refactor: Create Printer object to manage output

Makefile

@@ -33,6 +33,7 @@ LDFLAGS += -X $(PROJECT_PKG)/internal/version.GitTreeState=${GIT_DIRTY}
 
 .PHONY: test
 test: tidy vendor check-encoding  ## tidy and run tests
+	$(GO_EXE) build ./...
 	$(GO_EXE) test -race -v -coverprofile=coverage.txt -covermode=atomic -coverpkg=./... ./...
 
 .PHONY: teste2e

cmd/oras/internal/display/handler.go

@@ -26,12 +26,12 @@ import (
 )
 
 // NewPushHandler returns status and metadata handlers for push command.
-func NewPushHandler(format string, tty *os.File, verbose bool) (status.PushHandler, metadata.PushHandler) {
+func NewPushHandler(format string, tty *os.File, printer *status.Printer) (status.PushHandler, metadata.PushHandler) {
 	var statusHandler status.PushHandler
 	if tty != nil {
 		statusHandler = status.NewTTYPushHandler(tty)
 	} else if format == "" {
-		statusHandler = status.NewTextPushHandler(verbose)
+		statusHandler = status.NewTextPushHandler(printer)
 	} else {
 		statusHandler = status.NewDiscardHandler()
 	}
@@ -50,12 +50,12 @@ func NewPushHandler(format string, tty *os.File, verbose bool) (status.PushHandl
 }
 
 // NewAttachHandler returns status and metadata handlers for attach command.
-func NewAttachHandler(format string, tty *os.File, verbose bool) (status.AttachHandler, metadata.AttachHandler) {
+func NewAttachHandler(format string, tty *os.File, printer *status.Printer) (status.AttachHandler, metadata.AttachHandler) {
 	var statusHandler status.AttachHandler
 	if tty != nil {
 		statusHandler = status.NewTTYAttachHandler(tty)
 	} else if format == "" {
-		statusHandler = status.NewTextAttachHandler(verbose)
+		statusHandler = status.NewTextAttachHandler(printer)
 	} else {
 		statusHandler = status.NewDiscardHandler()
 	}

cmd/oras/internal/display/metadata/model/descriptor.go

@@ -16,8 +16,12 @@ limitations under the License.
 package model
 
 import (
+	"context"
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"oras.land/oras-go/v2/content"
+	"oras.land/oras/cmd/oras/internal/display/status"
+	"sync"
 )
 
 // DigestReference is a reference to an artifact with digest.
@@ -70,3 +74,42 @@ func FromDescriptor(name string, desc ocispec.Descriptor) Descriptor {
 	}
 	return ret
 }
+
+// ShortDigest converts the digest of the descriptor to a short form for displaying.
+func ShortDigest(desc ocispec.Descriptor) (digestString string) {
+	digestString = desc.Digest.String()
+	if err := desc.Digest.Validate(); err == nil {
+		if algo := desc.Digest.Algorithm(); algo == digest.SHA256 {
+			digestString = desc.Digest.Encoded()[:12]
+		}
+	}
+	return digestString
+}
+
+// PrintDescriptor prints descriptor status and name.
+func PrintDescriptor(printer *status.Printer, desc ocispec.Descriptor, status string) {
+	name, ok := desc.Annotations[ocispec.AnnotationTitle]
+	if !ok {
+		name = desc.MediaType
+		printer.PrintVerbose(status, ShortDigest(desc), name)
+		return
+	}
+	printer.Print(status, ShortDigest(desc), name)
+	return
+}
+
+// PrintSuccessorStatus prints transfer status of successors.
+func PrintSuccessorStatus(ctx context.Context, desc ocispec.Descriptor, fetcher content.Fetcher, committed *sync.Map, prompt string, printer *status.Printer) error {
+	successors, err := content.Successors(ctx, fetcher, desc)
+	if err != nil {
+		return err
+	}
+	for _, s := range successors {
+		name := s.Annotations[ocispec.AnnotationTitle]
+		if v, ok := committed.Load(s.Digest.String()); ok && v != name {
+			// Reprint status for deduplicated content
+			PrintDescriptor(printer, desc, prompt)
+		}
+	}
+	return nil
+}

cmd/oras/internal/display/status/print.go

@@ -19,63 +19,54 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"os"
 	"sync"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"oras.land/oras-go/v2"
-	"oras.land/oras-go/v2/content"
 	"oras.land/oras-go/v2/registry"
 )
 
