Re: SQLite locking for WCNG on NFS

Philip Martin <philip.martin_at_wandisco.com> writes:

> "C. Michael Pilato" <cmpilato_at_collab.net> writes:
>
>> On 02/14/2012 05:41 AM, Philip Martin wrote:
>>> A substantial performance improvement but at the cost of making write
>>> operations block read operations. This would mean things like TSVN
>>> would not be able to run status on a working copy while its checkout was
>>> running.
>>
>> Just to clarify, by "checkout" here, you mean "checkout or update", yes? I
>> ask because while checkout might be a relatively rare operation, we tend to
>> assume that updates happen all the time. Just want to properly frame the
>> scope of this blocking action.
>
> Yes, I believe anything that writes to the database will exclude
> readers. I don't know whether the blocking starts from the point the
> database is opened for writing or from the first write itself.

Another point is that 1.7 already restricts running status during a
checkout/update, it will only work if there are no workqueue items. If
items exist when status attempts to open wc.db then the command fails

svn: E155037: Previous operation has not finished; run 'cleanup' if it was interrupted

If there are no workqueue items then status will run and show the locked
working copy. This is different from 1.6 where status could always be
run even when log files existed.

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