Replace sort.Strings and sort.Ints with faster slices.Sort (#11318)

Use new experimental package `golang.org/x/exp/slices`.

slices.Sort works on values that are directly comparable, like ints,
so avoids the overhad of an interface call to `.Less()`.

Left tests unchanged, because they don't need the speed and it may be
a cross-check that slices.Sort gives the same answer.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

promql/engine.go

@@ -35,6 +35,7 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/model/timestamp"
@@ -1243,7 +1244,7 @@ func (ev *evaluator) eval(expr parser.Expr) (parser.Value, storage.Warnings) {
 	case *parser.AggregateExpr:
 		// Grouping labels must be sorted (expected both by generateGroupingKey() and aggregation()).
 		sortedGrouping := e.Grouping
-		sort.Strings(sortedGrouping)
+		slices.Sort(sortedGrouping)
 
 		// Prepare a function to initialise series helpers with the grouping key.
 		buf := make([]byte, 0, 1024)
@@ -2059,13 +2060,13 @@ func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *
 
 func signatureFunc(on bool, b []byte, names ...string) func(labels.Labels) string {
 	if on {
-		sort.Strings(names)
+		slices.Sort(names)
 		return func(lset labels.Labels) string {
 			return string(lset.BytesWithLabels(b, names...))
 		}
 	}
 	names = append([]string{labels.MetricName}, names...)
-	sort.Strings(names)
+	slices.Sort(names)
 	return func(lset labels.Labels) string {
 		return string(lset.BytesWithoutLabels(b, names...))
 	}
@@ -2267,7 +2268,7 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 			// operator is less frequently used than other aggregations, we're fine having to
 			// re-compute the grouping key on each step for this case.
 			grouping = append(grouping, valueLabel)
-			sort.Strings(grouping)
+			slices.Sort(grouping)
 			recomputeGroupingKey = true
 		}
 	}

storage/merge.go

@@ -18,9 +18,10 @@ import (
 	"container/heap"
 	"fmt"
 	"math"
-	"sort"
 	"sync"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
 	"github.com/prometheus/prometheus/tsdb/chunks"
@@ -240,7 +241,7 @@ func (q *mergeGenericQuerier) LabelNames(matchers ...*labels.Matcher) ([]string,
 	for name := range labelNamesMap {
 		labelNames = append(labelNames, name)
 	}
-	sort.Strings(labelNames)
+	slices.Sort(labelNames)
 	return labelNames, warnings, nil
 }
 

tsdb/block.go

@@ -19,13 +19,13 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"sort"
 	"sync"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
@@ -463,7 +463,7 @@ func (r blockIndexReader) SortedLabelValues(name string, matchers ...*labels.Mat
 	} else {
 		st, err = r.LabelValues(name, matchers...)
 		if err == nil {
-			sort.Strings(st)
+			slices.Sort(st)
 		}
 	}
 

tsdb/chunks/head_chunks.go

@@ -21,7 +21,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"sort"
 	"strconv"
 	"sync"
 
@@ -29,6 +28,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/atomic"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
 	tsdb_errors "github.com/prometheus/prometheus/tsdb/errors"
@@ -308,7 +308,7 @@ func (cdm *ChunkDiskMapper) openMMapFiles() (returnErr error) {
 	}
 
 	// Check for gaps in the files.
-	sort.Ints(chkFileIndices)
+	slices.Sort(chkFileIndices)
 	if len(chkFileIndices) == 0 {
 		return nil
 	}
@@ -777,7 +777,7 @@ func (cdm *ChunkDiskMapper) IterateAllChunks(f func(seriesRef HeadSeriesRef, chu
 	for seg := range cdm.mmappedChunkFiles {
 		segIDs = append(segIDs, seg)
 	}
-	sort.Ints(segIDs)
+	slices.Sort(segIDs)
 	for _, segID := range segIDs {
 		mmapFile := cdm.mmappedChunkFiles[segID]
 		fileEnd := mmapFile.byteSlice.Len()
@@ -894,7 +894,7 @@ func (cdm *ChunkDiskMapper) Truncate(fileNo uint32) error {
 	for seq := range cdm.mmappedChunkFiles {
 		chkFileIndices = append(chkFileIndices, seq)
 	}
-	sort.Ints(chkFileIndices)
+	slices.Sort(chkFileIndices)
 
 	var removedFiles []int
 	for _, seq := range chkFileIndices {
@@ -934,7 +934,7 @@ func (cdm *ChunkDiskMapper) Truncate(fileNo uint32) error {
 // deleteFiles deletes the given file sequences in order of the sequence.
 // In case of an error, it returns the sorted file sequences that were not deleted from the _disk_.
 func (cdm *ChunkDiskMapper) deleteFiles(removedFiles []int) ([]int, error) {
-	sort.Ints(removedFiles) // To delete them in order.
+	slices.Sort(removedFiles) // To delete them in order.
 	cdm.readPathMtx.Lock()
 	for _, seq := range removedFiles {
 		if err := cdm.closers[seq].Close(); err != nil {

tsdb/head_read.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
@@ -65,7 +66,7 @@ func (h *headIndexReader) Symbols() index.StringIter {
 func (h *headIndexReader) SortedLabelValues(name string, matchers ...*labels.Matcher) ([]string, error) {
 	values, err := h.LabelValues(name, matchers...)
 	if err == nil {
-		sort.Strings(values)
+		slices.Sort(values)
 	}
 	return values, err
 }
@@ -95,7 +96,7 @@ func (h *headIndexReader) LabelNames(matchers ...*labels.Matcher) ([]string, err
 
 	if len(matchers) == 0 {
 		labelNames := h.head.postings.LabelNames()
-		sort.Strings(labelNames)
+		slices.Sort(labelNames)
 		return labelNames, nil
 	}
 
