Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/filelock/_api.py: 70%
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1from __future__ import annotations
3import contextlib
4import inspect
5import logging
6import os
7import pathlib
8import sys
9import time
10import warnings
11from abc import ABCMeta, abstractmethod
12from dataclasses import dataclass
13from threading import local
14from typing import TYPE_CHECKING, Any, cast
15from weakref import WeakValueDictionary
17from ._error import Timeout
19#: Sentinel indicating that no explicit file permission mode was passed.
20#: When used, lock files are created with 0o666 (letting umask and default ACLs control the final permissions)
21#: and fchmod is skipped so that POSIX default ACL inheritance is preserved.
22_UNSET_FILE_MODE: int = -1
24if TYPE_CHECKING:
25 from collections.abc import Callable
26 from types import TracebackType
28 from ._read_write import ReadWriteLock
30 if sys.version_info >= (3, 11): # pragma: no cover (py311+)
31 from typing import Self
32 else: # pragma: no cover (<py311)
33 from typing_extensions import Self
36_LOGGER = logging.getLogger("filelock")
38# On Windows os.path.realpath calls CreateFileW with share_mode=0, which blocks concurrent DeleteFileW and causes
39# livelocks under threaded contention with SoftFileLock. os.path.abspath is purely string-based and avoids this.
40_canonical = os.path.abspath if sys.platform == "win32" else os.path.realpath
43class _ThreadLocalRegistry(local):
44 def __init__(self) -> None:
45 super().__init__()
46 self.held: dict[str, int] = {}
49_registry = _ThreadLocalRegistry()
52# This is a helper class which is returned by :meth:`BaseFileLock.acquire` and wraps the lock to make sure __enter__
53# is not called twice when entering the with statement. If we would simply return *self*, the lock would be acquired
54# again in the *__enter__* method of the BaseFileLock, but not released again automatically. issue #37 (memory leak)
55class AcquireReturnProxy:
56 """A context-aware object that will release the lock file when exiting."""
58 def __init__(self, lock: BaseFileLock | ReadWriteLock) -> None:
59 self.lock: BaseFileLock | ReadWriteLock = lock
61 def __enter__(self) -> BaseFileLock | ReadWriteLock:
62 return self.lock
64 def __exit__(
65 self,
66 exc_type: type[BaseException] | None,
67 exc_value: BaseException | None,
68 traceback: TracebackType | None,
69 ) -> None:
70 self.lock.release()
73@dataclass
74class FileLockContext:
75 """A dataclass which holds the context for a ``BaseFileLock`` object."""
77 # The context is held in a separate class to allow optional use of thread local storage via the
78 # ThreadLocalFileContext class.
80 #: The path to the lock file.
81 lock_file: str
83 #: The default timeout value.
84 timeout: float
86 #: The mode for the lock files
87 mode: int
89 #: Whether the lock should be blocking or not
90 blocking: bool
92 #: The default polling interval value.
93 poll_interval: float
95 #: The lock lifetime in seconds; ``None`` means the lock never expires.
96 lifetime: float | None = None
98 #: The file descriptor for the *_lock_file* as it is returned by the os.open() function, not None when lock held
99 lock_file_fd: int | None = None
101 #: The lock counter is used for implementing the nested locking mechanism.
102 lock_counter: int = 0 # When the lock is acquired is increased and the lock is only released, when this value is 0
105class ThreadLocalFileContext(FileLockContext, local):
106 """A thread local version of the ``FileLockContext`` class."""
