#!/usr/bin/env python

# Copyright 2013 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Script to cleanup old XenServer /var/lock/sm locks.

XenServer 5.6 and 6.0 do not appear to always cleanup locks when using a
FileSR. ext3 has a limit of 32K inode links, so when we have 32K-2 (31998)
locks laying around, builds will begin to fail because we can't create any
additional locks.  This cleanup script is something we can run periodically as
a stop-gap measure until this is fixed upstream.

This script should be run on the dom0 of the affected machine.
"""
import errno
import optparse
import os
import sys
import time

BASE = '/var/lock/sm'


def _get_age_days(secs):
    return float(time.time() - secs) / 86400


def _parse_args():
    parser = optparse.OptionParser()
    parser.add_option("-d", "--dry-run",
                      action="store_true", dest="dry_run", default=False,
                      help="don't actually remove locks")
    parser.add_option("-l", "--limit",
                      action="store", type='int', dest="limit",
                      default=sys.maxint,
                      help="max number of locks to delete (default: no limit)")
    parser.add_option("-v", "--verbose",
                      action="store_true", dest="verbose", default=False,
                      help="don't print status messages to stdout")

    options, args = parser.parse_args()

    try:
        days_old = int(args[0])
    except (IndexError, ValueError):
        parser.print_help()
        sys.exit(1)

    return options, days_old


def main():
    options, days_old = _parse_args()

    if not os.path.exists(BASE):
        print >> sys.stderr, "error: '%s' doesn't exist. Make sure you're"\
                             " running this on the dom0." % BASE
        sys.exit(1)

    lockpaths_removed = 0
    nspaths_removed = 0

    for nsname in os.listdir(BASE)[:options.limit]:
        nspath = os.path.join(BASE, nsname)

        if not os.path.isdir(nspath):
            continue

        # Remove old lockfiles
        removed = 0
        locknames = os.listdir(nspath)
        for lockname in locknames:
            lockpath = os.path.join(nspath, lockname)
            lock_age_days = _get_age_days(os.path.getmtime(lockpath))
            if lock_age_days > days_old:
                lockpaths_removed += 1
                removed += 1

                if options.verbose:
                    print 'Removing old lock: %03d %s' % (lock_age_days,
                                                          lockpath)

                if not options.dry_run:
                    os.unlink(lockpath)

        # Remove empty namespace paths
        if len(locknames) == removed:
            nspaths_removed += 1

            if options.verbose:
                print 'Removing empty namespace: %s' % nspath

            if not options.dry_run:
                try:
                    os.rmdir(nspath)
                except OSError, e:
                    if e.errno == errno.ENOTEMPTY:
                        print >> sys.stderr, "warning: directory '%s'"\
                                             " not empty" % nspath
                    else:
                        raise

    if options.dry_run:
        print "** Dry Run **"

    print "Total locks removed: ", lockpaths_removed
    print "Total namespaces removed: ", nspaths_removed


if __name__ == '__main__':
    main()