diff -r 4cad934aa9ce -r d72c4844e791 backup.py
--- a/backup.py	Fri Jan 19 14:42:27 2018 +0000
+++ b/backup.py	Fri Jan 19 15:41:45 2018 +0000
@@ -3,9 +3,10 @@
 #
 
 import config
+import logging
 from instance import BorgInstance
 from queue import Queue
-from threading import Thread
+from threading import Thread, Lock
 
 class Backup:
 
@@ -53,18 +54,42 @@
         self.lastrun=None
         self.borg_instance=None
         self.thread=None
+        self.lock=Lock()
 
     def __block_when_running(self):
-        assert(self.borg_instance is None and self.thread is None)
+        self.lock.acquire()
+        not_running=self.borg_instance is None and self.thread is None
+        self.lock.release()
+        assert(not_running)
 
     def __listener(self):
         for status in iter(self.borg_instance.read, None):
+            t=status['type']
+            if t=='progress_percent':
+                pass
+            elif t=='archive_progress':
+                pass
+            elif t=='progress_message':
+                pass
+            elif t=='progress_percent':
+                pass
+            elif t=='file_status':
+                pass
+            elif t=='log_message':
+                pass
+            elif t=='exception':
+                pass
+            elif t=='unparsed_error':
+                pass
             # What to do?
             print(status)
-        # What to do on error
-            #     queue.put({'identifier': instance.identifier,
-            #                'operation': instance.operation,
-            #                'status': status})
+
+        logging.info('Borg subprocess finished; terminating listener thread')
+
+        self.lock.acquire()
+        self.borg_instance=None
+        self.thread=None
+        self.lock.release()
 
     def __launch(self, queue, operation, archive_or_repository, *args):
 
@@ -95,6 +120,15 @@
         self.__launch(queue, 'prune', self.repository,
                       [{'prefix': self.archive_prefix}] + self.prune_parameters)
 
+    # TODO: Decide exact (manual) abort mechanism. Perhaps two stages
+    def abort(self):
+        self.lock.acquire()
+        if self.borg_instance:
+            self.borg_instance.terminate()
+        if self.thread:
+            self.thread.terminate()
+        self.lock.release()
+
     def join(self):
         if self.thread:
             self.thread.join()