On Mon, Aug 30, 2010 at 6:39 PM, Shane Hathaway <sh...@hathawaymix.org> wrote:
> On 08/30/2010 03:36 PM, Jim Fulton wrote:
>> The tricky thing about this is the last paragraph. If the method
>> doesn't raise an error, then there can't be updates to the object
>> until after the transaction commits. For most current
>> implementations, this implies that the storage lock is help when this
>> is called. For ZEO, some special care will be necessary because the
>> storage lock isn't acquired until the very end of the first phase of
>> 2-phase commit.
>> I'm particularly concerned about the impact on RelStorage.
> Thanks for calling attention to this. Like ZEO, RelStorage doesn't acquire
> the commit lock until the end of the first phase of 2-phase commit, for
> performance reasons. Therefore, if I understand correctly, ZEO and
> RelStorage will have to maintain a list of OID/serials that the transaction
> is depending on, then check that list after the commit lock is acquired (but
> still in the first phase). If anything has changed, we should raise a
> ReadConflictError. Does that sound right?
> BTW, perhaps the method name and signature could be as simple as
> "require(oid, serial)". It simply declares to the storage that the
> transaction requires a specific version of an object.
While I'm open to better names, I prefer a longer more descriptive name.
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