Add queue manager app

apps/queue_manager/models.py

@@ -0,0 +1,95 @@
+from __future__ import absolute_import
+
+from datetime import datetime
+
+from django.db import models
+from django.utils.translation import ugettext_lazy as _
+from django.utils.simplejson import loads, dumps
+from django.db import IntegrityError
+
+from .exceptions import QueuePushError
+
+queue_labels = {}
+
+
+class QueueManager(models.Manager):
+    def get_or_create(self, *args, **kwargs):
+        queue_labels[kwargs.get('name')] = kwargs.get('defaults', {}).get('label')
+        return super(QueueManager, self).get_or_create(*args, **kwargs)
+
+
+class Queue(models.Model):
+    # Internal name
+    name = models.CharField(max_length=32, verbose_name=_(u'name'), unique=True)
+    unique_names = models.BooleanField(verbose_name=_(u'unique names'), default=False)
+
+    objects = QueueManager()
+
+    def __unicode__(self):
+        return unicode(self.label) or self.name
+        
+    @property
+    def label(self):
+        return queue_labels.get(self.name)
+
+    def push(self, data, name=None):  # TODO: add replace flag
+        if not name:
+            name = u''
+        queue_item = QueueItem(queue=self, name=name, data=dumps(data))
+        queue_item.save()
+        return queue_item
+        
+    def pull(self):
+        queue_item_qs = QueueItem.objects.filter(queue=self).order_by('-creation_datetime')
+        if queue_item_qs:
+            queue_item = queue_item_qs[0]
+            queue_item.delete()
+            return loads(queue_item.data)
+        
+    @property
+    def items(self):
+        return self.queueitem_set
+        
+    def empty(self):
+        self.items.all().delete()
+        
+    def save(self, *args, **kwargs):
+        label = getattr(self, 'label', None)
+        if label:
+            queue_labels[self.name] = label
+        return super(Queue, self).save(*args, **kwargs)
+        
+    # TODO: custom runtime methods
+        
+    class Meta:
+        verbose_name = _(u'queue')
+        verbose_name_plural = _(u'queues')
+
+
+class QueueItem(models.Model):
+    queue = models.ForeignKey(Queue, verbose_name=_(u'queue'))
+    creation_datetime = models.DateTimeField(verbose_name=_(u'creation datetime'), editable=False)
+    unique_name = models.CharField(blank=True, max_length=32, verbose_name=_(u'name'), unique=True, editable=False)
+    name = models.CharField(blank=True, max_length=32, verbose_name=_(u'name'))
+    data = models.TextField(verbose_name=_(u'data'))
+    
+    def __unicode__(self):
+        return self.name
+    
+    def save(self, *args, **kwargs):
+        self.creation_datetime = datetime.now()
+
+        if self.queue.unique_names:
+            self.unique_name = self.name
+        else:
+            self.unique_name = unicode(self.creation_datetime)
+        try:
+            super(QueueItem, self).save(*args, **kwargs)
+        except IntegrityError:
+            # TODO: Maybe replace instead or rasining exception w/ replace flag
+            raise QueuePushError
+    
+    class Meta:
+        verbose_name = _(u'queue item')
+        verbose_name_plural = _(u'queue items')
+