Avoid using sets when existing slices suffice

Now that Go includes slice operations such as slices.Contains, some
uses of sets are no longer useful. In particular, creating a set using
a slice just to check whether the slice contains a specific item is
more expensive than checking the slice directly.

Signed-off-by: Stephen Kitt <skitt@redhat.com>

pkg/config/validation/general.go

@@ -5,9 +5,9 @@ import (
 	"net"
 	"net/url"
 	"os"
+	"slices"
 	"strings"
 
-	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 )
 
@@ -126,5 +126,5 @@ func HostnameMatchSpecCandidates(hostname string) []string {
 
 // HostnameMatches returns true if the given hostname is matched by the given matchSpec
 func HostnameMatches(hostname string, matchSpec string) bool {
-	return sets.New(HostnameMatchSpecCandidates(hostname)...).Has(matchSpec)
+	return slices.Contains(HostnameMatchSpecCandidates(hostname), matchSpec)
 }

pkg/controller/factory/controller_context.go

@@ -96,6 +96,7 @@ func (c syncContext) enqueueKeys(keys ...string) {
 // (or its tombstone) is a namespace  and it matches a name of any namespaces
 // that we are interested in
 func namespaceChecker(interestingNamespaces []string) func(obj interface{}) bool {
+	// This is used for quick lookups in informers
 	interestingNamespacesSet := sets.New(interestingNamespaces...)
 
 	return func(obj interface{}) bool {

pkg/oauth/tokenrequest/request_token.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"slices"
 	"strings"
 
 	"github.com/RangelReale/osincli"
@@ -192,7 +193,7 @@ func (o *RequestTokenOptions) SetDefaultOsinConfig(clientID string, redirectURL
 		config.RedirectUrl = *redirectURL
 	}
 
-	if !o.TokenFlow && sets.New(metadata.CodeChallengeMethodsSupported...).Has(pkce_s256) {
+	if !o.TokenFlow && slices.Contains(metadata.CodeChallengeMethodsSupported, pkce_s256) {
 		if err := osincli.PopulatePKCE(config); err != nil {
 			return err
 		}

pkg/operator/configobserver/featuregates/featuregate.go

@@ -2,9 +2,9 @@ package featuregates
 
 import (
 	"fmt"
+	"slices"
 
 	configv1 "github.com/openshift/api/config/v1"
-	"k8s.io/apimachinery/pkg/util/sets"
 )
 
 // FeatureGate indicates whether a given feature is enabled or not
@@ -17,32 +17,32 @@ type FeatureGate interface {
 }
 
 type featureGate struct {
-	enabled  sets.Set[configv1.FeatureGateName]
-	disabled sets.Set[configv1.FeatureGateName]
+	enabled  []configv1.FeatureGateName
+	disabled []configv1.FeatureGateName
 }
 
 func NewFeatureGate(enabled, disabled []configv1.FeatureGateName) FeatureGate {
 	return &featureGate{
-		enabled:  sets.New[configv1.FeatureGateName](enabled...),
-		disabled: sets.New[configv1.FeatureGateName](disabled...),
+		enabled:  enabled,
+		disabled: disabled,
 	}
 }
 
 func (f *featureGate) Enabled(key configv1.FeatureGateName) bool {
-	if f.enabled.Has(key) {
+	if slices.Contains(f.enabled, key) {
 		return true
 	}
-	if f.disabled.Has(key) {
+	if slices.Contains(f.disabled, key) {
 		return false
 	}
 
 	panic(fmt.Errorf("feature %q is not registered in FeatureGates %v", key, f.KnownFeatures()))
 }
 
 func (f *featureGate) KnownFeatures() []configv1.FeatureGateName {
-	allKnown := sets.New[string]()
-	allKnown.Insert(FeatureGateNamesToStrings(f.enabled.UnsortedList())...)
-	allKnown.Insert(FeatureGateNamesToStrings(f.disabled.UnsortedList())...)
+	allKnown := make([]configv1.FeatureGateName, 0, len(f.enabled)+len(f.disabled))
+	allKnown = append(allKnown, f.enabled...)
+	allKnown = append(allKnown, f.disabled...)
 
