mygpo/search/tasks.py

   1 import functools
   2 import operator
   3 from datetime import timedelta
   4
   5 from celery.decorators import periodic_task
   6
   7 from django.db import transaction
   8 from django.contrib.postgres.search import SearchVector
   9
  10 from mygpo.podcasts.models import Podcast
  11
  12 from . import INDEX_FIELDS
  13
  14 from celery.utils.log import get_task_logger
  15 logger = get_task_logger(__name__)
  16
  17
  18 # interval in which podcast updates are scheduled
  19 UPDATE_INTERVAL = timedelta(hours=1)
  20
  21 # Maximum number of podcasts to update in one job run
  22 MAX_INDEX = 1000
  23
  24
  25 @periodic_task(run_every=UPDATE_INTERVAL)
  26 def update_search_index(run_every=UPDATE_INTERVAL):
  27     """ Schedules podcast updates that are due within ``interval`` """
  28
  29     logger.info('Updating search index')
  30
  31     # We avoid an UPDATE, because it cannot be LIMITed, the thus might
  32     # be to expensive in a single statement.
  33     # We could use select_for_update(), but there is no need for consistency
  34     # between multiple podcasts.
  35     to_update = Podcast.objects\
  36         .filter(search_index_uptodate=False)\
  37         .only('pk')[:MAX_INDEX]
  38
  39     count = to_update.count()
  40     logger.info('Updating search index for {} podcasts'.format(count))
  41
  42     vectors = _get_search_vectors()
  43
  44     for podcast in to_update:
  45         Podcast.objects.filter(pk=podcast.pk)\
  46             .update(search_vector=vectors,
  47                     search_index_uptodate=True,
  48                     )
  49
  50     logger.info('Finished indexing podcasts')
  51
  52
  53 def _get_search_vectors():
  54     """ Return the combined search vector to use for indexing podcasts """
  55     vectors = []
  56     for (field, weight) in INDEX_FIELDS.items():
  57         # index the podcast based on the stored language
  58         vectors.append(SearchVector(field, weight=weight))
  59
  60     # vectors can be combined with +
  61     return functools.reduce(operator.__add__, vectors)