
+     %% Getter() -> T.
+     erl_syntax:function(
+       erl_syntax:atom(Getter),
+       [erl_syntax:clause([], none, [erl_syntax:abstract(T)])])].
+
+%%
+%% Tests
+%%
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+get_put_delete_test() ->
+    K = '$$test$$mochiglobal',
+    delete(K),
+    ?assertEqual(
+       bar,
+       get(K, bar)),
+    try
+        ?MODULE:put(K, baz),
+        ?assertEqual(
+           baz,
+           get(K, bar)),
+        ?MODULE:put(K, wibble),
+        ?assertEqual(
+           wibble,
+           ?MODULE:get(K))
+    after
+        delete(K)
+    end,
+    ?assertEqual(
+       bar,
+       get(K, bar)),
+    ?assertEqual(
+       undefined,
+       ?MODULE:get(K)),
+    ok.
+-endif.

src/lager_transform.erl

@@ -0,0 +1,120 @@
+%% Copyright (c) 2011 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.
+
+-module(lager_transform).
+-export([parse_transform/2]).
+
+-define(LEVELS, [debug, info, notice, warning, error, critical, alert,
+        emergency]).
+
+%% 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 mochiglobal 'loglevel' value, so the code isn't executed if
+%% nothing wishes to consume the message.
+
+parse_transform(AST, _Options) ->
+    %io:format("~n~p~n", [AST]),
+    walk_ast([], AST).
+
+walk_ast(Acc, []) ->
+    lists:reverse(Acc);
+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, [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}}, Arguments} = Stmt) ->
+    case lists:member(Severity, ?LEVELS) of
+        true ->
+            %io:format("call to lager ~p on line ~p in function ~p in module ~p~n",
+                %[Severity, Line, get(function), get(module)]),
+            %% a case to check the mochiglobal 'loglevel' key against the
+            %% message we're trying to log
+            {'case',Line,
+                    {op,Line,'=<',
+                        {call,Line,
+                            {remote,Line,{atom,Line,lager_util},{atom,Line,level_to_num}},
+                            [{call,Line,
+                                    {remote,Line,{atom,Line,lager_mochiglobal},{atom,Line,get}},
+                                    [{atom,Line,loglevel}]}]},
+                        {call,Line,
+                            {remote,Line,{atom,Line,lager_util},{atom,Line,level_to_num}},
+                            [{atom,Line,Severity}]}},
+                    [{clause,Line,
+                            [{atom,Line,true}], %% yes, we log!
+                            [],
+                            [{call, Line, {remote, Line1, {atom, Line2, lager},
+                                        {atom, Line3, log}}, [
+                                        {atom, Line3, Severity},
+                                        {atom, Line3, get(module)},
+                                        {atom, Line3, get(function)},
+                                        {integer, Line3, Line},
+                                        {call, Line3, {atom, Line3 ,self}, []},
+                                        {call, Line3, {remote, Line3,
+                                                {atom, Line3 ,riak_err_stdlib},
+                                                {atom,Line3,maybe_utc}},
+                                            [{call,Line3,{remote,Line3,
+                                                        {atom,Line3,erlang},
+                                                        {atom,Line3,localtime}},[]}]}
+                                        | Arguments
+                                    ]}]},
+                        %% No, don't log
+                        {clause,Line3,[{var,Line3,'_'}],[],[{atom,Line3,ok}]}]};
+            false ->
+                %io:format("skipping non-log lager call ~p~n", [Severity]),
+                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({'case', Line, Expr, Clauses}) ->
+    {'case', Line, Expr, walk_clauses([], Clauses)};
+transform_statement({'if', Line, Clauses}) ->
+    {'if', Line, walk_clauses([], Clauses)};
+transform_statement({block, Line, Body}) ->
+    {block, Line, walk_body([], Body)};
+transform_statement({lc, Line, Expression, Generator}) ->
+    {lc, Line, transform_statement(Expression), Generator};
+transform_statement({match, Line, Var, Expression}) ->
+    {match, Line, Var, transform_statement(Expression)};
+transform_statement(Stmt) ->
+    Stmt.
+
+
+

src/lager_util.erl

@@ -0,0 +1,41 @@
+%% Copyright (c) 2011 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.
+
+-module(lager_util).
+
+-export([levels/0, level_to_num/1]).
+
+levels() ->
+    [debug, info, notice, warning, error, critical, alert, emergency].
+
+level_to_num(debug) ->
+    0;
+level_to_num(info) ->
+    1;
+level_to_num(notice) ->
+    2;
+level_to_num(warning) ->
+    3;
+level_to_num(error) ->
+    4;
+level_to_num(critical) ->
+    5;
+level_to_num(alert) ->
+    6;
+level_to_num(emergency) ->
+    7;
+level_to_num(_) ->
+    0.