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Fixed a bug where pre-emptive priorities did not work with zero servers #210

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Merged
geraintpalmer merged 1 commit into from
Feb 7, 2023
+150 −1
Merged

Fixed a bug where pre-emptive priorities did not work with zero servers #210

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2 changes: 1 addition & 1 deletion ciw/node.py
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ def begin_service_if_possible_accept(self, next_individual):
self.decide_class_change(next_individual)

free_server = self.find_free_server(next_individual)
if free_server is None and isinf(self.c) is False:
if free_server is None and isinf(self.c) is False and self.c > 0:
self.decide_preempt(next_individual)
if free_server is not None or isinf(self.c):
if isinf(self.c) is False:
Expand Down
149 changes: 149 additions & 0 deletions ciw/tests/test_scheduling.py
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Original file line number Diff line number Diff line change
Expand Up @@ -375,3 +375,152 @@ def test_preemptive_schedules_resume_options(self):
self.assertEqual(r1.service_end_date, 29)
self.assertEqual(r1.service_time, 20)
self.assertEqual(r1.waiting_time, 8)

def test_priority_preemption_when_zero_servers(self):
"""
Test whether pre-emptive priorities and server schedules where there are zero servers work well together.

We will show two scenarios.
- The first where the one server goes off and back on duty while there are no customers present.
- The second where the server goes off duty but back on duty while there are customers waiting.
"""
# First scenario
N = ciw.create_network(
arrival_distributions={
'Class 0': [ciw.dists.Deterministic(7)],
'Class 1': [ciw.dists.Deterministic(13)]
},
service_distributions={
'Class 0': [ciw.dists.Deterministic(5.5)],
'Class 1': [ciw.dists.Deterministic(1.5)]
},
number_of_servers=[[[1, 20.3], [0, 20.6], [1, 100]]],
priority_classes=({
'Class 0': 1,
'Class 1': 0
}, ['continue'])
)

Q = ciw.Simulation(N)
Q.simulate_until_max_time(35)

recs = Q.get_all_records()
# Individual 1
self.assertEqual(recs[0].id_number, 1)
self.assertEqual(recs[0].customer_class, 0)
self.assertEqual(recs[0].arrival_date, 7)
self.assertEqual(recs[0].service_start_date, 7)
self.assertEqual(recs[0].service_end_date, 12.5)
self.assertEqual(recs[0].record_type, 'service')
# Individual 2
self.assertEqual(recs[1].id_number, 2)
self.assertEqual(recs[1].customer_class, 1)
self.assertEqual(recs[1].arrival_date, 13)
self.assertEqual(recs[1].service_start_date, 13)
self.assertEqual(recs[1].service_end_date, 14.5)
self.assertEqual(recs[1].record_type, 'service')
# Individual 3
self.assertEqual(recs[2].id_number, 3)
self.assertEqual(recs[2].customer_class, 0)
self.assertEqual(recs[2].arrival_date, 14)
self.assertEqual(recs[2].service_start_date, 14.5)
self.assertEqual(recs[2].service_end_date, 20)
self.assertEqual(recs[2].record_type, 'service')
# Individual 5
self.assertEqual(recs[3].id_number, 5)
self.assertEqual(recs[3].customer_class, 1)
self.assertEqual(recs[3].arrival_date, 26)
self.assertEqual(recs[3].service_start_date, 26)
self.assertEqual(recs[3].service_end_date, 27.5)
self.assertEqual(recs[3].record_type, 'service')
# Individual 4's interrupted service
self.assertEqual(recs[4].id_number, 4)
self.assertEqual(recs[4].customer_class, 0)
self.assertEqual(recs[4].arrival_date, 21)
self.assertEqual(recs[4].service_start_date, 21)
self.assertEqual(recs[4].record_type, 'interrupted service')
# Individual 4's resumed service
self.assertEqual(recs[5].id_number, 4)
self.assertEqual(recs[5].customer_class, 0)
self.assertEqual(recs[5].arrival_date, 21)
self.assertEqual(recs[5].service_start_date, 27.5)
self.assertEqual(recs[5].service_end_date, 28)
self.assertEqual(recs[5].record_type, 'service')
# Individual 6
self.assertEqual(recs[6].id_number, 6)
self.assertEqual(recs[6].customer_class, 0)
self.assertEqual(recs[6].arrival_date, 28)
self.assertEqual(recs[6].service_start_date, 28)
self.assertEqual(recs[6].service_end_date, 33.5)
self.assertEqual(recs[6].record_type, 'service')

# Second scenario
N = ciw.create_network(
arrival_distributions={
'Class 0': [ciw.dists.Deterministic(7)],
'Class 1': [ciw.dists.Deterministic(13)]
},
service_distributions={
'Class 0': [ciw.dists.Deterministic(5.5)],
'Class 1': [ciw.dists.Deterministic(1.5)]
},
number_of_servers=[[[1, 20.3], [0, 22], [1, 100]]],
priority_classes=({
'Class 0': 1,
'Class 1': 0
}, ['continue'])
)

Q = ciw.Simulation(N)
Q.simulate_until_max_time(35)

recs = Q.get_all_records()
# Individual 1
self.assertEqual(recs[0].id_number, 1)
self.assertEqual(recs[0].customer_class, 0)
self.assertEqual(recs[0].arrival_date, 7)
self.assertEqual(recs[0].service_start_date, 7)
self.assertEqual(recs[0].service_end_date, 12.5)
self.assertEqual(recs[0].record_type, 'service')
# Individual 2
self.assertEqual(recs[1].id_number, 2)
self.assertEqual(recs[1].customer_class, 1)
self.assertEqual(recs[1].arrival_date, 13)
self.assertEqual(recs[1].service_start_date, 13)
self.assertEqual(recs[1].service_end_date, 14.5)
self.assertEqual(recs[1].record_type, 'service')
# Individual 3
self.assertEqual(recs[2].id_number, 3)
self.assertEqual(recs[2].customer_class, 0)
self.assertEqual(recs[2].arrival_date, 14)
self.assertEqual(recs[2].service_start_date, 14.5)
self.assertEqual(recs[2].service_end_date, 20)
self.assertEqual(recs[2].record_type, 'service')
# Individual 5
self.assertEqual(recs[3].id_number, 5)
self.assertEqual(recs[3].customer_class, 1)
self.assertEqual(recs[3].arrival_date, 26)
self.assertEqual(recs[3].service_start_date, 26)
self.assertEqual(recs[3].service_end_date, 27.5)
self.assertEqual(recs[3].record_type, 'service')
# Individual 4's interrupted service
self.assertEqual(recs[4].id_number, 4)
self.assertEqual(recs[4].customer_class, 0)
self.assertEqual(recs[4].arrival_date, 21)
self.assertEqual(recs[4].service_start_date, 22)
self.assertEqual(recs[4].record_type, 'interrupted service')
# Individual 4's resumed service
self.assertEqual(recs[5].id_number, 4)
self.assertEqual(recs[5].customer_class, 0)
self.assertEqual(recs[5].arrival_date, 21)
self.assertEqual(recs[5].service_start_date, 27.5)
self.assertEqual(recs[5].service_end_date, 29)
self.assertEqual(recs[5].record_type, 'service')
# Individual 6
self.assertEqual(recs[6].id_number, 6)
self.assertEqual(recs[6].customer_class, 0)
self.assertEqual(recs[6].arrival_date, 28)
self.assertEqual(recs[6].service_start_date, 29)
self.assertEqual(recs[6].service_end_date, 34.5)
self.assertEqual(recs[6].record_type, 'service')