@@ -229,7 +230,7 @@ func (h *headIndexReader) LabelNamesFor(ids ...storage.SeriesRef) ([]string, err
 	for name := range namesMap {
 		names = append(names, name)
 	}
-	sort.Strings(names)
+	slices.Sort(names)
 	return names, nil
 }
 

tsdb/index/index.go

@@ -29,6 +29,7 @@ import (
 	"unsafe"
 
 	"github.com/pkg/errors"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
@@ -819,7 +820,7 @@ func (w *Writer) writePostingsToTmpFiles() error {
 	for n := range w.labelNames {
 		names = append(names, n)
 	}
-	sort.Strings(names)
+	slices.Sort(names)
 
 	if err := w.f.Flush(); err != nil {
 		return err
@@ -1469,7 +1470,7 @@ func (r *Reader) SymbolTableSize() uint64 {
 func (r *Reader) SortedLabelValues(name string, matchers ...*labels.Matcher) ([]string, error) {
 	values, err := r.LabelValues(name, matchers...)
 	if err == nil && r.version == FormatV1 {
-		sort.Strings(values)
+		slices.Sort(values)
 	}
 	return values, err
 }
@@ -1571,7 +1572,7 @@ func (r *Reader) LabelNamesFor(ids ...storage.SeriesRef) ([]string, error) {
 		names = append(names, name)
 	}
 
-	sort.Strings(names)
+	slices.Sort(names)
 
 	return names, nil
 }
@@ -1743,7 +1744,7 @@ func (r *Reader) LabelNames(matchers ...*labels.Matcher) ([]string, error) {
 		}
 		labelNames = append(labelNames, name)
 	}
-	sort.Strings(labelNames)
+	slices.Sort(labelNames)
 	return labelNames, nil
 }
 

tsdb/index/postings.go

@@ -91,7 +91,7 @@ func (p *MemPostings) Symbols() StringIter {
 		res = append(res, k)
 	}
 
-	sort.Strings(res)
+	slices.Sort(res)
 	return NewStringListIter(res)
 }
 

tsdb/querier.go

@@ -15,11 +15,11 @@ package tsdb
 
 import (
 	"math"
-	"sort"
 	"strings"
 	"unicode/utf8"
 
 	"github.com/pkg/errors"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
@@ -317,7 +317,7 @@ func postingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Postings, erro
 	if m.Type == labels.MatchRegexp {
 		setMatches := findSetMatches(m.GetRegexString())
 		if len(setMatches) > 0 {
-			sort.Strings(setMatches)
+			slices.Sort(setMatches)
 			return ix.Postings(m.Name, setMatches...)
 		}
 	}
@@ -344,7 +344,7 @@ func postingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Postings, erro
 	}
 
 	if !isSorted {
-		sort.Strings(res)
+		slices.Sort(res)
 	}
 	return ix.Postings(m.Name, res...)
 }
@@ -369,7 +369,7 @@ func inversePostingsForMatcher(ix IndexReader, m *labels.Matcher) (index.Posting
 	}
 
 	if !isSorted {
-		sort.Strings(res)
+		slices.Sort(res)
 	}
 	return ix.Postings(m.Name, res...)
 }

tsdb/wal/watcher.go

@@ -19,7 +19,6 @@ import (
 	"math"
 	"os"
 	"path"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -28,6 +27,7 @@ import (
 	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/model/timestamp"
 	"github.com/prometheus/prometheus/tsdb/record"
@@ -317,7 +317,7 @@ func (w *Watcher) segments(dir string) ([]int, error) {
 		}
 		refs = append(refs, k)
 	}
-	sort.Ints(refs)
+	slices.Sort(refs)
 	for i := 0; i < len(refs)-1; i++ {
 		if refs[i]+1 != refs[i+1] {
 			return nil, errors.New("segments are not sequential")

web/api/v1/api.go

@@ -23,7 +23,6 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -37,6 +36,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/common/route"
+	"golang.org/x/exp/slices"
 
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/model/exemplar"
@@ -628,7 +628,7 @@ func (api *API) labelNames(r *http.Request) apiFuncResult {
 		for key := range labelNamesSet {
 			names = append(names, key)
 		}
-		sort.Strings(names)
+		slices.Sort(names)
 	} else {
 		names, warnings, err = q.LabelNames()
 		if err != nil {
@@ -713,7 +713,7 @@ func (api *API) labelValues(r *http.Request) (result apiFuncResult) {
 		}
 	}
 
-	sort.Strings(vals)
+	slices.Sort(vals)
 
 	return apiFuncResult{vals, nil, warnings, closer}
 }
@@ -908,7 +908,7 @@ func (api *API) targets(r *http.Request) apiFuncResult {
 			keys = append(keys, k)
 			n += len(targets[k])
 		}
-		sort.Strings(keys)
+		slices.Sort(keys)
 		return keys, n
 	}