[Imap-protocol] SELECT/EXAMINE clarification of UNSEEN

Timo Sirainen tss at iki.fi
Wed Nov 16 06:43:45 PST 2011


On Wed, 2011-11-16 at 15:35 +0100, Bron Gondwana wrote:

>

> On Wednesday, November 16, 2011 2:38 PM, "Timo Sirainen" <tss at iki.fi> wrote:

> > Sounds like you're talking about your specific implementation, since I can't really think of why any of the above would be a problem or why there would be any need of blocking. I've actually thought of a way to create zero-lock-waits IMAP-compliant mailbox format on POSIX filesystems that do atomic writes with O_APPEND (practically all apparently), so I'm sure any blockers can be worked around.

>

> Teah - allowing gappyness certainly offers some nice properties.


There's no gappyness.


> But, I don't see how you can allow reads to see the messages until they are fully committed and indexed and "durable" for whatever level of guarantee you require. And because of that, I don't see how you can allow writes without ordering

> enforcement of "this commit is guaranteed to complete".

>

> Consider:

>

> * session A starts a write, gets GUID 101

> * session B starts a write, gets GUID 102


The messages don't get a (G)UID until they are complete and being
committed.


> * session B completes the write and return GUID 102 to its caller.






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