feat: parallelize catalogers per-file and hash contents in parallel (#3636)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

internal/file/digest.go

@@ -1,12 +1,15 @@
 package file
 
 import (
+	"context"
 	"crypto"
 	"fmt"
 	"hash"
 	"io"
 	"strings"
 
+	"github.com/anchore/go-sync"
+	"github.com/anchore/syft/syft/cataloging"
 	"github.com/anchore/syft/syft/file"
 )
 
@@ -21,7 +24,7 @@ func supportedHashAlgorithms() []crypto.Hash {
 	}
 }
 
-func NewDigestsFromFile(closer io.ReadCloser, hashes []crypto.Hash) ([]file.Digest, error) {
+func NewDigestsFromFile(ctx context.Context, closer io.ReadCloser, hashes []crypto.Hash) ([]file.Digest, error) {
 	hashes = NormalizeHashes(hashes)
 	// create a set of hasher objects tied together with a single writer to feed content into
 	hashers := make([]hash.Hash, len(hashes))
@@ -31,7 +34,7 @@ func NewDigestsFromFile(closer io.ReadCloser, hashes []crypto.Hash) ([]file.Dige
 		writers[idx] = hashers[idx]
 	}
 
-	size, err := io.Copy(io.MultiWriter(writers...), closer)
+	size, err := io.Copy(sync.ParallelWriter(ctx, cataloging.ExecutorCPU, writers...), closer)
 	if err != nil {
 		return nil, err
 	}

internal/file/digest_test.go

@@ -1,6 +1,7 @@
 package file
 
 import (
+	"context"
 	"crypto"
 	"os"
 	"testing"
@@ -81,7 +82,7 @@ func TestNewDigestsFromFile(t *testing.T) {
 			fh, err := os.Open(tt.fixture)
 			require.NoError(t, err)
 
-			got, err := NewDigestsFromFile(fh, tt.hashes)
+			got, err := NewDigestsFromFile(context.TODO(), fh, tt.hashes)
 			tt.wantErr(t, err)
 			if err != nil {
 				return