From af58e68243f3b6b10d7dd177f54c55c3f379ee92 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <LukeShu@sbcglobal.net>
Date: Wed, 28 Sep 2011 03:02:00 -0400
Subject: add offlineimap-runner

---
 .gitignore            | 21 +++++++++---------
 Makefile              |  1 +
 offlineimap-runner.sh | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+), 10 deletions(-)
 create mode 100644 offlineimap-runner.sh

diff --git a/.gitignore b/.gitignore
index 7cee854..ad1cfdc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,18 +1,19 @@
 *~
 arg
-ord
-urldecode
-roll
-v-www-browser
-v-editor
-whatismyip
 chardiff
 chardiff_pre
 chardiff_post
-newegg
-hangman
-sysfiles
 daemon
+e
 emacsmail
 emacsterm
-e
+hangman
+newegg
+offlineimap-runner
+ord
+roll
+sysfiles
+urldecode
+v-www-browser
+v-editor
+whatismyip
diff --git a/Makefile b/Makefile
index 59161c0..89d25f6 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@ BINFILES = \
   emacsterm \
   hangman \
   newegg \
+  offlineimap-runner \
   ord \
   roll \
   sysfiles \
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
-- 
cgit v1.2.3