Deryck Hodge has proposed merging
lp:~deryck/launchpad/avoid-extra-buglist-count-901124 into lp:launchpad.
Requested reviews:
Launchpad code reviewers (launchpad-reviewers)
Related bugs:
Bug #901124 in Launchpad itself: "New bug listings get length of collection
twice"
https://bugs.launchpad.net/launchpad/+bug/901124
For more details, see:
https://code.launchpad.net/~deryck/launchpad/avoid-extra-buglist-count-901124/+merge/85940
This branch will avoid doing two COUNTs in the new bug listing code. The
reason we were doing two is that the batch navigator hits listlength twice when
you're calling total() and lastBatch(). This avoids both those calls by
keeping a reference to listlength around and using batch navigator methods to
get the last_start number. Using listlength will still trigger one call to
count, but I can't see how to avoid that.
This should fix a great deal of the timeouts with the new bug listing work,
though I still need to get a branch ready to avoid late evaluation of new data
we're using, like bug.owner.
--
https://code.launchpad.net/~deryck/launchpad/avoid-extra-buglist-count-901124/+merge/85940
Your team Launchpad code reviewers is requested to review the proposed merge of
lp:~deryck/launchpad/avoid-extra-buglist-count-901124 into lp:launchpad.
=== modified file 'lib/lp/bugs/browser/bugtask.py'
--- lib/lp/bugs/browser/bugtask.py 2011-12-15 18:55:46 +0000
+++ lib/lp/bugs/browser/bugtask.py 2011-12-15 19:18:33 +0000
@@ -2701,12 +2701,20 @@
cache.objects['next'] = _getBatchInfo(next_batch)
prev_batch = batch_navigator.batch.prevBatch()
cache.objects['prev'] = _getBatchInfo(prev_batch)
- cache.objects['total'] = batch_navigator.batch.total()
cache.objects['order_by'] = ','.join(
get_sortorder_from_request(self.request))
cache.objects['forwards'] = batch_navigator.batch.range_forwards
- last_batch = batch_navigator.batch.lastBatch()
- cache.objects['last_start'] = last_batch.startNumber() - 1
+
+ # We have to do some work here to avoid the batch nav
+ # doing an expensive count() twice.
+ total_size = batch_navigator.batch.listlength
+ cache.objects['total'] = total_size
+ batch_size = batch_navigator.batch.size
+ last_batch_size = total_size % batch_size
+ if last_batch_size == 0:
+ last_batch_size = batch_size
+ cache.objects['last_start'] = total_size - last_batch_size
+
cache.objects.update(_getBatchInfo(batch_navigator.batch))
cache.objects['sort_keys'] = SORT_KEYS
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