139 lines
No EOL
5 KiB
Python
139 lines
No EOL
5 KiB
Python
from datetime import datetime, timedelta
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from data.database import QueueItem, db
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from util.morecollections import AttrDict
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MINIMUM_EXTENSION = timedelta(seconds=20)
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class WorkQueue(object):
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def __init__(self, queue_name, transaction_factory,
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canonical_name_match_list=None, reporter=None):
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self._queue_name = queue_name
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self._reporter = reporter
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self._transaction_factory = transaction_factory
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self._currently_processing = False
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if canonical_name_match_list is None:
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self._canonical_name_match_list = []
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else:
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self._canonical_name_match_list = canonical_name_match_list
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@staticmethod
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def _canonical_name(name_list):
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return '/'.join(name_list) + '/'
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def _running_jobs(self, now, name_match_query):
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return (QueueItem
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.select(QueueItem.queue_name)
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.where(QueueItem.available == False,
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QueueItem.processing_expires > now,
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QueueItem.queue_name ** name_match_query))
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def _available_jobs(self, now, name_match_query, running_query):
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return (QueueItem
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.select()
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.where(QueueItem.queue_name ** name_match_query, QueueItem.available_after <= now,
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((QueueItem.available == True) | (QueueItem.processing_expires <= now)),
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QueueItem.retries_remaining > 0, ~(QueueItem.queue_name << running_query)))
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def _name_match_query(self):
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return '%s%%' % self._canonical_name([self._queue_name] + self._canonical_name_match_list)
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def update_metrics(self):
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if self._reporter is None:
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return
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with self._transaction_factory(db):
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now = datetime.utcnow()
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name_match_query = self._name_match_query()
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running_query = self._running_jobs(now, name_match_query)
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running_count = running_query.distinct().count()
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avialable_query = self._available_jobs(now, name_match_query, running_query)
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available_count = avialable_query.select(QueueItem.queue_name).distinct().count()
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self._reporter(self._currently_processing, running_count, running_count + available_count)
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def put(self, canonical_name_list, message, available_after=0, retries_remaining=5):
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"""
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Put an item, if it shouldn't be processed for some number of seconds,
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specify that amount as available_after.
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"""
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params = {
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'queue_name': self._canonical_name([self._queue_name] + canonical_name_list),
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'body': message,
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'retries_remaining': retries_remaining,
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}
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available_date = datetime.utcnow() + timedelta(seconds=available_after or 0)
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params['available_after'] = available_date
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with self._transaction_factory(db):
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QueueItem.create(**params)
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def get(self, processing_time=300):
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"""
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Get an available item and mark it as unavailable for the default of five
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minutes. The result of this method must always be composed of simple
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python objects which are JSON serializable for network portability reasons.
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"""
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now = datetime.utcnow()
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name_match_query = self._name_match_query()
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with self._transaction_factory(db):
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running = self._running_jobs(now, name_match_query)
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avail = self._available_jobs(now, name_match_query, running)
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item = None
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try:
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db_item = avail.order_by(QueueItem.id).get()
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db_item.available = False
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db_item.processing_expires = now + timedelta(seconds=processing_time)
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db_item.retries_remaining -= 1
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db_item.save()
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item = AttrDict({
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'id': db_item.id,
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'body': db_item.body,
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})
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self._currently_processing = True
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except QueueItem.DoesNotExist:
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self._currently_processing = False
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# Return a view of the queue item rather than an active db object
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return item
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def complete(self, completed_item):
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with self._transaction_factory(db):
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completed_item_obj = QueueItem.get(QueueItem.id == completed_item.id)
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completed_item_obj.delete_instance()
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self._currently_processing = False
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def incomplete(self, incomplete_item, retry_after=300, restore_retry=False):
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with self._transaction_factory(db):
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retry_date = datetime.utcnow() + timedelta(seconds=retry_after)
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incomplete_item_obj = QueueItem.get(QueueItem.id == incomplete_item.id)
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incomplete_item_obj.available_after = retry_date
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incomplete_item_obj.available = True
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if restore_retry:
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incomplete_item_obj.retries_remaining += 1
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incomplete_item_obj.save()
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self._currently_processing = False
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def extend_processing(self, seconds_from_now, minimum_extension=MINIMUM_EXTENSION):
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with self._transaction_factory(db):
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queue_item = QueueItem.get(QueueItem.id == self.id)
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new_expiration = datetime.utcnow() + timedelta(seconds=seconds_from_now)
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# Only actually write the new expiration to the db if it moves the expiration some minimum
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if new_expiration - queue_item.processing_expires > minimum_extension:
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queue_item.processing_expires = new_expiration
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queue_item.save() |