Make repository deletes much faster by adding custom deletion code and have additional tests to verify the deletion code paths

data/database.py

@@ -245,6 +245,24 @@ class Repository(BaseModel):
       (('namespace_user', 'name'), True),
     )
 
+  def delete_instance(self, recursive=False, delete_nullable=False):
+    # Note: peewee generates extra nested deletion statements here that are slow and unnecessary.
+    # Therefore, we define our own deletion order here and use the dependency system to verify it.
+    ordered_dependencies = [RepositoryAuthorizedEmail, RepositoryTag, Image, LogEntry,
+                            RepositoryBuild, RepositoryBuildTrigger, RepositoryNotification,
+                            RepositoryPermission, AccessToken]                          
+
+    for query, fk in self.dependencies(search_nullable=True):
+      model = fk.model_class
+      if not model in ordered_dependencies:
+        raise Exception('Missing repository deletion dependency: %s', model)
+
+    for model in ordered_dependencies:
+      model.delete().where(model.repository == self).execute()
+
+    # Delete the repository itself.
+    super(Repository, self).delete_instance(recursive=False, delete_nullable=False)
+
 
 class Role(BaseModel):
   name = CharField(index=True, unique=True)
@@ -441,7 +459,6 @@ class LogEntry(BaseModel):
   performer = QuayUserField(allows_robots=True, index=True, null=True,
                             related_name='performer')  
   repository = ForeignKeyField(Repository, index=True, null=True)
-  access_token = ForeignKeyField(AccessToken, null=True)
   datetime = DateTimeField(default=datetime.now, index=True)
   ip = CharField(null=True)
   metadata_json = TextField(default='{}')