%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (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.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and
%% limitations under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developer of the Original Code is GoPivotal, Inc.
%% Copyright (c) 2007-2016 Pivotal Software, Inc.  All rights reserved.
%%

-module(prometheus_misc).

-export([all_module_attributes/1]).

all_module_attributes(Name) ->
  Targets =
    lists:usort(
      lists:append(
        [[{App, Module} || Module <- Modules] ||
          {App, _, _}   <- application:loaded_applications(),
          {ok, Modules} <- [application:get_key(App, modules)]])),
  lists:foldl(
    fun ({App, Module}, Acc) ->
        case lists:append([Atts || {N, Atts} <- module_attributes(Module),
                                   N =:= Name]) of
          []   -> Acc;
          Atts -> [{App, Module, Atts} | Acc]
        end
    end, [], Targets).

module_attributes(Module) ->
    case catch Module:module_info(attributes) of
        {'EXIT', {undef, [{Module, module_info, _} | _]}} ->
            io:format("WARNING: module ~p not found, so not scanned for boot steps.~n",
                      [Module]),
            [];
        {'EXIT', Reason} ->
            exit(Reason);
        V ->
            V
    end.