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|
-module(dummy_via).
-export([reset/0,
register_name/2,
whereis_name/1,
unregister_name/1,
send/2]).
reset() ->
P = whereis(?MODULE),
catch unlink(P),
Ref = erlang:monitor(process, P),
catch exit(P, kill),
receive {'DOWN',Ref,_,_,_} -> ok end,
Me = self(),
Pid = spawn_link(fun() ->
register(?MODULE, self()),
Me ! {self(), started},
loop([])
end),
receive
{Pid, started} ->
Pid
after 10000 ->
exit(timeout)
end.
register_name(Name, Pid) when is_pid(Pid) ->
call({register_name, Name, Pid}).
unregister_name(Name) ->
call({unregister_name, Name}).
whereis_name(Name) ->
call({whereis_name, Name}).
send(Name, Msg) ->
case whereis_name(Name) of
undefined ->
exit({badarg, {Name, Msg}});
Pid when is_pid(Pid) ->
Pid ! Msg,
Pid
end.
call(Req) ->
MRef = erlang:monitor(process, ?MODULE),
?MODULE ! {self(), MRef, Req},
receive
{'DOWN', MRef, _, _, _} ->
erlang:error(badarg);
{MRef, badarg} ->
erlang:demonitor(MRef),
erlang:error(badarg);
{MRef, Reply} ->
erlang:demonitor(MRef),
Reply
after 5000 ->
erlang:error(timeout)
end.
loop(Reg) ->
receive
{'DOWN', _, _, P, _} when is_pid(P) ->
loop([X || {_,Pid,_} = X <- Reg, Pid =/= P]);
{From, Ref, Request} when is_pid(From), is_reference(Ref) ->
{Reply, NewReg} = handle_request(Request, Reg),
From ! {Ref, Reply},
loop(NewReg)
end.
handle_request({register_name, Name, Pid}, Reg) when is_pid(Pid) ->
case lists:keyfind(Name, 1, Reg) of
false ->
Ref = erlang:monitor(process, Pid),
{yes, [{Name, Pid, Ref}|Reg]};
_ ->
{no, Reg}
end;
handle_request({whereis_name, Name}, Reg) ->
case lists:keyfind(Name, 1, Reg) of
{_, Pid, _} ->
{Pid, Reg};
false ->
{undefined, Reg}
end;
handle_request({unregister_name, Name}, Reg) ->
case lists:keyfind(Name, 1, Reg) of
{_, _, Ref} ->
catch erlang:demonitor(Ref);
_ ->
ok
end,
{ok, lists:keydelete(Name, 1, Reg)};
handle_request(_, Reg) ->
{badarg, Reg}.
|
