Delayed flags changes over IDLE

[Kostya Vasilyev]

Timo,

On Wed, Mar 13, 2019, at 9:36 AM, Kostya Vasilyev wrote:
> Timo,
> 
> On Wed, Mar 13, 2019, at 12:39 AM, Timo Sirainen wrote:
>> On 12 Mar 2019, at 10.21, Kostya Vasilyev via dovecot <dovecot at dovecot.org> wrote:
>>> 
>>> It makes no difference if the IDLE connection does SELECT or SELECT (CONDSTORE) prior to going IDLE.
>>> 
>>> But then as far as I know (?) - in Dovecot, once any connection uses CONDSTORE ever, even once, Dovecot creates data structures to track MODSEQ values, and those data structures are forever.
>> So are you saying that you can reproduce if you do for a completely new user:
>> 
>> doveadm exec imap -u testuser1
>> a select inbox
>> b idle
>> 
>> And then run:
>> echo foo | doveadm save -u testuser1
>> doveadm flags add -u testuser1 '\Seen' mailbox inbox 1
>> 
>> And the EXISTS shows up immediately after saving, but the flag change won't show up? It works fine with me.
>> 
>> Do you see any errors in "doveadm log errors"? Can you reproduce this if you try with some other mailbox format than mbox?
>> 
> 
> 1 - Yes I was able to reproduce with a completely new user.
> 
> I didn't use your doveadm commands above, but created a new Linux user in group mail, set a password in /etc/dovecot/users, and sent a few emails to that user from another mail account / web mail. My SMTP server is Postfix.
> 
> Then I used my IDLE client code (which does SELECT CONDSTORE) and a separate netcat connection to make flags changes.
> 
> Same thing as before: 1) no flags changes flushed to IDLE 2) until the other connection (which changed flags) does a SELECT.
> 
> The only difference from before - it was enough for netcat to do plain SELECT (i.e. SELECT CONDSTORE was not necessary).
> 
> I also tried a netcat connection instead of "my IDLE client" and did plain SELECT before going IDLE (i.e. SELECT without CONDSTORE). Same thing: 1) delay 2) flags changes are flushed after the other connection does SELECT.
> 
> 2 - I switched to Maildir last night - and the problem stopped for same old existing user.
> 
> So it looks triggered by a combination of mbox + SELECT (CONDSTORE)?
> 
> 3 - No errors in doveadm log errors
> 
> 4 - /var/log/mail.err has this
> 
> Mar 13 09:21:17 kman dovecot: auth: Error: Master requested auth for nonexistent client 29548 (created 0 msecs ago, handshake 0 msecs ago)
> Mar 13 09:21:18 kman dovecot: imap-login: Error: net_connect_unix(/var/run/dovecot/stats-writer) failed: No such file or directory
> 
> Probably means nothing - I tried to log in with IMAP before remembering to add my new user to /etc/dovecot/users
> 
> -- K
> 

One more test with this new "test" user.

I'd stopped postfix and dovecot, deleted this user's mail in /var/mail/%u and ~%u/mail and started over. Still mbox format.

This time I used netcat for the IDLE connection, plain SELECT without CONDSTORE.

Flags changes were sent quickly.

Then on the IDLE connection I sent DONE and SELECT Inbox (CONDSTORE) - without logging out or closing the connection.

The issue started again.

I also learned that it's enough for the "other" (non-idle, flag changing) connection to do just "tag SELECT" - i.e. without mailbox name - which results in

* OK [CLOSED] Previous mailbox closed.
tag BAD Error in IMAP command SELECT: Invalid arguments (0.001 + 0.000 secs).

but also does send the buffered up FLAGS changes on the IDLE connection.

Hope these are useful data points.

-- K
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