Add a few docstrings

neo/lib/protocol.py

@@ -1469,7 +1469,13 @@ class AddObject(Packet):
 
 class Replicate(Packet):
     """
+    Notify a storage node to replicate partitions up to given 'tid'
+    and from given sources.
     M -> S
+
+    - upstream_name: replicate from an upstream cluster
+    - address: address of the source storage node, or None if there's no new
+               data up to 'tid' for the given partition
     """
     _fmt = PStruct('replicate',
         PTID('tid'),

neo/tests/threaded/__init__.py

@@ -329,6 +329,13 @@ class ClientApplication(Node, neo.client.app.Application):
         self.em._lock = threading.Lock()
 
     def setPoll(self, master=False):
+        """Set whether this thread runs freely or not
+
+        The client must be switched in master mode (by passing True) before
+        doing any synchronous call to the ZODB, otherwise the test deadlocks.
+        When called with master=False, the cluster is suspended and will only
+        processe packets upon NEOCluster.tic() calls.
+        """
         if master:
             self.em._timeout = 1
             if not self.em._lock.acquire(0):

neo/tests/threaded/testReplication.py

@@ -263,6 +263,11 @@ class ReplicationTests(NEOThreadedTest):
 
     @backup_test()
     def testBackupDelayedUnlockTransaction(self, backup):
+        """
+        Check that a backup storage node is put on hold by upstream if
+        the requested transaction is still locked. Such case happens when
+        the backup cluster reacts very quickly to a new transaction.
+        """
         upstream = backup.upstream
         with upstream.master.filterConnection(upstream.storage) as f:
             f.add(lambda conn, packet: