refactor: optimize code with modern Go patterns and pre-allocation (#3576)

This commit modernizes code across multiple packages by:
- Using Go 1.18+ features (slices.IndexFunc, strings.Cut)
- Pre-allocating slices and maps with known capacity
- Consolidating defensive checks and improving code clarity
- Fixing test data and build tag issues

CLI client improvements:
- Pre-allocate slices in search functions and service methods
- Replace strings.Split with strings.Cut for username:password parsing
- Use range-based iteration instead of manual index loops

Search extension optimizations:
- Cache sort functions in pagination modules
- Pre-allocate page buffers and maps
- Consolidate defensive checks in filterBaseImages/filterDerivedImages
- Fix image bas and derived logic allowing out of sequence layers for base images
- Fix image pagination reporting images groupped by repos when sorted by update time
- Remove duplicate resolver_test.go file

Monitoring extension:
- Replace manual loops with slices.IndexFunc
- Pre-allocate bucketsFloat2String map

Sync extension:
- Pre-allocate slice in parseRegistryURLs

Test utilities:
- Fix build tags in oci_layout.go

Signed-off-by: Andrei Aaron <andreifdaaron@gmail.com>

Author: andaaron

pkg/cli/client/client.go

@@ -445,7 +445,8 @@ func fetchManifestStruct(ctx context.Context, repo, manifestReference string, se
 	imageSize += manifestResp.Config.Size
 	imageSize += manifestSize
 
-	layers := []common.LayerSummary{}
+	// Pre-allocate slice with known capacity
+	layers := make([]common.LayerSummary, 0, len(manifestResp.Layers))
 
 	for _, entry := range manifestResp.Layers {
 		imageSize += entry.Size

pkg/cli/client/search_functions.go

@@ -51,7 +51,8 @@ func SearchAllImagesGQL(config SearchConfig) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity
+	imageListData := make([]imageStruct, 0, len(imageList.Results))
 
 	for _, image := range imageList.Results {
 		imageListData = append(imageListData, imageStruct(image))
@@ -103,7 +104,8 @@ func SearchImageByNameGQL(config SearchConfig, imageName string) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity (may be filtered, but worst case is all results)
+	imageListData := make([]imageStruct, 0, len(imageList.Results))
 
 	for _, image := range imageList.Results {
 		if tag == "" || image.Tag == tag {
@@ -152,7 +154,8 @@ func SearchDerivedImageListGQL(config SearchConfig, derivedImage string) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity
+	imageListData := make([]imageStruct, 0, len(imageList.DerivedImageList.Results))
 
 	for _, image := range imageList.DerivedImageList.Results {
 		imageListData = append(imageListData, imageStruct(image))
@@ -173,7 +176,8 @@ func SearchBaseImageListGQL(config SearchConfig, baseImage string) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity
+	imageListData := make([]imageStruct, 0, len(imageList.BaseImageList.Results))
 
 	for _, image := range imageList.BaseImageList.Results {
 		imageListData = append(imageListData, imageStruct(image))
@@ -193,7 +197,8 @@ func SearchImagesForDigestGQL(config SearchConfig, digest string) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity
+	imageListData := make([]imageStruct, 0, len(imageList.Results))
 
 	for _, image := range imageList.Results {
 		imageListData = append(imageListData, imageStruct(image))
@@ -344,7 +349,8 @@ func SearchImagesByCVEIDGQL(config SearchConfig, repo, cveid string) error {
 		return err
 	}
 
-	imageListData := []imageStruct{}
+	// Pre-allocate slice with known capacity
+	imageListData := make([]imageStruct, 0, len(imageList.Results))
 
 	for _, image := range imageList.Results {
 		imageListData = append(imageListData, imageStruct(image))
@@ -403,13 +409,14 @@ func GlobalSearchGQL(config SearchConfig, query string) error {
 		return err
 	}
 
-	imagesList := []imageStruct{}
+	// Pre-allocate slices with known capacity
+	imagesList := make([]imageStruct, 0, len(globalSearchResult.Images))
 
 	for _, image := range globalSearchResult.Images {
 		imagesList = append(imagesList, imageStruct(image))
 	}
 
-	reposList := []repoStruct{}
+	reposList := make([]repoStruct, 0, len(globalSearchResult.Repos))
 
 	for _, repo := range globalSearchResult.Repos {
 		reposList = append(reposList, repoStruct(repo))

pkg/cli/client/service.go

@@ -403,7 +403,9 @@ func (service searchService) getTagsForCVEGQL(ctx context.Context, config Search
 		return result, nil
 	}
 
