Replace StringTuples with []string

Benchmarks show slight cpu/allocs improvements.

benchmark                                                               old ns/op      new ns/op      delta
BenchmarkPostingsForMatchers/Head/n="1"-4                               269978625      235305110      -12.84%
BenchmarkPostingsForMatchers/Head/n="1",j="foo"-4                       129739974      121646193      -6.24%
BenchmarkPostingsForMatchers/Head/j="foo",n="1"-4                       123826274      122056253      -1.43%
BenchmarkPostingsForMatchers/Head/n="1",j!="foo"-4                      126962188      130038235      +2.42%
BenchmarkPostingsForMatchers/Head/i=~".*"-4                             6423653989     5991126455     -6.73%
BenchmarkPostingsForMatchers/Head/i=~".+"-4                             6934647521     7033370634     +1.42%
BenchmarkPostingsForMatchers/Head/i=~""-4                               1177781285     1121497736     -4.78%
BenchmarkPostingsForMatchers/Head/i!=""-4                               7033680256     7246094991     +3.02%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",j="foo"-4               293702332      287440212      -2.13%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",i!="2",j="foo"-4        307628268      307039964      -0.19%
BenchmarkPostingsForMatchers/Head/n="1",i!=""-4                         512247746      480003862      -6.29%
BenchmarkPostingsForMatchers/Head/n="1",i!="",j="foo"-4                 361199794      367066917      +1.62%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",j="foo"-4               478863761      476037784      -0.59%
BenchmarkPostingsForMatchers/Head/n="1",i=~"1.+",j="foo"-4              103394659      102902098      -0.48%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!="2",j="foo"-4        482552781      475453903      -1.47%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!~"2.*",j="foo"-4      559257389      589297047      +5.37%
BenchmarkPostingsForMatchers/Block/n="1"-4                              36492          37012          +1.42%
BenchmarkPostingsForMatchers/Block/n="1",j="foo"-4                      557788         611903         +9.70%
BenchmarkPostingsForMatchers/Block/j="foo",n="1"-4                      554443         573814         +3.49%
BenchmarkPostingsForMatchers/Block/n="1",j!="foo"-4                     553227         553826         +0.11%
BenchmarkPostingsForMatchers/Block/i=~".*"-4                            113855090      111707221      -1.89%
BenchmarkPostingsForMatchers/Block/i=~".+"-4                            133994674      136520728      +1.89%
BenchmarkPostingsForMatchers/Block/i=~""-4                              38138091       36299898       -4.82%
BenchmarkPostingsForMatchers/Block/i!=""-4                              28861213       27396723       -5.07%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",j="foo"-4              112699941      110853868      -1.64%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",i!="2",j="foo"-4       113198026      111389742      -1.60%
BenchmarkPostingsForMatchers/Block/n="1",i!=""-4                        28994069       27363804       -5.62%
BenchmarkPostingsForMatchers/Block/n="1",i!="",j="foo"-4                29709406       28589223       -3.77%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",j="foo"-4              134695119      135736971      +0.77%
BenchmarkPostingsForMatchers/Block/n="1",i=~"1.+",j="foo"-4             26783286       25826928       -3.57%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!="2",j="foo"-4       134733254      134116739      -0.46%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!~"2.*",j="foo"-4     160713937      158802768      -1.19%

