Re: [Evolution] Scope of filtering rules ; IMAP + filtering: The network load issue.

[Jeffrey Stedfast <fejj ximian com>]

On Thu, 2002-10-03 at 04:05, Francois Taiani wrote:
> Hi Not Zed,
>
> On Wed, 2002-10-02 at 11:56, Not Zed wrote:
> > On Wed, 2002-10-02 at 20:51, Francois Taiani wrote:
> > > Hi everybody,
> [-snip-]
> > > 2) The knowledge database says that with IMAP: "New messages don't get
> > > filtered until you open the INBOX folder." The motivation is that : "It
> > > [...] prevent[s] unnecessary traffic on your network."
> > > Though that certainly apply at home, the traffic load is absolutely not
> > > an issue at my office. I would find it very useful to be able to tell
> > > evol it can filter my mail even if I'm not looking at the INBOX (in the
> > > same way Mozilla does it for IMAP).
> >
> > i dont know what the knowledge base is on, the only reason its done like
> > that is that until you open the inbox, it doesn't know if you have any
> > new messages to filter.
>
> In my account editor I've selected "Automatically check for new mail
> every 1 minute". I would have though that by doing this evol would knwo
> if new mails have arrived (and in fact it does display the number of new
> mails available in Inbox in the folder tree). What I was thinking of
> would be a suboption like 

A few notes:

\Seen - flag marking a message as seen, the absence of this flag means
"unseen" or "unread" as some like to put it.

\Recent - flag for marking a message as a rwecent message, ie it's "new"

Now, \UnSeen (made up flag for the opposite of \Seen for the use of my
explanation) does not imply \Recent. Nor does \Recent imply \UnSeen.

There, now that we've covered that... the way "check all folders for new
mail" works is it issues a STATUS (UNSEEN) command for each folder and
we get a response back saying how many unread messages are in each
folder. This is what is used to populate your folder-tree unread counts.

Whatever folder is currently selected, we re-SELECT it which tells us
the number of \Recent messages there are (and a total number of
messages). If this folder happens to be your INBOX, joy of joys, it is
filtered because we know which messages are \Recent.

Let me re-iterate: \UnSeen does *not* mean \Recent, and so if INBOX is
not the currently selected folder, we have no way of knowing if the
INBOX has \Recent messages short of SELECTing it (which is a slow
operation - ever have >20,000 messages in a folder and select it for the
first time? yea, takes a while).

This is why we don't SELECT the INBOX everytime you do a send&receive to
filter INBOX. It's just too slow and you would probably complain. This
isn't what you want, trust me.


Now... in the future, we want to completely rewrite the IMAP plugin and
we will possibly make it multithreaded so that it can spawn multiple
connections to your IMAP server and queue a thread to go and filter
INBOX at every send&receive. This is probably how Mozilla does it (if it
indeed does filter the INBOX right away).

Jeff

-- 
Jeffrey Stedfast
Evolution Hacker - Ximian, Inc.
fejj ximian com  - www.ximian.com