%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% 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.
%%
%% %CopyrightEnd%
%%
-module(diameter_util).
%%
%% Utility functions.
%%
-export([consult/2,
run/1,
fold/3,
foldl/3,
scramble/1,
ps/0]).
-define(L, atom_to_list).
%% consult/2
%%
%% Extract info from the app/appup file (presumably) of the named
%% application.
consult(Name, Suf)
when is_atom(Name), is_atom(Suf) ->
case code:lib_dir(Name, ebin) of
{error = E, Reason} ->
{E, {Name, Reason}};
Dir ->
consult(filename:join([Dir, ?L(Name) ++ "." ++ ?L(Suf)]))
end.
consult(Path) ->
case file:consult(Path) of
{ok, Terms} ->
Terms;
{error, Reason} ->
{error, {Path, Reason}}
end.
%% Name/Path in the return value distinguish the errors and allow for
%% a useful badmatch.
%% run/1
%%
%% Evaluate functions in parallel and return a list of those that
%% failed to return. The fun takes a boolean (did the function return
%% or not), the function that was evaluated, the return value or exit
%% reason and the prevailing accumulator.
run(L) ->
fold(fun cons/4, [], L).
cons(true, _, _, Acc) ->
Acc;
cons(false, F, RC, Acc) ->
[{F, RC} | Acc].
%% fold/3
%%
%% Parallel fold. Results are folded in the order received.
fold(Fun, Acc0, L)
when is_function(Fun, 4) ->
Ref = make_ref(),
%% Spawn a middleman to collect down messages from processes
%% spawned for each function so as not to assume that all DOWN
%% messages are ours.
MRef = run1([fun fold/4, Ref, Fun, Acc0, L], Ref),
{Ref, RC} = down(MRef),
RC.
fold(Ref, Fun, Acc0, L) ->
recv(run(Ref, L), Ref, Fun, Acc0).
run(Ref, L) ->
[{run1(F, Ref), F} || F <- L].
run1(F, Ref) ->
{_, MRef} = spawn_monitor(fun() -> exit({Ref, eval(F)}) end),
MRef.
recv([], _, _, Acc) ->
Acc;
recv(L, Ref, Fun, Acc) ->
{MRef, R} = down(),
{MRef, F} = lists:keyfind(MRef, 1, L),
recv(lists:keydelete(MRef, 1, L),
Ref,
Fun,
acc(R, Ref, F, Fun, Acc)).
acc({Ref, RC}, Ref, F, Fun, Acc) ->
Fun(true, F, RC, Acc);
acc(Reason, _, F, Fun, Acc) ->
Fun(false, F, Reason, Acc).
down(MRef) ->
receive {'DOWN', MRef, process, _, Reason} -> Reason end.
down() ->
receive {'DOWN', MRef, process, _, Reason} -> {MRef, Reason} end.
%% foldl/3
%%
%% Parallel fold. Results are folded in order of the function list.
foldl(Fun, Acc0, L)
when is_function(Fun, 4) ->
Ref = make_ref(),
recvl(run(Ref, L), Ref, Fun, Acc0).
recvl([], _, _, Acc) ->
Acc;
recvl([{MRef, F} | L], Ref, Fun, Acc) ->
R = down(MRef),
recvl(L, Ref, Fun, acc(R, Ref, F, Fun, Acc)).
%% scramble/1
%%
%% Sort a list into random order.
scramble(L) ->
foldl(fun(true, _, S, false) -> S end,
false,
[[fun s/1, L]]).
s(L) ->
random:seed(now()),
s([], L).
s(Acc, []) ->
Acc;
s(Acc, L) ->
{H, [T|Rest]} = lists:split(random:uniform(length(L)) - 1, L),
s([T|Acc], H ++ Rest).
%% ps/0
ps() ->
[{P, process_info(P)} || P <- erlang:processes()].
%% eval/1
eval({M,[F|A]})
when is_atom(F) ->
apply(M,F,A);
eval({M,F,A}) ->
apply(M,F,A);
eval([F|A])
when is_function(F) ->
apply(F,A);
eval(L)
when is_list(L) ->
run(L);
eval(F)
when is_function(F,0) ->
F().
