use absolute time

sess.go

@@ -183,7 +183,7 @@ func newUDPSession(conv uint32, dataShards, parityShards int, l *Listener, conn
 	}
 
 	// start per-session updater
-	SystemTimedSched.Put(sess.update, 0)
+	SystemTimedSched.Put(sess.update, time.Now())
 
 	currestab := atomic.AddUint64(&DefaultSnmp.CurrEstab, 1)
 	maxconn := atomic.LoadUint64(&DefaultSnmp.MaxConn)
@@ -593,7 +593,7 @@ func (s *UDPSession) update() {
 		s.uncork()
 		s.mu.Unlock()
 		// self-synchronized timed scheduling
-		SystemTimedSched.Put(s.update, time.Duration(interval)*time.Millisecond)
+		SystemTimedSched.Put(s.update, time.Now().Add(time.Duration(interval)*time.Millisecond))
 	}
 }
 

timedsched.go

@@ -125,10 +125,10 @@ func (ts *TimedSched) prepend() {
 	}
 }
 
-// Put a function awaiting to be executed
-func (ts *TimedSched) Put(f func(), duration time.Duration) {
+// Put a function 'f' awaiting to be executed at 'deadline'
+func (ts *TimedSched) Put(f func(), deadline time.Time) {
 	ts.prependLock.Lock()
-	ts.prependTasks = append(ts.prependTasks, timedFunc{f, time.Now().Add(duration)})
+	ts.prependTasks = append(ts.prependTasks, timedFunc{f, deadline})
 	ts.prependLock.Unlock()
 
 	select {