From 471fe60108f1b3fa72b7cb8439884f0df57b475e Mon Sep 17 00:00:00 2001
From: Uriziel <urizieli@gmail.com>
Date: Sun, 13 Oct 2013 23:32:17 +0200
Subject: [PATCH] Added ping service

---
 syncplay/protocols.py | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/syncplay/protocols.py b/syncplay/protocols.py
index 3f058d9..f6b01d5 100644
--- a/syncplay/protocols.py
+++ b/syncplay/protocols.py
@@ -402,3 +402,32 @@ class SyncServerProtocol(JSONCommandProtocol):
     def sendError(self, message):
         self.sendMessage({"Error": {"message": message}})
 
+
+class PingService(object):
+
+    def __init__(self):
+        self._rtt = 0
+        self._t0 = None
+        self._fdDiff = 0
+        self._fd = 0
+
+    def newTimestamp(self):
+        return time.time()
+
+    def receiveMessage(self, timestamp, senderRtt):
+        prevRtt = self._rtt
+        self._rtt = time.time() - timestamp
+        if(self._t0 == None):
+            self._t0 = self._rtt / 2
+            return
+        if(senderRtt <= 0):
+            return
+        self._fdDiff = self._fdDiff + (prevRtt - senderRtt)
+        self._fd = self._t0 - self._fdDiff
+
+    def getLastForwardDelay(self):
+        return self._fd
+
+    def getRtt(self):
+        return self._rtt
+