Expose Evacuate Finished API in Helix-Rest

[GrantPSpencer]

Issues

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

isEvacuateFinished API not available in helix-rest

Description

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

Expose isEvacuateFinished API in helix-rest. setInstanceOperation is already exposed.

One key thing to note is the way we return the true/false value. Should we always return a 200 response code if we do not encounter an error? If so, then how do we represent the true/false value? Do we want to send it as json {"isEvacuateFinished": "true"} or just as a raw "true" / "false" string? Ideally we should decide on 1 way of returning true/false's and stick to that

Tests

• The following tests are written for this issue:

Added tests to updateInstance method in testPerInstanceAccessor.java

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

$ mvn test -o -Dtest=TestPerInstanceAccessor -pl=helix-rest

[INFO] Tests run: 24, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 52.578 s - in org.apache.helix.rest.server.TestPerInstanceAccessor
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 24, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] 
[INFO] --- jacoco:0.8.6:report (generate-code-coverage-report) @ helix-rest ---
[INFO] Loading execution data file /Users/gspencer/Desktop/git-repos/helix/helix-rest/target/jacoco.exec
[INFO] Analyzed bundle 'Apache Helix :: Restful Interface' with 92 classes
[WARNING] Classes in bundle 'Apache Helix :: Restful Interface' do not match with execution data. For report generation the same class files must be used as at runtime.
[WARNING] Execution data for class org/apache/helix/rest/server/resources/helix/ResourceAssignmentOptimizerAccessor does not match.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  57.262 s
[INFO] Finished at: 2023-11-06T16:13:53-08:00
[INFO] ------------------------------------------------------------------------

Commits

• My commits all reference appropriate Apache Helix GitHub issues in their subject lines. 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"

Code Quality

• My diff has been formatted using helix-style.xml
  (helix-style-intellij.xml if IntelliJ IDE is used)

[desaikomal]

Grant to answer your question:

• we should return true/false as JSON and not as pure text. If request was successfully processed - independent of the response, HTTP Return code should be 200.
• all our existing APIs (getResource etc) returns JSON. so it is good to return as JSON

[GrantPSpencer]

Changed response to JSON of
{"evacuateFinished": BOOLEAN}

[GrantPSpencer]

Pull request approved by @zpinto
Commit message: Expose isEvacuateFinished API in helix-rest