benchmark                                                               old allocs     new allocs     delta
BenchmarkPostingsForMatchers/Head/n="1"-4                               36             36             +0.00%
BenchmarkPostingsForMatchers/Head/n="1",j="foo"-4                       38             38             +0.00%
BenchmarkPostingsForMatchers/Head/j="foo",n="1"-4                       38             38             +0.00%
BenchmarkPostingsForMatchers/Head/n="1",j!="foo"-4                      42             40             -4.76%
BenchmarkPostingsForMatchers/Head/i=~".*"-4                             61             59             -3.28%
BenchmarkPostingsForMatchers/Head/i=~".+"-4                             100088         100087         -0.00%
BenchmarkPostingsForMatchers/Head/i=~""-4                               100053         100051         -0.00%
BenchmarkPostingsForMatchers/Head/i!=""-4                               100087         100085         -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",j="foo"-4               44             42             -4.55%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",i!="2",j="foo"-4        50             48             -4.00%
BenchmarkPostingsForMatchers/Head/n="1",i!=""-4                         100076         100074         -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i!="",j="foo"-4                 100077         100075         -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",j="foo"-4               100077         100074         -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~"1.+",j="foo"-4              11167          11165          -0.02%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!="2",j="foo"-4        100082         100080         -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!~"2.*",j="foo"-4      111265         111261         -0.00%
BenchmarkPostingsForMatchers/Block/n="1"-4                              6              6              +0.00%
BenchmarkPostingsForMatchers/Block/n="1",j="foo"-4                      11             11             +0.00%
BenchmarkPostingsForMatchers/Block/j="foo",n="1"-4                      11             11             +0.00%
BenchmarkPostingsForMatchers/Block/n="1",j!="foo"-4                     15             13             -13.33%
BenchmarkPostingsForMatchers/Block/i=~".*"-4                            12             10             -16.67%
BenchmarkPostingsForMatchers/Block/i=~".+"-4                            100040         100038         -0.00%
BenchmarkPostingsForMatchers/Block/i=~""-4                              100045         100043         -0.00%
BenchmarkPostingsForMatchers/Block/i!=""-4                              100041         100039         -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",j="foo"-4              17             15             -11.76%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",i!="2",j="foo"-4       23             21             -8.70%
BenchmarkPostingsForMatchers/Block/n="1",i!=""-4                        100046         100044         -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i!="",j="foo"-4                100050         100048         -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",j="foo"-4              100049         100047         -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~"1.+",j="foo"-4             11150          11148          -0.02%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!="2",j="foo"-4       100055         100053         -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!~"2.*",j="foo"-4     111238         111234         -0.00%

benchmark                                                               old bytes     new bytes     delta
BenchmarkPostingsForMatchers/Head/n="1"-4                               10887816      10887817      +0.00%
BenchmarkPostingsForMatchers/Head/n="1",j="foo"-4                       5456648       5456648       +0.00%
BenchmarkPostingsForMatchers/Head/j="foo",n="1"-4                       5456648       5456648       +0.00%
BenchmarkPostingsForMatchers/Head/n="1",j!="foo"-4                      5456792       5456712       -0.00%
BenchmarkPostingsForMatchers/Head/i=~".*"-4                             258254408     258254328     -0.00%
BenchmarkPostingsForMatchers/Head/i=~".+"-4                             273912888     273912904     +0.00%
BenchmarkPostingsForMatchers/Head/i=~""-4                               17266680      17266600      -0.00%
BenchmarkPostingsForMatchers/Head/i!=""-4                               273912416     273912336     -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",j="foo"-4               7062578       7062498       -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".*",i!="2",j="foo"-4        7062770       7062690       -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i!=""-4                         28152346      28152266      -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i!="",j="foo"-4                 22721178      22721098      -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",j="foo"-4               22721336      22721224      -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~"1.+",j="foo"-4              3623804       3623733       -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!="2",j="foo"-4        22721480      22721400      -0.00%
BenchmarkPostingsForMatchers/Head/n="1",i=~".+",i!~"2.*",j="foo"-4      24816652      24816444      -0.00%
BenchmarkPostingsForMatchers/Block/n="1"-4                              296           296           +0.00%
BenchmarkPostingsForMatchers/Block/n="1",j="foo"-4                      424           424           +0.00%
BenchmarkPostingsForMatchers/Block/j="foo",n="1"-4                      424           424           +0.00%
BenchmarkPostingsForMatchers/Block/n="1",j!="foo"-4                     1544          1464          -5.18%
BenchmarkPostingsForMatchers/Block/i=~".*"-4                            1606114       1606045       -0.00%
BenchmarkPostingsForMatchers/Block/i=~".+"-4                            17264709      17264629      -0.00%
BenchmarkPostingsForMatchers/Block/i=~""-4                              17264780      17264696      -0.00%
BenchmarkPostingsForMatchers/Block/i!=""-4                              17264680      17264600      -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",j="foo"-4              1606253       1606165       -0.01%
BenchmarkPostingsForMatchers/Block/n="1",i=~".*",i!="2",j="foo"-4       1606445       1606348       -0.01%
BenchmarkPostingsForMatchers/Block/n="1",i!=""-4                        17264808      17264728      -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i!="",j="foo"-4                17264936      17264856      -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",j="foo"-4              17264965      17264885      -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~"1.+",j="foo"-4             3148262       3148182       -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!="2",j="foo"-4       17265141      17265061      -0.00%
BenchmarkPostingsForMatchers/Block/n="1",i=~".+",i!~"2.*",j="foo"-4     20416944      20416784      -0.00%

