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Diffstat (limited to 'offlineimap-runner.sh')
| -rw-r--r-- | offlineimap-runner.sh | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/offlineimap-runner.sh b/offlineimap-runner.sh new file mode 100644 index 0000000..4828f35 --- /dev/null +++ b/offlineimap-runner.sh @@ -0,0 +1,60 @@ +#!/bin/sh + +# offlineimap is pretty nifty, and generally does the right thing, and is +# remarkably fault-tolerant, even of it's own code. +# +# One nifty thing it doesn is to check if an instance of it is already running, +# and to exit and let the original insance do it's thing. That lets us do +# things like put it in a crontab. We wouldn't want to do this if it didn't have +# that feature, because then +# * If the previous run hadn't finished, things would break +# I have it run every at m="*/5". 5 minutes is usually plenty of time, but +# for large attachments, it might not be enough. +# * If I wanted to run it manually, at say m="*/5+4", if it takes more than a +# minute to run, then the instance invoked by cron would bork everything. + +# As awesome as this is, it has one fatal flaw: an instance hanging. +# I've only had this happen once, but an instance of offlineimap invoked by cron +# decided to hang up. After 2 days of recieving suspiciously little email, I +# decided to check if offlineimap was running ok. That instance had hung up, not +# recieving any mail, but preventing cron from starting another instance. +# +# So, here is my workaround: keep track of how many times in a row that we've +# tried to start offlineimap, and it failed. If that number exceeds a specified +# number, then assume the running instance hung, and kill it. + +# A note on notation: +# the number/limit is the number of failures allowed *before* anything is killed. +# So, if the limit is "1", the first time, it will just pass by. The second +# time, it will see that we've already failed once, so if it's still running, +# kill it. +default_limit=2 +limit=${1-$default_limit} + +cookie_file="$HOME/.offlineimap.cookie" +offlineimap='offlineimap -u quiet' + +# Try running offlineimap +if $offlineimap; then + # Everything went smoothly, remove any record of failures + echo '0' > "$cookie_file" +else + # oh noez! + # we interupt your regularly scheduled panic for a sanity check + if [ ! -f "$cookie_file" ]; then + echo '0' > "$cookie_file" + fi + # you may now resume panicing + number=`cat "$cookie_file"` + if [ "$number" -ge "$limit" ]; then # kill it! + # extract the first argument from our offlineimap command + set -- $offlineimap + killall $1 + # We invoke offlineimap directly, instead of recursing on + # ourself because if something else is causing it to fail, then + # we'll fork-bomb + $offlineimap + else + echo $(($number+1)) > "$cookie_file" + fi +fi |