refactor: enable cases where return values are not needed in pipeline (#4443)

pkg/fanal/artifact/image/image.go

@@ -14,7 +14,6 @@ import (
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/samber/lo"
 	"golang.org/x/exp/slices"
-	"golang.org/x/sync/errgroup"
 	"golang.org/x/xerrors"
 
 	"github.com/aquasecurity/trivy/pkg/fanal/analyzer"
@@ -25,6 +24,7 @@ import (
 	"github.com/aquasecurity/trivy/pkg/fanal/types"
 	"github.com/aquasecurity/trivy/pkg/fanal/walker"
 	"github.com/aquasecurity/trivy/pkg/mapfs"
+	"github.com/aquasecurity/trivy/pkg/parallel"
 	"github.com/aquasecurity/trivy/pkg/semaphore"
 	"github.com/aquasecurity/trivy/pkg/syncx"
 )
@@ -216,18 +216,9 @@ func (a Artifact) consolidateCreatedBy(diffIDs, layerKeys []string, configFile *
 func (a Artifact) inspect(ctx context.Context, missingImage string, layerKeys, baseDiffIDs []string,
 	layerKeyMap map[string]LayerInfo, configFile *v1.ConfigFile) error {
 
-	group, groupCtx := errgroup.WithContext(ctx)
-	concurrencyLimit := 5
-	if a.artifactOption.Slow {
-		concurrencyLimit = 1
-	}
-	group.SetLimit(concurrencyLimit)
-
 	var osFound types.OS
-	for _, k := range layerKeys {
+	workers := lo.Ternary(a.artifactOption.Slow, 1, 5)
-		layerKey := k
+	p := parallel.NewPipeline(workers, false, layerKeys, func(ctx context.Context, layerKey string) (any, error) {
-		ctx := groupCtx
-		group.Go(func() error {
 		layer := layerKeyMap[layerKey]
 
 		// If it is a base layer, secret scanning should not be performed.
@@ -238,27 +229,20 @@ func (a Artifact) inspect(ctx context.Context, missingImage string, layerKeys, b
 
 		layerInfo, err := a.inspectLayer(ctx, layer, disabledAnalyzers)
 		if err != nil {
-				return xerrors.Errorf("failed to analyze layer (%s): %w", layer.DiffID, err)
+			return nil, xerrors.Errorf("failed to analyze layer (%s): %w", layer.DiffID, err)
 		}
 		if err = a.cache.PutBlob(layerKey, layerInfo); err != nil {
-				return xerrors.Errorf("failed to store layer: %s in cache: %w", layerKey, err)
+			return nil, xerrors.Errorf("failed to store layer: %s in cache: %w", layerKey, err)
 		}
 		if lo.IsNotEmpty(layerInfo.OS) {
 			osFound = layerInfo.OS
 		}
-			return nil
+		return nil, nil
-		})
 
-		if ctx.Err() != nil {
+	}, nil)
-			break
-		}
-	}
 
-	if err := group.Wait(); err != nil {
+	if err := p.Do(ctx); err != nil {
-		if ctx.Err() != nil {
+		return xerrors.Errorf("pipeline error: %w", err)
-			return xerrors.Errorf("timeout: %w", ctx.Err())
-		}
-		return err
 	}
 
 	if missingImage != "" {
@@ -268,7 +252,6 @@ func (a Artifact) inspect(ctx context.Context, missingImage string, layerKeys, b
 	}
 
 	return nil
-
 }
 
 func (a Artifact) inspectLayer(ctx context.Context, layerInfo LayerInfo, disabled []analyzer.Type) (types.BlobInfo, error) {

pkg/k8s/scanner/scanner.go

@@ -54,7 +54,7 @@ func (s *Scanner) Scan(ctx context.Context, artifactsData []*artifacts.Artifact)
 		misconfig report.Resource
 	}
 
