Qiskit / qiskit / 37006714324

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main: 88%

Build Type

push

github

Committed by web-flow

Commit Message

Define `Pass` and `PassContext` handles for Python (#17104)

* Define `Pass` and `PassContext` handles for Python

This doesn't add the mechanism of _running_ these objects yet, but it
does set up the infrastructure for doing so.

The `PassContext` lifetime extension is some nasty `unsafe` to safely
send the lifetimes into Python which _could_ keep hold of them forever,
but hopefully the logic is _reasonably_ encapsulated to ensure that we
only hold the erased lifetime for the length of a `StolenContext`
object, which dies before the inner lifetime does, and steals the
context back.  We also require that the Python handle object does not
permit moving the object.

The addition of the `Send + Sync` bounds into the `PassManagerContext`
are because Python might attempt to send things between threads, so the
objects have to be safe to work with that, and similarly we use a
`static` reference to a dummy object, which is accessible from any
thread.

* Add partial integration with garbage collection

We cannot fully integrate; we currently have no system to traverse the
type-erased `dyn Any` objects that form individual passes.  This will
likely become solvable once we extend the dynamic-typing system to
attach trait implementations to the dynamic type objects.

Coverage Stats

5 of 150 new or added lines in 3 files covered. (3.33%)

16 existing lines in 3 files now uncovered.

122872 of 139665 relevant lines covered (87.98%)

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