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zerver/lib/context_managers.py
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Anders Kaseorg
ruff: Fix SIM117 Use a single `with` statement with multiple contexts.
14 июл 2024, 23:48
14 июл 2024, 23:48
b96feb3
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""" Context managers, i.e. things you can use with the 'with' statement. """ import fcntl from collections.abc import Iterator from contextlib import contextmanager from typing import IO, Any @contextmanager def flock(lockfile: int | IO[Any], shared: bool = False) -> Iterator[None]: """Lock a file object using flock(2) for the duration of a 'with' statement. If shared is True, use a LOCK_SH lock, otherwise LOCK_EX.""" fcntl.flock(lockfile, fcntl.LOCK_SH if shared else fcntl.LOCK_EX) try: yield finally: fcntl.flock(lockfile, fcntl.LOCK_UN) @contextmanager def lockfile(filename: str, shared: bool = False) -> Iterator[None]: """Lock a file using flock(2) for the duration of a 'with' statement. If shared is True, use a LOCK_SH lock, otherwise LOCK_EX. The file is given by name and will be created if it does not exist.""" with open(filename, "w") as lock, flock(lock, shared=shared): yield @contextmanager def lockfile_nonblocking(filename: str) -> Iterator[bool]: # nocoverage """Lock a file using flock(2) for the duration of a 'with' statement. Doesn't block, yields False immediately if the lock can't be acquired.""" with open(filename, "w") as f: lock_acquired = False try: fcntl.flock(f, fcntl.LOCK_EX | fcntl.LOCK_NB) lock_acquired = True yield lock_acquired except BlockingIOError: yield False finally: if lock_acquired: fcntl.flock(f, fcntl.LOCK_UN)