all: simplify and clean up

This patch modernizes the for-range-loop code to copy a map with
"maps.Clone" and "maps.Copy", also eliminates "copyMap" and "copyFloats"
functions.

Also simplify "aggSort" and "sortMap" with slices and maps functions.

Signed-off-by: Jes Cok <[email protected]>

pkg/featuregate/feature_gate.go

@@ -18,6 +18,7 @@ package featuregate
 import (
 	"flag"
 	"fmt"
+	"maps"
 	"sort"
 	"strconv"
 	"strings"
@@ -171,10 +172,7 @@ func New(name string, lg *zap.Logger) *featureGate {
 	if lg == nil {
 		lg = zap.NewNop()
 	}
-	known := map[Feature]FeatureSpec{}
-	for k, v := range defaultFeatures {
-		known[k] = v
-	}
+	known := maps.Clone(defaultFeatures)
 
 	f := &featureGate{
 		lg:              lg,
@@ -216,14 +214,8 @@ func (f *featureGate) SetFromMap(m map[string]bool) error {
 	defer f.lock.Unlock()
 
 	// Copy existing state
-	known := map[Feature]FeatureSpec{}
-	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
-		known[k] = v
-	}
-	enabled := map[Feature]bool{}
-	for k, v := range f.enabled.Load().(map[Feature]bool) {
-		enabled[k] = v
-	}
+	known := maps.Clone(f.known.Load().(map[Feature]FeatureSpec))
+	enabled := maps.Clone(f.enabled.Load().(map[Feature]bool))
 
 	for k, v := range m {
 		k := Feature(k)
@@ -279,10 +271,7 @@ func (f *featureGate) Add(features map[Feature]FeatureSpec) error {
 	}
 
 	// Copy existing state
-	known := map[Feature]FeatureSpec{}
-	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
-		known[k] = v
-	}
+	known := maps.Clone(f.known.Load().(map[Feature]FeatureSpec))
 
 	for name, spec := range features {
 		if existingSpec, found := known[name]; found {
@@ -335,11 +324,7 @@ func (f *featureGate) OverrideDefault(name Feature, override bool) error {
 
 // GetAll returns a copy of the map of known feature names to feature specs.
 func (f *featureGate) GetAll() map[Feature]FeatureSpec {
-	retval := map[Feature]FeatureSpec{}
-	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
-		retval[k] = v
-	}
-	return retval
+	return maps.Clone(f.known.Load().(map[Feature]FeatureSpec))
 }
 
 // Enabled returns true if the key is enabled.  If the key is not known, this call will panic.
@@ -396,14 +381,8 @@ func (f *featureGate) KnownFeatures() []string {
 // config against potential feature gate changes before committing those changes.
 func (f *featureGate) DeepCopy() MutableFeatureGate {
 	// Copy existing state.
-	known := map[Feature]FeatureSpec{}
-	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
-		known[k] = v
-	}
-	enabled := map[Feature]bool{}
-	for k, v := range f.enabled.Load().(map[Feature]bool) {
-		enabled[k] = v
-	}
+	known := maps.Clone(f.known.Load().(map[Feature]FeatureSpec))
+	enabled := maps.Clone(f.enabled.Load().(map[Feature]bool))
 
 	// Construct a new featureGate around the copied state.
 	// Note that specialFeatures is treated as immutable by convention,

pkg/report/report.go

@@ -18,7 +18,9 @@ package report
 
 import (
 	"fmt"
+	"maps"
 	"math"
+	"slices"
 	"sort"
 	"strings"
 	"time"
@@ -62,8 +64,8 @@ type Stats struct {
 
 func (s *Stats) copy() Stats {
 	ss := *s
-	ss.ErrorDist = copyMap(ss.ErrorDist)
-	ss.Lats = copyFloats(ss.Lats)
+	ss.ErrorDist = maps.Clone(ss.ErrorDist)
+	ss.Lats = slices.Clone(ss.Lats)
 	return ss
 }
 
@@ -122,20 +124,6 @@ func (r *report) Stats() <-chan Stats {
 	return donec
 }
 
-func copyMap(m map[string]int) (c map[string]int) {
-	c = make(map[string]int, len(m))
-	for k, v := range m {
-		c[k] = v
-	}
-	return c
-}
-
-func copyFloats(s []float64) (c []float64) {
-	c = make([]float64, len(s))
-	copy(c, s)
-	return c
-}
-
 func (r *report) String() (s string) {
 	if len(r.stats.Lats) > 0 {
 		s += "\nSummary:\n"

server/auth/jwt_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"maps"
 	"testing"
 	"time"
 
@@ -117,10 +118,7 @@ func testJWTInfo(t *testing.T, opts map[string]string) {
 	// test verify-only provider
 	if opts["pub-key"] != "" && opts["priv-key"] != "" {
 		t.Run("verify-only", func(t *testing.T) {
-			newOpts := make(map[string]string, len(opts))
-			for k, v := range opts {
-				newOpts[k] = v
-			}
+			newOpts := maps.Clone(opts)
 			delete(newOpts, "priv-key")
 			verify, err := newTokenProviderJWT(lg, newOpts)
 			if err != nil {

server/proxy/grpcproxy/adapter/chan_stream.go

@@ -16,6 +16,7 @@ package adapter
 
 import (
 	"context"
+	"maps"
 
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
@@ -38,9 +39,7 @@ func (ss *chanServerStream) SendHeader(md metadata.MD) error {
 	}
 	outmd := make(map[string][]string)
 	for _, h := range append(ss.headers, md) {
-		for k, v := range h {
-			outmd[k] = v
-		}
+		maps.Copy(outmd, h)
 	}
 	select {
 	case ss.headerc <- outmd:

tests/framework/e2e/cluster.go

@@ -19,6 +19,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"maps"
 	"net/url"
 	"path"
 	"path/filepath"
@@ -633,10 +634,7 @@ func (cfg *EtcdProcessClusterConfig) EtcdServerProcessConfig(tb testing.TB, i in
 		}
 		args = append(args, fmt.Sprintf("--%s=%s", flag, value))
 	}
-	envVars := map[string]string{}
-	for key, value := range cfg.EnvVars {
-		envVars[key] = value
-	}
+	envVars := maps.Clone(cfg.EnvVars)
 	var gofailPort int
 	if cfg.GoFailEnabled {
 		gofailPort = (i+1)*10000 + 2381

tools/etcd-dump-metrics/utils.go

@@ -14,26 +14,17 @@
 
 package main
 
-import "sort"
+import (
+	"maps"
+	"slices"
+)
 
 func aggSort(ss []string) (sorted []string) {
-	set := make(map[string]struct{})
-	for _, s := range ss {
-		set[s] = struct{}{}
-	}
-	sorted = make([]string, 0, len(set))
-	for k := range set {
-		sorted = append(sorted, k)
-	}
-	sort.Strings(sorted)
-	return sorted
+	dup := slices.Clone(ss)
+	slices.Sort(dup)
+	return slices.Compact(dup)
 }
 
 func sortMap(set map[string]struct{}) (sorted []string) {
-	sorted = make([]string, 0, len(set))
-	for k := range set {
-		sorted = append(sorted, k)
-	}
-	sort.Strings(sorted)
-	return sorted
+	return slices.Sorted(maps.Keys(set))
 }