Merge branch 'uw/extending_gen' into maint

* uw/extending_gen:
  Add plugin support for alternative name lookup

OTP-9945

4 files changed, 69 insertions, 11 deletions

diff --git a/lib/stdlib/src/gen.erl b/lib/stdlib/src/gen.erl
index 5d803091b6..42555aedd7 100644
--- a/lib/stdlib/src/gen.erl
+++ b/lib/stdlib/src/gen.erl
@@ -36,7 +36,7 @@
 %%-----------------------------------------------------------------
 
 -type linkage()    :: 'link' | 'nolink'.
--type emgr_name()  :: {'local', atom()} | {'global', term()}.
+-type emgr_name()  :: {'local', atom()} | {'global', term()} | {via, atom(), term()}.
 
 -type start_ret()  :: {'ok', pid()} | 'ignore' | {'error', term()}.
 
@@ -53,7 +53,7 @@
 %% start(GenMod, LinkP, Name, Mod, Args, Options)
 %%    GenMod = atom(), callback module implementing the 'real' fsm
 %%    LinkP = link | nolink
-%%    Name = {local, atom()} | {global, term()}
+%%    Name = {local, atom()} | {global, term()} | {via, atom(), term()}
 %%    Args = term(), init arguments (to Mod:init/1)
 %%    Options = [{timeout, Timeout} | {debug, [Flag]} | {spawn_opt, OptionList}]
 %%      Flag = trace | log | {logfile, File} | statistics | debug
@@ -158,9 +158,12 @@ call(Name, Label, Request, Timeout)
 	    exit(noproc)
     end;
 %% Global by name
-call({global, _Name}=Process, Label, Request, Timeout)
-  when Timeout =:= infinity;
-       is_integer(Timeout), Timeout >= 0 ->
+call(Process, Label, Request, Timeout)
+  when ((tuple_size(Process) == 2 andalso element(1, Process) == global)
+	orelse
+	  (tuple_size(Process) == 3 andalso element(1, Process) == via))
+       andalso
+       (Timeout =:= infinity orelse (is_integer(Timeout) andalso Timeout >= 0)) ->
     case where(Process) of
 	Pid when is_pid(Pid) ->
 	    Node = node(Pid),
@@ -274,6 +277,7 @@ reply({To, Tag}, Reply) ->
 %%%  Misc. functions.
 %%%-----------------------------------------------------------------
 where({global, Name}) -> global:whereis_name(Name);
+where({via, Module, Name}) -> Module:whereis_name(Name);
 where({local, Name})  -> whereis(Name).
 
 name_register({local, Name} = LN) ->
@@ -287,8 +291,16 @@ name_register({global, Name} = GN) ->
     case global:register_name(Name, self()) of
 	yes -> true;
 	no -> {false, where(GN)}
+    end;
+name_register({via, Module, Name} = GN) ->
+    case Module:register_name(Name, self()) of
+	yes ->
+	    true;
+	no ->
+	    {false, where(GN)}
     end.
 
+
 timeout(Options) ->
     case opt(timeout, Options) of
 	{ok, Time} ->
diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl
index 3317b30e5c..ca05df20c0 100644
--- a/lib/stdlib/src/gen_event.erl
+++ b/lib/stdlib/src/gen_event.erl
@@ -107,8 +107,10 @@
 -type add_handler_ret()  :: ok | term() | {'EXIT',term()}.
 -type del_handler_ret()  :: ok | term() | {'EXIT',term()}.
 
--type emgr_name() :: {'local', atom()} | {'global', atom()}.
--type emgr_ref()  :: atom() | {atom(), atom()} |  {'global', atom()} | pid().
+-type emgr_name() :: {'local', atom()} | {'global', atom()}
+		   | {'via', atom(), term()}.
+-type emgr_ref()  :: atom() | {atom(), atom()} |  {'global', atom()}
+		   | {'via', atom(), term()} | pid().
 -type start_ret() :: {'ok', pid()} | {'error', term()}.
 
 %%---------------------------------------------------------------------------
@@ -143,6 +145,7 @@ init_it(Starter, Parent, Name0, _, _, Options) ->
 
 name({local,Name}) -> Name;
 name({global,Name}) -> Name;
+name({via,_, Name}) -> Name;
 name(Pid) when is_pid(Pid) -> Pid.
 
 -spec add_handler(emgr_ref(), handler(), term()) -> term().
@@ -209,6 +212,9 @@ call1(M, Handler, Query, Timeout) ->
 send({global, Name}, Cmd) ->
     catch global:send(Name, Cmd),
     ok;
+send({via, Mod, Name}, Cmd) ->
+    catch Mod:send(Name, Cmd),
+    ok;
 send(M, Cmd) ->
     M ! Cmd,
     ok.
diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl
index 80866c0806..51dc0bcee2 100644
--- a/lib/stdlib/src/gen_fsm.erl
+++ b/lib/stdlib/src/gen_fsm.erl
@@ -165,7 +165,7 @@
 %%% start(Name, Mod, Args, Options)
 %%% start_link(Mod, Args, Options)
 %%% start_link(Name, Mod, Args, Options) where:
-%%%    Name ::= {local, atom()} | {global, atom()}
+%%%    Name ::= {local, atom()} | {global, atom()} | {via, atom(), term()}
 %%%    Mod  ::= atom(), callback module implementing the 'real' fsm
 %%%    Args ::= term(), init arguments (to Mod:init/1)
 %%%    Options ::= [{debug, [Flag]}]
@@ -191,6 +191,9 @@ start_link(Name, Mod, Args, Options) ->
 send_event({global, Name}, Event) ->
     catch global:send(Name, {'$gen_event', Event}),
     ok;
+send_event({via, Mod, Name}, Event) ->
+    catch Mod:send(Name, {'$gen_event', Event}),
+    ok;
 send_event(Name, Event) ->
     Name ! {'$gen_event', Event},
     ok.
@@ -214,6 +217,9 @@ sync_send_event(Name, Event, Timeout) ->
 send_all_state_event({global, Name}, Event) ->
     catch global:send(Name, {'$gen_all_state_event', Event}),
     ok;
+send_all_state_event({via, Mod, Name}, Event) ->
+    catch Mod:send(Name, {'$gen_all_state_event', Event}),
+    ok;
 send_all_state_event(Name, Event) ->
     Name ! {'$gen_all_state_event', Event},
     ok.
@@ -273,7 +279,10 @@ cancel_timer(Ref) ->
 enter_loop(Mod, Options, StateName, StateData) ->
     enter_loop(Mod, Options, StateName, StateData, self(), infinity).
 