+	// Pre-allocate filtered results slice with estimated capacity
 	filteredResults := &common.ImagesForCve{}
+	filteredResults.Results = make([]common.ImageSummary, 0, len(result.Results))
 
 	for _, image := range result.Results {
 		if image.RepoName == repo {
@@ -476,7 +478,8 @@ func (service searchService) getReferrers(ctx context.Context, config SearchConf
 		return referrersResult{}, err
 	}
 
-	referrersList := referrersResult{}
+	// Pre-allocate referrers list with known capacity
+	referrersList := make(referrersResult, 0, len(referrerResp.Manifests))
 
 	for _, referrer := range referrerResp.Manifests {
 		referrersList = append(referrersList, common.Referrer{
@@ -954,7 +957,8 @@ func (ref referrersResult) stringPlainText(maxArtifactTypeLen int) (string, erro
 	var builder strings.Builder
 
 	maxDigestWidth := digestWidth
-	rows := [][]string{}
+	// Pre-allocate rows slice with known capacity
+	rows := make([][]string, 0, len(ref))
 
 	for _, referrer := range ref {
 		artifactType := ellipsize(referrer.ArtifactType, maxArtifactTypeLen, ellipsis)
@@ -1390,12 +1394,14 @@ func (service searchService) getRepos(ctx context.Context, config SearchConfig,
 	fmt.Fprintln(config.ResultWriter, "\nREPOSITORY NAME")
 
 	if config.SortBy == SortByAlphabeticAsc {
-		for i := 0; i < len(catalog.Repositories); i++ {
-			fmt.Fprintln(config.ResultWriter, catalog.Repositories[i])
+		for _, repo := range catalog.Repositories {
+			fmt.Fprintln(config.ResultWriter, repo)
 		}
 	} else {
-		for i := len(catalog.Repositories) - 1; i >= 0; i-- {
-			fmt.Fprintln(config.ResultWriter, catalog.Repositories[i])
+		// Iterate in reverse order
+		repos := catalog.Repositories
+		for i := len(repos) - 1; i >= 0; i-- {
+			fmt.Fprintln(config.ResultWriter, repos[i])
 		}
 	}
 }

pkg/cli/client/utils.go

@@ -93,9 +93,9 @@ func collectResults(config SearchConfig, wg *sync.WaitGroup, imageErr chan strin
 
 func getUsernameAndPassword(user string) (string, string) {
 	if strings.Contains(user, ":") {
-		split := strings.Split(user, ":")
+		username, password, _ := strings.Cut(user, ":")
 
-		return split[0], split[1]
+		return username, password
 	}
 
 	return "", ""

pkg/extensions/monitoring/minimal.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"math"
 	"path"
+	"slices"
 	"strconv"
 	"sync"
 	"time"
@@ -236,9 +237,12 @@ func NewMetricsServer(enabled bool, log log.Logger) MetricServer {
 		Histograms: make([]*HistogramValue, 0),
 	}
 	// convert to a map for returning easily the string corresponding to a bucket
-	bucketsFloat2String := map[float64]string{}
+	// Pre-allocate with known size: default buckets + storage latency buckets
+	defaultBuckets := GetDefaultBuckets()
+	storageBuckets := GetStorageLatencyBuckets()
+	bucketsFloat2String := make(map[float64]string, len(defaultBuckets)+len(storageBuckets))
 
-	for _, fvalue := range append(GetDefaultBuckets(), GetStorageLatencyBuckets()...) {
+	for _, fvalue := range append(defaultBuckets, storageBuckets...) {
 		if fvalue == math.MaxFloat64 {
 			bucketsFloat2String[fvalue] = "+Inf"
 		} else {
@@ -314,54 +318,38 @@ func isMetricMatch(lValues, metricValues []string) bool {
 
 // returns {-1, false} in case metric was not found in the slice.
 func findCounterValueIndex(metricSlice []*CounterValue, name string, labelValues []string) (int, bool) {
-	for i, m := range metricSlice {
-		if m.Name == name {
-			if isMetricMatch(labelValues, m.LabelValues) {
-				return i, true
-			}
-		}
-	}
+	idx := slices.IndexFunc(metricSlice, func(m *CounterValue) bool {
+		return m.Name == name && isMetricMatch(labelValues, m.LabelValues)
+	})
 
-	return -1, false
+	return idx, idx != -1
 }
 
 // returns {-1, false} in case metric was not found in the slice.
 func findGaugeValueIndex(metricSlice []*GaugeValue, name string, labelValues []string) (int, bool) {
-	for i, m := range metricSlice {
-		if m.Name == name {
-			if isMetricMatch(labelValues, m.LabelValues) {
-				return i, true
-			}
-		}
-	}
+	idx := slices.IndexFunc(metricSlice, func(m *GaugeValue) bool {
+		return m.Name == name && isMetricMatch(labelValues, m.LabelValues)
+	})
 
