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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2016 Samsung Electronics Co., Ltd All Rights Reserved
#
# 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.
##
# @author Aleksander Mistewicz <a.mistewicz@samsung.com>
import os
import time
import subprocess
import argparse
import logging
__version__ = "0.0.1"
__license__ = "APACHE-2.0"
__author__ = "Aleksander Mistewicz"
__author_email__ = "a.mistewicz@samsung.com"
USAGE = "%prog <opts>"
UUID_DIR = "/var/tmp/"
UUID_PREFIX="uuid-"
LOCK_SUFFIX=".lock"
CNT_SUFFIX=".cnt"
class Lockfile(object):
@classmethod
def lock(self, filename):
logging.debug("Lock: %s", filename)
return subprocess.call(["lockfile-create", "--retry", "0", "--use-pid", filename])
@classmethod
def unlock(self, filename):
logging.debug("Unlock: %s", filename)
return subprocess.call(["lockfile-remove", filename])
@classmethod
def check(self, filename):
logging.debug("Check: %s", filename)
return subprocess.call(["lockfile-check", "--use-pid", filename])
class UUIDlist(object):
@classmethod
def all(self):
return os.listdir(UUID_DIR)
@classmethod
def uuid(self):
ret = set()
for f in self.all():
if f.startswith(UUID_PREFIX) \
and not f.endswith(LOCK_SUFFIX) \
and not f.endswith(CNT_SUFFIX):
ret.add(f)
return ret
@classmethod
def target(self, target):
ret = set()
for f in self.uuid():
if f.startswith(UUID_PREFIX + target):
ret.add(f)
return ret
@classmethod
def not_locked(self, target_list):
ret = set()
for f in target_list:
if Lockfile.check(UUID_DIR + f):
ret.add(f)
return ret
@classmethod
def get_cnt(self, uuid):
fname = UUID_DIR + uuid + CNT_SUFFIX
logging.debug("Get counter from: %s", fname)
if os.path.isfile(fname):
with open(fname, 'r') as f:
return int(f.read())
return 0
@classmethod
def set_cnt(self, uuid, value):
fname = UUID_DIR + uuid + CNT_SUFFIX
logging.debug("Set counter (%d) for: %s", value, fname)
with open(fname, 'w') as f:
f.write(str(value))
@classmethod
def sort_cnt(self, targets):
cnt = dict()
ret = list(targets)
for u in ret:
cnt[u]=self.get_cnt(u)
logging.debug("UUID files with counters: %s", cnt)
ret.sort(key=cnt.__getitem__)
logging.debug("Sorted list of UUIDs: %s", ret)
return ret
class UUIDmanager:
def __init__(self, target, inc, holdoff):
self.target = target
self.inc = inc
self.holdoff = holdoff
def lock(self):
# go through the list of not locked uuid files and stop on the first successfully locked
# returns False if none of the uuid files was locked
# otherwise it returns True and prints filename on stdout
for uuid in UUIDlist.sort_cnt(UUIDlist.not_locked(UUIDlist.target(self.target))):
if Lockfile.lock(UUID_DIR + uuid) == 0:
logging.info("Locked: %s", uuid)
with open(UUID_DIR + uuid + LOCK_SUFFIX, 'w') as f:
f.write(str(os.getppid()))
UUIDlist.set_cnt(uuid, UUIDlist.get_cnt(uuid)+1)
print uuid[len(UUID_PREFIX):]
return True
logging.info("Failed to lock")
return False
def target_list_is_empty(self):
# return True if there are no files available for target (including locked)
# False otherwise
target_list = UUIDlist.target(self.target)
if len(target_list) == 0:
logging.error("Target list for \"%s\" is empty", self.target)
return True
return False
def unlock(self):
# remove lock on specified target
# returns True if operation was successful (no lock is present)
# False otherwise
logging.info("Unlocking: %s", self.target)
return Lockfile.unlock(UUID_DIR + UUID_PREFIX + self.target) == 0
def retrylock(self):
# try to lock a target every self.holdoff seconds
# returns False if there are no available targets
# True otherwise
while not self.lock():
if self.target_list_is_empty():
return False
time.sleep(self.holdoff)
return True
def unlockfailed(self):
# unlock target as usual and increase its counter by self.inc
if not self.unlock():
logging.warn("Unlock failed: %s", self.target)
uuid = UUID_PREFIX + self.target
UUIDlist.set_cnt(uuid, UUIDlist.get_cnt(uuid) + self.inc)
def parse_arguments():
parser = argparse.ArgumentParser(description="Manager of locks on UUID files")
group = parser.add_mutually_exclusive_group()
parser.add_argument("target",
help="Choose type of a target device to lock/unlock")
group.add_argument("-l", "--lock",
action="store_true", default=False, dest="lock",
help="Lock a device")
group.add_argument("-r", "--retrylock",
action="store_true", default=False, dest="retrylock",
help="Try to lock a device every HOLDOFF seconds until successful")
parser.add_argument("--holdoff", type=int,
action="store", default=60, dest="holdoff",
help="Set HOLDOFF value (default: 60)")
group.add_argument("-u", "--unlock",
action="store_true", default=False, dest="unlock",
help="Unlock a device")
group.add_argument("-f", "--unlockfailed",
action="store_true", default=False, dest="unlockfailed",
help="Unlock a device and increment counter by INC")
parser.add_argument("--inc", type=int,
action="store", default=10, dest="inc",
help="Set INC value (default: 10)")
parser.add_argument("-L", "--log",
action="store", dest="loglevel",
help="Verbosity level")
args = parser.parse_args()
return args
def main():
args = parse_arguments()
if args.loglevel:
numeric_level = getattr(logging, args.loglevel.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: %s' % args.loglevel)
logging.basicConfig(format='%(asctime)s %(message)s',level=numeric_level)
logging.debug("Begin")
uuid_man = UUIDmanager(args.target, args.inc, args.holdoff)
if args.lock:
if not uuid_man.lock():
logging.warn("File locking unsuccessful!")
elif args.unlock:
if not uuid_man.unlock():
logging.warn("File unlocking unsuccessful!")
elif args.retrylock:
if not uuid_man.retrylock():
logging.warn("Retrylock unsuccessful!")
elif args.unlockfailed:
uuid_man.unlockfailed()
logging.debug("End")
if __name__ == '__main__':
main()
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