making connection consistency more configurable

cqlengine/connection.py

@@ -27,7 +27,7 @@ _max_connections = 10
 # global connection pool
 connection_pool = None
 
-def setup(hosts, username=None, password=None, max_connections=10, default_keyspace=None):
+def setup(hosts, username=None, password=None, max_connections=10, default_keyspace=None, consistency='ONE'):
     """
     Records the hosts and connects to one of them
 
@@ -55,16 +55,17 @@ def setup(hosts, username=None, password=None, max_connections=10, default_keysp
     if not _hosts:
         raise CQLConnectionError("At least one host required")
 
-    connection_pool = ConnectionPool(_hosts, username, password)
+    connection_pool = ConnectionPool(_hosts, username, password, consistency)
 
 
 class ConnectionPool(object):
     """Handles pooling of database connections."""
 
-    def __init__(self, hosts, username=None, password=None):
+    def __init__(self, hosts, username=None, password=None, consistency=None):
         self._hosts = hosts
         self._username = username
         self._password = password
+        self._consistency = consistency
 
         self._queue = Queue.Queue(maxsize=_max_connections)
 
@@ -120,7 +121,13 @@ class ConnectionPool(object):
 
         for host in hosts:
             try:
-                new_conn = cql.connect(host.name, host.port, user=self._username, password=self._password)
+                new_conn = cql.connect(
+                    host.name,
+                    host.port,
+                    user=self._username,
+                    password=self._password,
+                    consistency_level=self._consistency
+                )
                 new_conn.set_cql_version('3.0.0')
                 return new_conn
             except Exception as e:

docs/topics/connection.rst

@@ -7,11 +7,20 @@ Connection
 The setup function in `cqlengine.connection` records the Cassandra servers to connect to.
 If there is a problem with one of the servers, cqlengine will try to connect to each of the other connections before failing.
 
-.. function:: setup(hosts [, username=None, password=None])
+.. function:: setup(hosts [, username=None, password=None, consistency='ONE'])
 
     :param hosts: list of hosts, strings in the <hostname>:<port>, or just <hostname>
     :type hosts: list
 
+    :param username: a username, if required
+    :type username: str
+
+    :param password: a password, if required
+    :type password: str
+
+    :param consistency: the consistency level of the connection, defaults to 'ONE'
+    :type consistency: str
+
     Records the hosts and connects to one of them
 
 See the example at :ref:`getting-started`