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Simplified the locking procedure

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This commit is contained in:
Raphael Michel
2015-09-16 11:59:07 +02:00
parent 0680f940a6
commit c268da02a2
8 changed files with 240 additions and 248 deletions
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115
src/pretix/base/models.py
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@@ -1,8 +1,7 @@
import copy
import random
import time
import uuid
from datetime import datetime, timedelta
from datetime import datetime
from itertools import product
import six
@@ -453,6 +452,7 @@ class Event(Versionable):
null=True, blank=True,
verbose_name=_("Plugins"),
)
locked_here = False
class Meta:
verbose_name = _("Event")
@@ -531,6 +531,13 @@ class Event(Versionable):
return False
return True
def lock(self):
"""
Returns a contextmanager that can be used to lock an event for bookings
"""
from .services import locking
return locking.LockManager(self)
class EventPermission(Versionable):
"""
@@ -1372,10 +1379,6 @@ class Quota(Versionable):
blank=True,
verbose_name=_("Variations")
)
locked = models.DateTimeField(
null=True, blank=True
)
locked_here = False
class Meta:
verbose_name = _("Quota")
@@ -1443,34 +1446,9 @@ class Quota(Versionable):
return Quota.AVAILABILITY_OK, self.size - paid_orders - pending_valid_orders - valid_cart_positions
class LockTimeoutException(Exception):
pass
class QuotaExceededException(Exception):
pass
def lock(self):
"""
Issue a lock on this quota so nobody can take tickets from this quota until
you release the lock. Will retry 5 times on failure.
:raises Quota.LockTimeoutException: if the quota is locked every time we try
to obtain the lock
"""
from .services import locking
return locking.lock_quota(self)
def release(self, force=False):
"""
Release a lock placed by :py:meth:`lock()`. If the parameter force is not set to ``True``,
the lock will only be released if it was issued in _this_ python
representation of the database object.
"""
from .services import locking
return locking.release_quota(self, force)
class Order(Versionable):
"""
@@ -1637,22 +1615,22 @@ class Order(Versionable):
order.save()
return order
def _can_be_paid(self, keep_locked=False):
def _can_be_paid(self):
error_messages = {
'late': _("The payment is too late to be accepted."),
}
if self.event.settings.get('payment_term_last') \
and now() > self.event.settings.get('payment_term_last'):
return error_messages['late'], None
return error_messages['late']
if now() < self.expires:
return True, None
return True
if not self.event.settings.get('payment_term_accept_late'):
return error_messages['late'], None
return error_messages['late']
return self._is_still_available(keep_locked)
return self._is_still_available()
def _is_still_available(self, keep_locked=False):
def _is_still_available(self):
error_messages = {
'unavailable': _('Some of the ordered products were no longer available.'),
'busy': _('We were not able to process the request completely as the '
@@ -1664,43 +1642,34 @@ class Order(Versionable):
'variation__values', 'variation__values__prop',
'item__questions', 'answers'
))
quotas_locked = set()
release = True
quota_cache = {}
try:
for i, op in enumerate(positions):
quotas = list(op.item.quotas.all()) if op.variation is None else list(op.variation.quotas.all())
if len(quotas) == 0:
raise Quota.QuotaExceededException(error_messages['unavailable'])
for quota in quotas:
# Lock the quota, so no other thread is allowed to perform sales covered by this
# quota while we're doing so.
if quota.identity not in [q.identity for q in quotas_locked]:
quota.lock()
quotas_locked.add(quota)
quota.cached_availability = quota.availability()[1]
else:
# Use cached version
quota = [q for q in quotas_locked if q.identity == quota.identity][0]
quota.cached_availability -= 1
if quota.cached_availability < 0:
# This quota is sold out/currently unavailable, so do not sell this at all
with self.event.lock():
for i, op in enumerate(positions):
quotas = list(op.item.quotas.all()) if op.variation is None else list(op.variation.quotas.all())
if len(quotas) == 0:
raise Quota.QuotaExceededException(error_messages['unavailable'])
for quota in quotas:
# Lock the quota, so no other thread is allowed to perform sales covered by this
# quota while we're doing so.
if quota.identity not in quota_cache:
quota_cache[quota.identity] = quota
quota.cached_availability = quota.availability()[1]
else:
# Use cached version
quota = quota_cache[quota.identity]
quota.cached_availability -= 1
if quota.cached_availability < 0:
# This quota is sold out/currently unavailable, so do not sell this at all
raise Quota.QuotaExceededException(error_messages['unavailable'])
except Quota.QuotaExceededException as e:
return str(e), None
except Quota.LockTimeoutException:
return str(e)
except EventLock.LockTimeoutException:
# Is raised when there are too many threads asking for quota locks and we were
# unaible to get one
return error_messages['busy'], None
else:
release = False
finally:
# Release the locks. This is important ;)
if release or not keep_locked:
for quota in quotas_locked:
quota.release()
return True, quotas_locked
return error_messages['busy']
return True
class CachedTicket(models.Model):
@@ -1905,3 +1874,11 @@ class OrganizerSetting(Versionable):
object = VersionedForeignKey(Organizer, related_name='setting_objects')
key = models.CharField(max_length=255)
value = models.TextField()
class EventLock(models.Model):
event = models.CharField(max_length=36, primary_key=True)
date = models.DateTimeField(auto_now=True)
class LockTimeoutException(Exception):
pass