-enter_loop(Mod, Options, StateName, StateData, ServerName = {_,_}) ->
+enter_loop(Mod, Options, StateName, StateData, {Scope,_} = ServerName)
+  when Scope == local; Scope == global ->
+    enter_loop(Mod, Options, StateName, StateData, ServerName,infinity);
+enter_loop(Mod, Options, StateName, StateData, {via,_,_} = ServerName) ->
     enter_loop(Mod, Options, StateName, StateData, ServerName,infinity);
 enter_loop(Mod, Options, StateName, StateData, Timeout) ->
     enter_loop(Mod, Options, StateName, StateData, self(), Timeout).
@@ -303,6 +312,15 @@ get_proc_name({global, Name}) ->
 	    Name;
 	_Pid ->
 	    exit(process_not_registered_globally)
+    end;
+get_proc_name({via, Mod, Name}) ->
+    case Mod:whereis_name(Name) of
+	undefined ->
+	    exit({process_not_registered_via, Mod});
+	Pid when Pid =:= self() ->
+	    Name;
+	_Pid ->
+	    exit({process_not_registered_via, Mod})
     end.
 
 get_parent() ->
@@ -367,12 +385,15 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
 
 name({local,Name}) -> Name;
 name({global,Name}) -> Name;
+name({via,_, Name}) -> Name;
 name(Pid) when is_pid(Pid) -> Pid.
 
 unregister_name({local,Name}) ->
     _ = (catch unregister(Name));
 unregister_name({global,Name}) ->
     _ = global:unregister_name(Name);
+unregister_name({via, Mod, Name}) ->
+    _ = Mod:unregister_name(Name);
 unregister_name(Pid) when is_pid(Pid) ->
     Pid.
 
diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl
index f720ec15f5..b384e8baf7 100644
--- a/lib/stdlib/src/gen_server.erl
+++ b/lib/stdlib/src/gen_server.erl
@@ -142,7 +142,7 @@
 %%% start(Name, Mod, Args, Options)
 %%% start_link(Mod, Args, Options)
 %%% start_link(Name, Mod, Args, Options) where:
-%%%    Name ::= {local, atom()} | {global, atom()}
+%%%    Name ::= {local, atom()} | {global, atom()} | {via, atom(), term()}
 %%%    Mod  ::= atom(), callback module implementing the 'real' server
 %%%    Args ::= term(), init arguments (to Mod:init/1)
 %%%    Options ::= [{timeout, Timeout} | {debug, [Flag]}]
@@ -194,6 +194,9 @@ call(Name, Request, Timeout) ->
 cast({global,Name}, Request) ->
     catch global:send(Name, cast_msg(Request)),
     ok;
+cast({via, Mod, Name}, Request) ->
+    catch Mod:send(Name, cast_msg(Request)),
+    ok;
 cast({Name,Node}=Dest, Request) when is_atom(Name), is_atom(Node) -> 
     do_cast(Dest, Request);
 cast(Dest, Request) when is_atom(Dest) ->
@@ -266,7 +269,11 @@ multi_call(Nodes, Name, Req, Timeout)
 enter_loop(Mod, Options, State) ->
     enter_loop(Mod, Options, State, self(), infinity).
 
-enter_loop(Mod, Options, State, ServerName = {_, _}) ->
+enter_loop(Mod, Options, State, ServerName = {Scope, _})
+  when Scope == local; Scope == local ->
+    enter_loop(Mod, Options, State, ServerName, infinity);
+
+enter_loop(Mod, Options, State, ServerName = {via, _, _}) ->
     enter_loop(Mod, Options, State, ServerName, infinity);
 
 enter_loop(Mod, Options, State, Timeout) ->
@@ -327,12 +334,15 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
 
 name({local,Name}) -> Name;
 name({global,Name}) -> Name;
+name({via,_, Name}) -> Name;
 name(Pid) when is_pid(Pid) -> Pid.
 
 unregister_name({local,Name}) ->
     _ = (catch unregister(Name));
 unregister_name({global,Name}) ->
     _ = global:unregister_name(Name);
+unregister_name({via, Mod, Name}) ->
+    _ = Mod:unregister_name(Name);
 unregister_name(Pid) when is_pid(Pid) ->
     Pid.
     
@@ -827,6 +837,15 @@ get_proc_name({global, Name}) ->
 	    Name;
 	_Pid ->
 	    exit(process_not_registered_globally)
+    end;
+get_proc_name({via, Mod, Name}) ->
+    case Mod:whereis_name(Name) of
+	undefined ->
+	    exit({process_not_registered_via, Mod});
+	Pid when Pid =:= self() ->
+	    Name;
+	_Pid ->
+	    exit({process_not_registered_via, Mod})
     end.
 
 get_parent() ->