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

tsdb/block.go

@@ -63,7 +63,7 @@ type IndexReader interface {
 	Symbols() index.StringIter
 
 	// LabelValues returns sorted possible label values.
-	LabelValues(name string) (index.StringTuples, error)
+	LabelValues(name string) ([]string, error)
 
 	// Postings returns the postings list iterator for the label pairs.
 	// The Postings here contain the offsets to the series inside the index.
@@ -87,14 +87,6 @@ type IndexReader interface {
 	Close() error
 }
 
-// StringTuples provides access to a sorted list of string tuples.
-type StringTuples interface {
-	// Total number of tuples in the list.
-	Len() int
-	// At returns the tuple at position i.
-	At(i int) ([]string, error)
-}
-
 // ChunkWriter serializes a time block of chunked series data.
 type ChunkWriter interface {
 	// WriteChunks writes several chunks. The Chunk field of the ChunkMetas
@@ -433,7 +425,7 @@ func (r blockIndexReader) Symbols() index.StringIter {
 	return r.ir.Symbols()
 }
 
-func (r blockIndexReader) LabelValues(name string) (index.StringTuples, error) {
+func (r blockIndexReader) LabelValues(name string) ([]string, error) {
 	st, err := r.ir.LabelValues(name)
 	return st, errors.Wrapf(err, "block: %s", r.b.Meta().ULID)
 }

tsdb/cmd/tsdb/main.go

@@ -559,17 +559,9 @@ func analyzeBlock(b tsdb.BlockReader, limit int) error {
 			return err
 		}
 		var cumulativeLength uint64
-
+		for _, str := range values {
-		for i := 0; i < values.Len(); i++ {
+			cumulativeLength += uint64(len(str))
-			value, err := values.At(i)
-			if err != nil {
-				return err
-			}
-			for _, str := range value {
-				cumulativeLength += uint64(len(str))
-			}
 		}
-
 		postingInfos = append(postingInfos, postingInfo{n, cumulativeLength})
 	}
 
@@ -582,7 +574,7 @@ func analyzeBlock(b tsdb.BlockReader, limit int) error {
 		if err != nil {
 			return err
 		}
-		postingInfos = append(postingInfos, postingInfo{n, uint64(lv.Len())})
+		postingInfos = append(postingInfos, postingInfo{n, uint64(len(lv))})
 	}
 	fmt.Printf("\nHighest cardinality labels:\n")
 	printInfo(postingInfos)
@@ -592,25 +584,19 @@ func analyzeBlock(b tsdb.BlockReader, limit int) error {
 	if err != nil {
 		return err
 	}
-	for i := 0; i < lv.Len(); i++ {
+	for _, n := range lv {
-		names, err := lv.At(i)
+		postings, err := ir.Postings("__name__", n)
 		if err != nil {
 			return err
 		}
-		for _, n := range names {
+		count := 0
-			postings, err := ir.Postings("__name__", n)
+		for postings.Next() {
-			if err != nil {
+			count++
-				return err
-			}
-			count := 0
-			for postings.Next() {
-				count++
-			}
-			if postings.Err() != nil {
-				return postings.Err()
-			}
-			postingInfos = append(postingInfos, postingInfo{n, uint64(count)})
 		}
+		if postings.Err() != nil {
+			return postings.Err()
+		}
+		postingInfos = append(postingInfos, postingInfo{n, uint64(count)})
 	}
 	fmt.Printf("\nHighest cardinality metric names:\n")
 	printInfo(postingInfos)

