src/lockcli/handlers.py

   1 # Copyright 2019 Nokia
   2
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #     http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 from __future__ import print_function
  16 import sys
  17 import inspect
  18 import etcd
  19
  20
  21 class VerboseLogger(object):
  22     def __call__(self, msg):
  23         print(msg)
  24
  25
  26 class CLIHandler(object):
  27     def __init__(self):
  28         self.sock = None
  29         self.verbose_logger = VerboseLogger()
  30         self.client = None
  31
  32     def _init_api(self, server, port, verbose):
  33         logger = None
  34         if verbose:
  35             logger = self.verbose_logger
  36
  37         if server == 'none':
  38             import socket
  39             server = socket.gethostname()
  40
  41         self.client = etcd.Client(server, port)
  42
  43     def set_handler(self, subparser):
  44         subparser.set_defaults(handler=self)
  45
  46     def init_subparser(self, subparsers):
  47         raise Error('Not implemented')
  48
  49     def __call__(self, args):
  50         raise Error('Not implemented')
  51
  52
  53 class CLILockHandler(CLIHandler):
  54     def init_subparser(self, subparsers):
  55         subparser = subparsers.add_parser('lock', help='Acquire a lock')
  56         subparser.add_argument('--id',
  57                                required=True,
  58                                dest='id',
  59                                metavar='ID',
  60                                type=str,
  61                                action='store')
  62
  63         subparser.add_argument('--timeout',
  64                                required=True,
  65                                dest='timeout',
  66                                metavar='TIMEOUT',
  67                                type=int,
  68                                action='store')
  69
  70         self.set_handler(subparser)
  71
  72     def __call__(self, args):
  73         self._init_api(args.server, args.port, args.verbose)
  74         lock = etcd.Lock(self.client, args.id)
  75         result = lock.acquire(blocking=False, lock_ttl=args.timeout)
  76         if not result:
  77             raise Exception('Lock taken!')
  78
  79         print('Lock acquired successfully!')
  80         print('uuid=%s' % lock.uuid)
  81
  82 class CLIUnlockHandler(CLIHandler):
  83     def init_subparser(self, subparsers):
  84         subparser = subparsers.add_parser('unlock', help='Release a lock')
  85         subparser.add_argument('--id',
  86                                required=True,
  87                                dest='id',
  88                                metavar='ID',
  89                                type=str,
  90                                action='store')
  91
  92         subparser.add_argument('--uuid',
  93                                required=True,
  94                                dest='uuid',
  95                                metavar='UUID',
  96                                type=str,
  97                                action='store')
  98         self.set_handler(subparser)
  99
 100     def __call__(self, args):
 101         self._init_api(args.server, args.port, args.verbose)
 102         lock = etcd.Lock(self.client, args.id)
 103         try:
 104             lock._uuid = args.uuid
 105             lock.release()
 106             print('Lock released successfully!')
 107         except ValueError:
 108             print('Lock is not held!')
 109
 110 def get_handlers_list():
 111     handlers = []
 112     for name, obj in inspect.getmembers(sys.modules[__name__]):
 113         if inspect.isclass(obj):
 114             if name is not 'CLIHandler':
 115                 if issubclass(obj, CLIHandler):
 116                     handlers.append(obj())
 117     return handlers
 118
 119
 120 def main():
 121     handlers = get_handlers_list()
 122     for handler in handlers:
 123         print('handler is ', handler)
 124
 125
 126 if __name__ == '__main__':
 127     main()