On Thu, 15 Mar 2007, Bron Gondwana wrote:
* Make UUIDs work at all. The initialisation order of the UUID
subsystem was wrong, so we had very few messages with a non-zero UUID.
message_uuid_master_init() should only be called after become_cyrus().
Every time that message_uuid_master_next_child() overflows, master needs
to update MASTER_UUID_FILE.
Is MASTER_UUID_FILE owned by a user other than cyrus on your systems? I
can't see any other obvious reason that moving message_uuid_master_init()
up a few lines would help. service_create() is binding ports, which
obviously has to happen as root, while masterconf_getsection() is just
parsing master.conf. I am probably missing something obvious here, but the
current ordering works for me.
* MD5 UUIDs - we've created a new scheme for UUID generation, of
the format: 02[first 11 bytes of message file md5]. This allows
some basic integrity checking of the file on disk, and is still
plenty random. Also adds the non standard IMAP FETCHable items
UUID, RFC822.MD5 (calculated on the fly), RFC822.FILESIZE (does
a stat or looks at the MMAP result if something else needs it)
I don't think that this is safe. It is important that the UUIDs really are
unique, which is the reason for the paranoia in message_uuid_master_init.
The assertion:
Is it safe? - we calulated that with one billion messages you have a one
in 1 billion chance of a birthday collision (two random messages with
the same UUID). They then have to get in the same MAILBOXES collection
to sync_client to affect each other anyway.
Isn't the case: UUIDs span all MAILBOXES and APPEND event until a restart.
If a UUID appears in one event and then is referenced by a second event
some minutes later then the first message seen will be reused.
At the moment sync_client in 2.3 tracks the last few thousand messages by
UUIDs. My original code tracked the last few hundred thousand messages
(diminishing returns, but useful when seeding accounts). There is a much
greater chance of collisions there than just comparing two messages.
--
David Carter Email: David.Carter@xxxxxxxxxxxxx
University Computing Service, Phone: (01223) 334502
New Museums Site, Pembroke Street, Fax: (01223) 334679
Cambridge UK. CB2 3QH.
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