proper logging, add signal handler for graceful termination

secop.py

@@ -3,6 +3,7 @@ import os
 import json
 import time
 import socket
+import logging
 from collections import namedtuple
 from select import select
 from streams import Stream, Base, StreamDead
@@ -112,7 +113,7 @@ class SecopStream(Stream):
 
         except Exception as e:
             # probably other end closed
-            print(self.uri, repr(e))
+            logging.info('%r on %s', e, self.uri)
 
 
 SECOP_UDP_PORT = 10767
@@ -154,7 +155,7 @@ class ScanReply(UdpStream):
             sock.sendto(json.dumps(dict(SECoP='discover')).encode('utf-8'),
                         ('255.255.255.255', SECOP_UDP_PORT))
         except OSError as e:
-            print('could not send the broadcast:', e)
+            logging.info('could not send the broadcast %r:', e)
         self.socket = sock
         self.select_read[sock.fileno()] = self
 
@@ -193,12 +194,11 @@ class TrySecopConnect(Base):
             try:
                 self.socket.sendall(b'*IDN?\n')
                 self.idn_sent = True
-                print('SEND IDN', self.uri)
+                logging.debug('SEND IDN %s', self.uri)
                 self.select_read[self.fno] = self
                 return
             except Exception as e:
-                print('NO CONN TO', self.uri)
-                print(e)
+                logging.info('NO CONN TO %s %r', self.uri, e)
         else:
             reply = b''
             try:
@@ -206,12 +206,12 @@ class TrySecopConnect(Base):
                 if chunk:
                     self.idn += chunk
                     if b'SECoP' in self.idn:
-                        print('CONN TO', self.uri)
+                        logging.info('connected to %s', self.uri)
                         yield SecopStream, self.uri, {'stream': self.uri}
                     if b'\n' not in self.idn:
                         return
-            except Exception as e:
-                print(e)
+            except Exception:
+                logging.exception('receiving')
         self.select_read.pop(self.fno)