-	onItem := func(artifact *artifacts.Artifact) (scanResult, error) {
+	onItem := func(ctx context.Context, artifact *artifacts.Artifact) (scanResult, error) {
 		scanResults := scanResult{}
 		if s.opts.Scanners.AnyEnabled(types.VulnerabilityScanner, types.SecretScanner) {
 			vulns, err := s.scanVulns(ctx, artifact)

pkg/parallel/pipeline.go

@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/cheggaaa/pb/v3"
-
 	"golang.org/x/sync/errgroup"
 )
 
@@ -19,13 +18,17 @@ type Pipeline[T, U any] struct {
 }
 
 // onItem represents a function type that takes an input element and returns an output element.
-type onItem[T, U any] func(T) (U, error)
+type onItem[T, U any] func(context.Context, T) (U, error)
 
 // onResult represents a function type that takes an output element.
 type onResult[U any] func(U) error
 
 func NewPipeline[T, U any](numWorkers int, progress bool, items []T,
 	fn1 onItem[T, U], fn2 onResult[U]) Pipeline[T, U] {
+	if fn2 == nil {
+		// In case where there is no need to process the return values
+		fn2 = func(_ U) error { return nil }
+	}
 	return Pipeline[T, U]{
 		numWorkers: numWorkers,
 		progress:   progress,
@@ -71,7 +74,7 @@ func (p *Pipeline[T, U]) Do(ctx context.Context) error {
 	for i := 0; i < p.numWorkers; i++ {
 		g.Go(func() error {
 			for item := range itemCh {
-				res, err := p.onItem(item)
+				res, err := p.onItem(ctx, item)
 				if err != nil {
 					return err
 				}

pkg/parallel/pipeline_test.go

@@ -2,6 +2,7 @@ package parallel_test
 
 import (
 	"context"
+	"fmt"
 	"math"
 	"testing"
 
@@ -15,13 +16,13 @@ func TestPipeline_Do(t *testing.T) {
 	type field struct {
 		numWorkers int
 		items      []float64
-		onItem     func(float64) (float64, error)
+		onItem     func(context.Context, float64) (float64, error)
 	}
 	type testCase struct {
 		name    string
 		field   field
 		want    float64
-		wantErr bool
+		wantErr require.ErrorAssertionFunc
 	}
 	tests := []testCase{
 		{
@@ -40,11 +41,12 @@ func TestPipeline_Do(t *testing.T) {
 					9,
 					10,
 				},
-				onItem: func(f float64) (float64, error) {
+				onItem: func(_ context.Context, f float64) (float64, error) {
 					return math.Pow(f, 2), nil
 				},
 			},
 			want:    385,
+			wantErr: require.NoError,
 		},
 		{
 			name: "ceil",
@@ -60,11 +62,41 @@ func TestPipeline_Do(t *testing.T) {
 					-2.2,
 					-3.3,
 				},
-				onItem: func(f float64) (float64, error) {
+				onItem: func(_ context.Context, f float64) (float64, error) {
 					return math.Round(f), nil
 				},
 			},
 			want:    10,
+			wantErr: require.NoError,
+		},
+		{
+			name: "error in series",
+			field: field{
+				numWorkers: 1,
+				items: []float64{
+					1,
+					2,
+					3,
+				},
+				onItem: func(_ context.Context, f float64) (float64, error) {
+					return 0, fmt.Errorf("error")
+				},
+			},
+			wantErr: require.Error,
+		},
+		{
+			name: "error in parallel",
+			field: field{
+				numWorkers: 3,
+				items: []float64{
+					1,
+					2,
+				},
+				onItem: func(_ context.Context, f float64) (float64, error) {
+					return 0, fmt.Errorf("error")
+				},
+			},
+			wantErr: require.Error,
 		},
 	}
 	for _, tt := range tests {
@@ -75,7 +107,7 @@ func TestPipeline_Do(t *testing.T) {
 				return nil
 			})
 			err := p.Do(context.Background())
-			require.NoError(t, err)
+			tt.wantErr(t, err)
 			assert.Equal(t, tt.want, got)
 		})
 	}