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__`
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`	A `DelayedCall` based on `deferUntilLocked`'s timeout argument. This is in charge of timing out our attempt to acquire the lock.
Instance Variable	`_tryLockCall`	A `DelayedCall` 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, scheduler=None): (source)

overrides twisted.python.lockfile.FilesystemLock.__init__

Parameters
name	The name of the lock to acquire
scheduler	An object which provides `IReactorTime`

def deferUntilLocked(self, timeout=None): (source)

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

Parameters
timeout:`float` or `int`	the number of seconds after which to time out if the lock has not been acquired.
Returns
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.

_interval: int = (source)

The retry interval for an IReactorTime based scheduler.

_scheduler = (source)

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

_timeoutCall = (source)

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

_tryLockCall = (source)

A DelayedCall based on _interval that will manage the next retry for acquiring the lock.