-	return StringsToFeatureGateNames(sets.List(allKnown))
+	return allKnown
 }

pkg/operator/configobserver/featuregates/observe_featuregates_test.go

@@ -3,6 +3,7 @@ package featuregates
 import (
 	"errors"
 	"reflect"
+	"slices"
 	"testing"
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -167,6 +168,8 @@ func TestObserveFeatureFlags(t *testing.T) {
 			if err != nil {
 				t.Fatalf("unexpected error: %v", err)
 			}
+			// Sort the result for comparison with the expected result
+			slices.Sort(actual)
 			if !reflect.DeepEqual(tc.expectedResult, actual) {
 				t.Errorf("Unexpected features gates\n  got:      %v\n  expected: %v", actual, tc.expectedResult)
 			}

pkg/operator/encryption/controllers/prune_controller.go

@@ -2,6 +2,7 @@ package controllers
 
 import (
 	"context"
+	"slices"
 	"sort"
 	"time"
 
@@ -10,7 +11,6 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
-	"k8s.io/apimachinery/pkg/util/sets"
 	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
 	"k8s.io/klog/v2"
 
@@ -160,9 +160,9 @@ NextEncryptionSecret:
 
 		// remove our finalizer if it is present
 		secret := s.DeepCopy()
-		if finalizers := sets.New(secret.Finalizers...); finalizers.Has(secrets.EncryptionSecretFinalizer) {
-			delete(finalizers, secrets.EncryptionSecretFinalizer)
-			secret.Finalizers = sets.List(finalizers)
+		idx := slices.Index(secret.Finalizers, secrets.EncryptionSecretFinalizer)
+		if idx > -1 {
+			secret.Finalizers = slices.Delete(secret.Finalizers, idx, idx+1)
 			var updateErr error
 			secret, updateErr = c.secretClient.Secrets("openshift-config-managed").Update(ctx, secret, metav1.UpdateOptions{})
 			deleteErrs = append(deleteErrs, updateErr)

pkg/operator/staticpod/prune/cmd.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -13,8 +14,6 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"k8s.io/klog/v2"
-
-	"k8s.io/apimachinery/pkg/util/sets"
 )
 
 type PruneOptions struct {
@@ -77,8 +76,6 @@ func (o *PruneOptions) Validate() error {
 }
 
 func (o *PruneOptions) Run() error {
-	protectedIDs := sets.New(o.ProtectedRevisions...)
-
 	files, err := os.ReadDir(o.ResourceDir)
 	if err != nil {
 		return err
@@ -102,7 +99,7 @@ func (o *PruneOptions) Run() error {
 		}
 
 		// And is not protected...
-		if protected := protectedIDs.Has(revisionID); protected {
+		if protected := slices.Contains(o.ProtectedRevisions, revisionID); protected {
 			continue
 		}
 		// And is less than or equal to the maxEligibleRevisionID

pkg/route/validation/validation.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"regexp"
+	"slices"
 	"strings"
 
 	authorizationv1 "k8s.io/api/authorization/v1"
@@ -400,8 +401,7 @@ func validateInsecureEdgeTerminationPolicy(tls *routev1.TLSConfig, fldPath *fiel
 }
 
 var (
-	allowedWildcardPolicies    = []string{string(routev1.WildcardPolicyNone), string(routev1.WildcardPolicySubdomain)}
-	allowedWildcardPoliciesSet = sets.New(allowedWildcardPolicies...)
+	allowedWildcardPolicies = []routev1.WildcardPolicyType{routev1.WildcardPolicyNone, routev1.WildcardPolicySubdomain}
 )
 
 // validateWildcardPolicy tests that the wildcard policy is either empty or one of the supported types.
@@ -411,7 +411,7 @@ func validateWildcardPolicy(host string, policy routev1.WildcardPolicyType, fldP
 	}
 
 	// Check if policy is one of None or Subdomain.
-	if !allowedWildcardPoliciesSet.Has(string(policy)) {
+	if !slices.Contains(allowedWildcardPolicies, policy) {
 		return field.NotSupported(fldPath, policy, allowedWildcardPolicies)
 	}
 
@@ -424,7 +424,6 @@ func validateWildcardPolicy(host string, policy routev1.WildcardPolicyType, fldP
 
 var (
 	notAllowedHTTPHeaders        = []string{"strict-transport-security", "proxy", "cookie", "set-cookie"}
-	notAllowedHTTPHeaderSet      = sets.New(notAllowedHTTPHeaders...)
 	notAllowedHTTPHeadersMessage = fmt.Sprintf("the following headers may not be modified using this API: %v", strings.Join(notAllowedHTTPHeaders, ", "))
 )
 
@@ -451,7 +450,7 @@ func validateHeaders(fldPath *field.Path, headers []routev1.RouteHTTPHeader, val
 		case nameLength > maxHeaderNameSize:
 			err := field.Invalid(idxPath.Child("name"), header.Name, fmt.Sprintf("name exceeds the maximum length, which is %d", maxHeaderNameSize))
 			allErrs = append(allErrs, err)
-		case notAllowedHTTPHeaderSet.Has(strings.ToLower(header.Name)):
+		case slices.Contains(notAllowedHTTPHeaders, strings.ToLower(header.Name)):
 			err := field.Forbidden(idxPath.Child("name"), notAllowedHTTPHeadersMessage)
 			allErrs = append(allErrs, err)
 		case !permittedHeaderNameRE.MatchString(header.Name):