-var printLock sync.Mutex
+type Printer struct {
+	printLock sync.Mutex
+	verbose   bool
+	errors    bool
+}
 
-// PrintFunc is the function type returned by StatusPrinter.
-type PrintFunc func(ocispec.Descriptor) error
+var printer Printer
 
-// Print objects to display concurrent-safely.
-func Print(a ...any) error {
-	printLock.Lock()
-	defer printLock.Unlock()
-	_, err := fmt.Println(a...)
-	return err
+// NewPrinter creates a printer object
+func NewPrinter(verbose bool) *Printer {
+	printer = Printer{verbose: verbose}
+	return &printer
 }
 
-// StatusPrinter returns a tracking function for transfer status.
-func StatusPrinter(status string, verbose bool) PrintFunc {
-	return func(desc ocispec.Descriptor) error {
-		return PrintStatus(desc, status, verbose)
+// Print objects to display concurrent-safely.
+func (p *Printer) Print(a ...any) {
+	p.printLock.Lock()
+	defer p.printLock.Unlock()
+	_, err := fmt.Println(a...)
+	if err != nil {
+		if !p.errors {
+			p.errors = true
+			_, _ = fmt.Fprintf(os.Stderr, "Display output error: %w\n", err)
+			return
+		}
 	}
+	return
 }
 
-// PrintStatus prints transfer status.
-func PrintStatus(desc ocispec.Descriptor, status string, verbose bool) error {
-	name, ok := desc.Annotations[ocispec.AnnotationTitle]
-	if !ok {
-		// no status for unnamed content
-		if !verbose {
-			return nil
-		}
-		name = desc.MediaType
+// PrintVerbose display in verbose mode.
+func (p *Printer) PrintVerbose(a ...any) {
+	if p.verbose {
+		p.Print(a...)
 	}
-	return Print(status, ShortDigest(desc), name)
+	return
 }
 
-// PrintSuccessorStatus prints transfer status of successors.
-func PrintSuccessorStatus(ctx context.Context, desc ocispec.Descriptor, fetcher content.Fetcher, committed *sync.Map, print PrintFunc) error {
-	successors, err := content.Successors(ctx, fetcher, desc)
-	if err != nil {
-		return err
-	}
-	for _, s := range successors {
-		name := s.Annotations[ocispec.AnnotationTitle]
-		if v, ok := committed.Load(s.Digest.String()); ok && v != name {
-			// Reprint status for deduplicated content
-			if err := print(s); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
+// Print objects to display concurrent-safely.
+func Print(a ...any) {
+	printer.Print(a...)
 }
 
 // NewTagStatusPrinter creates a wrapper type for printing tag status.
@@ -119,13 +110,14 @@ func (p *tagManifestStatusForRepo) PushReference(ctx context.Context, expected o
 	if p.printHint != nil {
 		p.printHint.Do(func() {
 			ref := p.refPrefix + "@" + expected.Digest.String()
-			_ = Print("Tagging", ref)
+			Print("Tagging", ref)
 		})
 	}
 	if err := p.Repository.PushReference(ctx, expected, content, reference); err != nil {
 		return err
 	}
-	return Print("Tagged", reference)
+	Print("Tagged", reference)
+	return nil
 }
 
 type tagManifestStatusForTarget struct {
@@ -139,12 +131,13 @@ func (p *tagManifestStatusForTarget) Tag(ctx context.Context, desc ocispec.Descr
 	if p.printHint != nil {
 		p.printHint.Do(func() {
 			ref := p.refPrefix + "@" + desc.Digest.String()
-			_ = Print("Tagging", ref)
+			Print("Tagging", ref)
 		})
 	}
 
 	if err := p.Target.Tag(ctx, desc, reference); err != nil {
 		return err
 	}
-	return Print("Tagged", reference)
+	Print("Tagged", reference)
+	return nil
 }

cmd/oras/internal/display/status/text.go

@@ -18,6 +18,7 @@ package status
 import (
 	"context"
 	"fmt"
+	"oras.land/oras/cmd/oras/internal/display/metadata/model"
 	"sync"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -27,23 +28,20 @@ import (
 
