helpers

MultiQueueLazyWorker

MultiQueueLazyWorker(running_slots: int = 1)

A scheduling worker that controls access to an (implicit) shared resource.

The shared resource is not managed by the worker itself, but assumed to be accessed by the coroutine given to run. The maximum number of concurrent accesses is controlled by the running_slots parameter.

Items from the queues are scheduled fairly, favouring the queue with the least recent access to the resource. If the resource is equally contended by all queues, this results in round-robin scheduling.

Each queue has a fixed size of one, where new requests (by calls to run) displace old ones, similar to the mechanism used by the LazyWorker.

Note: The implementation is not threadsafe, so it should not be used to synchronize access from different threads (e.g., by using a multi threaded async runtime).

Initialize the worker with a fixed number of running slots.

Parameters:

Name	Type	Description	Default
running_slots	int	Maximum number coroutines running concurrently.	1

run async

run(
    queue_id: str, coro: Coroutine[Any, Any, _T]
) -> _T | None

Try to run the given coroutine. A later call with the same queue_idwill displace this one. In that caseNone` is returned.

Parameters:

Name	Type	Description	Default
queue_id	str	Uniquely identifies the queue that coro will be pushed to	required
coro	Coroutine[Any, Any, _T]	Coroutine which accesses a shared resource	required

Returns:

Type	Description
_T | None	None if a later call displaced this one, the return value of the coroutine otherwise