Feature/mpi sendrecv replace

[andreapiacentini]

This is a tentative implementation of issue #53
It most probably will require some adjustment by the reviewers, especially for the Serial implementation.
Nevertheless, this feature is quite urgently needed for an oops development.
Thanks

[FussyDuck]

All committers have signed the CLA.

[dtip]

Hi @andreapiacentini - thanks for this PR! Could you sign the ECMWF CLA please.

[wdeconinck]

Hello @andreapiacentini that looks good to me.
But please could you add a unit test both for parallel and serial execution?
I will then test it out locally with MPI before approving, because the eckit Github-actions-CI does not use MPI (yet).

[wdeconinck]

Unit-test required

[wdeconinck]

@dtip do you have any clue why CI is failing? It does not seem related to this PR.

[dtip]

@dtip do you have any clue why CI is failing? It does not seem related to this PR.

Yep, it's a permissions issue with accessing the secrets we need to run CI from this public PR. We'll update the CI shortly to fix it.

[dtip]

@wdeconinck do we want to also modify the CI to compile and test both with and without MPI enabled?

[andreapiacentini]

@wdeconinck I've commited unit tests for these features.
The MPI test passes and I am happy with that.
The serial test passes too and I am pleasantly astonished. It passes as well if I comment out all the contents of the serial implementation of sendReceiveReplace and I just return an empty Status.
Most probably it is telling me that a "Replace" function is completely meaningless in serial mode. What do you think?
If you agree on that, please proceed to clipping the serial implementation.

[dtip]

We've (hopefully) just fixed the CI issue in #58

@andreapiacentini could you rebase this PR onto the latest develop branch please, then @wdeconinck can approve the CI run.

[andreapiacentini]

@dtip I did it via the github "Sync fork" link.
I hope it worked ok.
Thanks

[wdeconinck]

@wdeconinck do we want to also modify the CI to compile and test both with and without MPI enabled?

I would definitely suggest to enable MPI. For Atlas and fckit this was enough reason to build eckit as an internal CI cache rather than reuse an existing artifact. It would also be able to test MPI feature changes here rather than offline.

[tlmquintino]

@wdeconinck do we want to also modify the CI to compile and test both with and without MPI enabled?

I would definitely suggest to enable MPI. For Atlas and fckit this was enough reason to build eckit as an internal CI cache rather than reuse an existing artifact. It would also be able to test MPI feature changes here rather than offline.

I think we need to have test with and without MPI. This should be part of the matrix of builds, and we did discuss the possibility of having different builds based on options not only on platforms x compilers.

[dtip]

I think we need to have test with and without MPI. This should be part of the matrix of builds, and we did discuss the possibility of having different builds based on options not only on platforms x compilers.

Exactly - we can build both with and without MPI with a matrix of build options.

[wdeconinck]

I have added some cosmetic changes, and tested both with Parallel and Serial backend. All seems to be in good shape.

[wdeconinck]

@dtip something is not right with the GitHub token

[dtip]

@wdeconinck Yep, the fix we made yesterday didn't work so we've had to revert it. If you're confident with the PR, please feel free to merge it. Otherwise, if you want to run CI, the temporary workaround is to push the come from this PR to a branch within the eckit repo, then open a new PR.