Improve performance of generatings IDs from tags in M3Coordinator

src/query/functions/temporal/base.go

@@ -248,7 +248,7 @@ func (c *baseNode) processSingleRequest(request processRequest) error {
 	for i, m := range seriesMeta {
 		tags := m.Tags.WithoutName()
 		resultSeriesMeta[i].Tags = tags
-		resultSeriesMeta[i].Name = tags.ID()
+		resultSeriesMeta[i].Name = tags.StringID()
 	}
 
 	builder, err := c.controller.BlockBuilder(seriesIter.Meta(), resultSeriesMeta)

src/query/models/tag.go

@@ -25,6 +25,7 @@ import (
 	"hash/fnv"
 	"regexp"
 	"sort"
+	"strings"
 )
 
 const (
@@ -145,17 +146,46 @@ func (m Matchers) ToTags() (Tags, error) {
 	return Normalize(tags), nil
 }
 
-// ID returns a string representation of the tags
-func (t Tags) ID() string {
-	b := make([]byte, 0, len(t))
+// StringID returns a string representation of the tags
+func (t Tags) StringID() string {
+	var (
+		idLen      = t.IDLen()
+		strBuilder = strings.Builder{}
+	)
+
+	strBuilder.Grow(idLen)
+	for _, tag := range t {
+		strBuilder.WriteString(tag.Name)
+		strBuilder.WriteByte(eq)
+		strBuilder.WriteString(tag.Value)
+		strBuilder.WriteByte(sep)
+	}
+
+	return strBuilder.String()
+}
+
+// WriteBytesID writes out the ID representation
+// of the tags into the provided buffer.
+func (t Tags) WriteBytesID(b []byte) []byte {
 	for _, tag := range t {
 		b = append(b, tag.Name...)
 		b = append(b, eq)
 		b = append(b, tag.Value...)
 		b = append(b, sep)
 	}
 
-	return string(b)
+	return b
+}
+
+// IDLen returns the length of the ID that would be
+// generated from the tags.
+func (t Tags) IDLen() int {
+	idLen := 2 * len(t) // account for eq and sep
+	for _, tag := range t {
+		idLen += len(tag.Name)
+		idLen += len(tag.Value)
+	}
+	return idLen
 }
 
 // IDWithExcludes returns a string representation of the tags excluding some tag keys

src/query/models/tag_test.go

@@ -113,9 +113,17 @@ func createTags(withName bool) Tags {
 	return tags
 }
 
-func TestTagID(t *testing.T) {
+func TestTagStringID(t *testing.T) {
 	tags := createTags(false)
-	assert.Equal(t, tags.ID(), "t1=v1,t2=v2,")
+	assert.Equal(t, "t1=v1,t2=v2,", tags.StringID())
+}
+
+func TestTagByteID(t *testing.T) {
+	var (
+		tags = createTags(false)
+		b    = tags.WriteBytesID([]byte{})
+	)
+	assert.Equal(t, []byte("t1=v1,t2=v2,"), b)
 }
 
 func TestWithoutName(t *testing.T) {

src/query/policy/resolver/static.go

@@ -51,7 +51,7 @@ func (r *staticResolver) Resolve(
 		return nil, err
 	}
 	requests[0] = tsdb.FetchRequest{
-		ID:     tags.ID(),
+		ID:     tags.StringID(),
 		Ranges: ranges,
 	}
 

src/query/storage/m3/storage.go

@@ -269,11 +269,15 @@ func (s *m3storage) Write(
 		return errors.ErrNilWriteQuery
 	}
 
-	id := query.Tags.ID()
-	// TODO: Consider caching id -> identID
-	identID := ident.StringID(id)
+	// TODO: Consider caching id -> identID (requires setting NoFinalize()).
+	var (
+		// TODO: Pool this once an ident pool is setup.
+		buf   = make([]byte, 0, query.Tags.IDLen())
+		idBuf = query.Tags.WriteBytesID(buf)
+		id    = ident.BytesID(idBuf)
+	)
 	// Set id to NoFinalize to avoid cloning it in write operations
-	identID.NoFinalize()
+	id.NoFinalize()
 	tagIterator := storage.TagsToIdentTagIterator(query.Tags)
 
 	var (
@@ -287,7 +291,7 @@ func (s *m3storage) Write(
 		datapoint := datapoint
 		wg.Add(1)
 		s.writeWorkerPool.Go(func() {
-			if err := s.writeSingle(ctx, query, datapoint, identID, tagIter); err != nil {
+			if err := s.writeSingle(ctx, query, datapoint, id, tagIter); err != nil {
 				multiErr.add(err)
 			}
 

src/query/test/util.go

@@ -109,7 +109,7 @@ type match struct {
 type matches []match
 
 func (m matches) Len() int           { return len(m) }
-func (m matches) Less(i, j int) bool { return m[i].metas.Tags.ID() > m[j].metas.Tags.ID() }
+func (m matches) Less(i, j int) bool { return m[i].metas.Tags.StringID() > m[j].metas.Tags.StringID() }
 func (m matches) Swap(i, j int)      { m[i], m[j] = m[j], m[i] }
 
 // CompareLists compares series meta / index pairs