Here's the way I'd like to use offlineimap on my laptop:
1. Have a regular cron job running infrequently. The cron job
checks to see
if I'm online, plugged in, and that no other copy of offlineimap is
running. If
all of these conditions are satisfied, it runs offlineimap just once:
"offlineimap -o -u Noninteractive.Quiet"
2. When I start up mutt, I do it by calling a wrapper script that
delays
until cron-started copies of offlineimap have finished, then starts
offlineimap
on its regular, stay-alive and keep checking schedule. When I quit
mutt, the
wrapper script tells offlineimap to stop.
This way I get frequent regular checks while I have mutt running, but
I don't
waste my battery/cpu checking frequently for mail when I'm not
interested in
it.
To make this work, though, it'd be nicer if it were easier to tell
offlineimap,
from the outside, things like "terminate cleanly now" and "when you've
finished
synching, then terminate instead of sleeping and synching again."
OK, to put my money where my mouth is, I attach two patches against
offlineimap
6.0.3.
The first, "cleanup.patch", cleans up a few spots that tend to throw
exceptions
for me as offlineimap is exiting from a KeyboardInterrupt.
The second adds signaling capabilities to offlineimap.
* sending a SIGTERM tells offlineimap to terminate immediately but
cleanly,
just as if "q" had been pressed in the GUI interface
* sending a SIGUSR1 tells every account to do a full sync asap: if
it's
sleeping, then wake up and do the sync now. If it's mid-sync, then
re-synch
any folders whose syncing has already been started or completed, and
continue
to synch the other, queued but not-yet-synched folders.
* sending a SIGHUP tells every account to die as soon as it can (but
not
immediately: only after finishing any synch it's now engaged in)
* sending a SIGUSR2 tells every account to do a full sync asap (as
with
SIGUSR1), then die
It's tricky to mix signals with threads, but I think I've done this
correctly.
I've been using it now for a few weeks without any obvious
problems. But I'm passing it
on so that others can review the code and test it out on their
systems. I developed the
patch when I was running Python 2.5.2, but to my knowledge I don't use
any Python 2.5-specific
code. Now I'm using the patch with Python 2.6.
Although I said "without any obvious problems," let me confess that
I'm
seeing offlineimap regularly choke when I do things like this: start
up
my offlineimap-wrapped copy of mutt, wait a while, put the machine to
sleep (not sure if offlineimap is active in the background or idling),
move to a different spot, wake the machine up again and it acquires a
new network, sometimes a wired network instead of wifi. Offlineimap
doesn't like that so much. I don't yet have any reason to think the
problems here come from my patches. But I'm just acknowledging them,
so
that if others are able to use offlineimap without any difficulty in
situations like I described, then maybe the fault is with my patches.
fixes deb#433732
Date: Sun, 30 Sep 2007 13:54:56 -0400
From: Daniel Jacobowitz <drow@false.org>
To: offlineimap@complete.org
Subject: Assorted patches
Here's the result of a lazy Sunday hacking on offlineimap. Sorry for
not breaking this into multiple patches. They're mostly logically
independent so just ask if that would make a difference.
First, a new -q (quick) option. The quick option means to only update
folders that seem to have had significant changes. For Maildir, any
change to any message UID or flags is significant, because checking
the flags doesn't add a significant cost. For IMAP, only a change to
the total number of messages or a change in the UID of the most recent
message is significant. This should catch everything except for
flags changes.
The difference in bandwidth is astonishing: a quick sync takes 80K
instead of 5.3MB, and 28 seconds instead of 90.
There's a configuration variable that lets you say every tenth sync
should update flags, but let all the intervening ones be lighter.
Second, a fix to the UID validity problems many people have been
reporting with Courier. As discussed in Debian bug #433732, I changed
the UID validity check to use SELECT unless the server complains that
the folder is read-only. This avoids the Courier bug (see the Debian
log for more details). This won't fix existing validity errors, you
need to remove the local status and validity files by hand and resync.
Third, some speedups in Maildir checking. It's still pretty slow
due to a combination of poor performance in os.listdir (never reads
more than 4K of directory entries at a time) and some semaphore that
leads to lots of futex wake operations, but at least this saves
20% or so of the CPU time running offlineimap on a single folder:
Time with quick refresh and md5 in loop: 4.75s user 0.46s system 12%
cpu 41.751 total
Time with quick refresh and md5 out of loop: 4.38s user 0.50s system
14% cpu 34.799 total
Time using string compare to check folder: 4.11s user 0.47s system 13%
cpu 34.788 total
And fourth, some display fixes for Curses.Blinkenlights. I made
warnings more visible, made the new quick sync message cyan, and
made all not explicitly colored messages grey. That last one was
really bugging me. Any time OfflineIMAP printed a warning in
this UI, it had even odds of coming out black on black!
Anyway, I hope these are useful. I'm happy to revise them if you see
a problem.
--
Daniel Jacobowitz
CodeSourcery
