RE: [Xen-devel] xs transaction

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Vincent Hanquez [mailto:vincent@xxxxxxxxxxxxx]
>Sent: 2007年9月11日 19:45
>
>xenstored is single threaded and the libxs accesses are serialed through
>a mutex which prevent two threads to access the ring at the same time.
>if it was not, you'ld have much more problems than having two
>transactions at the same time.
>
>xenstored will always complete a process_message function until it try
>to read a new packet. at this point the conn->transaction is back to
>NULL.

Thanks, and I see the point now.

>
>> Since we're sure that current implementation doesn't handle parallel
>> transactions (though API level allows), I think do_transaction_start
>> should check conn->transaction_list instead of conn->transaction to
>> ensure it.
>
>how are you sure it doesn't handle parallel transactions ?

My fault actually and it does handle. If multiple transactions are in 
parallel, 1st end will update its changes into global tdb with the rest 
failed (EAGAIN) to caller for retry. :-)

Thanks,
Kevin

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