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Improved initial session scheduling for tight schedules

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- Legacy-Id: 17904
This commit is contained in:
Sasha Romijn 2020-06-01 12:26:21 +00:00
parent 2c49e7b2dd
commit fc2693370e
1 changed files with 18 additions and 10 deletions
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28
ietf/meeting/management/commands/schedule_generator.py
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@ -140,7 +140,11 @@ class Schedule(object):
"""
Check the number of sessions, their required capacity and duration against availability.
If there are too many sessions, the generator exits.
If sessions can't fit, they are trimmed, and a fixed cost is applied.
If sessions can't fit, they are trimmed, and a fixed cost is applied.
Note that the trim is only applied on the in-memory object. The purpose
of trimming in advance is to prevent the optimiser from trying to resolve
a constraint that can never be resolved.
"""
if len(self.sessions) > len(self.timeslots):
raise CommandError('More sessions ({}) than timeslots ({})'
@ -218,6 +222,9 @@ class Schedule(object):
- Second: shortest duration that still fits
- Third: smallest room that still fits
If there are multiple options with equal value, a random one is picked.
For initial scheduling, it is not a hard requirement that the timeslot is long
or large enough, though that will be preferred due to the lower cost.
"""
if self.verbosity >= 2:
self.stdout.write('== Initial scheduler starting, scheduling {} sessions in {} timeslots =='
@ -225,14 +232,9 @@ class Schedule(object):
sessions = sorted(self.sessions, key=lambda s: s.complexity, reverse=True)
for session in sessions:
possible_slots = [t for t in self.timeslots if
t not in self.schedule.keys() and session.fits_in_timeslot(t)]
possible_slots = [t for t in self.timeslots if t not in self.schedule.keys()]
random.shuffle(possible_slots)
if not len(possible_slots):
# TODO: this needs better handling
raise Exception('No timeslot was left for {} ({})'
.format(session.group, session.session_pk))
def timeslot_preference(t):
proposed_schedule = self.schedule.copy()
proposed_schedule[t] = session
@ -339,8 +341,6 @@ class Schedule(object):
break
def _schedule_session(self, session, timeslot):
if not session.fits_in_timeslot(timeslot):
raise ValueError
self.schedule[timeslot] = session
def _cost_for_switch(self, timeslot1, timeslot2):
@ -555,6 +555,14 @@ class Session(object):
violations, cost = [], 0
overlapping_sessions = tuple(overlapping_sessions)
if self.attendees > my_timeslot.capacity:
violations.append('{}: scheduled scheduled in too small room'.format(self.group))
cost += self.business_constraint_costs['session_requires_trim']
if self.requested_duration > my_timeslot.duration:
violations.append('{}: scheduled scheduled in too short timeslot'.format(self.group))
cost += self.business_constraint_costs['session_requires_trim']
if my_timeslot.time_group in self.timeranges_unavailable:
violations.append('{}: scheduled in unavailable timerange {}'
.format(self.group, my_timeslot.time_group))