apps/waiter/models.py

   1 from os.path import join, abspath, exists
   2 from django.db import models
   3 from waiter.settings import WAITER_ROOT, WAITER_URL
   4 from django.core.urlresolvers import reverse
   5
   6 class WaitedFile(models.Model):
   7     path = models.CharField(max_length=255, unique=True, db_index=True)
   8     task = models.CharField(max_length=64, null=True, editable=False)
   9     description = models.CharField(max_length=255, null=True, blank=True)
  10
  11     @staticmethod
  12     def abspath(path):
  13         abs_path = abspath(join(WAITER_ROOT, path))
  14         if not abs_path.startswith(WAITER_ROOT):
  15             raise ValueError('Path not inside WAITER_ROOT.')
  16         return abs_path
  17
  18     @classmethod
  19     def exists(cls, path):
  20         """Returns opened file or None.
  21
  22         `path` is relative to WAITER_ROOT.
  23         Won't open a path leading outside of WAITER_ROOT.
  24         """
  25         abs_path = cls.abspath(path)
  26         # Pre-fetch objects to avoid minor race condition
  27         relevant = [o.id for o in cls.objects.filter(path=path)]
  28         print abs_path
  29         if exists(abs_path):
  30             cls.objects.filter(id__in=relevant).delete()
  31             return True
  32         else:
  33             return False
  34
  35     @classmethod
  36     def order(cls, path, task_creator, description=None):
  37         """
  38         Returns an URL for the user to follow.
  39         If the file is ready, returns download URL.
  40         If not, starts preparing it and returns waiting URL.
  41         """
  42         already = cls.exists(path)
  43         if not already:
  44             waited, created = cls.objects.get_or_create(path=path)
  45             if created:
  46                 # TODO: makedirs
  47                 waited.task = task_creator(cls.abspath(path))
  48                 print waited.task
  49                 waited.description = description
  50                 waited.save()
  51             # TODO: it the task exists, if stale delete, send some mail and restart
  52             return reverse("waiter", args=[path])
  53         return join(WAITER_URL, path)