203 lines
7.6 KiB
Python
203 lines
7.6 KiB
Python
from datetime import datetime, timedelta
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from data.database import QueueItem, db, db_for_update
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from util.morecollections import AttrDict
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MINIMUM_EXTENSION = timedelta(seconds=20)
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class NoopWith:
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def __enter__(self):
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pass
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def __exit__(self, type, value, traceback):
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pass
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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):
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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))
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def _available_jobs_not_running(self, now, name_match_query, running_query):
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return (self
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._available_jobs(now, name_match_query)
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.where(~(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 _item_by_id_for_update(self, queue_id):
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return db_for_update(QueueItem.select().where(QueueItem.id == queue_id)).get()
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def get_metrics(self, require_transaction=True):
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guard = self._transaction_factory(db) if require_transaction else NoopWith()
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with guard:
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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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available_query = self._available_jobs(now, name_match_query)
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available_count = available_query.select(QueueItem.queue_name).distinct().count()
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available_not_running_query = self._available_jobs_not_running(now, name_match_query,
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running_query)
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available_not_running_count = (available_not_running_query.select(QueueItem.queue_name)
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.distinct().count())
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return (running_count, available_not_running_count, available_count)
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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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(running_count, available_not_running_count, available_count) = self.get_metrics()
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self._reporter(self._currently_processing, running_count,
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running_count + available_not_running_count)
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def has_retries_remaining(self, item_id):
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""" Returns whether the queue item with the given id has any retries remaining. If the
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queue item does not exist, returns False. """
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with self._transaction_factory(db):
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try:
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return QueueItem.get(id=item_id).retries_remaining > 0
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except QueueItem.DoesNotExist:
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return False
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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. Returns the ID of the queue item added.
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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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return str(QueueItem.create(**params).id)
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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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running = self._running_jobs(now, name_match_query)
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avail = self._available_jobs_not_running(now, name_match_query, running)
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item = None
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try:
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db_item_candidate = avail.order_by(QueueItem.id).get()
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with self._transaction_factory(db):
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still_available_query = (db_for_update(self
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._available_jobs(now, name_match_query)
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.where(QueueItem.id == db_item_candidate.id)))
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db_item = still_available_query.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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'retries_remaining': db_item.retries_remaining
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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 cancel(self, item_id):
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""" Attempts to cancel the queue item with the given ID from the queue. Returns true on success
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and false if the queue item could not be canceled. A queue item can only be canceled if
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if is available and has retries remaining.
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"""
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with self._transaction_factory(db):
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# Load the build queue item for update.
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try:
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queue_item = db_for_update(QueueItem.select()
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.where(QueueItem.id == item_id)).get()
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except QueueItem.DoesNotExist:
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return False
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# Check the queue item.
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if not queue_item.available or queue_item.retries_remaining == 0:
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return False
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# Delete the queue item.
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queue_item.delete_instance(recursive=True)
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return True
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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 = self._item_by_id_for_update(completed_item.id)
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completed_item_obj.delete_instance(recursive=True)
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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 = self._item_by_id_for_update(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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return incomplete_item_obj.retries_remaining > 0
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def extend_processing(self, item, seconds_from_now, minimum_extension=MINIMUM_EXTENSION):
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with self._transaction_factory(db):
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queue_item = self._item_by_id_for_update(item.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()
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