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