twisted.internet.defer.DeferredFilesystemLock

class documentation

class DeferredFilesystemLock(lockfile.FilesystemLock): (source)

A FilesystemLock that allows for a Deferred to be fired when the lock is acquired.

Method	`__init__`	No summary
Method	`deferUntilLocked`	Wait until we acquire this lock. This method is not safe for concurrent use.
Instance Variable	`_interval`	The retry interval for an `IReactorTime` based scheduler.
Instance Variable	`_scheduler`	The object in charge of scheduling retries. In this implementation this is parameterized for testing.
Instance Variable	`_timeoutCall`	An `IDelayedCall` based on `deferUntilLocked`'s timeout argument. This is in charge of timing out our attempt to acquire the lock.
Instance Variable	`_tryLockCall`	An `IDelayedCall` based on `_interval` that will manage the next retry for acquiring the lock.

Inherited from FilesystemLock:

Method	`lock`	Acquire this lock.
Method	`unlock`	Release this lock.
Instance Variable	`clean`	Indicates whether this lock was released cleanly by its last owner. Only meaningful after `lock` has been called and returns True.
Instance Variable	`locked`	Indicates whether the lock is currently held by this object.
Instance Variable	`name`	The name of the file associated with this lock.

def __init__(self, name: str, scheduler: IReactorTime | None = None): (source) ¶

overrides twisted.python.lockfile.FilesystemLock.__init__

Parameters
name:`str`	The name of the lock to acquire
scheduler:`IReactorTime \| None`	An object which provides `IReactorTime`

def deferUntilLocked(self, timeout: float | None = None) -> Deferred[None]: (source) ¶

Wait until we acquire this lock. This method is not safe for concurrent use.

Parameters
timeout:`float \| None`	the number of seconds after which to time out if the lock has not been acquired.
Returns
`Deferred[None]`	a `Deferred` which will callback when the lock is acquired, or errback with a `TimeoutError` after timing out or an `AlreadyTryingToLockError` if the `deferUntilLocked` has already been called and not successfully locked the file.

The retry interval for an IReactorTime based scheduler.

The object in charge of scheduling retries. In this implementation this is parameterized for testing.

_timeoutCall: IDelayedCall | None = (source) ¶

An IDelayedCall based on deferUntilLocked's timeout argument. This is in charge of timing out our attempt to acquire the lock.

_tryLockCall: IDelayedCall | None = (source) ¶

An IDelayedCall based on _interval that will manage the next retry for acquiring the lock.