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_worker(
).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()
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
reserved_resource.assigned_queue = resources.get_least_busy_worker().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()
return reserved_resource.assigned_queue
def test_ignores_queues_that_arent_workers(self):
"""
It is possible for the assigned_queue in a ReservedResource to reference a queue that is not
in the workers collection. This test ensures that this queue is properly ignored, even if it
is the most "enticing" choice.
"""
# Set up three Workers, 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.
now = datetime.utcnow()
worker_1 = Worker('busy_worker', now)
worker_2 = Worker('less_busy_worker', now)
worker_3 = Worker('most_busy_worker', now)
for worker in (worker_1, worker_2, worker_3):
worker.save()
# Now we need to make some reservations against these Workers' queues. We'll give worker_1
# 8 reservations, putting it in the middle of busyness.
rr_1 = ReservedResource(name='resource_1',
assigned_queue=worker_1.queue_name,
num_reservations=8)
# These next two will give worker_2 a total of 7 reservations, so it should get picked.
rr_2 = ReservedResource(name='resource_2',
assigned_queue=worker_2.queue_name,
num_reservations=3)
rr_3 = ReservedResource(name='resource_3',
assigned_queue=worker_2.queue_name,
num_reservations=4)
# These next three will give worker_3 a total of 9 reservations, so it should be the most
# busy.
rr_4 = ReservedResource(name='resource_4',
assigned_queue=worker_3.queue_name,
num_reservations=2)
rr_5 = ReservedResource(name='resource_5',
assigned_queue=worker_3.queue_name,
num_reservations=3)
rr_6 = ReservedResource(name='resource_6',
assigned_queue=worker_3.queue_name,
num_reservations=4)
# Now we will make a ReservedResource that references a queue that does not correspond to a
# Worker and has the lowest reservation count. This RR should be ignored.
rr_7 = ReservedResource(name='resource_7',
assigned_queue='doesnt_exist',
num_reservations=1)
for rr in (rr_1, rr_2, rr_3, rr_4, rr_5, rr_6, rr_7):
rr.save()
worker = resources.get_least_busy_worker()
self.assertEqual(type(worker), Worker)
self.assertEqual(worker.name, 'less_busy_worker')
def test_picks_least_busy_worker(self):
"""
Test that the function picks the least busy worker.
"""
# Set up three Workers, 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.
now = datetime.utcnow()
worker_1 = Worker('busy_worker', now)
worker_2 = Worker('less_busy_worker', now)
worker_3 = Worker('most_busy_worker', now)
for worker in (worker_1, worker_2, worker_3):
worker.save()
# Now we need to make some reservations against these Workers' queues. We'll give worker_1
# 8 reservations, putting it in the middle of busyness.
rr_1 = ReservedResource(name='resource_1',
assigned_queue=worker_1.queue_name,
num_reservations=8)
# These next two will give worker_2 a total of 7 reservations, so it should get picked.
rr_2 = ReservedResource(name='resource_2',
assigned_queue=worker_2.queue_name,
num_reservations=3)
rr_3 = ReservedResource(name='resource_3',
assigned_queue=worker_2.queue_name,
num_reservations=4)
# These next three will give worker_3 a total of 9 reservations, so it should be the most
# busy.
rr_4 = ReservedResource(name='resource_4',
assigned_queue=worker_3.queue_name,
num_reservations=2)
rr_5 = ReservedResource(name='resource_5',
assigned_queue=worker_3.queue_name,
num_reservations=3)
rr_6 = ReservedResource(name='resource_6',
assigned_queue=worker_3.queue_name,
num_reservations=4)
for rr in (rr_1, rr_2, rr_3, rr_4, rr_5, rr_6):
rr.save()
worker = resources.get_least_busy_worker()
self.assertEqual(type(worker), Worker)
self.assertEqual(worker.name, 'less_busy_worker')
def test_ignores_queues_that_arent_workers(self):
"""
It is possible for the assigned_queue in a ReservedResource to reference a queue that is not
in the workers collection. This test ensures that this queue is properly ignored, even if it
is the most "enticing" choice.
"""
# Set up three Workers, 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.
now = datetime.utcnow()
worker_1 = Worker('busy_worker', now)
worker_2 = Worker('less_busy_worker', now)
worker_3 = Worker('most_busy_worker', now)
for worker in (worker_1, worker_2, worker_3):
worker.save()
# Now we need to make some reservations against these Workers' queues. We'll give worker_1
# 8 reservations, putting it in the middle of busyness.
rr_1 = ReservedResource(name='resource_1', assigned_queue=worker_1.queue_name,
num_reservations=8)
# These next two will give worker_2 a total of 7 reservations, so it should get picked.
rr_2 = ReservedResource(name='resource_2', assigned_queue=worker_2.queue_name,
num_reservations=3)
rr_3 = ReservedResource(name='resource_3', assigned_queue=worker_2.queue_name,
num_reservations=4)
# These next three will give worker_3 a total of 9 reservations, so it should be the most
# busy.
rr_4 = ReservedResource(name='resource_4', assigned_queue=worker_3.queue_name,
num_reservations=2)
rr_5 = ReservedResource(name='resource_5', assigned_queue=worker_3.queue_name,
num_reservations=3)
rr_6 = ReservedResource(name='resource_6', assigned_queue=worker_3.queue_name,
num_reservations=4)
# Now we will make a ReservedResource that references a queue that does not correspond to a
# Worker and has the lowest reservation count. This RR should be ignored.
rr_7 = ReservedResource(name='resource_7', assigned_queue='doesnt_exist',
num_reservations=1)
for rr in (rr_1, rr_2, rr_3, rr_4, rr_5, rr_6, rr_7):
rr.save()
worker = resources.get_least_busy_worker()
self.assertEqual(type(worker), Worker)
self.assertEqual(worker.name, 'less_busy_worker')
def test_picks_least_busy_worker(self):
"""
Test that the function picks the least busy worker.
"""
# Set up three Workers, 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.
now = datetime.utcnow()
worker_1 = Worker('busy_worker', now)
worker_2 = Worker('less_busy_worker', now)
worker_3 = Worker('most_busy_worker', now)
for worker in (worker_1, worker_2, worker_3):
worker.save()
# Now we need to make some reservations against these Workers' queues. We'll give worker_1
# 8 reservations, putting it in the middle of busyness.
rr_1 = ReservedResource(name='resource_1', assigned_queue=worker_1.queue_name,
num_reservations=8)
# These next two will give worker_2 a total of 7 reservations, so it should get picked.
rr_2 = ReservedResource(name='resource_2', assigned_queue=worker_2.queue_name,
num_reservations=3)
rr_3 = ReservedResource(name='resource_3', assigned_queue=worker_2.queue_name,
num_reservations=4)
# These next three will give worker_3 a total of 9 reservations, so it should be the most
# busy.
rr_4 = ReservedResource(name='resource_4', assigned_queue=worker_3.queue_name,
num_reservations=2)
rr_5 = ReservedResource(name='resource_5', assigned_queue=worker_3.queue_name,
num_reservations=3)
rr_6 = ReservedResource(name='resource_6', assigned_queue=worker_3.queue_name,
num_reservations=4)
for rr in (rr_1, rr_2, rr_3, rr_4, rr_5, rr_6):
rr.save()
worker = resources.get_least_busy_worker()
self.assertEqual(type(worker), Worker)
self.assertEqual(worker.name, 'less_busy_worker')