109class FileLockMeta(ABCMeta):
110 _instances: WeakValueDictionary[str, BaseFileLock]
112 def __call__( # noqa: PLR0913
113 cls,
114 lock_file: str | os.PathLike[str],
115 timeout: float = -1,
116 mode: int = _UNSET_FILE_MODE,
117 thread_local: bool = True, # noqa: FBT001, FBT002
118 *,
119 blocking: bool = True,
120 is_singleton: bool = False,
121 poll_interval: float = 0.05,
122 lifetime: float | None = None,
123 **kwargs: Any, # capture remaining kwargs for subclasses # noqa: ANN401
124 ) -> BaseFileLock:
125 if is_singleton:
126 instance = cls._instances.get(str(lock_file))
127 if instance:
128 params_to_check = {
129 "thread_local": (thread_local, instance.is_thread_local()),
130 "timeout": (timeout, instance.timeout),
131 "mode": (mode, instance._context.mode), # noqa: SLF001
132 "blocking": (blocking, instance.blocking),
133 "poll_interval": (poll_interval, instance.poll_interval),
134 "lifetime": (lifetime, instance.lifetime),
135 }
137 non_matching_params = {
138 name: (passed_param, set_param)
139 for name, (passed_param, set_param) in params_to_check.items()
140 if passed_param != set_param
141 }
142 if not non_matching_params:
143 return cast("BaseFileLock", instance)
145 # parameters do not match; raise error
146 msg = "Singleton lock instances cannot be initialized with differing arguments"
147 msg += "\nNon-matching arguments: "
148 for param_name, (passed_param, set_param) in non_matching_params.items():
149 msg += f"\n\t{param_name} (existing lock has {set_param} but {passed_param} was passed)"
150 raise ValueError(msg)
152 # Workaround to make `__init__`'s params optional in subclasses
153 # E.g. virtualenv changes the signature of the `__init__` method in the `BaseFileLock` class descendant
154 # (https://github.com/tox-dev/filelock/pull/340)
156 all_params = {
157 "timeout": timeout,
158 "mode": mode,
159 "thread_local": thread_local,
160 "blocking": blocking,
161 "is_singleton": is_singleton,
162 "poll_interval": poll_interval,
163 "lifetime": lifetime,
164 **kwargs,
165 }
167 present_params = inspect.signature(cls.__init__).parameters
168 init_params = {key: value for key, value in all_params.items() if key in present_params}
170 instance = super().__call__(lock_file, **init_params)
172 if is_singleton:
173 cls._instances[str(lock_file)] = instance
175 return cast("BaseFileLock", instance)
178class BaseFileLock(contextlib.ContextDecorator, metaclass=FileLockMeta):
179 """
180 Abstract base class for a file lock object.
182 Provides a reentrant, cross-process exclusive lock backed by OS-level primitives. Subclasses implement the actual
183 locking mechanism (:class:`UnixFileLock <filelock.UnixFileLock>`, :class:`WindowsFileLock
184 <filelock.WindowsFileLock>`, :class:`SoftFileLock <filelock.SoftFileLock>`).
186 """
188 _instances: WeakValueDictionary[str, BaseFileLock]
190 def __init_subclass__(cls, **kwargs: dict[str, Any]) -> None:
191 """Setup unique state for lock subclasses."""
192 super().__init_subclass__(**kwargs)
193 cls._instances = WeakValueDictionary()
195 def __init__( # noqa: PLR0913
196 self,
197 lock_file: str | os.PathLike[str],
198 timeout: float = -1,
199 mode: int = _UNSET_FILE_MODE,
200 thread_local: bool = True, # noqa: FBT001, FBT002
201 *,
202 blocking: bool = True,
203 is_singleton: bool = False,
204 poll_interval: float = 0.05,
205 lifetime: float | None = None,
206 ) -> None:
207 """
208 Create a new lock object.
210 :param lock_file: path to the file
211 :param timeout: default timeout when acquiring the lock, in seconds. It will be used as fallback value in the
212 acquire method, if no timeout value (``None``) is given. If you want to disable the timeout, set it to a
213 negative value. A timeout of 0 means that there is exactly one attempt to acquire the file lock.
214 :param mode: file permissions for the lockfile. When not specified, the OS controls permissions via umask and
215 default ACLs, preserving POSIX default ACL inheritance in shared directories.
