[GLUTEN-12655][CORE] Reset the component graph after ComponentSuite

[LuciferYang]

What changes were proposed in this pull request?

ComponentSuite registers dummy components into the JVM-global component graph, including a deliberate dependency cycle, and never removes them. Any later suite in the same JVM that calls Component.sorted() then fails with Cycle detected in the component graph: B, D, C, naming components unrelated to the failing test. Nothing in gluten-core calls sorted() after ComponentSuite today, but ten call sites in main sources reach it, so a suite that boots a SparkContext with the Gluten plugin fails as soon as it is ordered after ComponentSuite.

Component's graph and the allComponentsLoaded discovery latch are object-level state with no reset, so a suite that registers components cannot clean up after itself. This adds a testing-only reset that empties the graph, clears each component's registration flag so it can register again, and re-arms the latch. ComponentSuite#afterAll calls it.

ensureRegistered now rolls its flag back when graph.add throws. A component that never entered the graph is invisible to Registry#clear, so without the rollback its flag stays set and it can never register again. The rollback covers only graph.add, not dependencies(): a component that is already in the graph would then fail its next registration with a misleading "UID already registered". resetRegisteredForTesting is final, since nine of the eleven in-repo Component implementations sit in this package and could otherwise override it to a no-op and silently defeat the clear.

Four values survive the reset, and the clearAllForTesting scaladoc now says so: BackendsApiManager.backend, GlutenCostModel.costModelRegistry, the graphCache inside Transition.factory, and the per-vertex TransitionGraph.Vertex.initialized flags all keep what they computed from the pre-clear component set. Rediscovery also constructs fresh instances, so one of those values can end up holding an instance that is no longer the one in the graph. The latch line carries a comment explaining it serves the backend modules, whose classpath carries component files, so it does not read as dead code here.

How was this patch tested?

Added ComponentGraphResetSuite with three tests, each covering one part of the reset:

• register a cycle, reset, assert the graph is empty;
• register a component, reset, register the same instance again, assert it is back in the graph. This fails without the registration-flag reset;
• run ComponentSuite in-process via new ComponentSuite().run(None, Args(reporter)) and assert the graph is empty afterwards. That covers the fix's own call site without depending on suite execution order, and fails when ComponentSuite#afterAll is removed.

Cleanup lives in afterAll so a failed assertion cannot leak the cycle the suite registers. I verified each test fails against the corresponding mutant, and that mvn -pl gluten-core,gluten-substrait test passes (37 + 51), both in the natural suite order and with ComponentSuite forced to run first.

Closes #12655

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Pull request overview

This PR fixes a JVM-global test isolation problem in gluten-core where ComponentSuite registers dummy components (including a deliberate dependency cycle) into the global component graph and leaves them behind, breaking later suites that call Component.sorted().

Changes:

• Add a testing-only reset (clearAllForTesting) that clears the component graph and re-arms the discovery latch.
• Make Component.ensureRegistered() roll back its registration flag if graph.add() fails, and ensure graph clearing resets per-component registration flags.
• Add ComponentGraphResetSuite to validate the reset behavior and that ComponentSuite cleans up in afterAll.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
gluten-core/src/test/scala/org/apache/gluten/component/ComponentSuite.scala	Clears the JVM-global component graph in afterAll to avoid leaking dummy components into later suites.
gluten-core/src/test/scala/org/apache/gluten/component/ComponentGraphResetSuite.scala	Adds regression tests proving the graph reset works and that ComponentSuite leaves the graph empty.
gluten-core/src/main/scala/org/apache/gluten/component/package.scala	Introduces clearAllForTesting() to clear the graph and re-arm component discovery.
gluten-core/src/main/scala/org/apache/gluten/component/Component.scala	Adds graph-clearing hooks and registration-flag reset logic to support test isolation and re-registration.

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Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

gluten-core/src/test/scala/org/apache/gluten/component/ComponentGraphResetSuite.scala:94

• FailureCollectingReporter mutates a shared mutable.Buffer without any synchronization. ScalaTest can deliver Reporter events from different threads (e.g., when suites/tests are run concurrently), which can lead to races/corruption and flaky failures when the nested ComponentSuite is run.

  private class FailureCollectingReporter extends Reporter {
    private val buffer = mutable.Buffer[String]()

    def failures: Seq[String] = buffer.toSeq

gluten-core/src/main/scala/org/apache/gluten/component/package.scala:59

• Scaladoc grammar is a bit confusing here: "Neither are the per-vertex ... flags" is missing the verb (e.g., "reset"). Rewording makes the behavior and non-reset guarantees clearer.

   * Only the graph and the latch are reset. Values derived from an earlier [[Component.sorted]] are
   * not: `BackendsApiManager.backend`, `GlutenCostModel.costModelRegistry` and the `graphCache`
   * inside `Transition.factory` keep what they computed from the pre-clear component set. Neither
   * are the per-vertex `TransitionGraph.Vertex.initialized` flags, so a re-registered component
   * does not add its transition edges a second time. Rediscovery also constructs fresh component

[LuciferYang]

cc @jackylee-ch

[jackylee-ch]

cc @zhztheplayer

[LuciferYang]

Thank you @zhztheplayer @jackylee-ch