refactor(stringlabels): Support stringlabels in chunkenc

pkg/chunkenc/memchunk.go

@@ -1443,14 +1443,14 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 		if err != nil {
 			if err != io.EOF {
 				si.err = err
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 			if si.readBufValid == 0 { // Got EOF and no data in the buffer.
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 			if si.readBufValid == lastAttempt { // Got EOF and could not parse same data last time.
 				si.err = fmt.Errorf("invalid data in chunk")
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 		}
 		var l uint64
@@ -1465,7 +1465,7 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 
 	if lineSize >= maxLineLength {
 		si.err = fmt.Errorf("line too long %d, maximum %d", lineSize, maxLineLength)
-		return 0, nil, nil, false
+		return 0, nil, labels.EmptyLabels(), false
 	}
 	// If the buffer is not yet initialize or too small, we get a new one.
 	if si.buf == nil || lineSize > cap(si.buf) {
@@ -1476,7 +1476,7 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 		si.buf = BytesBufferPool.Get(lineSize).([]byte)
 		if lineSize > cap(si.buf) {
 			si.err = fmt.Errorf("could not get a line buffer of size %d, actual %d", lineSize, cap(si.buf))
-			return 0, nil, nil, false
+			return 0, nil, labels.EmptyLabels(), false
 		}
 	}
 	si.buf = si.buf[:lineSize]
@@ -1496,7 +1496,7 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 				continue
 			}
 			si.err = err
-			return 0, nil, nil, false
+			return 0, nil, labels.EmptyLabels(), false
 		}
 	}
 
@@ -1505,7 +1505,7 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 	if si.format < ChunkFormatV4 {
 		si.stats.AddDecompressedBytes(decompressedBytes)
 		si.stats.AddDecompressedLines(1)
-		return ts, si.buf[:lineSize], nil, true
+		return ts, si.buf[:lineSize], labels.EmptyLabels(), true
 	}
 
 	lastAttempt = 0
@@ -1516,14 +1516,14 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 		if err != nil {
 			if err != io.EOF {
 				si.err = err
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 			if si.readBufValid == 0 { // Got EOF and no data in the buffer.
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 			if si.readBufValid == lastAttempt { // Got EOF and could not parse same data last time.
 				si.err = fmt.Errorf("invalid data in chunk")
-				return 0, nil, nil, false
+				return 0, nil, labels.EmptyLabels(), false
 			}
 		}
 		var l uint64
@@ -1573,7 +1573,7 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 		si.symbolsBuf = SymbolsPool.Get(nSymbols).([]symbol)
 		if nSymbols > cap(si.symbolsBuf) {
 			si.err = fmt.Errorf("could not get a symbols matrix of size %d, actual %d", nSymbols, cap(si.symbolsBuf))
-			return 0, nil, nil, false
+			return 0, nil, labels.EmptyLabels(), false
 		}
 	}
 
@@ -1589,14 +1589,14 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 			if err != nil {
 				if err != io.EOF {
 					si.err = err
-					return 0, nil, nil, false
+					return 0, nil, labels.EmptyLabels(), false
 				}
 				if si.readBufValid == 0 { // Got EOF and no data in the buffer.
-					return 0, nil, nil, false
+					return 0, nil, labels.EmptyLabels(), false
 				}
 				if si.readBufValid == lastAttempt { // Got EOF and could not parse same data last time.
 					si.err = fmt.Errorf("invalid data in chunk")
-					return 0, nil, nil, false
+					return 0, nil, labels.EmptyLabels(), false
 				}
 			}
 			sName, nWidth = binary.Uvarint(si.readBuf[:si.readBufValid])
@@ -1615,7 +1615,8 @@ func (si *bufferedIterator) moveNext() (int64, []byte, labels.Labels, bool) {
 	si.stats.AddDecompressedStructuredMetadataBytes(decompressedStructuredMetadataBytes)
 	si.stats.AddDecompressedBytes(decompressedBytes + decompressedStructuredMetadataBytes)
 
-	return ts, si.buf[:lineSize], si.symbolizer.Lookup(si.symbolsBuf[:nSymbols], si.currStructuredMetadata), true
+	labelsBuilder := log.NewBufferedLabelsBuilder(si.currStructuredMetadata)
+	return ts, si.buf[:lineSize], si.symbolizer.Lookup(si.symbolsBuf[:nSymbols], labelsBuilder), true
 }
 
 func (si *bufferedIterator) Err() error { return si.err }
@@ -1644,9 +1645,9 @@ func (si *bufferedIterator) close() {
 		si.symbolsBuf = nil
 	}
 
-	if si.currStructuredMetadata != nil {
+	if !si.currStructuredMetadata.IsEmpty() {
 		structuredMetadataPool.Put(si.currStructuredMetadata) // nolint:staticcheck
-		si.currStructuredMetadata = nil
+		si.currStructuredMetadata = labels.EmptyLabels()      // TODO: maybe a reset would be better
 	}
 
 	si.origBytes = nil

pkg/chunkenc/memchunk_test.go

@@ -1120,6 +1120,7 @@ func BenchmarkHeadBlockIterator(b *testing.B) {
 					for iter.Next() {
 						_ = iter.At()
 					}
+					iter.Close()
 				}
 			})
 		}

pkg/chunkenc/symbols.go

@@ -13,6 +13,7 @@ import (
 	"github.com/prometheus/prometheus/model/labels"
 
