Let throttling callback return a notification pid

In addition to returning ok or {timeout, Tmo}, let a throttling callback
for message reception return a pid(), which is then notified if the
message in question is either discarded or results in a request process.
Notification is by way of messages of the form

  {diameter, discard | {request, pid()}}

where the pid is that of a request process resulting from the received
message. This allows the notification process to keep track of the
maximum number of request processes a peer connection can have given
rise to.

1 files changed, 27 insertions, 6 deletions

diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index a9ee4940a3..83e0dda501 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2015. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2016. 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
@@ -426,8 +426,8 @@ transition({connection_timeout, _}, _) ->
     ok;
 
 %% Incoming message from the transport.
-transition({diameter, {recv, Pkt}}, S) ->
-    recv(Pkt, S);
+transition({diameter, {recv, MsgT}}, S) ->
+    incoming(MsgT, S);
 
 %% Timeout when still in the same state ...
 transition({timeout = T, PS}, #state{state = PS}) ->
@@ -553,6 +553,28 @@ encode(Rec, Dict) ->
     diameter_codec:encode(Dict, #diameter_packet{header = Hdr,
                                                  msg = Rec}).
 
+%% incoming/2
+
+incoming({Msg, NPid}, S) ->
+    try recv(Msg, S) of
+        T ->
+            NPid ! {diameter, discard},
+            T
+    catch
+        {?MODULE, Name, Pkt} ->
+            S#state.parent ! {recv, self(), Name, {Pkt, NPid}},
+            rcv(Name, Pkt, S)
+    end;
+
+incoming(Msg, S) ->
+    try
+        recv(Msg, S)
+    catch
+        {?MODULE, Name, Pkt} ->
+            S#state.parent ! {recv, self(), Name, Pkt},
+            rcv(Name, Pkt, S)
+    end.
+
 %% recv/2
 
 recv(#diameter_packet{header = #diameter_header{} = Hdr}
@@ -607,9 +629,8 @@ recv1('DPA' = N,
 
 %% Any other message with a header and no length errors: send to the
 %% parent.
-recv1(Name, Pkt, #state{parent = Pid} = S) ->
-    Pid ! {recv, self(), Name, Pkt},
-    rcv(Name, Pkt, S).
+recv1(Name, Pkt, #state{}) ->
+    throw({?MODULE, Name, Pkt}).
 
 %% recv/3