DRIVERS-2868 Adjust getMore maxTimeMS Calculation for tailable awaitData Cursors

[prestonvasquez]

DRIVERS-2868

Please complete the following before merging:

• Update changelog.
• Test changes in at least one language driver. (POC) GODRIVER-3444 Adjust getMore maxTimeMS Calculation for tailable awaitData Cursors mongo-go-driver#1925
• Test these changes against all server versions and topologies (including standalone, replica set, sharded
  clusters, and serverless).

[vbabanin]

LGTM!

[ShaneHarvey]

@vbabanin can you confirm this test passes in .net Java on both linux and windows?

[vbabanin]

@ShaneHarvey @prestonvasquez

With the changes introduced by this spec update and the added unified tests, all tests pass in Java across all topologies. However, I observed some flakiness over multiple runs in apply remaining timeoutMS if less than maxAwaitTimeMS, likely because the first getMore sometimes completes too quickly, causing lte: 99 ms to fail. In my earlier testing, this issue did not appear, but after running more iterations, I observed an assertion failure couple of times.

I also tested using a failPoint to delay the first getMore, which made the test more reliable.

I suggest adding a failPoint here to reduce raciness. Here’s a reference comment in the Java driver: mongodb/mongo-java-driver#1650 (comment).

What do you think?

[ShaneHarvey]

According to @vbabanin this failpoint should be moved to the "apply remaining timeoutMS if less than maxAwaitTimeMS" test.

[ShaneHarvey]

@vbabanin could you run the new tests and confirm the flakes are gone?

[vbabanin]

@vbabanin could you run the new tests and confirm the flakes are gone?

I re-ran the tests in this Java driver PR: mongodb/mongo-java-driver#1650 that includes tailable-awaitData.json changes. All tests passed with no flakiness observed.

Here are the relevant details:
Evergreen patch changes: : https://evergreen.mongodb.com/filediff/67d351fec9bb0a0007cd5b53/?file_name=driver-core%2Fsrc%2Ftest%2Fresources%2Funified-test-format%2Fclient-side-operation-timeout%2Ftailable-awaitData.json&patch_number=0&commit_number=1
Successful patch execution: https://spruce.mongodb.com/version/67d351fec9bb0a0007cd5b53/tasks?sorts=STATUS%3AASC%3BBASE_STATUS%3ADESC