src/openpower/decoder/test/crtl_path.py

   1 # SPDX-License-Identifier: LGPL-3-or-later
   2 # Copyright 2022 Jacob Lifshay
   3
   4
   5 from contextlib import contextmanager
   6 from itertools import count
   7 import os
   8 from pathlib import Path
   9 import shutil
  10 from tempfile import NamedTemporaryFile
  11 from threading import local
  12
  13 __ctrl_path = local()
  14
  15
  16 @contextmanager
  17 def __try_lock_file(path):
  18     path = Path(path)
  19     try:
  20         file = path.open("xb")
  21     except FileExistsError:
  22         yield False
  23         return
  24     try:
  25         yield True
  26     finally:
  27         file.close()
  28         path.unlink()
  29
  30
  31 def get_crtl_path():
  32     # type: () -> str
  33     path = getattr(__ctrl_path, "path", None)
  34     if path is not None:
  35         assert isinstance(path, str), "invalid state"
  36         return path
  37     for i in range(10000):
  38         path = f"crtl{i}"
  39         with __try_lock_file(f"crtl{i}.lock") as locked:
  40             if locked and next(Path(path).glob(".lock_*"), None) is None:
  41                 shutil.rmtree(path, ignore_errors=True)
  42                 Path(path).mkdir(parents=True, exist_ok=True)
  43                 tmpfile = NamedTemporaryFile(prefix=".lock_", dir=path)
  44                 __ctrl_path.tmpfile = tmpfile
  45                 __ctrl_path.path = path
  46                 return path
  47     assert False, "can't create crtl* path"