Simplify transport shutdown

Service process informs the watchdog process which informs the peer
process. (Instead of going directly to the latter in one case.)

3 files changed, 24 insertions, 42 deletions

diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 5dab6214b1..b515a599ed 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -393,8 +393,6 @@ transition({send, Msg}, #state{transport = TPid}) ->
 
 %% Request for graceful shutdown at remove_transport, stop_service of
 %% application shutdown.
-transition({shutdown = T, Pid}, S) ->
-    transition({T, Pid, transport}, S);
 transition({shutdown, Pid, Reason}, #state{parent = Pid, dpr = false} = S) ->
     dpr(Reason, S);
 transition({shutdown, Pid, _}, #state{parent = Pid}) ->
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 4e6cb3cd79..d01a5e5ab6 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -716,46 +716,30 @@ mod_state(Alias, ModS) ->
 %%% # shutdown/2
 %%% ---------------------------------------------------------------------------
 
-%% remove_transport: ask watchdogs to terminate their transport.
+%% remove_transport
 shutdown(Refs, #state{peerT = PeerT})
   when is_list(Refs) ->
-    ets:foldl(fun(P,ok) -> sp(P, Refs), ok end, ok, PeerT);
+    ets:foldl(fun(P,ok) -> st(P, Refs), ok end, ok, PeerT);
 
-%% application/service shutdown: ask transports to terminate themselves.
-shutdown(Reason, #state{peerT = PeerT}) ->
-    %% A transport might not be alive to receive the shutdown request
-    %% but give those that are a chance to shutdown gracefully.
-    shutdown(conn, Reason, PeerT),
-    %% Kill the watchdogs explicitly in case there was no transport.
-    shutdown(peer, Reason, PeerT).
+%% application/service shutdown
+shutdown(Reason, #state{peerT = PeerT})
+  when Reason == application;
+       Reason == service ->
+    diameter_lib:wait(ets:foldl(fun(P,A) -> st(P, Reason, A) end,
+                                [],
+                                PeerT)).
 
-%% sp/2
+%% st/2
 
-sp(#peer{ref = Ref, pid = Pid}, Refs) ->
+st(#peer{ref = Ref, pid = Pid}, Refs) ->
     lists:member(Ref, Refs)
-        andalso (Pid ! {shutdown, self()}).  %% 'DOWN' cleans up
-
-%% shutdown/3
-
-shutdown(Who, Reason, T) ->
-    diameter_lib:wait(ets:foldl(fun(X,A) -> shutdown(Who, X, Reason, A) end,
-                                [],
-                                T)).
+        andalso (Pid ! {shutdown, self(), transport}).  %% 'DOWN' cleans up
 
-shutdown(conn,
-         #peer{pid = Pid, op_state = {?STATE_UP, _}, conn = TPid},
-         Reason,
-         Acc) ->
-    TPid ! {shutdown, Pid, Reason},
-    [TPid | Acc];
+%% st/3
 
-shutdown(peer, #peer{pid = Pid}, _Reason, Acc)
-  when is_pid(Pid) ->
-    exit(Pid, shutdown),
-    [Pid | Acc];
-
-shutdown(_, #peer{}, _, Acc) ->
-    Acc.
+st(#peer{pid = Pid}, Reason, Acc) ->
+    Pid ! {shutdown, self(), Reason},
+    [Pid | Acc].
 
 %%% ---------------------------------------------------------------------------
 %%% # call_service/2
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index ad4a142f76..49b6776a84 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -208,15 +208,15 @@ transition(close, #watchdog{}) ->
     ok;
 
 %% Service is asking for the peer to be taken down gracefully.
-transition({shutdown, Pid}, #watchdog{parent = Pid,
-                                      transport = undefined,
-                                      status = S}) ->
-    down = S,  %% sanity check
+transition({shutdown, Pid, _}, #watchdog{parent = Pid,
+                                         transport = undefined,
+                                         status = S}) ->
+    down = S,  %% assert
     stop;
-transition({shutdown = T, Pid}, #watchdog{parent = Pid,
-                                          transport = TPid}
-                                = S) ->
-    TPid ! {T, self()},
+transition({shutdown = T, Pid, Reason}, #watchdog{parent = Pid,
+                                                  transport = TPid}
+                                        = S) ->
+    TPid ! {T, self(), Reason},
     S#watchdog{shutdown = true};
 
 %% Parent process has died,