Aluode/PerceptionLabPortable

1from __future__ import annotations2 3import os4import sys5from contextlib import suppress6from errno import EACCES, EEXIST7from pathlib import Path8 9from ._api import BaseFileLock10from ._util import ensure_directory_exists, raise_on_not_writable_file11 12 13class SoftFileLock(BaseFileLock):14    """Simply watches the existence of the lock file."""15 16    def _acquire(self) -> None:17        raise_on_not_writable_file(self.lock_file)18        ensure_directory_exists(self.lock_file)19        # first check for exists and read-only mode as the open will mask this case as EEXIST20        flags = (21            os.O_WRONLY  # open for writing only22            | os.O_CREAT23            | os.O_EXCL  # together with above raise EEXIST if the file specified by filename exists24            | os.O_TRUNC  # truncate the file to zero byte25        )26        try:27            file_handler = os.open(self.lock_file, flags, self._context.mode)28        except OSError as exception:  # re-raise unless expected exception29            if not (30                exception.errno == EEXIST  # lock already exist31                or (exception.errno == EACCES and sys.platform == "win32")  # has no access to this lock32            ):  # pragma: win32 no cover33                raise34        else:35            self._context.lock_file_fd = file_handler36 37    def _release(self) -> None:38        assert self._context.lock_file_fd is not None  # noqa: S10139        os.close(self._context.lock_file_fd)  # the lock file is definitely not None40        self._context.lock_file_fd = None41        with suppress(OSError):  # the file is already deleted and that's what we want42            Path(self.lock_file).unlink()43 44 45__all__ = [46    "SoftFileLock",47]48