[SPARK-46401][CORE] Use !isEmpty() on RoaringBitmap instead of getCardinality() > 0 in RemoteBlockPushResolver

[LuciferYang]

What changes were proposed in this pull request?

This pr use !mapTracker.isEmpty() instead of mapTracker.getCardinality() > 0 in RemoteBlockPushResolver to reduce some computational costs, as the getCardinality() method triggers a recount every time it is called.

• getCardinality

  /**
   * Returns the number of distinct integers added to the bitmap (e.g., number of bits set).
   *
   * @return the cardinality
   */
  @Override
  public long getLongCardinality() {
    long size = 0;
    for (int i = 0; i < this.highLowContainer.size(); i++) {
      size += this.highLowContainer.getContainerAtIndex(i).getCardinality();
    }
    return size;
  }

  @Override
  public int getCardinality() {
    return (int) getLongCardinality();
  }

• isEmpty

 /**
   * Checks whether the bitmap is empty.
   *
   * @return true if this bitmap contains no set bit
   */
  @Override
  public boolean isEmpty() {
    return highLowContainer.size() == 0;
  }

This change is refer to RoaringBitmap/RoaringBitmap#239 | RoaringBitmap/RoaringBitmap#684

Why are the changes needed?

Use a more appropriate API to reduce the computational cost of empty-checking for RoaringBitmap.

Does this PR introduce any user-facing change?

No

How was this patch tested?

Pass GitHub Actions

Was this patch authored or co-authored using generative AI tooling?

No

[LuciferYang]

There should only be this one place where getCardinality() > 0 is used for empty-checking on RoaringBitmap

[mridulm]

Nice catch @LuciferYang !
Looks good to me.

Why is this still DRAFT ? :-)

[mridulm]

+CC @otterc as well

[LuciferYang]

Nice catch @LuciferYang ! Looks good to me.

Why is this still DRAFT ? :-)

Thanks @mridulm ~
Set to ready to review :)

[yaooqinn]

LGTM

[otterc]

Thanks for this change. LGTM

[LuciferYang]

Merged into master for Spark 4.0. Thanks @mridulm @yaooqinn @otterc ~