216 :param thread_local: Whether this object's internal context should be thread local or not. If this is set to
217 ``False`` then the lock will be reentrant across threads.
218 :param blocking: whether the lock should be blocking or not
219 :param is_singleton: If this is set to ``True`` then only one instance of this class will be created per lock
220 file. This is useful if you want to use the lock object for reentrant locking without needing to pass the
221 same object around.
222 :param poll_interval: default interval for polling the lock file, in seconds. It will be used as fallback value
223 in the acquire method, if no poll_interval value (``None``) is given.
224 :param lifetime: maximum time in seconds a lock can be held before it is considered expired. When set, a waiting
225 process will break a lock whose file modification time is older than ``lifetime`` seconds. ``None`` (the
226 default) means locks never expire.
228 """
229 self._is_thread_local = thread_local
230 self._is_singleton = is_singleton
232 # Create the context. Note that external code should not work with the context directly and should instead use
233 # properties of this class.
234 kwargs: dict[str, Any] = {
235 "lock_file": os.fspath(lock_file),
236 "timeout": timeout,
237 "mode": mode,
238 "blocking": blocking,
239 "poll_interval": poll_interval,
240 "lifetime": lifetime,
241 }
242 self._context: FileLockContext = (ThreadLocalFileContext if thread_local else FileLockContext)(**kwargs)
244 def is_thread_local(self) -> bool:
245 """:returns: a flag indicating if this lock is thread local or not"""
246 return self._is_thread_local
248 @property
249 def is_singleton(self) -> bool:
250 """
251 :returns: a flag indicating if this lock is singleton or not
253 .. versionadded:: 3.13.0
255 """
256 return self._is_singleton
258 @property
259 def lock_file(self) -> str:
260 """:returns: path to the lock file"""
261 return self._context.lock_file
263 @property
264 def timeout(self) -> float:
265 """
266 :returns: the default timeout value, in seconds
268 .. versionadded:: 2.0.0
270 """
271 return self._context.timeout
273 @timeout.setter
274 def timeout(self, value: float | str) -> None:
275 """
276 Change the default timeout value.
278 :param value: the new value, in seconds
280 """
281 self._context.timeout = float(value)
283 @property
284 def blocking(self) -> bool:
285 """
286 :returns: whether the locking is blocking or not
288 .. versionadded:: 3.14.0
290 """
291 return self._context.blocking
293 @blocking.setter
294 def blocking(self, value: bool) -> None:
295 """
296 Change the default blocking value.
298 :param value: the new value as bool
300 """
301 self._context.blocking = value
303 @property
304 def poll_interval(self) -> float:
305 """
306 :returns: the default polling interval, in seconds
308 .. versionadded:: 3.24.0
310 """
311 return self._context.poll_interval
313 @poll_interval.setter
314 def poll_interval(self, value: float) -> None:
315 """
316 Change the default polling interval.
318 :param value: the new value, in seconds
320 """
321 self._context.poll_interval = value
323 @property
324 def lifetime(self) -> float | None:
325 """
326 :returns: the lock lifetime in seconds, or ``None`` if the lock never expires
328 .. versionadded:: 3.24.0
330 """
331 return self._context.lifetime
333 @lifetime.setter
334 def lifetime(self, value: float | None) -> None:
335 """
336 Change the lock lifetime.
338 :param value: the new value in seconds, or ``None`` to disable expiration
340 """
341 self._context.lifetime = value
343 @property
344 def mode(self) -> int:
345 """:returns: the file permissions for the lockfile"""
346 return 0o644 if self._context.mode == _UNSET_FILE_MODE else self._context.mode
348 @property
349 def has_explicit_mode(self) -> bool:
350 """:returns: whether the file permissions were explicitly set"""
351 return self._context.mode != _UNSET_FILE_MODE
353 def _open_mode(self) -> int:
354 """:returns: the mode for os.open() — 0o666 when unset (let umask/ACLs decide), else the explicit mode"""
355 return 0o666 if self._context.mode == _UNSET_FILE_MODE else self._context.mode
357 def _try_break_expired_lock(self) -> None:
358 """Remove the lock file if its modification time exceeds the configured :attr:`lifetime`."""
