Add Kegboard.wait_for_ping().

python/bin/kegboard-info.py

@@ -39,13 +39,7 @@ def _MainLoop(self):
     board.open()
     self._logger.debug('Got kegboard: %s' % board)
 
-    msg = None
-    for i in xrange(4):
-      board.ping()
-      candidate = board.read_message(timeout=3)
-      if isinstance(candidate, kegboard.HelloMessage):
-        msg = candidate
-
+    msg = board.wait_for_ping()
     if not msg:
       print 'Gave up pinging kegboard!'
       sys.exit(1)

python/bin/set-kegboard-serialnumber

@@ -32,13 +32,7 @@ class KegboardMonitorApp(app.App):
     pass
 
   def _wait_for_response(self, board):
-    msg = None
-    for i in xrange(4):
-      board.ping()
-      msg = board.read_message(timeout=3)
-      if isinstance(msg, kegboard.HelloMessage):
-        break
-
+    msg = board.wait_for_ping()
     if not msg:
       print 'Gave up pinging kegboard!'
       sys.exit(1)

python/kegbot/kegboard/kegboard.py

@@ -210,6 +210,15 @@ def read_message(self, timeout=None, interval=0.1):
         return None
       time.sleep(interval)
 
+  def wait_for_ping(self, attempts=5):
+    self.drain_messages()
+    for i in xrange(attempts):
+      self.ping()
+      messages = [self.read_message(timeout=1)] + self.drain_messages()
+      for message in messages:
+        if isinstance(message, HelloMessage):
+          return message
+
   def write_message(self, message):
     """Send a message to the device."""
     self._assert_open()