improve error handling on client connections

- send a heartbeat, if no events for 5 sec.
  an interrupted connection (not closed by the other end) may
  not be detected for a long time when nothing is sent
+ make the error reply on a non SECoPEror more verbose
  e.g. "KeyError('foo')" instead of just "foo"
+ allow cfg file without nodeinterface
+ shorter logger name in HasIodev

Change-Id: I6b1ff23f9bf8c96feb25af44935596437b7d726f
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/23098
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/client/__init__.py

@@ -30,10 +30,11 @@ from collections import defaultdict
 
 from secop.lib import mkthread, formatExtendedTraceback, formatExtendedStack
 from secop.lib.asynconn import AsynConn, ConnectionClosed
-from secop.datatypes import get_datatype, EnumType
+from secop.datatypes import get_datatype
 from secop.protocol.interface import encode_msg_frame, decode_msg
 from secop.protocol.messages import REQUEST2REPLY, ERRORPREFIX, EVENTREPLY, WRITEREQUEST, WRITEREPLY, \
-    READREQUEST, READREPLY, IDENTREQUEST, IDENTPREFIX, ENABLEEVENTSREQUEST, COMMANDREQUEST, DESCRIPTIONREQUEST
+    READREQUEST, READREPLY, IDENTREQUEST, IDENTPREFIX, ENABLEEVENTSREQUEST, COMMANDREQUEST, \
+    DESCRIPTIONREQUEST, HEARTBEATREQUEST
 import secop.errors
 import secop.params
 
@@ -290,13 +291,19 @@ class SecopClient(ProxyClient):
         self.disconnect(False)
 
     def __rxthread(self):
+        noactivity = 0
         while self._running:
             try:
                 reply = self.io.readline()
                 if reply is None:
+                    noactivity += 1
+                    if noactivity % 5 == 0:
+                        # send ping to check if the connection is still alive
+                        self.queue_request(HEARTBEATREQUEST, str(noactivity))
                     continue
             except ConnectionClosed:
                 break
+            noactivity = 0
             action, ident, data = decode_msg(reply)
             if ident == '.':
                 ident = None