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RE: Efficient revprop access in lib_repos

From: Bert Huijben <bert_at_qqmail.nl>
Date: Mon, 12 Oct 2015 00:10:08 +0200



Another reply:


How does this affect multiple processes accessing the same repository?


This caching looks like a nice speedup in some common cases, but I’m wondering if we are adding new race conditions on revision property updates. We had to add specific atomic revprop change apis to resolve/limit some older race conditions and this looks at the surface like it might introduce a few new cases.




From: Stefan Fuhrmann [mailto:stefan.fuhrmann_at_wandisco.com]
Sent: zondag 11 oktober 2015 14:26
To: Subversion Development <dev_at_subversion.apache.org>
Subject: Efficient revprop access in lib_repos


[This is the rationale and additional documentation to an upcoming

set of commits.]

When changing a revprop, we provide the following visibility guarantees:

1. A request that ends before the set_revprop started, sees the old value (duh!).
2. A request that starts after the set_revprop completes, sees the new value.
3. A request that starts before the set_revprop completes, may see the old or
   the new value and may not be consistent about it.
Received on 2015-10-12 00:10:24 CEST

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