# Copyright DataStax, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from collections import defaultdict
import logging
import six
import threading
from cassandra.cluster import Cluster, _NOT_SET, NoHostAvailable, UserTypeDoesNotExist, ConsistencyLevel
from cassandra.query import SimpleStatement, dict_factory
from cassandra.cqlengine import CQLEngineException
from cassandra.cqlengine.statements import BaseCQLStatement
log = logging.getLogger(__name__)
NOT_SET = _NOT_SET # required for passing timeout to Session.execute
cluster = None
session = None
# connections registry
DEFAULT_CONNECTION = object()
_connections = {}
# Because type models may be registered before a connection is present,
# and because sessions may be replaced, we must register UDTs here, in order
# to have them registered when a new session is established.
udt_by_keyspace = defaultdict(dict)
def format_log_context(msg, connection=None, keyspace=None):
"""Format log message to add keyspace and connection context"""
connection_info = connection or 'DEFAULT_CONNECTION'
if keyspace:
msg = '[Connection: {0}, Keyspace: {1}] {2}'.format(connection_info, keyspace, msg)
else:
msg = '[Connection: {0}] {1}'.format(connection_info, msg)
return msg
class UndefinedKeyspaceException(CQLEngineException):
pass
class Connection(object):
"""CQLEngine Connection"""
name = None
hosts = None
consistency = None
retry_connect = False
lazy_connect = False
lazy_connect_lock = None
cluster_options = None
cluster = None
session = None
def __init__(self, name, hosts, consistency=None,
lazy_connect=False, retry_connect=False, cluster_options=None):
self.hosts = hosts
self.name = name
self.consistency = consistency
self.lazy_connect = lazy_connect
self.retry_connect = retry_connect
self.cluster_options = cluster_options if cluster_options else {}
self.lazy_connect_lock = threading.RLock()
@classmethod
def from_session(cls, name, session):
instance = cls(name=name, hosts=session.hosts)
instance.cluster, instance.session = session.cluster, session
instance.setup_session()
return instance
def setup(self):
"""Setup the connection"""
global cluster, session
if 'username' in self.cluster_options or 'password' in self.cluster_options:
raise CQLEngineException("Username & Password are now handled by using the native driver's auth_provider")
if self.lazy_connect:
return
self.cluster = Cluster(self.hosts, **self.cluster_options)
try:
self.session = self.cluster.connect()
log.debug(format_log_context("connection initialized with internally created session", connection=self.name))
except NoHostAvailable:
if self.retry_connect:
log.warning(format_log_context("connect failed, setting up for re-attempt on first use", connection=self.name))
self.lazy_connect = True
raise
if self.consistency is not None:
self.session.default_consistency_level = self.consistency
if DEFAULT_CONNECTION in _connections and _connections[DEFAULT_CONNECTION] == self:
cluster = _connections[DEFAULT_CONNECTION].cluster
session = _connections[DEFAULT_CONNECTION].session
self.setup_session()
def setup_session(self):
self.session.row_factory = dict_factory
enc = self.session.encoder
enc.mapping[tuple] = enc.cql_encode_tuple
_register_known_types(self.session.cluster)
def handle_lazy_connect(self):
# if lazy_connect is False, it means the cluster is setup and ready
# No need to acquire the lock
if not self.lazy_connect:
return
with self.lazy_connect_lock:
# lazy_connect might have been set to False by another thread while waiting the lock
# In this case, do nothing.
if self.lazy_connect:
log.debug(format_log_context("Lazy connect enabled", connection=self.name))
self.lazy_connect = False
self.setup()
[docs] def register_connection(name, hosts=None, consistency=None, lazy_connect=False,
retry_connect=False, cluster_options=None, default=False,
session=None):
"""
Add a connection to the connection registry. ``hosts`` and ``session`` are
mutually exclusive, and ``consistency``, ``lazy_connect``,
``retry_connect``, and ``cluster_options`` only work with ``hosts``. Using
``hosts`` will create a new :class:`cassandra.cluster.Cluster` and
:class:`cassandra.cluster.Session`.
:param list hosts: list of hosts, (``contact_points`` for :class:`cassandra.cluster.Cluster`).
:param int consistency: The default :class:`~.ConsistencyLevel` for the
registered connection's new session. Default is the same as
:attr:`.Session.default_consistency_level`. For use with ``hosts`` only;
will fail when used with ``session``.
:param bool lazy_connect: True if should not connect until first use. For
use with ``hosts`` only; will fail when used with ``session``.
:param bool retry_connect: True if we should retry to connect even if there
was a connection failure initially. For use with ``hosts`` only; will
fail when used with ``session``.
:param dict cluster_options: A dict of options to be used as keyword
arguments to :class:`cassandra.cluster.Cluster`. For use with ``hosts``
only; will fail when used with ``session``.
:param bool default: If True, set the new connection as the cqlengine
default
:param Session session: A :class:`cassandra.cluster.Session` to be used in
the created connection.
