from collections import deque
from hashlib import sha224
from logging import getLogger
from time import time
from django.contrib.auth.models import User
from django.core.cache import cache
from django.db.models import (CharField, DateTimeField, ForeignKey,
NullBooleanField, TextField)
from django.utils import timezone
from django.utils.translation import ugettext_lazy as _
from model_utils.models import TimeStampedModel
logger = getLogger(__name__)
class WorkerNotFound(Exception):
pass
def activitycontextimpl(act, on_abort=None, on_commit=None):
try:
yield act
except BaseException as e:
# BaseException is the common parent of Exception and
# system-exiting exceptions, e.g. KeyboardInterrupt
handler = None if on_abort is None else lambda a: on_abort(a, e)
act.finish(succeeded=False, result=str(e), event_handler=handler)
raise e
else:
act.finish(succeeded=True, event_handler=on_commit)
class ActivityModel(TimeStampedModel):
activity_code = CharField(max_length=100, verbose_name=_('activity code'))
parent = ForeignKey('self', blank=True, null=True, related_name='children')
task_uuid = CharField(blank=True, max_length=50, null=True, unique=True,
help_text=_('Celery task unique identifier.'),
verbose_name=_('task_uuid'))
user = ForeignKey(User, blank=True, null=True, verbose_name=_('user'),
help_text=_('The person who started this activity.'))
started = DateTimeField(verbose_name=_('started at'),
blank=True, null=True,
help_text=_('Time of activity initiation.'))
finished = DateTimeField(verbose_name=_('finished at'),
blank=True, null=True,
help_text=_('Time of activity finalization.'))
succeeded = NullBooleanField(blank=True, null=True,
help_text=_('True, if the activity has '
'finished successfully.'))
result = TextField(verbose_name=_('result'), blank=True, null=True,
help_text=_('Human readable result of activity.'))
def __unicode__(self):
if self.parent:
return self.parent.activity_code + "->" + self.activity_code
else:
return self.activity_code
class Meta:
abstract = True
def finish(self, succeeded, result=None, event_handler=None):
if not self.finished:
self.finished = timezone.now()
self.succeeded = succeeded
if result is not None:
self.result = result
if event_handler is not None:
event_handler(self)
self.save()
@property
def has_succeeded(self):
return self.finished and self.succeeded
@property
def has_failed(self):
return self.finished and not self.succeeded
def method_cache(memcached_seconds=60, instance_seconds=5): # noqa
"""Cache return value of decorated method to memcached and memory.
:param memcached_seconds: Invalidate memcached results after this time.
:param instance_seconds: Invalidate results cached to static memory after
this time.
If a result is cached on instance, return that first. If that fails, check
memcached. If all else fails, run the method and cache on instance and in
memcached.
Do not use for methods with side effects.
Instances are hashed by their id attribute, args by their unicode
representation.
** NOTE: Methods that return None are always "recached".
Based on https://djangosnippets.org/snippets/2477/
"""
def inner_cache(method):
def get_key(instance, *args, **kwargs):
return sha224(unicode(method.__module__) +
unicode(method.__name__) +
unicode(instance.id) +
unicode(args) +
unicode(kwargs)).hexdigest()
def x(instance, *args, **kwargs):
invalidate = kwargs.pop('invalidate_cache', False)
now = time()
key = get_key(instance, *args, **kwargs)
result = None
try:
vals = getattr(instance, key)
except AttributeError:
pass
else:
if vals['time'] + instance_seconds > now:
# has valid on class cache, return that
result = vals['value']
if result is None:
result = cache.get(key)
if invalidate or (result is None):
# all caches failed, call the actual method
result = method(instance, *args, **kwargs)
# save to memcache and class attr
cache.set(key, result, memcached_seconds)
setattr(instance, key, {'time': now, 'value': result})
logger.debug('Value of <%s>.%s(%s)=<%s> saved to cache.',
unicode(instance), method.__name__,
unicode(args), unicode(result))
return result
return x
return inner_cache
class HumanSortField(CharField):
"""
A CharField that monitors another field on the same model and sets itself
to a normalized value, which can be used for sensible lexicographycal
sorting for fields containing numerals. (Avoiding technically correct
orderings like [a1, a10, a2], which can be annoying for file or host
names.)
Apart from CharField's default arguments, an argument is requered:
- monitor sets the base field, whose value is normalized.
- maximum_number_length can also be provided, and defaults to 4. If
you have to sort values containing numbers greater than 9999, you
should increase it.
Code is based on carljm's django-model-utils.
"""
def __init__(self, *args, **kwargs):
logger.debug('Initing HumanSortField(%s %s)',
unicode(args), unicode(kwargs))
kwargs.setdefault('default', "")
self.maximum_number_length = kwargs.pop('maximum_number_length', 4)
monitor = kwargs.pop('monitor', None)
if not monitor:
raise TypeError(
'%s requires a "monitor" argument' % self.__class__.__name__)
self.monitor = monitor
kwargs['blank'] = True
super(HumanSortField, self).__init__(*args, **kwargs)
def get_monitored_value(self, instance):
return getattr(instance, self.monitor)
@staticmethod
def _partition(s, pred):
"""Partition a deque of chars to a tuple of a
- string of the longest prefix matching pred,
- string of the longest prefix after the former one not matching,
- deque of the remaining characters.
>>> HumanSortField._partition(deque("1234abc567"),
... lambda s: s.isdigit())
('1234', 'abc', deque(['5', '6', '7']))
>>> HumanSortField._partition(deque("12ab"), lambda s: s.isalpha())
('', '12', deque(['a', 'b']))
"""
match, notmatch = deque(), deque()
while s and pred(s[0]):
match.append(s.popleft())
while s and not pred(s[0]):
notmatch.append(s.popleft())
return (''.join(match), ''.join(notmatch), s)
def get_normalized_value(self, val):
logger.debug('Normalizing value: %s', val)
norm = ""
val = deque(val)
while val:
numbers, letters, val = self._partition(val,
lambda s: s[0].isdigit())
if numbers:
norm += numbers.rjust(self.maximum_number_length, '0')
norm += letters
logger.debug('Normalized value: %s', norm)
return norm
def pre_save(self, model_instance, add):
logger.debug('Pre-saving %s.%s. %s',
model_instance, self.attname, add)
value = self.get_normalized_value(
self.get_monitored_value(model_instance))
setattr(model_instance, self.attname, value[:self.max_length])
return super(HumanSortField, self).pre_save(model_instance, add)
# allow South to handle these fields smoothly
try:
from south.modelsinspector import add_introspection_rules
add_introspection_rules(rules=[
(
(HumanSortField,),
[],
{'monitor': ('monitor', {}),
'maximum_number_length': ('maximum_number_length', {}), }
),
], patterns=['common\.models\.'])
except ImportError:
pass