101219 - Don't download headers when checking for new mail (in folders other than INBOX)

Status: RESOLVED WORKSFORME

(MailNews Core :: Networking: IMAP, defect)

Description

[Ben Bucksch (:BenB)]

Spin-off from bug 18266.

The implementation there downloads the headers to check, if there is new mail.
this might be a waste of resources, because the IMAP server can give statistics
about the folders (total, unread, unseen).

I think that it would be sufficient to just get those numbers and update the
numbers in the folder pane. But then again, I don't care about Mozilla's biff
and I thus don't know, if that would work with the biff.

bienvenu says about that:
The way [it] ... would work might be something like this:
In the first pass, do an examine/select of a folder, and remember the total, and
unseen counts for a folder. In the subsequent passes, do the same and compare
the values. If the unseen counts have gone up, then there have been new messages
put in the folder. There are some tricky aspects to this - because by default,
we don't show you deleted messages, but the imap server counts them, we can't
know if we're really going to show/download a new header. Also, we wouldn't want
to do this for the inbox for similar reasons, since we filter messages out of
the inbox ourselves but leave them there unread but deleted. And, the UNSEEN
count is not really that reliable. Also, if the user selects a folder, causing
us to download all the headers, we should reset our counts. That's all a little
involved, but I'm just writing it down.

Comment 1

[Ben Bucksch (:BenB)]

s/unseen/recent/, s/unread/unseen/

Comment 2

[leg+mozilla]

in some servers, STATUS is more efficient than SELECT.
on low-bandwidth situations, STATUS has better performance (SELECT is very wordy).

does mozilla pipeline IMAP commands?  it is conceptually easier to pipeline
STATUS than it is to pipeline SELECT.

Comment 3

[Henrik Gemal]

this sounds like a very good idea...

Comment 4

[Henrik Gemal]

is this really "backend" or should it be moved to "IMAP"?

Comment 5

[[e-mail]]

Could you EXAMINE the flags instead of SELECTing the headers?
I also don't understand why the subject includes (in folders other than INBOX).
When you have a folder current then you want the headers, otherwise the flags.

Comment 6

[leg+mozilla]

EXAMINE is a read-only SELECT.  it is probably somewhat faste than SELECT on
some servers, but probably not as fast as STATUS.

EXAMINE lets you do everything SELECT does except change the state of the mailbox.

Comment 7

[Christian :Biesinger (don't email me, ping me on IRC)]

surely this is Networking: IMAP

Comment 8

[David :Bienvenu]

taking

Comment 9

[David :Bienvenu]

by default, we use STATUS for the other folders, and have for a long time.