106 lines
2.9 KiB
Python
106 lines
2.9 KiB
Python
# -*- coding: utf-8 -*-
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# flake8: noqa
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# The MIT License (MIT)
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#
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# Copyright (c) 2014 Stephan Schultchen
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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# -*- coding: utf-8 -*-
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"""
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Simple PidFile Module for a pep3143 daemon implementation.
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"""
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__author__ = 'schlitzer'
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import atexit
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import fcntl
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import os
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class PidFile(object):
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"""
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PidFile implementation for PEP 3143 Daemon.
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This Class can also be used with pythons 'with'
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statement.
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:param pidfile:
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filename to be used as pidfile, including path
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:type pidfile: str
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"""
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def __init__(self, pidfile):
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"""
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Create a new instance
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"""
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self._pidfile = pidfile
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self.pidfile = None
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def __enter__(self):
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self.acquire()
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return self
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def __exit__(self, exc_type, exc_value, exc_tb):
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if exc_type is not None:
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self.release()
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return False
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self.release()
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return True
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def acquire(self):
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"""Acquire the pidfile.
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Create the pidfile, lock it, write the pid into it
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and register the release with atexit.
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:return: None
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:raise: SystemExit
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"""
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try:
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pidfile = open(self._pidfile, "a")
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except IOError as err:
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raise SystemExit(err)
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try:
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fcntl.flock(pidfile.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
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except IOError:
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raise SystemExit('Already running according to ' + self._pidfile)
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pidfile.seek(0)
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pidfile.truncate()
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pidfile.write(str(os.getpid()) + '\n')
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pidfile.flush()
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self.pidfile = pidfile
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atexit.register(self.release)
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def release(self):
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"""Release the pidfile.
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Close and delete the Pidfile.
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:return: None
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"""
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try:
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self.pidfile.close()
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os.remove(self._pidfile)
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except OSError as err:
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if err.errno != 2:
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raise
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