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20ac736200
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44735 Reviewed By: mruberry Differential Revision: D23731306 Pulled By: ezyang fbshipit-source-id: 0ba009a99e475ddbe22981be8ac636f8a1c8b02f
56 lines
1.5 KiB
Python
56 lines
1.5 KiB
Python
import os
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import sys
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import time
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if sys.version < '3.3':
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# Note(jiayq): in Python 2, FileExistsError is not defined and the
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# error manifests it as OSError.
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FileExistsError = OSError
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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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Creates 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 periorically 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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Tries 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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'''Releases 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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