tsdb/head.go

@@ -1352,7 +1352,7 @@ func (h *headIndexReader) Symbols() index.StringIter {
 }
 
 // LabelValues returns the possible label values
-func (h *headIndexReader) LabelValues(name string) (index.StringTuples, error) {
+func (h *headIndexReader) LabelValues(name string) ([]string, error) {
 	h.head.symMtx.RLock()
 	sl := make([]string, 0, len(h.head.values[name]))
 	for s := range h.head.values[name] {
@@ -1360,8 +1360,7 @@ func (h *headIndexReader) LabelValues(name string) (index.StringTuples, error) {
 	}
 	h.head.symMtx.RUnlock()
 	sort.Strings(sl)
-
+	return sl, nil
-	return index.NewStringTuples(sl)
 }
 
 // LabelNames returns all the unique label names present in the head.

tsdb/index/index.go

@@ -993,14 +993,6 @@ func (w *Writer) Close() error {
 	return ensureErr
 }
 
-// StringTuples provides access to a sorted list of string tuples.
-type StringTuples interface {
-	// Total number of tuples in the list.
-	Len() int
-	// At returns the tuple at position i.
-	At(i int) (string, error)
-}
-
 // StringIter iterates over a sorted list of strings.
 type StringIter interface {
 	// Next advances the iterator and returns true if another value was found.
@@ -1424,26 +1416,26 @@ func (r *Reader) SymbolTableSize() uint64 {
 // LabelValues returns value tuples that exist for the given label name.
 // It is not safe to use the return value beyond the lifetime of the byte slice
 // passed into the Reader.
-func (r *Reader) LabelValues(name string) (StringTuples, error) {
+func (r *Reader) LabelValues(name string) ([]string, error) {
 	if r.version == FormatV1 {
 		e, ok := r.postingsV1[name]
 		if !ok {
-			return emptyStringTuples{}, nil
+			return nil, nil
 		}
 		values := make([]string, 0, len(e))
 		for k := range e {
 			values = append(values, k)
 		}
 		sort.Strings(values)
-		return NewStringTuples(values, 1)
+		return values, nil
 
 	}
 	e, ok := r.postings[name]
 	if !ok {
-		return emptyStringTuples{}, nil
+		return nil, nil
 	}
 	if len(e) == 0 {
-		return emptyStringTuples{}, nil
+		return nil, nil
 	}
 	values := make([]string, 0, len(e)*symbolFactor)
 
@@ -1473,14 +1465,9 @@ func (r *Reader) LabelValues(name string) (StringTuples, error) {
 	if d.Err() != nil {
 		return nil, errors.Wrap(d.Err(), "get postings offset entry")
 	}
-	return NewStringTuples(values)
+	return values, nil
 }
 
-type emptyStringTuples struct{}
-
-func (emptyStringTuples) At(i int) (string, error) { return "", nil }
-func (emptyStringTuples) Len() int                 { return 0 }
-
 // Series reads the series with the given ID and writes its labels and chunks into lbls and chks.
 func (r *Reader) Series(id uint64, lbls *labels.Labels, chks *[]chunks.Meta) error {
 	offset := id
@@ -1621,27 +1608,6 @@ func (r *Reader) LabelNames() ([]string, error) {
 	return labelNames, nil
 }
 
-type stringTuples struct {
-	entries []string // flattened tuple entries
-}
-
-func NewStringTuples(entries []string) (*stringTuples, error) {
-	return &stringTuples{
-		entries: entries,
-	}, nil
-}
-
-func (t *stringTuples) Len() int                 { return len(t.entries) }
-func (t *stringTuples) At(i int) (string, error) { return t.entries[i], nil }
-
-func (t *stringTuples) Swap(i, j int) {
-	t.entries[i], t.entries[j] = t.entries[j], t.entries[i]
-}
-
-func (t *stringTuples) Less(i, j int) bool {
-	return t.entries[i] < t.entries[j]
-}
-
 // NewStringListIterator returns a StringIter for the given sorted list of strings.
 func NewStringListIter(s []string) StringIter {
 	return &stringListIter{l: s}

