def _reserve_resource(resource_id):
"""
When you wish you queue a task that needs to reserve a resource, you should make a call to this
function() first, queueing it in the RESOURCE_MANAGER_QUEUE. This Task will return the
name of the queue you should put your task in.
Please be sure to also add a task to run _queue_release_resource() in the same queue name that
this function returns to you. It is important that _release_resource() is called after your task
is completed, regardless of whether your task completes successfully or not.
:param resource_id: The name of the resource you wish to reserve for your task. The system
will ensure that no other tasks that want that same reservation will run
concurrently with yours.
:type resource_id: basestring
:return: The name of a queue that you should put your task in
:rtype: basestring
"""
reserved_resource = resources.get_or_create_reserved_resource(resource_id)
if reserved_resource.assigned_queue is None:
# The assigned_queue will be None if the reserved_resource was just created, so we'll
# need to assign a queue to it
reserved_resource.assigned_queue = resources.get_least_busy_available_queue().name
reserved_resource.save()
else:
# The assigned_queue is set, so we just need to increment the num_reservations on the
# reserved resource
reserved_resource.increment_num_reservations()
AvailableQueue(reserved_resource.assigned_queue).increment_num_reservations()
return reserved_resource.assigned_queue
def _reserve_resource(resource_id):
"""
When you wish you queue a task that needs to reserve a resource, you should make a call to this
function() first, queueing it in the RESOURCE_MANAGER_QUEUE. This Task will return the
name of the queue you should put your task in.
Please be sure to also add a task to run _queue_release_resource() in the same queue name that
this function returns to you. It is important that _release_resource() is called after your task
is completed, regardless of whether your task completes successfully or not.
:param resource_id: The name of the resource you wish to reserve for your task. The system
will ensure that no other tasks that want that same reservation will run
concurrently with yours.
:type resource_id: basestring
:return: The name of a queue that you should put your task in
:rtype: basestring
"""
reserved_resource = resources.get_or_create_reserved_resource(resource_id)
if reserved_resource.assigned_queue is None:
# The assigned_queue will be None if the reserved_resource was just created, so we'll
# need to assign a queue to it
# get the dedicated queue name by adding '.dq' to the end of the worker name
reserved_resource.assigned_queue = resources.get_least_busy_available_queue().name + '.dq'
reserved_resource.save()
else:
# The assigned_queue is set, so we just need to increment the num_reservations on the
# reserved resource
reserved_resource.increment_num_reservations()
# Remove the '.dq' from the queue name to get the worker name
worker_name = reserved_resource.assigned_queue.rstrip('.dq')
aqc = Criteria(filters={'_id': worker_name})
aq_list = list(resources.filter_available_queues(aqc))
aq_list[0].increment_num_reservations()
return reserved_resource.assigned_queue
def test_picks_least_busy_queue(self):
"""
Test that the function picks the least busy queue.
"""
# Set up three available queues, with the least busy one in the middle so that we can
# demonstrate that it did pick the least busy and not the last or first.
available_queue_1 = AvailableQueue('busy_queue', 7)
available_queue_1.save()
available_queue_2 = AvailableQueue('less_busy_queue', 3)
available_queue_2.save()
available_queue_3 = AvailableQueue('most_busy_queue', 10)
available_queue_3.save()
queue = resources.get_least_busy_available_queue()
self.assertEqual(type(queue), AvailableQueue)
self.assertEqual(queue.num_reservations, 3)
self.assertEqual(queue.name, 'less_busy_queue')