[PATCH 3 of 3 v2] repoview: cache repoview class instances (issue5043)

[Gregory Szorc]

> On Jan 17, 2016, at 17:10, Pierre-Yves David <pierre-yves.david at ens-lyon.org> wrote:
> 
> 
> 
>> On 01/17/2016 02:18 PM, Gregory Szorc wrote:
>> # HG changeset patch
>> # User Gregory Szorc <gregory.szorc at gmail.com>
>> # Date 1453069024 28800
>> #      Sun Jan 17 14:17:04 2016 -0800
>> # Node ID 3a418d20ca9d0345416d65b82fd3f49101bcc5b2
>> # Parent  91969eee20a1dcd52470258164bc44528861a4c6
>> repoview: cache repoview class instances (issue5043)
>> 
>> The Python garbage collector was reporting the proxycls instances
>> created on every invocation of localrepository.filtered() were
>> uncollectable. This led to leaking memory.
>> 
>> We fix the leak by introducing a cache of the proxy classes. After
>> this patch, the garbage collector no longer reports uncollectable
>> objects after each iteration of `hg convert`. This likely prevents
>> memory leaks in a number of other operations as well (pretty much
>> anything relying heavily on repo.filtered() calls).
>> 
>> We stop short of caching the instantiated proxycls instances, which
>> we /should/ be able to do safely. This feels a bit too risky for
>> a change just before code freeze, however.
> 
> I'm either missing something or the behavior of this patch is incorrect.
> 
> If the class of the repo objet changes, we won't invalidate the cache, and the next call to "filtered" will return an object with an outdated proxy class.

That's a valid observation. But the class should be static after reposetup functions are called. And we shouldn't be obtaining a repoview before reposetup is called, right?