Expose stream-ordering to interop APIs

[shrshi]

Description

Adds stream parameter to

cudf::from_dlpack
cudf::to_dlpack

Added stream gtests to verify correct stream forwarding.

Reference: #13744

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[kingcrimsontianyu]

Should these two tests contain assertions, such as EXPECT_NO_THROW ?
Irrelevant to this PR, I noticed that many other tests out there under cpp/tests/streams don't have assertions. I'm curious if there's any special consideration for that.

[shrshi]

Stream tests only verify if the stream is being forwarded correctly. We do not check functional correctness here; the test tracks the test stream passed and verifies that it is used for all device operations.

[kingcrimsontianyu]

Thanks. I guess my question is what would be a signal of problem for these tests. Say I artificially introduced a bug where one device operation is on a stream separate from others. Do we expect cudf::to_dlpack() to error out?

[shrshi]

Ah sorry, I misunderstood what you were asking. Yes, if we use a stream other than cudf::test::get_default_stream() for a device operation anywhere in the test, a runtime error is thrown. CUDA APIs are overloaded to check the passed stream and either raise an exception for an unexpected stream, or forward arguments to the original function.
Reference:

cudf/cpp/tests/utilities/identify_stream_usage.cpp

Line 135 in f54c1a5

throw std::runtime_error("cudf_identify_stream_usage found unexpected stream!");

TLDR: If we invoke cudf::to_dlpack(empty, cudf::get_default_stream()) in this test, a runtime error is thrown.

[kingcrimsontianyu]

Would it make sense to (also) use a non-default stream for testing purpose?

[shrshi]

Good question, stream testing here depends on the compile-time option STREAM_MODE_TESTING. When it is defined, cudf::test::get_default_stream() returns a non-default stream and the test throws for CUDA calls being invoked on any stream other than cudf::test::get_default_stream.
Reference:

cudf/cpp/tests/utilities/identify_stream_usage.cpp

Line 65 in f54c1a5

rmm::cuda_stream_view const get_default_stream()

[kingcrimsontianyu]

Thanks. I learned something new today.
In this case, I still think EXPECT/ASSERT_NO_THROW is a good practice as opposed to let the application itself throw, but that's a nit for this PR.

[shrshi]

/merge