Fix active block test

src/dbnode/integration/index_active_block_rotate_test.go

@@ -290,6 +290,17 @@ func TestIndexActiveBlockRotate(t *testing.T) {
 
 		expectedNumGCSeries := prevNumGCSeries + numWrites - minCompactSize
 		gcSeries := xclock.WaitUntil(func() bool {
+			// Run background compaction path to check that this path correctly
+			// identifies these series as "empty" post the warm flush above.
+			// Note: typically this path gets called from just WriteBatch calls but
+			// for this test we just explcitly invoke the background compact path.
+			for _, ns := range testSetup.DB().Namespaces() {
+				idx, err := ns.Index()
+				require.NoError(t, err)
+
+				idx.BackgroundCompact()
+			}
+
 			numGCSeries := counterValue(t, scope, metricGCSeries)
 			return numGCSeries >= expectedNumGCSeries
 		}, defaultTimeout)

src/dbnode/storage/index.go

@@ -1125,6 +1125,16 @@ func (i *nsIndex) WarmFlushBlockStarts() []xtime.UnixNano {
 	return flushed
 }
 
+// BackgroundCompact background compacts eligible segments.
+func (i *nsIndex) BackgroundCompact() {
+	if i.activeBlock != nil {
+		i.activeBlock.BackgroundCompact()
+	}
+	for _, b := range i.state.blocksByTime {
+		b.BackgroundCompact()
+	}
+}
+
 func (i *nsIndex) readInfoFilesAsMap() map[xtime.UnixNano][]fs.ReadIndexInfoFileResult {
 	fsOpts := i.opts.CommitLogOptions().FilesystemOptions()
 	infoFiles := i.readIndexInfoFilesFn(fs.ReadIndexInfoFilesOptions{

src/dbnode/storage/index/block.go

@@ -288,6 +288,11 @@ func (b *block) EndTime() xtime.UnixNano {
 	return b.blockEnd
 }
 
+// BackgroundCompact background compacts eligible segments.
+func (b *block) BackgroundCompact() {
+	b.mutableSegments.BackgroundCompact()
+}
+
 func (b *block) WriteBatch(inserts *WriteBatch) (WriteBatchResult, error) {
 	b.RLock()
 	if !b.writesAcceptedWithRLock() {

src/dbnode/storage/index/mutable_segments.go

@@ -384,6 +384,14 @@ func (m *mutableSegments) maybeBackgroundCompactWithLock() {
 	m.backgroundCompactWithLock()
 }
 
+// BackgroundCompact background compacts eligible segments.
+func (m *mutableSegments) BackgroundCompact() {
+	m.Lock()
+	defer m.Unlock()
+
+	m.backgroundCompactWithLock()
+}
+
 func (m *mutableSegments) backgroundCompactWithLock() {
 	// Create a logical plan.
 	segs := make([]compaction.Segment, 0, len(m.backgroundSegments))

src/dbnode/storage/index/types.go

@@ -449,6 +449,9 @@ type Block interface {
 	// MemorySegmentsData returns all in memory segments data.
 	MemorySegmentsData(ctx context.Context) ([]fst.SegmentData, error)
 
+	// BackgroundCompact background compacts eligible segments.
+	BackgroundCompact()
+
 	// Close will release any held resources and close the Block.
 	Close() error
 }

src/dbnode/storage/types.go

@@ -780,6 +780,9 @@ type NamespaceIndex interface {
 	// DebugMemorySegments allows for debugging memory segments.
 	DebugMemorySegments(opts DebugMemorySegmentsOptions) error
 
+	// BackgroundCompact background compacts eligible segments.
+	BackgroundCompact()
+
 	// Close will release the index resources and close the index.
 	Close() error
 }