Simplify acks to transport processes

What's interesting when implementing some form of load regulation is
when an incoming request has been answered or discarded.  Acknowledge
exactly this, not the identity of handler processes as previously. A
transport process can request acks of nonforthcoming answers by sending
{diameter, ack} to the parent peer_fsm, a handler processes identifies
itself with a {handler, pid()} message, and the peer_fsm monitors on
this to be able to send a notification to the transport if the handler
dies before sending an answer.

1 files changed, 15 insertions, 22 deletions

diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index 4484b7ee2c..a2eb661870 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -283,7 +283,7 @@ event(Msg,
     ?LOG(transition, {From, To}).
 
 data(Msg, TPid, reopen, okay) ->
-    {recv, TPid, false, 'DWA', _Pkt, _NPid} = Msg,  %% assert
+    {recv, TPid, _, 'DWA', _Pkt} = Msg,  %% assert
     {TPid, T} = eraser(open),
     [T];
 
@@ -302,6 +302,8 @@ tpid(_, Pid)
 tpid(Pid, _) ->
     Pid.
 
+%% send/2
+
 send(Pid, T) ->
     Pid ! T.
 
@@ -447,14 +449,15 @@ transition({'DOWN', _, process, TPid, _Reason} = D,
     end;
 
 %% Incoming message.
-transition({recv, TPid, Route, Name, Pkt, NPid},
+transition({recv, TPid, Route, Name, Pkt},
            #watchdog{transport = TPid}
            = S) ->
-    try
-        incoming(Name, Pkt, NPid, S)
-    catch
+    try incoming(Route, Name, Pkt, S) of
         #watchdog{dictionary = Dict0, receive_data = T} = NS ->
-            diameter_traffic:receive_message(TPid, Route, Pkt, NPid, Dict0, T),
+            diameter_traffic:receive_message(TPid, Route, Pkt, Dict0, T),
+            NS
+    catch
+        #watchdog{} = NS ->
             NS
     end;
 
@@ -586,23 +589,13 @@ send_watchdog(#watchdog{pending = false,
 
 %% incoming/4
 
-incoming(Name, Pkt, false, S) ->
-    recv(Name, Pkt, S);
-
-incoming(Name, Pkt, NPid, S) ->
-    NS = recv(Name, Pkt, S),
-    NPid ! {diameter, discard},
-    NS.
-
-%% recv/3
-
-recv(Name, Pkt, S) ->
-    try rcv(Name, Pkt, rcv(Name, S)) of
-        #watchdog{} = NS ->
-            throw(NS)
+incoming(Route, Name, Pkt, S) ->
+    try rcv(Name, S) of
+        NS -> rcv(Name, Pkt, NS)
     catch
-        #watchdog{} = NS ->  %% throwaway
-            NS
+        #watchdog{transport = TPid} = NS when Route ->  %% incoming request
+            send(TPid, {send, false}),                  %%    requiring ack
+            throw(NS)
     end.
 
 %% rcv/3