"""
if name in _connections:
log.warning("Registering connection '{0}' when it already exists.".format(name))
if session is not None:
invalid_config_args = (hosts is not None or
consistency is not None or
lazy_connect is not False or
retry_connect is not False or
cluster_options is not None)
if invalid_config_args:
raise CQLEngineException(
"Session configuration arguments and 'session' argument are mutually exclusive"
)
conn = Connection.from_session(name, session=session)
conn.setup_session()
else: # use hosts argument
if consistency is None:
consistency = ConsistencyLevel.LOCAL_ONE
conn = Connection(
name, hosts=hosts,
consistency=consistency, lazy_connect=lazy_connect,
retry_connect=retry_connect, cluster_options=cluster_options
)
conn.setup()
_connections[name] = conn
if default:
set_default_connection(name)
return conn
[docs] def unregister_connection(name):
global cluster, session
if name not in _connections:
return
if DEFAULT_CONNECTION in _connections and _connections[name] == _connections[DEFAULT_CONNECTION]:
del _connections[DEFAULT_CONNECTION]
cluster = None
session = None
conn = _connections[name]
if conn.cluster:
conn.cluster.shutdown()
del _connections[name]
log.debug("Connection '{0}' has been removed from the registry.".format(name))
[docs] def set_default_connection(name):
global cluster, session
if name not in _connections:
raise CQLEngineException("Connection '{0}' doesn't exist.".format(name))
log.debug("Connection '{0}' has been set as default.".format(name))
_connections[DEFAULT_CONNECTION] = _connections[name]
cluster = _connections[name].cluster
session = _connections[name].session
def get_connection(name=None):
if not name:
name = DEFAULT_CONNECTION
if name not in _connections:
raise CQLEngineException("Connection name '{0}' doesn't exist in the registry.".format(name))
conn = _connections[name]
conn.handle_lazy_connect()
return conn
[docs] def default():
"""
Configures the default connection to localhost, using the driver defaults
(except for row_factory)
"""
try:
conn = get_connection()
if conn.session:
log.warning("configuring new default connection for cqlengine when one was already set")
except:
pass
register_connection('default', hosts=None, default=True)
log.debug("cqlengine connection initialized with default session to localhost")
[docs] def set_session(s):
"""
Configures the default connection with a preexisting :class:`cassandra.cluster.Session`
Note: the mapper presently requires a Session :attr:`~.row_factory` set to ``dict_factory``.
This may be relaxed in the future
"""
try:
conn = get_connection()
except CQLEngineException:
# no default connection set; initalize one
register_connection('default', session=s, default=True)
conn = get_connection()
if conn.session:
log.warning("configuring new default connection for cqlengine when one was already set")
if s.row_factory is not dict_factory:
raise CQLEngineException("Failed to initialize: 'Session.row_factory' must be 'dict_factory'.")
conn.session = s
conn.cluster = s.cluster
# Set default keyspace from given session's keyspace
if conn.session.keyspace:
from cassandra.cqlengine import models
models.DEFAULT_KEYSPACE = conn.session.keyspace
conn.setup_session()
log.debug("cqlengine default connection initialized with %s", s)
[docs] def setup(
hosts,
default_keyspace,
consistency=None,
lazy_connect=False,
retry_connect=False,
**kwargs):
"""
Setup a the driver connection used by the mapper
:param list hosts: list of hosts, (``contact_points`` for :class:`cassandra.cluster.Cluster`)
:param str default_keyspace: The default keyspace to use
:param int consistency: The global default :class:`~.ConsistencyLevel` - default is the same as :attr:`.Session.default_consistency_level`
:param bool lazy_connect: True if should not connect until first use
:param bool retry_connect: True if we should retry to connect even if there was a connection failure initially
:param \*\*kwargs: Pass-through keyword arguments for :class:`cassandra.cluster.Cluster`
"""
from cassandra.cqlengine import models
models.DEFAULT_KEYSPACE = default_keyspace
register_connection('default', hosts=hosts, consistency=consistency, lazy_connect=lazy_connect,
retry_connect=retry_connect, cluster_options=kwargs, default=True)
def execute(query, params=None, consistency_level=None, timeout=NOT_SET, connection=None):
conn = get_connection(connection)
if not conn.session:
raise CQLEngineException("It is required to setup() cqlengine before executing queries")
if isinstance(query, SimpleStatement):
pass #
elif isinstance(query, BaseCQLStatement):
params = query.get_context()
query = SimpleStatement(str(query), consistency_level=consistency_level, fetch_size=query.fetch_size)
elif isinstance(query, six.string_types):
query = SimpleStatement(query, consistency_level=consistency_level)
log.debug(format_log_context(query.query_string, connection=connection))
result = conn.session.execute(query, params, timeout=timeout)
return result
def get_session(connection=None):
conn = get_connection(connection)
return conn.session
def get_cluster(connection=None):
conn = get_connection(connection)
if not conn.cluster:
raise CQLEngineException("%s.cluster is not configured. Call one of the setup or default functions first." % __name__)
return conn.cluster
def register_udt(keyspace, type_name, klass, connection=None):
udt_by_keyspace[keyspace][type_name] = klass
try:
cluster = get_cluster(connection)
except CQLEngineException:
cluster = None
if cluster:
try:
cluster.register_user_type(keyspace, type_name, klass)
except UserTypeDoesNotExist:
pass # new types are covered in management sync functions
def _register_known_types(cluster):
from cassandra.cqlengine import models
for ks_name, name_type_map in udt_by_keyspace.items():
for type_name, klass in name_type_map.items():
try:
cluster.register_user_type(ks_name or models.DEFAULT_KEYSPACE, type_name, klass)
except UserTypeDoesNotExist:
pass # new types are covered in management sync functions