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Third party integrations

Celery

Here’s how, in substance, CQLengine can be plugged to Celery:

from celery import Celery
from celery.signals import worker_process_init, beat_init
from cassandra.cqlengine import connection
from cassandra.cqlengine.connection import (
    cluster as cql_cluster, session as cql_session)

def cassandra_init(**kwargs):
    """ Initialize a clean Cassandra connection. """
    if cql_cluster is not None:
        cql_cluster.shutdown()
    if cql_session is not None:
        cql_session.shutdown()
    connection.setup()

# Initialize worker context for both standard and periodic tasks.
worker_process_init.connect(cassandra_init)
beat_init.connect(cassandra_init)

app = Celery()

uWSGI

This is the code required for proper connection handling of CQLengine for a uWSGI-run application:

from cassandra.cqlengine import connection
from cassandra.cqlengine.connection import (
    cluster as cql_cluster, session as cql_session)

try:
    from uwsgidecorators import postfork
except ImportError:
    # We're not in a uWSGI context, no need to hook Cassandra session
    # initialization to the postfork event.
    pass
else:
    @postfork
    def cassandra_init(**kwargs):
        """ Initialize a new Cassandra session in the context.

        Ensures that a new session is returned for every new request.
        """
        if cql_cluster is not None:
            cql_cluster.shutdown()
        if cql_session is not None:
            cql_session.shutdown()
        connection.setup()