From 24dfd1cb2af256999a75f6de6fcf11842529a505 Mon Sep 17 00:00:00 2001
From: Anders Svensson <anders@erlang.org>
Date: Sun, 10 Feb 2013 13:07:58 +0100
Subject: Only start a fragment timer when there's something to flush

---
 lib/diameter/src/transport/diameter_tcp.erl | 38 +++++++++++++++++++----------
 1 file changed, 25 insertions(+), 13 deletions(-)

(limited to 'lib/diameter/src/transport')

diff --git a/lib/diameter/src/transport/diameter_tcp.erl b/lib/diameter/src/transport/diameter_tcp.erl
index 080eff2055..132088b514 100644
--- a/lib/diameter/src/transport/diameter_tcp.erl
+++ b/lib/diameter/src/transport/diameter_tcp.erl
@@ -88,7 +88,8 @@
          frag = <<>> :: frag(),     %% message fragment
          ssl     :: boolean() | [term()],       %% ssl options
          timeout :: infinity | 0..16#FFFFFFFF,  %% fragment timeout
-         flush = false :: boolean()}).          %% flush fragment at timeout
+         tref = false  :: false | reference(),  %% fragment timer reference
+         flush = false :: boolean()}).          %% flush fragment at timeout?
 %% The usual transport using gen_tcp can be replaced by anything
 %% sufficiently gen_tcp-like by passing a 'module' option as the first
 %% (for simplicity) transport option. The transport_module diameter_etcp
@@ -176,7 +177,6 @@ i({T, Ref, Mod, Pid, Opts, Addrs})
     M = if SslOpts -> ssl; true -> Mod end,
     setopts(M, Sock),
     putr(?REF_KEY, Ref),
-    infinity == Tmo orelse erlang:start_timer(Tmo, self(), flush),
     #transport{parent = Pid,
                module = M,
                socket = Sock,
@@ -465,6 +465,7 @@ t(T,S) ->
 
 %% Initial incoming message when we might need to upgrade to TLS:
 %% don't request another message until we know.
+
 transition({tcp, Sock, Bin}, #transport{socket = Sock,
                                         parent = Pid,
                                         frag = Head,
@@ -478,7 +479,7 @@ transition({tcp, Sock, Bin}, #transport{socket = Sock,
             S#transport{frag = B};
         Frag ->
             setopts(M, Sock),
-            S#transport{frag = Frag}
+            start_fragment_timer(S#transport{frag = Frag})
     end;
 
 %% Incoming message.
@@ -489,7 +490,7 @@ transition({P, Sock, Bin}, #transport{socket = Sock,
   when P == tcp, not B;
        P == ssl, B ->
     setopts(M, Sock),
-    recv(Bin, S);
+    start_fragment_timer(recv(Bin, S));
 
 %% Capabilties exchange has decided on whether or not to run over TLS.
 transition({diameter, {tls, Ref, Type, B}}, #transport{parent = Pid}
@@ -500,7 +501,7 @@ transition({diameter, {tls, Ref, Type, B}}, #transport{parent = Pid}
         = tls_handshake(Type, B, S),
     Pid ! {diameter, {tls, Ref}},
     setopts(M, Sock),
-    NS#transport{ssl = B};
+    start_fragment_timer(NS#transport{ssl = B});
 
 transition({C, Sock}, #transport{socket = Sock,
                                  ssl = B})
@@ -533,9 +534,8 @@ transition({diameter, {close, Pid}}, #transport{parent = Pid,
     stop;
 
 %% Timeout for reception of outstanding packets.
-transition({timeout, _TRef, flush}, #transport{timeout = Tmo} = S) ->
-    erlang:start_timer(Tmo, self(), flush),
-    flush(S);
+transition({timeout, TRef, flush}, #transport{tref = TRef} = S) ->
+    flush(S#transport{tref = false});
 
 %% Request for the local port number.
 transition({resolve_port, Pid}, #transport{socket = Sock,
@@ -684,19 +684,31 @@ bin(Bin)
 %% since all messages with length problems are discarded this should
 %% also eventually lead to watchdog failover.
 
+%% No fragment to flush.
+flush(#transport{frag = <<>>} = S) ->
+    S;
+
 %% Messages have been received since last timer expiry.
 flush(#transport{flush = false} = S) ->
-    S#transport{flush = true};
-
-%% No fragment to flush.
-flush(#transport{frag = <<>>}) ->
-    ok;
+    start_fragment_timer(S#transport{flush = true});
 
 %% No messages since last expiry.
 flush(#transport{frag = Frag, parent = Pid} = S) ->
     diameter_peer:recv(Pid, bin(Frag)),
     S#transport{frag = <<>>}.
 
+%% start_fragment_timer/1
+%%
+%% Start a timer only if there's none running and a message to flush.
+
+start_fragment_timer(#transport{frag = B, tref = TRef} = S)
+  when B == <<>>;
+       TRef /= false ->
+    S;
+
+start_fragment_timer(#transport{timeout = Tmo} = S) ->
+    S#transport{tref = erlang:start_timer(Tmo, self(), flush)}.
+
 %% accept/2
 
 accept(ssl, LSock) ->
-- 
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