From 444095d3740e5d6c8f21d4c9121bd8d7a100e35d Mon Sep 17 00:00:00 2001
From: bustico
Date: Mon, 6 Jul 2009 12:15:37 +0000
Subject: put tcp socket in no_delay mode to reduce latency

---
 Ivy.pm | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

(limited to 'Ivy.pm')

diff --git a/Ivy.pm b/Ivy.pm
index ad0ec41..e57f4d6 100644
--- a/Ivy.pm
+++ b/Ivy.pm
@@ -212,6 +212,18 @@ use constant CALL_BY_REF => 1;
 use constant BIND_ONCE => 2;
 use constant MAX_TIMOUT => 1000;
 
+
+#  TCP_NODELAY is for a specific purpose; to disable the Nagle buffering
+#    algorithm. It should only be set for applications that send frequent
+#    small bursts of information without getting an immediate response,
+#    where timely delivery of data is required (the canonical example is
+#    mouse movements).
+use constant TCP_NO_DELAY_ACTIVATED => 1;
+
+
+#    Since Ivy is most of the time used to send events, we will priviligiate
+#    lag over throughtput, so  _TCP_NO_DELAY_ACTIVATED is set to 1
+use constant MAX_TIMOUT => 1000;
 # pour pouvoir employer les regexps perl. Attention lors de l'utilisation
 # ne pas mettre un \n dans une chaine entre "" car l'\n sera interprete.
 use constant REG_PERLISSISME => ('w' => '[a-zA-Z0-9_]',
@@ -1400,6 +1412,8 @@ sub _getBonjour ($)
       carp "Warning[$appName] Can't set flags for the socket: $!\n";
       return;
     }
+    $appSock->sockopt(Socket::TCP_NODELAY, TCP_NO_DELAY_ACTIVATED);
+
 
     binmode ($appSock);
     # on cree une entree pour $appSock dans la liste des regexp
@@ -1443,8 +1457,10 @@ sub _getConnections ($)
     unless (fcntl($appSock, F_SETFL, $flags | O_NONBLOCK)) {
       carp "Can't set flags for the socket: $!\n";
       return;
-      binmode ($appSock);
     }
+
+    $appSock->sockopt(Socket::TCP_NODELAY, TCP_NO_DELAY_ACTIVATED);
+    binmode ($appSock);
   }
 
 
@@ -1704,7 +1720,11 @@ sub _getMessages ($$)
 	$self->_pong ($appSock, $id);
       }
 
-      elsif ($type == PONG) {
+
+# le traitement est basique, ne fonctionne que si le recepteur traite le pong
+# avant qu'il n'envoie un deuxieme ping. Si les pings sont envoyés trop rapidement,
+# aucun pong ne sera émit.
+     elsif ($type == PONG) {
 	if (exists $self->[pongQueue]->{$appSock}) {
 	  my ($pingid, $time, $funcRef) =  @{$self->[pongQueue]->{$appSock}};
 #	  printf ("DBG>>> stocked Id = $pingid;; message id = $id\n");
@@ -2860,9 +2880,9 @@ Send a suicide to the application named $to.
 =item B<ping>
 
  $ivyobj->ping($to, $timeout);
- Ivy::ping($to, $timeout);
+ Ivy::ping($to, \&callBack);
 
-Send a ping message and wait until timeout to receive a pong.
+Send a ping message, callBack will be called on response.
 
 =item B<after>
 
-- 
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