Improve mailsync script with parallel IMAP fetching

mailsync

@@ -1,20 +1,29 @@
 #!/bin/sh
 
-# Temp disable
-#exit 0
+maildir=~/mail
+# find "$maildir" -mindepth 1 -maxdepth 1 -type d ! -name cur ! -name tmp ! -name new ! -name .notmuch -printf '%f\0' | xargs -0 -n1 --max-procs=0 mbsync
+mailboxes=$(find "$maildir" -mindepth 1 -maxdepth 1 -type d ! -name cur ! -name tmp ! -name new ! -name .notmuch -printf '%f\n')
 
-if pgrep -x mbsync > /dev/null ; then
-    >&2 echo "Isync is already running, aborting..."
+LOCKFILE="/tmp/.mailsync.$USER.lock"
+# /!\ locking method is susceptible to race condition
+# Should be fine for cron job
+if [ -e "$LOCKFILE" ] && kill -0 "$(cat "$LOCKFILE")"; then
+    echo "mailsync is already running"
     exit 1
 fi
 
-timeout 10m mbsync -a
-if [ "$?" -eq 124 ];then
-    >&2 echo "Command mbync -a timed out"
-elif [ "$?" -eq 0 ];then
-    >&2 echo "Successful mail synchronisation"
-else
-    >&2 echo "Isync exited with status $?"
-fi
+# make sure the lockfile is removed when we exit and then claim it
+trap "rm -f $LOCKFILE; exit" INT TERM EXIT
+echo $$ > "$LOCKFILE"
+
+for m in $mailboxes; do
+    mbsync "$m" &
+    sleep 1
+done
+
+wait
+
 fdm fetch
 notmuch new
+
+rm -f "$LOCKFILE"