359 if (lifetime := self._context.lifetime) is None:
360 return
361 with contextlib.suppress(OSError):
362 if time.time() - pathlib.Path(self.lock_file).stat().st_mtime < lifetime:
363 return
364 break_path = f"{self.lock_file}.break.{os.getpid()}"
365 pathlib.Path(self.lock_file).rename(break_path)
366 pathlib.Path(break_path).unlink()
368 @abstractmethod
369 def _acquire(self) -> None:
370 """If the file lock could be acquired, self._context.lock_file_fd holds the file descriptor of the lock file."""
371 raise NotImplementedError
373 @abstractmethod
374 def _release(self) -> None:
375 """Releases the lock and sets self._context.lock_file_fd to None."""
376 raise NotImplementedError
378 @property
379 def is_locked(self) -> bool:
380 """
381 :returns: A boolean indicating if the lock file is holding the lock currently.
383 .. versionchanged:: 2.0.0
385 This was previously a method and is now a property.
387 """
388 return self._context.lock_file_fd is not None
390 @property
391 def lock_counter(self) -> int:
392 """:returns: The number of times this lock has been acquired (but not yet released)."""
393 return self._context.lock_counter
395 @staticmethod
396 def _check_give_up( # noqa: PLR0913
397 lock_id: int,
398 lock_filename: str,
399 *,
400 blocking: bool,
401 cancel_check: Callable[[], bool] | None,
402 timeout: float,
403 start_time: float,
404 ) -> bool:
405 if blocking is False:
406 _LOGGER.debug("Failed to immediately acquire lock %s on %s", lock_id, lock_filename)
407 return True
408 if cancel_check is not None and cancel_check():
409 _LOGGER.debug("Cancellation requested for lock %s on %s", lock_id, lock_filename)
410 return True
411 if 0 <= timeout < time.perf_counter() - start_time:
412 _LOGGER.debug("Timeout on acquiring lock %s on %s", lock_id, lock_filename)
413 return True
414 return False
416 def acquire( # noqa: C901
417 self,
418 timeout: float | None = None,
419 poll_interval: float | None = None,
420 *,
421 poll_intervall: float | None = None,
422 blocking: bool | None = None,
423 cancel_check: Callable[[], bool] | None = None,
424 ) -> AcquireReturnProxy:
425 """
426 Try to acquire the file lock.
428 :param timeout: maximum wait time for acquiring the lock, ``None`` means use the default :attr:`~timeout` is and
429 if ``timeout < 0``, there is no timeout and this method will block until the lock could be acquired
430 :param poll_interval: interval of trying to acquire the lock file, ``None`` means use the default
431 :attr:`~poll_interval`
432 :param poll_intervall: deprecated, kept for backwards compatibility, use ``poll_interval`` instead
433 :param blocking: defaults to True. If False, function will return immediately if it cannot obtain a lock on the
434 first attempt. Otherwise, this method will block until the timeout expires or the lock is acquired.
435 :param cancel_check: a callable returning ``True`` when the acquisition should be canceled. Checked on each poll
436 iteration. When triggered, raises :class:`~Timeout` just like an expired timeout.
438 :returns: a context object that will unlock the file when the context is exited
440 :raises Timeout: if fails to acquire lock within the timeout period
442 .. code-block:: python
444 # You can use this method in the context manager (recommended)
445 with lock.acquire():
446 pass
448 # Or use an equivalent try-finally construct:
449 lock.acquire()
450 try:
451 pass
452 finally:
453 lock.release()
455 .. versionchanged:: 2.0.0
457 This method returns now a *proxy* object instead of *self*, so that it can be used in a with statement
458 without side effects.
