50 lines
1.4 KiB
Python
50 lines
1.4 KiB
Python
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import os
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import time
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class FileBaton:
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"""A primitive, file-based synchronization utility."""
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def __init__(self, lock_file_path, wait_seconds=0.1):
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"""
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Create a new :class:`FileBaton`.
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Args:
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lock_file_path: The path to the file used for locking.
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wait_seconds: The seconds to periodically sleep (spin) when
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calling ``wait()``.
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"""
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self.lock_file_path = lock_file_path
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self.wait_seconds = wait_seconds
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self.fd = None
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def try_acquire(self):
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"""
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Try to atomically create a file under exclusive access.
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Returns:
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True if the file could be created, else False.
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"""
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try:
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self.fd = os.open(self.lock_file_path, os.O_CREAT | os.O_EXCL)
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return True
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except FileExistsError:
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return False
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def wait(self):
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"""
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Periodically sleeps for a certain amount until the baton is released.
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The amount of time slept depends on the ``wait_seconds`` parameter
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passed to the constructor.
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"""
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while os.path.exists(self.lock_file_path):
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time.sleep(self.wait_seconds)
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def release(self):
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"""Release the baton and removes its file."""
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if self.fd is not None:
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os.close(self.fd)
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os.remove(self.lock_file_path)
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