 	"github.com/grafana/loki/v3/pkg/compression"
+	"github.com/grafana/loki/v3/pkg/logql/log"
 	"github.com/grafana/loki/v3/pkg/util"
 )
 
@@ -58,16 +59,18 @@ func (s *symbolizer) Reset() {
 
 // Add adds new labels pairs to the collection and returns back a symbol for each existing and new label pair
 func (s *symbolizer) Add(lbls labels.Labels) symbols {
-	if len(lbls) == 0 {
+	if lbls.IsEmpty() {
 		return nil
 	}
 
-	syms := make([]symbol, len(lbls))
+	syms := make([]symbol, 0, lbls.Len())
 
-	for i, label := range lbls {
-		syms[i].Name = s.add(label.Name)
-		syms[i].Value = s.add(label.Value)
-	}
+	lbls.Range(func(label labels.Label) {
+		syms = append(syms, symbol{
+			Name:  s.add(label.Name),
+			Value: s.add(label.Value),
+		})
+	})
 
 	return syms
 }
@@ -97,20 +100,20 @@ func (s *symbolizer) add(lbl string) uint32 {
 }
 
 // Lookup coverts and returns labels pairs for the given symbols
-func (s *symbolizer) Lookup(syms symbols, buf labels.Labels) labels.Labels {
+func (s *symbolizer) Lookup(syms symbols, buf *log.BufferedLabelsBuilder) labels.Labels {
 	if len(syms) == 0 {
-		return nil
+		return labels.EmptyLabels()
 	}
+
 	if buf == nil {
-		buf = structuredMetadataPool.Get().(labels.Labels)
+		structuredMetadata := structuredMetadataPool.Get().(labels.Labels)
+		buf = log.NewBufferedLabelsBuilder(structuredMetadata)
 	}
-	buf = buf[:0]
-
 	for _, symbol := range syms {
-		buf = append(buf, labels.Label{Name: s.lookup(symbol.Name), Value: s.lookup(symbol.Value)})
+		buf.Add(labels.Label{Name: s.lookup(symbol.Name), Value: s.lookup(symbol.Value)})
 	}
 
-	return buf
+	return buf.Labels()
 }
 
 func (s *symbolizer) lookup(idx uint32) string {

pkg/chunkenc/symbols_test.go

@@ -29,22 +29,11 @@ func TestSymbolizer(t *testing.T) {
 		{
 			name: "no duplicate labels",
 			labelsToAdd: []labels.Labels{
-				{
-					labels.Label{
-						Name:  "foo",
-						Value: "bar",
-					},
-				},
-				{
-					labels.Label{
-						Name:  "fizz",
-						Value: "buzz",
-					},
-					labels.Label{
-						Name:  "ping",
-						Value: "pong",
-					},
-				},
+				labels.FromStrings("foo", "bar"),
+				labels.FromStrings(
+					"fizz", "buzz",
+					"ping", "pong",
+				),
 			},
 			expectedSymbols: []symbols{
 				{
@@ -71,30 +60,15 @@ func TestSymbolizer(t *testing.T) {
 		{
 			name: "with duplicate labels",
 			labelsToAdd: []labels.Labels{
-				{
-					labels.Label{
-						Name:  "foo",
-						Value: "bar",
-					},
-					{
-						Name:  "bar",
-						Value: "foo",
-					},
-				},
-				{
-					labels.Label{
-						Name:  "foo",
-						Value: "bar",
-					},
-					labels.Label{
-						Name:  "fizz",
-						Value: "buzz",
-					},
-					labels.Label{
-						Name:  "ping",
-						Value: "pong",
-					},
-				},
+				labels.FromStrings(
+					"foo", "bar",
+					"bar", "foo",
+				),
+				labels.FromStrings(
+					"foo", "bar",
+					"fizz", "buzz",
+					"ping", "pong",
+				),
 			},
 			expectedSymbols: []symbols{
 				{
@@ -108,14 +82,14 @@ func TestSymbolizer(t *testing.T) {
 					},
 				},
 				{
-					symbol{
-						Name:  0,
-						Value: 1,
-					},
 					symbol{
 						Name:  2,
 						Value: 3,
 					},
+					symbol{
+						Name:  1,
+						Value: 0,
+					},
 					symbol{
 						Name:  4,
 						Value: 5,
@@ -130,10 +104,10 @@ func TestSymbolizer(t *testing.T) {
 		for _, encoding := range testEncodings {
 			t.Run(fmt.Sprintf("%s - %s", tc.name, encoding), func(t *testing.T) {
 				s := newSymbolizer()
-				for i, labels := range tc.labelsToAdd {
-					symbols := s.Add(labels)
+				for i, lbls := range tc.labelsToAdd {
+					symbols := s.Add(lbls)
 					require.Equal(t, tc.expectedSymbols[i], symbols)
-					require.Equal(t, labels, s.Lookup(symbols, nil))
+					require.Equal(t, lbls, s.Lookup(symbols, nil))
 				}
 
