93 lines
3.2 KiB
Python
93 lines
3.2 KiB
Python
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#! /usr/bin/env python
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import logging
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import os
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import sys
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import tempfile
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if sys.platform != "win32":
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import fcntl
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class SingleInstanceException(BaseException):
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pass
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class SingleInstance(object):
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"""Class that can be instantiated only once per machine.
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If you want to prevent your script from running in parallel just instantiate SingleInstance() class. If is there another instance already running it will throw a `SingleInstanceException`.
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>>> import tendo
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... me = SingleInstance()
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This option is very useful if you have scripts executed by crontab at small amounts of time.
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Remember that this works by creating a lock file with a filename based on the full path to the script file.
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Providing a flavor_id will augment the filename with the provided flavor_id, allowing you to create multiple singleton instances from the same file. This is particularly useful if you want specific functions to have their own singleton instances.
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"""
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def __init__(self, flavor_id="", lockfile=""):
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self.initialized = False
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if lockfile:
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self.lockfile = lockfile
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else:
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basename = os.path.splitext(os.path.abspath(sys.argv[0]))[0].replace(
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"/", "-").replace(":", "").replace("\\", "-") + '-%s' % flavor_id + '.lock'
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self.lockfile = os.path.normpath(
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tempfile.gettempdir() + '/' + basename)
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logger.debug("SingleInstance lockfile: " + self.lockfile)
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if sys.platform == 'win32':
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try:
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# file already exists, we try to remove (in case previous
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# execution was interrupted)
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if os.path.exists(self.lockfile):
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os.unlink(self.lockfile)
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self.fd = os.open(
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self.lockfile, os.O_CREAT | os.O_EXCL | os.O_RDWR)
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except OSError:
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type, e, tb = sys.exc_info()
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if e.errno == 13:
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logger.error(
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"Another instance is already running, quitting.")
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raise SingleInstanceException()
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print(e.errno)
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raise
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else: # non Windows
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self.fp = open(self.lockfile, 'w')
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self.fp.flush()
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try:
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fcntl.lockf(self.fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
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except IOError:
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logger.warning(
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"Another instance is already running, quitting.")
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raise SingleInstanceException()
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self.initialized = True
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def __del__(self):
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if not self.initialized:
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return
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try:
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if sys.platform == 'win32':
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if hasattr(self, 'fd'):
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os.close(self.fd)
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os.unlink(self.lockfile)
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else:
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fcntl.lockf(self.fp, fcntl.LOCK_UN)
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# os.close(self.fp)
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if os.path.isfile(self.lockfile):
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os.unlink(self.lockfile)
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except Exception as e:
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if logger:
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logger.warning(e)
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else:
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print("Unloggable error: %s" % e)
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sys.exit(-1)
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logger = logging.getLogger("tendo.singleton")
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