Shawyeok opened a new pull request, #26128:
URL: https://github.com/apache/pulsar/pull/26128
### Motivation
Several batch-ack paths allocate a `BitSet` or `BitSetRecyclable` instance
only to compute a
cardinality or perform an AND/intersect on raw `long[]` word arrays. These
allocations are
unnecessary — the results can be computed directly via `Long.bitCount` and
bitwise operators.
### Modifications
**New `AckSetUtil` utility class** (`pulsar-common`):
| Method | Description |
|--------|-------------|
| `cardinality(long[])` | Popcount of a word array — no `BitSet` alloc |
| `intersect(long[], long[])` | Element-wise AND; result length = `min(len1,
len2)` |
| `cardinalityOfIntersection(long[], long[])` | Popcount of AND without
allocating a result array |
**Refactored call sites** — replaced allocation-heavy patterns with
`AckSetUtil` in:
- `Consumer` (broker) — `BitSet.valueOf(x).cardinality()` and
`BitSetRecyclable.create().resetWords(x).cardinality()` patterns (4 sites)
- `EntryBatchIndexesAcks` (broker) — same pattern (1 site)
- `PositionAckSetUtil` (managed-ledger) — `isAckSetEmpty` (1 site)
**Refactored `PositionAckSetUtil`**:
- `andAckSet(long[], long[])` now delegates to `AckSetUtil.intersect` —
eliminates two `BitSetRecyclable` allocs
- `isAckSetOverlap` rewritten with bitwise ops: a bit of `0` means *acked*;
overlap exists when any position is acked in both sets, i.e. `~(a[i] | b[i]) !=
0` for some word pair — eliminates two `BitSetRecyclable` allocs plus two full
`flip` passes
**Tests**: dedicated `AckSetUtilTest` with full coverage of all three
methods (empty arrays, all-zero, all-set, mixed, asymmetric lengths,
no/full/partial overlap).
### Verifying this change
- [x] Make sure that the change passes the CI checks.
```bash
# Unit tests
./gradlew :pulsar-common:test --tests
org.apache.pulsar.common.util.AckSetUtilTest
./gradlew :pulsar-common:test --tests
org.apache.pulsar.common.util.collections.BitSetRecyclableRecyclableTest
# Compilation
./gradlew :pulsar-common:compileJava :pulsar-common:compileTestJava \
:pulsar-broker:compileJava :managed-ledger:compileJava
# Style
./gradlew :pulsar-common:checkstyleMain :pulsar-common:checkstyleTest \
:pulsar-broker:checkstyleMain :managed-ledger:checkstyleMain
```
### Does this pull request potentially affect one of the following parts:
- [ ] Dependencies (add or upgrade a dependency)
- [ ] The public API
- [ ] The schema
- [ ] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] The metrics
- [ ] Anything that affects deployment
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