Add new interface IZkStateListener to provide session aware handleNewSession for ZkHelixManager

[huizhilu]

Issues

• My PR addresses the following Helix issues and references them in the PR description:

Fixes #643

Description

• Here are some details about my PR, including screenshots of any UI changes:

Current I0ITec IZkStateListener doesn't have an API handleNewSession(sessionId), which is needed for #642
To avoid creating a new stateListener extends IZkStateListener, it seems better to move IZkStateListener to helix internal. So we would have flexible control to add the new API.

Changelist:

1. Add new IZkStateListener to helix. The new IZkStateListener has new api handleNewSession(sessionId), and removes handleNewSession()
2. Add tests for this new IZkStateListener.
3. Add session id to ZkEvent as a field.
4. For state change events, pass session id in zk events.

Tests

• The following tests are written for this issue:

• testSubscribeStateChanges()

• testSessionExpiry()

• testSubscribeStateChangesForI0ItecIZkStateListener()

• testSessionExpiryForI0IItecZkStateListener()

• The following is the result of the "mvn test" command on the appropriate module:

[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR] TestJobQueueCleanUp.testJobQueueAutoCleanUp » ThreadTimeout Method org.testng....
[ERROR] TestTaskRebalancerStopResume.stopDeleteJobAndResumeNamedQueue:199 » Helix Fail...
[INFO]
[ERROR] Tests run: 887, Failures: 2, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:00 h
[INFO] Finished at: 2019-12-04T12:38:29-08:00
[INFO] ------------------------------------------------------------------------

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 10.316 s - in org.apache.helix.integration.task.TestJobQueueCleanUp
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 21.841 s - in org.apache.helix.integration.task.TestTaskRebalancerStopResume
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

Commits

• My commits all reference appropriate Apache Helix GitHub issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation in the following wiki page:

(Link the GitHub wiki you added)

Code Quality

• My diff has been formatted using helix-style.xml

[narendly]

Overall looks okay to me. But let's discuss if removing public methods would be okay. I think ZkCache is an internal concept that users shouldn't be using for their own logic, but let's double check.

Also please address other comments.

[huizhilu]

Thanks, @narendly, for the review and approval. I will address the comments.

[huizhilu]

Rerun tests. All passed.

[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR] TestRenamePartition.testRenamePartitionCustomIS:124 expected:true but was:false
[ERROR] TestDeleteJobFromJobQueue.testForceDeleteJobFromJobQueue:75 » Helix Failed to ...
[INFO]
[ERROR] Tests run: 890, Failures: 2, Errors: 0, Skipped: 0

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 8.371 s - in org.apache.helix.integration.TestRenamePartition
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 7.033 s - in org.apache.helix.integration.task.TestDeleteJobFromJobQueue
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS

[huizhilu]

Tests passed.

[INFO] Tests run: 890, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 3,384.407 s - in TestSuite
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 890, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 56:29 min
[INFO] Finished at: 2019-12-11T16:44:46-08:00

This PR is ready to be merged, approved by @jiajunwang @narendly

Commit message:

I0Itec IZkStateListener doesn't have an API handleNewSession(sessionId) to handle session aware operation,
which is needed to fix session race condition for creating ephemeral node in ZkClient.
So this new IZkStateListener interface is introduced to provide session aware handleNewSession method for ZkHelixManager.

Changelist:
- Introduce new IZkStateListener to helix. The new IZkStateListener adds new method
handleNewSession(String sessionId), and removes the old method handleNewSession().
- Add default implementations I0ItecIZkStateListenerHelixImpl in IZkStateListener
and IZkStateListenerI0ItecImpl in ZkClient for backward compatibility.
- Add session id to ZkEvent as a private field to help debug ZkEvent.
- Add unit tests to test subscribe/unsubscribe state changes.