 				// Test that Lookup returns empty labels if no symbols are provided.
@@ -144,8 +118,7 @@ func TestSymbolizer(t *testing.T) {
 							Value: 0,
 						},
 					}, nil)
-					require.Equal(t, "", ret[0].Name)
-					require.Equal(t, "", ret[0].Value)
+					require.Equal(t, `{""=""}`, ret.String())
 				}
 
 				require.Equal(t, tc.expectedNumLabels, len(s.labels))

pkg/chunkenc/unordered.go

@@ -115,7 +115,7 @@ func (e *nsEntries) ValueAtDimension(_ uint64) int64 {
 func (hb *unorderedHeadBlock) Append(ts int64, line string, structuredMetadata labels.Labels) (bool, error) {
 	if hb.format < UnorderedWithStructuredMetadataHeadBlockFmt {
 		// structuredMetadata must be ignored for the previous head block formats
-		structuredMetadata = nil
+		structuredMetadata = labels.EmptyLabels()
 	}
 	// This is an allocation hack. The rangetree lib does not
 	// support the ability to pass a "mutate" function during an insert
@@ -155,17 +155,17 @@ func (hb *unorderedHeadBlock) Append(ts int64, line string, structuredMetadata l
 	}
 
 	hb.size += len(line)
-	hb.size += len(structuredMetadata) * 2 * 4 // 4 bytes per label and value pair as structuredMetadataSymbols
+	hb.size += structuredMetadata.Len() * 2 * 4 // 4 bytes per label and value pair as structuredMetadataSymbols
 	hb.lines++
 
 	return false, nil
 }
 
 func metaLabelsLen(metaLabels labels.Labels) int {
 	length := 0
-	for _, label := range metaLabels {
+	metaLabels.Range(func(label labels.Label) {
 		length += len(label.Name) + len(label.Value)
-	}
+	})
 	return length
 }
 
@@ -252,14 +252,15 @@ func (hb *unorderedHeadBlock) Iterator(ctx context.Context, direction logproto.D
 	// cutting of blocks.
 	streams := map[string]*logproto.Stream{}
 	baseHash := pipeline.BaseLabels().Hash()
-	var structuredMetadata labels.Labels
+	structuredMetadata := structuredMetadataPool.Get().(labels.Labels)
+	labelsBuilder := log.NewBufferedLabelsBuilder(structuredMetadata)
 	_ = hb.forEntries(
 		ctx,
 		direction,
 		mint,
 		maxt,
 		func(statsCtx *stats.Context, ts int64, line string, structuredMetadataSymbols symbols) error {
-			structuredMetadata = hb.symbolizer.Lookup(structuredMetadataSymbols, structuredMetadata)
+			structuredMetadata = hb.symbolizer.Lookup(structuredMetadataSymbols, labelsBuilder)
 			newLine, parsedLbs, matches := pipeline.ProcessString(ts, line, structuredMetadata)
 			if !matches {
 				return nil
@@ -298,9 +299,7 @@ func (hb *unorderedHeadBlock) Iterator(ctx context.Context, direction logproto.D
 	}
 
 	return iter.EntryIteratorWithClose(iter.NewStreamsIterator(streamsResult, direction), func() error {
-		if structuredMetadata != nil {
-			structuredMetadataPool.Put(structuredMetadata) // nolint:staticcheck
-		}
+		structuredMetadataPool.Put(structuredMetadata) // nolint:staticcheck
 		return nil
 	})
 }
@@ -313,14 +312,15 @@ func (hb *unorderedHeadBlock) SampleIterator(
 ) iter.SampleIterator {
 	series := map[string]*logproto.Series{}
 	setQueryReferencedStructuredMetadata := false
-	var structuredMetadata labels.Labels
+	structuredMetadata := structuredMetadataPool.Get().(labels.Labels)
+	labelsBuilder := log.NewBufferedLabelsBuilder(structuredMetadata)
 	_ = hb.forEntries(
 		ctx,
 		logproto.FORWARD,
 		mint,
 		maxt,
 		func(statsCtx *stats.Context, ts int64, line string, structuredMetadataSymbols symbols) error {
-			structuredMetadata = hb.symbolizer.Lookup(structuredMetadataSymbols, structuredMetadata)
+			structuredMetadata = hb.symbolizer.Lookup(structuredMetadataSymbols, labelsBuilder)
 
 			for _, extractor := range extractor {
 				value, lbls, ok := extractor.ProcessString(ts, line, structuredMetadata)
@@ -372,9 +372,7 @@ func (hb *unorderedHeadBlock) SampleIterator(
 		for _, s := range series {
 			SamplesPool.Put(s.Samples)
 		}
-		if structuredMetadata != nil {
-			structuredMetadataPool.Put(structuredMetadata) // nolint:staticcheck
-		}
+		structuredMetadataPool.Put(structuredMetadata) // nolint:staticcheck
 		return nil
 	})
 }