Revert "Revert "Adding xxhash as a subtree""

[donnadionne]

Adding xxhash as a subtree

Attempting to submit the same code after taking care of import issues.

[jtattermusch]

there's a bunch of failures and you'll also need a passing adhoc artifacts - packages - distribtest (distribtests were broken the last time) run before this can go in (see bullet point 2 here: https://github.com/grpc/grpc/tree/master/third_party#checklist-for-adding-a-new-third-party-dependency)

[donnadionne]

there's a bunch of failures and you'll also need a passing adhoc artifacts - packages - distribtest (distribtests were broken the last time) run before this can go in (see bullet point 2 here: https://github.com/grpc/grpc/tree/master/third_party#checklist-for-adding-a-new-third-party-dependency)

started: https://fusion2.corp.google.com/invocations/8e76a837-d153-4677-987e-2a373e9df5ea/targets

[jtattermusch]

there's a bunch of failures and you'll also need a passing adhoc artifacts - packages - distribtest (distribtests were broken the last time) run before this can go in (see bullet point 2 here: https://github.com/grpc/grpc/tree/master/third_party#checklist-for-adding-a-new-third-party-dependency)

started: https://fusion2.corp.google.com/invocations/8e76a837-d153-4677-987e-2a373e9df5ea/targets

That build seemed stuck for some reason, so I started another one https://sponge2.corp.google.com/e5a04e01-2ed9-4776-976f-528021b103ae

[donnadionne]

Linux and windows run from the previous ad-hoc run passed:
https://sponge2.corp.google.com/e5a04e01-2ed9-4776-976f-528021b103ae

mac run encountered "Tools failures" from previous ad-hoc runs; triggered another one after synching:
https://fusion2.corp.google.com/invocations/0046ece3-ddd0-4e84-ba7a-93836099cbb2/targets

The latest ad-hoc run passed!
https://fusion2.corp.google.com/invocations/0046ece3-ddd0-4e84-ba7a-93836099cbb2/targets

[donnadionne]

Known issues: #25660 (interop test failures)

[donnadionne]

kokoro failure: due to unable to access the commitsha that is not yet submitted

[donnadionne]

All Required tests pass; failed test have explainations.

This is really the same change as last week; just now it's ready to be imported.

PTAL thank you!

[jtattermusch]

https://fusion2.corp.google.com/invocations/0046ece3-ddd0-4e84-ba7a-93836099cbb2/targets

Following through the chained jobs, the python-dev distribtests are failing:
https://fusion2.corp.google.com/invocations/8378f432-3d21-4b82-889c-fd7cae48eefa/targets/github%2Fgrpc;config=default/tests

[jtattermusch]

FTR, as discussed I think the issue with python-dev distribtests is that the python "sdist" archive is missing the newly added xxhash.h header:

https://pantheon.corp.google.com/storage/browser/_details/grpc-testing-kokoro-prod/test_result_public/prod/grpc/core/master/linux/grpc_build_artifacts/16172/20210309-131926/github/grpc/artifacts/python_manylinux2010_x86_cp38-cp38/grpcio-1.37.0.dev0.tar.gz (and indeed, if you open the archive you'll see that third_party/xxhash/xxhash.h is not there).

Made a one line change in setup.py (similar fix as #24450: to allow grpcio to build with xxhash), re-running adhoc to test it out:
https://fusion2.corp.google.com/invocations/a7a23ae2-39a6-4d02-9f14-ca4dcf8ef25d/targets

This was not the right fix; setup.py restored now

[donnadionne]

Updated PYTHON-MANIFEST.in which fixed the grpc/core/experimental/grpc_distribtests_multiplatform: grpc/core/master/linux/grpc_distribtests:
https://source.cloud.google.com/results/invocations/dcd3d928-cf65-4fed-9cf0-d075eacaaed8/targets

Everything passed! https://fusion2.corp.google.com/invocations/75c8fbe4-d169-472e-86d3-098c8d4b813f/targets/grpc%2Fcore%2Fexperimental%2Fgrpc_distribtests_multiplatform;config=default/log

[donnadionne]

Known issues: #25660 (interop test failures)

Ruby Failue is just a timeout, and this test has passed in previous runs before the 1 line change for Python.

[jtattermusch]

LGTM (assuming you've tried the cherrypick into google3 and it worked fine).