twisted.internet.defer.DeferredSemaphore(_ConcurrencyPrimitive)
class documentationtwisted.internet.defer
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A semaphore for event driven systems.
If you are looking into this as a means of limiting parallelism, you
might find twisted.internet.task.Cooperator
more useful.
Instance Variable | limit | At most this many users may acquire this semaphore at once. (type: int ) |
Instance Variable | tokens | The difference between limit and the number of users which
have currently acquired this semaphore. (type: int ) |
Method | __init__ | |
Method | acquire | Attempt to acquire the token. |
Method | release | Release the token. |
Method | _cancelAcquire | Remove a deferred d from our waiting list, as the deferred has been canceled. |
Inherited from _ConcurrencyPrimitive:
Method | run | Acquire, run, release. |
Method | _releaseAndReturn | Undocumented |
limit
and the number of users which
have currently acquired this semaphore. (type: int
)
Remove a deferred d from our waiting list, as the deferred has been canceled.
Note: We do not need to wrap this in a try/except to catch d not being in self.waiting because this canceller will not be called if d has fired. release() pops a deferred out of self.waiting and calls it, so the canceller will no longer be called.
Parameters | d | The deferred that has been canceled. |