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Implementation of executor factory holding an executor per cardinality.

Inherits From: ExecutorFactory

executor_stack_fn Callable taking a mapping from placement_literals.PlacementLiteral to integers, and returning an executor_base.Executor. The returned executor will be configured to handle these cardinalities.
ensure_closed Optional sequence of executor_base.Excutors which should always be closed on a clean_up_executors call. Defaults to empty.



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Calls close on all constructed executors, resetting internal cache.

If a caller holds a name bound to any of the executors returned from create_executor, this executor should be assumed to be in an invalid state, and should not be used after this method is called. Instead, callers should again invoke create_executor.


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Constructs or gets existing executor.

Returns a previously-constructed executor if this method has already been invoked with cardinalities. If not, invokes self._executor_stack_fn with cardinalities and returns the result.

cardinalities dict with placement_literals.PlacementLiteral keys and integer values, specifying the population size at each placement. The executor stacks returned from this method are not themselves polymorphic; a concrete stack must have fixed sizes at each placement.

Instance of executor_base.Executor as described above.