75 lines
2.3 KiB
Python
75 lines
2.3 KiB
Python
# Copyright 2018 Mycroft AI Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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from threading import Lock
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from fasteners.process_lock import InterProcessLock
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from os.path import exists
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from os import chmod
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class ComboLock:
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""" A combined process and thread lock.
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Arguments:
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path (str): path to the lockfile for the lock
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"""
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def __init__(self, path):
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# Create lock file if it doesn't exist and set permissions for
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# all users to lock/unlock
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if not exists(path):
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f = open(path, 'w+')
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f.close()
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chmod(path, 0o777)
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self.plock = InterProcessLock(path)
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self.tlock = Lock()
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def acquire(self, blocking=True):
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""" Acquire lock, locks thread and process lock.
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Arguments:
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blocking(bool): Set's blocking mode of acquire operation.
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Default True.
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Returns: True if lock succeeded otherwise False
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"""
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if not blocking:
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# Lock thread
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tlocked = self.tlock.acquire(blocking=False)
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if not tlocked:
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return False
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# Lock process
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plocked = self.plock.acquire(blocking=False)
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if not plocked:
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# Release thread lock if process couldn't be locked
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self.tlock.release()
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return False
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else: # blocking, just wait and acquire ALL THE LOCKS!!!
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self.tlock.acquire()
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self.plock.acquire()
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return True
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def release(self):
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""" Release acquired lock. """
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self.plock.release()
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self.tlock.release()
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def __enter__(self):
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""" Context handler, acquires lock in blocking mode. """
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self.acquire()
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return self
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def __exit__(self, _type, value, traceback):
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""" Releases the lock. """
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self.release()
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