460 """
461 # Use the default timeout, if no timeout is provided.
462 if timeout is None:
463 timeout = self._context.timeout
465 if blocking is None:
466 blocking = self._context.blocking
468 if poll_intervall is not None:
469 msg = "use poll_interval instead of poll_intervall"
470 warnings.warn(msg, DeprecationWarning, stacklevel=2)
471 poll_interval = poll_intervall
473 poll_interval = poll_interval if poll_interval is not None else self._context.poll_interval
475 # Increment the number right at the beginning. We can still undo it, if something fails.
476 self._context.lock_counter += 1
478 lock_id = id(self)
479 lock_filename = self.lock_file
480 canonical = _canonical(lock_filename)
482 would_block = self._context.lock_counter == 1 and not self.is_locked and timeout < 0 and blocking
483 if would_block and (existing := _registry.held.get(canonical)) is not None and existing != lock_id:
484 self._context.lock_counter -= 1
485 msg = (
486 f"Deadlock: lock '{lock_filename}' is already held by a different "
487 f"FileLock instance in this thread. Use is_singleton=True to "
488 f"enable reentrant locking across instances."
489 )
490 raise RuntimeError(msg)
492 start_time = time.perf_counter()
493 try:
494 while True:
495 if not self.is_locked:
496 self._try_break_expired_lock()
497 _LOGGER.debug("Attempting to acquire lock %s on %s", lock_id, lock_filename)
498 self._acquire()
499 if self.is_locked:
500 _LOGGER.debug("Lock %s acquired on %s", lock_id, lock_filename)
501 break
502 if self._check_give_up(
503 lock_id,
504 lock_filename,
505 blocking=blocking,
506 cancel_check=cancel_check,
507 timeout=timeout,
508 start_time=start_time,
509 ):
510 raise Timeout(lock_filename) # noqa: TRY301
511 msg = "Lock %s not acquired on %s, waiting %s seconds ..."
512 _LOGGER.debug(msg, lock_id, lock_filename, poll_interval)
513 time.sleep(poll_interval)
514 except BaseException:
515 self._context.lock_counter = max(0, self._context.lock_counter - 1)
516 if self._context.lock_counter == 0:
517 _registry.held.pop(canonical, None)
518 raise
519 if self._context.lock_counter == 1:
520 _registry.held[canonical] = lock_id
521 return AcquireReturnProxy(lock=self)
523 def release(self, force: bool = False) -> None: # noqa: FBT001, FBT002
524 """
525 Release the file lock. The lock is only completely released when the lock counter reaches 0. The lock file
526 itself is not automatically deleted.
528 :param force: If true, the lock counter is ignored and the lock is released in every case.
530 """
531 if self.is_locked:
532 self._context.lock_counter -= 1
534 if self._context.lock_counter == 0 or force:
535 lock_id, lock_filename = id(self), self.lock_file
537 _LOGGER.debug("Attempting to release lock %s on %s", lock_id, lock_filename)
538 self._release()
539 self._context.lock_counter = 0
540 _registry.held.pop(_canonical(lock_filename), None)
541 _LOGGER.debug("Lock %s released on %s", lock_id, lock_filename)
543 def __enter__(self) -> Self:
544 """
545 Acquire the lock.
547 :returns: the lock object
549 """
550 self.acquire()
551 return self
553 def __exit__(
554 self,
555 exc_type: type[BaseException] | None,
556 exc_value: BaseException | None,
557 traceback: TracebackType | None,
558 ) -> None:
559 """
560 Release the lock.
562 :param exc_type: the exception type if raised
563 :param exc_value: the exception value if raised
564 :param traceback: the exception traceback if raised
566 """
567 self.release()
569 def __del__(self) -> None:
570 """Called when the lock object is deleted."""
571 self.release(force=True)
574__all__ = [
575 "_UNSET_FILE_MODE",
576 "AcquireReturnProxy",
577 "BaseFileLock",
578]