Get rid of remaining slow query for garbage collection.

data/model/repository.py

@@ -1,14 +1,16 @@
 import logging
+import random
 
-from peewee import JOIN_LEFT_OUTER, fn
 from datetime import timedelta, datetime
+from peewee import JOIN_LEFT_OUTER, fn
+from cachetools import ttl_cache
 
 from data.model import (DataModelException, tag, db_transaction, storage, permission,
-                        _basequery, config)
+                        _basequery)
 from data.database import (Repository, Namespace, RepositoryTag, Star, Image, User,
-                           Visibility, RepositoryPermission, TupleSelector, RepositoryActionCount,
+                           Visibility, RepositoryPermission, RepositoryActionCount,
                            Role, RepositoryAuthorizedEmail, TagManifest, DerivedStorageForImage,
-                           db_for_update, get_epoch_timestamp, db_random_func)
+                           get_epoch_timestamp, db_random_func)
 
 
 logger = logging.getLogger(__name__)
@@ -71,8 +73,24 @@ def purge_repository(namespace_name, repository_name):
   fetched.delete_instance(recursive=True, delete_nullable=False)
 
 
-def find_repository_with_garbage():
-  epoch_timestamp = get_epoch_timestamp()
+@ttl_cache(maxsize=1, ttl=600)
+def _get_gc_expiration_policies():
+  policy_tuples_query = (Namespace
+                         .select(Namespace.removed_tag_expiration_s)
+                         .distinct()
+                         .limit(100)  # This sucks but it's the only way to limit memory
+                         .tuples())
+  return [policy[0] for policy in policy_tuples_query]
+
+
+def get_random_gc_policy():
+  """ Return a single random policy from the database to use when garbage collecting.
+      """
+  return random.choice(_get_gc_expiration_policies())
+
+
+def find_repository_with_garbage(limit_to_gc_policy_s):
+  expiration_timestamp = get_epoch_timestamp() - limit_to_gc_policy_s
 
   try:
     candidates = (RepositoryTag
@@ -80,8 +98,8 @@ def find_repository_with_garbage():
                   .join(Repository)
                   .join(Namespace, on=(Repository.namespace_user == Namespace.id))
                   .where(~(RepositoryTag.lifetime_end_ts >> None),
-                         (RepositoryTag.lifetime_end_ts <=
-                          (epoch_timestamp - Namespace.removed_tag_expiration_s)))
+                         (RepositoryTag.lifetime_end_ts <= expiration_timestamp),
+                         (Namespace.removed_tag_expiration_s == limit_to_gc_policy_s))
                   .limit(500)
                   .distinct()
                   .alias('candidates'))

test/test_gc.py

@@ -1,8 +1,6 @@
 import unittest
 import time
 
-from peewee import fn, JOIN_LEFT_OUTER
-
 from app import app, storage
 from initdb import setup_database_for_testing, finished_database_for_testing
 from data import model, database
@@ -166,13 +164,13 @@ class TestGarbageCollection(unittest.TestCase):
     repository = self.createRepository(latest=['i1', 'i2', 'i3'])
 
     # Ensure that no repositories are returned by the has garbage check.
-    self.assertIsNone(model.repository.find_repository_with_garbage())
+    self.assertIsNone(model.repository.find_repository_with_garbage(1000000000))
 
     # Delete a tag.
     self.deleteTag(repository, 'latest', perform_gc=False)
 
     # There should still not be any repositories with garbage, due to time machine.
-    self.assertIsNone(model.repository.find_repository_with_garbage())
+    self.assertIsNone(model.repository.find_repository_with_garbage(1000000000))
 
     # Change the time machine expiration on the namespace.
     (database.User.update(removed_tag_expiration_s=0)
@@ -180,7 +178,7 @@ class TestGarbageCollection(unittest.TestCase):
                   .execute())
 
     # Now we should find the repository for GC.
-    repository = model.repository.find_repository_with_garbage()
+    repository = model.repository.find_repository_with_garbage(0)
     self.assertIsNotNone(repository)
     self.assertEquals(REPO, repository.name)
 
@@ -188,7 +186,7 @@ class TestGarbageCollection(unittest.TestCase):
     model.repository.garbage_collect_repository(repository.namespace_user.username, repository.name)
 
     # There should now be no repositories with garbage.
-    self.assertIsNone(model.repository.find_repository_with_garbage())
+    self.assertIsNone(model.repository.find_repository_with_garbage(0))
 
 
   def test_one_tag(self):

workers/gcworker.py

@@ -1,7 +1,8 @@
 import logging
 
 from app import app
-from data.model.repository import find_repository_with_garbage, garbage_collect_repo
+from data.model.repository import (find_repository_with_garbage, garbage_collect_repo,
+
 from workers.worker import Worker
 
 logger = logging.getLogger(__name__)
@@ -14,7 +15,7 @@ class GarbageCollectionWorker(Worker):
 
   def _garbage_collection_repos(self):
     """ Performs garbage collection on repositories. """
-    repository = find_repository_with_garbage()
+    repository = find_repository_with_garbage(get_random_gc_policy())
     if repository is None:
       logger.debug('No repository with garbage found')
       return