add MPIEagerJAXArrayContext

[matthiasdiener]

Needs inducer/arraycontext#315 (perhaps)

Please squash

[alexfikl]

Left a few comments for that _signed_face_ones function 😁

[alexfikl]

I have a hard time remembering why this was written this way (I think those signed_face_ones arrays are just created this way so that they have the right shape?), but maybe we can improve it a bit.

How about this?

• Remove the signed_face_ones and signed_face_ones_numpy things.
• Get the discretization discr = dcoll.discr_from_dd(dd.with_discr_tag(DISCR_TAG_BASE))
• For each zip(discr.groups, conn.groups), mask = np.ones((dgrp.nelements, dgrp.nunit_dofs), dtype=discr.real_dtype)
• The rest just stays the same (?)

Would something like that work? The main idea being that we'll just create everything in numpy and then transfer it over to the array context, so we don't have to worry about how writable the arrays are.

We might want to tag the end result in the same way that Discretization.zeros does too?

[matthiasdiener]

Thanks for the suggestion! What do you think of 85a0d54? (feel free to push directly to this branch if I did something silly, I am very unfamiliar with this code).

[alexfikl]

Looks good to me! (doesn't look like the test failure is related?)

[matthiasdiener]

Closing in favor of #388.