Add Consumer.setup() method for datasync

rattail/datasync/consumers.py

@@ -40,6 +40,11 @@ class DataSyncConsumer(object):
         self.key = key
         self.dbkey = dbkey
 
+    def setup(self):
+        """
+        This method is called when the consumer thread is first started.
+        """
+
     def process_changes(self, session, changes):
         """
         Process (consume) a set of changes.

rattail/datasync/daemon.py

@@ -179,6 +179,10 @@ def consume_changes(profile, consumers):
     """
     from rattail.db import Session, model
 
+    # Let consumers do any setup they need.
+    for consumer in consumers:
+        consumer.setup()
+
     def process(session, consumer, changes):
         try:
             consumer.process_changes(session, changes)