start to refactor persistence layer to prepare for direct path

[m-trieu]

Change classes that explicitly inject a MetricTrackingWindmillServerStub to take in a Function.
This will give flexibility in later refactoring as we apply different ways to fetch the data without MetricTrackingWindmillServerStub.
Add PersistentStateReadMetricsTracker, which is similar to MetricTrackingWindmillServerStub but allows callers to inject a GetDataStream (which is necessary for direct path since the calls need to be appropriately routed) and is streaming engine specific.

R: @scwhittle

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[scwhittle]

Can you merge with the conflicts? Otherwise looking good

[m-trieu]

ready for another look @scwhittle

[m-trieu]

Run Java Precommit

[scwhittle]

Run Java PreCommit

[scwhittle]

Looks like this assert failed in test:

beam/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorkerTest.java

Line 3355 in 0bce6d7

assertEquals(1, commits.size());

Could be flaky if doesn't wait enough to get commit or it could be an indication that the heartbeat response plumbing isn't working.

[m-trieu]

Looks like this assert failed in test:

beam/runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorkerTest.java

Line 3355 in 0bce6d7

assertEquals(1, commits.size());

Could be flaky if doesn't wait enough to get commit or it could be an indication that the heartbeat response plumbing isn't working.

@scwhittle ran locally and it passed. looks we depend on sleep() in the test, and i wonder if that leads to flakiness in the GitHub actions environment?

    Map<Long, Windmill.WorkItemCommitRequest> commits =
        server.waitForAndGetCommitsWithTimeout(2, Duration.standardSeconds((5)));
    assertEquals(1, commits.size());

also kind of strange that we are waiting for 2 commits but are asserting that there is only 1 commit.

But looks like this is a flaky test failure

[scwhittle]

Run Java PreCommit

[scwhittle]

That test expects 1 commit but meant to wait for some extra time to make sure there were not 2.
But it should do so perhaps with larger time limit for 1 and then shorter time limit to verify more don't show up.

[scwhittle]

I don't see where this is setup if the forTesting method is used.

Are you sure this isn't the cause of the test failure?

[m-trieu]

it gets set up here in FakeWindmillServer

[m-trieu]

it gets set up here in FakeWindmillServer

[m-trieu]

figured it out looks like the work isn't being populated in the computation map will fix it

thanks!

[m-trieu]

fixed

[scwhittle]

This appears unused in this PR

[scwhittle]

I'm going to remove it for now to merge the rest to avoid review delay.