[refactor] simplify appender commit

Signed-off-by: Nicolas Takashi <nicolas.tcs@hotmail.com>

tsdb/head_append.go

@@ -869,11 +869,13 @@ func (a *headAppender) Commit() (err error) {
 		}
 		enc record.Encoder
 	)
+
 	defer func() {
 		for i := range oooRecords {
 			a.head.putBytesBuffer(oooRecords[i][:0])
 		}
 	}()
+
 	collectOOORecords := func() {
 		if a.head.wbl == nil {
 			// WBL is not enabled. So no need to collect.
@@ -906,6 +908,7 @@ func (a *headAppender) Commit() (err error) {
 		wblSamples = nil
 		oooMmapMarkers = nil
 	}
+
 	for i, s := range a.samples {
 		series = a.sampleSeries[i]
 		series.Lock()
@@ -935,27 +938,18 @@ func (a *headAppender) Commit() (err error) {
 		case oooSample:
 			// Sample is OOO and OOO handling is enabled
 			// and the delta is within the OOO tolerance.
-			var mmapRef chunks.ChunkDiskMapperRef
-			ok, chunkCreated, mmapRef = series.insert(s.T, s.V, a.head.chunkDiskMapper, oooCapMax)
-			if chunkCreated {
-				r, ok := oooMmapMarkers[series.ref]
-				if !ok || r != 0 {
-					// !ok means there are no markers collected for these samples yet. So we first flush the samples
-					// before setting this m-map marker.
-
-					// r != 0 means we have already m-mapped a chunk for this series in the same Commit().
-					// Hence, before we m-map again, we should add the samples and m-map markers
-					// seen till now to the WBL records.
-					collectOOORecords()
-				}
+			ok, chunkCreated, oooMmapMarkers, wblSamples = handleOutOfOrderSample(
+				series,
+				s,
+				a.head.chunkDiskMapper,
+				oooCapMax,
+				oooMmapMarkers,
+				collectOOORecords,
+				wblSamples,
+			)
 
-				if oooMmapMarkers == nil {
-					oooMmapMarkers = make(map[chunks.HeadSeriesRef]chunks.ChunkDiskMapperRef)
-				}
-				oooMmapMarkers[series.ref] = mmapRef
-			}
 			if ok {
-				wblSamples = append(wblSamples, s)
+				// wblSamples = append(wblSamples, s)
 				if s.T < ooomint {
 					ooomint = s.T
 				}
@@ -1075,6 +1069,42 @@ func (a *headAppender) Commit() (err error) {
 	return nil
 }
 
+func handleOutOfOrderSample(
+	series *memSeries,
+	s record.RefSample,
+	chunkDiskMapper *chunks.ChunkDiskMapper,
+	oooCapMax int64,
+	oooMmapMarkers map[chunks.HeadSeriesRef]chunks.ChunkDiskMapperRef,
+	collectOOORecords func(),
+	wblSamples []record.RefSample,
+) (bool, bool, map[chunks.HeadSeriesRef]chunks.ChunkDiskMapperRef, []record.RefSample) {
+	var mmapRef chunks.ChunkDiskMapperRef
+
+	ok, chunkCreated, mmapRef := series.insert(s.T, s.V, chunkDiskMapper, oooCapMax)
+	if chunkCreated {
+		if r, ok := oooMmapMarkers[series.ref]; !ok || r != 0 {
+			// !ok means there are no markers collected for these samples yet. So we first flush the samples
+			// before setting this m-map marker.
+
+			// r != 0 means we have already m-mapped a chunk for this series in the same Commit().
+			// Hence, before we m-map again, we should add the samples and m-map markers
+			// seen till now to the WBL records.
+			collectOOORecords()
+		}
+
+		if oooMmapMarkers == nil {
+			oooMmapMarkers = make(map[chunks.HeadSeriesRef]chunks.ChunkDiskMapperRef)
+		}
+		oooMmapMarkers[series.ref] = mmapRef
+	}
+
+	if ok {
+		wblSamples = append(wblSamples, s)
+	}
+
+	return ok, chunkCreated, oooMmapMarkers, wblSamples
+}
+
 // insert is like append, except it inserts. Used for OOO samples.
 func (s *memSeries) insert(t int64, v float64, chunkDiskMapper *chunks.ChunkDiskMapper, oooCapMax int64) (inserted, chunkCreated bool, mmapRef chunks.ChunkDiskMapperRef) {
 	if s.ooo == nil {