L2SS-244: Detect if threads die on us.

devices/clients/sst_client.py

@@ -63,6 +63,13 @@ class sst_client(CommClient):
 
         return super().connect()
 
+    def ping(self):
+        if not self.sst.isAlive():
+            raise Exception("SST thread died unexpectedly")
+
+        if not self.udp.isAlive():
+            raise Exception("UDP thread died unexpectedly")
+
     def disconnect(self):
         # explicit disconnect, instead of waiting for the GC to kick in after "del" below
         self.sst.disconnect()