-	return -1, false
+	return idx, idx != -1
 }
 
 // returns {-1, false} in case metric was not found in the slice.
 func findSummaryValueIndex(metricSlice []*SummaryValue, name string, labelValues []string) (int, bool) {
-	for i, m := range metricSlice {
-		if m.Name == name {
-			if isMetricMatch(labelValues, m.LabelValues) {
-				return i, true
-			}
-		}
-	}
+	idx := slices.IndexFunc(metricSlice, func(m *SummaryValue) bool {
+		return m.Name == name && isMetricMatch(labelValues, m.LabelValues)
+	})
 
-	return -1, false
+	return idx, idx != -1
 }
 
 // returns {-1, false} in case metric was not found in the slice.
 func findHistogramValueIndex(metricSlice []*HistogramValue, name string, labelValues []string) (int, bool) {
-	for i, m := range metricSlice {
-		if m.Name == name {
-			if isMetricMatch(labelValues, m.LabelValues) {
-				return i, true
-			}
-		}
-	}
+	idx := slices.IndexFunc(metricSlice, func(m *HistogramValue) bool {
+		return m.Name == name && isMetricMatch(labelValues, m.LabelValues)
+	})
 
-	return -1, false
+	return idx, idx != -1
 }
 
 func (ms *metricServer) CounterInc(cv *CounterValue) {

pkg/extensions/search/convert/metadb.go

@@ -73,7 +73,8 @@ func getAnnotationsFromMap(annotationsMap map[string]string) []*gql_generated.An
 func getImageBlobsInfo(manifestDigest string, manifestSize int64, configDigest string, configSize int64,
 	layers []ispec.Descriptor,
 ) (int64, map[string]int64) {
-	imageBlobsMap := map[string]int64{}
+	// Pre-allocate map with known size: config + manifest + layers
+	imageBlobsMap := make(map[string]int64, 2+len(layers))
 	imageSize := int64(0)
 
 	// add config size

pkg/extensions/search/cve/cve.go

@@ -2,7 +2,7 @@ package cveinfo
 
 import (
 	"context"
-	"sort"
+	"slices"
 	"strings"
 	"time"
 
@@ -528,8 +528,15 @@ func (cveinfo BaseCveInfo) GetCVESummaryForImageMedia(ctx context.Context, repo,
 }
 
 func GetFixedTags(allTags, vulnerableTags []cvemodel.TagInfo) []cvemodel.TagInfo {
-	sort.Slice(allTags, func(i, j int) bool {
-		return allTags[i].Timestamp.Before(allTags[j].Timestamp)
+	slices.SortFunc(allTags, func(a, b cvemodel.TagInfo) int {
+		if a.Timestamp.Before(b.Timestamp) {
+			return -1
+		}
+		if a.Timestamp.Equal(b.Timestamp) {
+			return 0
+		}
+
+		return 1
 	})
 
 	earliestVulnerable := vulnerableTags[0]
@@ -597,7 +604,10 @@ func GetFixedTags(allTags, vulnerableTags []cvemodel.TagInfo) []cvemodel.TagInfo
 				}
 
 				// check if the current manifest doesn't have the vulnerability
-				if !indexHasVulnerableManifest || !containsDescriptorInfo(vulnTagInfo.Manifests, manifestDesc) {
+				if !indexHasVulnerableManifest ||
+					!slices.ContainsFunc(vulnTagInfo.Manifests, func(di cvemodel.DescriptorInfo) bool {
+						return di.Digest == manifestDesc.Digest
+					}) {
 					fixedManifests = append(fixedManifests, manifestDesc)
 				}
 			}
@@ -616,16 +626,6 @@ func GetFixedTags(allTags, vulnerableTags []cvemodel.TagInfo) []cvemodel.TagInfo
 	return fixedTags
 }
 
-func containsDescriptorInfo(slice []cvemodel.DescriptorInfo, descriptorInfo cvemodel.DescriptorInfo) bool {
-	for _, di := range slice {
-		if di.Digest == descriptorInfo.Digest {
-			return true
-		}
-	}
-
-	return false
-}
-
 func initCVESummaryFromCVEMap(cveMap map[string]cvemodel.CVE) cvemodel.ImageCVESummary {
 	// Counters are initialized with 0 by default
 	imageCVESummary := cvemodel.ImageCVESummary{