tsdb/index/index_test.go

@@ -85,14 +85,14 @@ func (m mockIndex) Close() error {
 	return nil
 }
 
-func (m mockIndex) LabelValues(name string) (StringTuples, error) {
+func (m mockIndex) LabelValues(name string) ([]string, error) {
 	values := []string{}
 	for l := range m.postings {
 		if l.Name == name {
 			values = append(values, l.Value)
 		}
 	}
-	return NewStringTuples(values)
+	return values, nil
 }
 
 func (m mockIndex) Postings(name string, values ...string) (Postings, error) {
@@ -451,21 +451,13 @@ func TestPersistence_index_e2e(t *testing.T) {
 	}
 	for k, v := range labelPairs {
 		sort.Strings(v)
-		tplsExp, err := NewStringTuples(v)
+
+		res, err := ir.LabelValues(k)
 		testutil.Ok(t, err)
 
-		tplsRes, err := ir.LabelValues(k)
+		testutil.Equals(t, len(v), len(res))
-		testutil.Ok(t, err)
+		for i := 0; i < len(v); i++ {
-
+			testutil.Equals(t, v[i], res[i])
-		testutil.Equals(t, tplsExp.Len(), tplsRes.Len())
-		for i := 0; i < tplsExp.Len(); i++ {
-			strsExp, err := tplsExp.At(i)
-			testutil.Ok(t, err)
-
-			strsRes, err := tplsRes.At(i)
-			testutil.Ok(t, err)
-
-			testutil.Equals(t, strsExp, strsRes)
 		}
 	}
 

tsdb/querier.go

@@ -218,20 +218,7 @@ func (q *blockQuerier) Select(ms ...*labels.Matcher) (SeriesSet, error) {
 }
 
 func (q *blockQuerier) LabelValues(name string) ([]string, error) {
-	tpls, err := q.index.LabelValues(name)
+	return q.index.LabelValues(name)
-	if err != nil {
-		return nil, err
-	}
-	res := make([]string, 0, tpls.Len())
-
-	for i := 0; i < tpls.Len(); i++ {
-		val, err := tpls.At(i)
-		if err != nil {
-			return nil, err
-		}
-		res = append(res, val)
-	}
-	return res, nil
 }
 
 func (q *blockQuerier) LabelNames() ([]string, error) {
@@ -412,17 +399,13 @@ func postingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Postings, erro
 		}
 	}
 
-	tpls, err := ix.LabelValues(m.Name)
+	vals, err := ix.LabelValues(m.Name)
 	if err != nil {
 		return nil, err
 	}
 
 	var res []string
-	for i := 0; i < tpls.Len(); i++ {
+	for _, val := range vals {
-		val, err := tpls.At(i)
-		if err != nil {
-			return nil, err
-		}
 		if m.Matches(val) {
 			res = append(res, val)
 		}
@@ -437,18 +420,13 @@ func postingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Postings, erro
 
 // inversePostingsForMatcher returns the postings for the series with the label name set but not matching the matcher.
 func inversePostingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Postings, error) {
-	tpls, err := ix.LabelValues(m.Name)
+	vals, err := ix.LabelValues(m.Name)
 	if err != nil {
 		return nil, err
 	}
 
 	var res []string
-	for i := 0; i < tpls.Len(); i++ {
+	for _, val := range vals {
-		val, err := tpls.At(i)
-		if err != nil {
-			return nil, err
-		}
-
 		if !m.Matches(val) {
 			res = append(res, val)
 		}

tsdb/querier_test.go

@@ -1356,14 +1356,15 @@ func (m mockIndex) Close() error {
 	return nil
 }
 
-func (m mockIndex) LabelValues(name string) (index.StringTuples, error) {
+func (m mockIndex) LabelValues(name string) ([]string, error) {
 	values := []string{}
 	for l := range m.postings {
 		if l.Name == name {
 			values = append(values, l.Value)
 		}
 	}
-	return index.NewStringTuples(values)
+	sort.Strings(values)
+	return values, nil
 }
 
 func (m mockIndex) Postings(name string, values ...string) (index.Postings, error) {