mbsyncd

#!/usr/bin/env python

# mbsync seems to work well but, weirdly, doesn't have a daemon mode
# (surely 95% of users will want to run it that way?)
# Here's a wrapper for it that forks into background
# and runs forever, printing the time each time.

# XXX WISHLIST: catch a signal that starts a refresh.
# Actually, might this happen automatically
# because it would wake up from sleep?

from __future__ import print_function

import time
import subprocess
import os, sys


# Change this to whereever you want the log:
logfile = os.path.expanduser("~/.mutt/mbsync.log")


def Usage():
    print("Usage: %s [seconds]" % os.path.basename(sys.argv[0]))
    sys.exit(1)


if __name__ == '__main__':
    if len(sys.argv) > 2:
        Usage()

    if len(sys.argv) == 2:
        try:
            secs = int(sys.argv[1])
        except:
            Usage()
    else:
        secs = 120

    # Is an mbsync or mbsyncd process already running?
    # Running two at once would be bad.
    PROCDIR = '/proc'
    for proc in os.listdir(PROCDIR):
        if not proc[0].isdigit():
            continue

        # Is it the current process? Obviously that doesn't count.
        if int(proc) == os.getpid():
            continue

        # Race condition: processes can come and go, so we may not be
        # able to open something just because it was there when we
        # did the listdir.
        try:
            with open(os.path.join(PROCDIR, proc, 'cmdline')) as procfp:
                procline = procfp.readline()
                if "mbsync" in procline:
                    print("There's already an mbsync running, pid %s: %s"
                          % (proc, ' '.join(procline.split('\0'))))
                    sys.exit(1)
        except Exception as e:
            print("Exception", e)
            pass

    # Fork and run in the background.
    rc = os.fork()
    if rc:
        sys.exit(0)

    logfp = open(logfile, 'w')
    print("mbsync daemon, time %d, ouput to %s" % (secs, logfile))

    while True:
        subprocess.call(["date"], stdout=logfp, stderr=logfp)

        # mbsync suppresses its summary when stdout isn't a tty,
        # and there's no way to request a summary.
        # So nothing will go to the log; but if output isn't redirected,
        # it will print its summary to the terminal every time.
        subprocess.call(["mbsync", "-a"], stdout=logfp, stderr=logfp)

        time.sleep(secs)