 // TextPushHandler handles text status output for push events.
 type TextPushHandler struct {
-	verbose bool
+	printer *Printer
 }
 
 // NewTextPushHandler returns a new handler for push command.
-func NewTextPushHandler(verbose bool) PushHandler {
+func NewTextPushHandler(printer *Printer) PushHandler {
 	return &TextPushHandler{
-		verbose: verbose,
+		printer: printer,
 	}
 }
 
 // OnFileLoading is called when a file is being prepared for upload.
 func (ph *TextPushHandler) OnFileLoading(name string) error {
-	if !ph.verbose {
-		return nil
-	}
-	_, err := fmt.Println("Preparing", name)
-	return err
+	printer.PrintVerbose("Preparing", name)
+	return nil
 }
 
 // OnEmptyArtifact is called when an empty artifact is being uploaded.
@@ -68,21 +66,22 @@ func (ph *TextPushHandler) UpdateCopyOptions(opts *oras.CopyGraphOptions, fetche
 	committed := &sync.Map{}
 	opts.OnCopySkipped = func(ctx context.Context, desc ocispec.Descriptor) error {
 		committed.Store(desc.Digest.String(), desc.Annotations[ocispec.AnnotationTitle])
-		return PrintStatus(desc, promptExists, ph.verbose)
+		model.PrintDescriptor(ph.printer, desc, promptExists)
+		return nil
 	}
 	opts.PreCopy = func(ctx context.Context, desc ocispec.Descriptor) error {
-		return PrintStatus(desc, promptUploading, ph.verbose)
+		model.PrintDescriptor(ph.printer, desc, promptUploading)
+		return nil
 	}
 	opts.PostCopy = func(ctx context.Context, desc ocispec.Descriptor) error {
 		committed.Store(desc.Digest.String(), desc.Annotations[ocispec.AnnotationTitle])
-		if err := PrintSuccessorStatus(ctx, desc, fetcher, committed, StatusPrinter(promptSkipped, ph.verbose)); err != nil {
-			return err
-		}
-		return PrintStatus(desc, promptUploaded, ph.verbose)
+		PrintSuccessorStatus(ctx, desc, fetcher, committed, promptSkipped, ph.printer)
+		model.PrintDescriptor(ph.printer, desc, promptUploaded)
+		return nil
 	}
 }
 
 // NewTextAttachHandler returns a new handler for attach command.
-func NewTextAttachHandler(verbose bool) AttachHandler {
-	return NewTextPushHandler(verbose)
+func NewTextAttachHandler(printer *Printer) AttachHandler {
+	return NewTextPushHandler(printer)
 }

cmd/oras/internal/display/status/track/target.go

@@ -30,7 +30,7 @@ import (
 type GraphTarget interface {
 	oras.GraphTarget
 	io.Closer
-	Prompt(desc ocispec.Descriptor, prompt string) error
+	Prompt(desc ocispec.Descriptor) error
 	Inner() oras.GraphTarget
 }
 

cmd/oras/root/attach.go

@@ -19,6 +19,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"oras.land/oras/cmd/oras/internal/display/status"
 
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/spf13/cobra"
@@ -113,7 +114,8 @@ func runAttach(cmd *cobra.Command, opts *attachOptions) error {
 			Recommendation: `To attach to an existing artifact, please provide files via argument or annotations via flag "--annotation". Run "oras attach -h" for more options and examples`,
 		}
 	}
-	displayStatus, displayMetadata := display.NewAttachHandler(opts.Template, opts.TTY, opts.Verbose)
+	printer := status.NewPrinter(opts.Verbose)
+	displayStatus, displayMetadata := display.NewAttachHandler(opts.Template, opts.TTY, printer)
 
 	// prepare manifest
 	store, err := file.New("")