This has several benefits:
• Clip.get_layers() (used by smart edits) and Item.get_layers() pick up
the select_related('user') optimization added for static edits in
r5007.
• Static edits and items pick up the optimization from r4941 to select
annotations once, not once per layer.
Fetching an item with ~1000 annotations took ~1s without this patch,
~0.34s with this patch. Another item with ~6000 annotations took ~11.6s
before, ~8.6s after.
Because this block is moved out to the top:
if user and user.is_anonymous():
user = None
then, for anonymous users,
"editable": false,
is no longer included in the annotations. The old behaviour ended up
including this key in all layers listed before the first private layer
in the config, and leaving it out from later ones. So this new behaviour
is more consistent.
The expensive part of fetching an edit is JSONifying the clips'
annotations. Profiling showed that the main cost was Annotation.json(),
and within that:
File: /srv/pandora/pandora/annotation/models.py
Function: json at line 216
Line # Hits Time Per Hit % Time Line Contents
==============================================================
216 def json(self, layer=False, keys=None, user=None):
217 632 827 1.3 0.1 j = {
218 632 1048170 1658.5 89.6 'user': self.user.username,
219 }
Obviously this join just moves some of the cost further out, but it
brings my micro-benchmark down from 1.3s to 0.3s.
