added delayed reader and blob head check

api/oci/artdesc/index.go

@@ -2,7 +2,6 @@ package artdesc
 
 import (
 	"encoding/json"
-	"fmt"
 
 	"github.com/mandelsoft/goutils/errors"
 	"github.com/opencontainers/go-digest"
@@ -105,7 +104,6 @@ func (i *Index) AddManifest(d *Descriptor) {
 ////////////////////////////////////////////////////////////////////////////////
 
 func DecodeIndex(data []byte) (*Index, error) {
-	fmt.Println("index handler")
 	var d Index
 
 	if err := json.Unmarshal(data, &d); err != nil {

api/oci/cpi/state.go

@@ -1,7 +1,6 @@
 package cpi
 
 import (
-	"fmt"
 	"reflect"
 
 	"ocm.software/ocm/api/oci/artdesc"
@@ -77,7 +76,6 @@ func (i ArtifactStateHandler) Encode(d interface{}) ([]byte, error) {
 }
 
 func (i ArtifactStateHandler) Decode(data []byte) (interface{}, error) {
-	fmt.Println("artifact state handler")
 	return artdesc.Decode(data)
 }
 

api/tech/docker/fetcher.go

@@ -25,8 +25,6 @@ type dockerFetcher struct {
 func (r dockerFetcher) Fetch(ctx context.Context, desc ocispec.Descriptor) (io.ReadCloser, error) {
 	ctx = log.WithLogger(ctx, log.G(ctx).WithField("digest", desc.Digest))
 
-	fmt.Println("Fetching: ", r.refspec, desc)
-
 	hosts := r.filterHosts(HostCapabilityPull)
 	if len(hosts) == 0 {
 		return nil, errors.Wrap(errdefs.ErrNotFound, "no pull hosts")
@@ -41,7 +39,6 @@ func (r dockerFetcher) Fetch(ctx context.Context, desc ocispec.Descriptor) (io.R
 		// firstly try fetch via external urls
 		for _, us := range desc.URLs {
 			ctx = log.WithLogger(ctx, log.G(ctx).WithField("url", us))
-			fmt.Println("us: ", r.refspec, desc, us)
 			u, err := url.Parse(us)
 			if err != nil {
 				log.G(ctx).WithError(err).Debug("failed to parse")

api/tech/regclient/client.go

@@ -24,7 +24,6 @@ import (
 )
 
 type ClientOptions struct {
-	// TODO: add multiple hosts parsing
 	Host    []config.Host
 	Version string
 }
@@ -40,8 +39,9 @@ type pushRequest struct {
 	ref  regref.Ref
 }
 
-// Commit and Status are actually not really used. Commit is a second stage operation and Status is never called in
-// the library.
+// Commit and Status are actually not really used in the library. Commit is a second stage operation and Status is never called in
+// the library. The Status was a thing mostly in docker being used to track chunk reads. But that's taken care of
+// by regclient internally.
 func (p *pushRequest) Commit(ctx context.Context, size int64, expected digest.Digest, opts ...content.Opt) error {
 	return p.rc.Close(ctx, p.ref)
 }
@@ -133,7 +133,6 @@ func (c *Client) convertDescriptorToRegClient(desc ociv1.Descriptor) descriptor.
 }
 
 func (c *Client) Resolve(ctx context.Context, ref string) (string, ociv1.Descriptor, error) {
-	// TODO: figure out what to do about closing c.rc.
 	r, err := regref.New(ref)
 	if err != nil {
 		return "", ociv1.Descriptor{}, err
@@ -257,12 +256,13 @@ func (c *Client) Fetch(ctx context.Context, desc ociv1.Descriptor) (_ io.ReadClo
 		desc.Size = 0
 	}
 
-	fmt.Println("in fetch: ", desc, c.ref)
-
 	if c.isManifest(desc) {
-		fmt.Println("in manifest: ", desc, c.ref)
 		manifestContent, err := c.rc.ManifestGet(ctx, c.ref, regclient.WithManifestDesc(c.convertDescriptorToRegClient(desc)))
 		if err != nil {
+			if errors.Is(err, regerr.ErrNotFound) {
+				return nil, errdefs.ErrNotFound
+			}
+
 			return nil, err
 		}
 
@@ -274,14 +274,21 @@ func (c *Client) Fetch(ctx context.Context, desc ociv1.Descriptor) (_ io.ReadClo
 		return io.NopCloser(bytes.NewReader(body)), nil
 	}
 
-	fmt.Println("in blob get: ", desc, c.ref)
-
-	reader, err := c.rc.BlobGet(ctx, c.ref, c.convertDescriptorToRegClient(desc))
+	// check if the blob exists so we can bail early
+	_, err = c.rc.BlobHead(ctx, c.ref, c.convertDescriptorToRegClient(desc))
 	if err != nil {
-		return nil, fmt.Errorf("failed to get the blob reader: %w", err)
+		if errors.Is(err, regerr.ErrNotFound) {
+			return nil, errdefs.ErrNotFound
+		}
+
+		return nil, err
+	}
+
+	delayer := func() (io.ReadCloser, error) {
+		return c.rc.BlobGet(ctx, c.ref, c.convertDescriptorToRegClient(desc))
 	}
 
-	return reader, nil
+	return newDelayedReader(delayer)
 }
 
 func (c *Client) List(ctx context.Context) (_ []string, err error) {

api/tech/regclient/client_test.go

@@ -8,6 +8,9 @@ import (
 )
 
 func TestNew(t *testing.T) {
-	n := New(ClientOptions{Host: config.HostNew()})
+	host := config.HostNew()
+	n := New(ClientOptions{Host: []config.Host{
+		*host,
+	}})
 	require.NotNil(t, n)
 }

api/tech/regclient/delayed_reader.go

@@ -0,0 +1,56 @@
+package regclient
+
+import "io"
+
+// delayedReader sets up a reader that only fetches a blob
+// upon explicit reading request, otherwise, it stores the
+// way of getting the reader.
+type delayedReader struct {
+	open   func() (io.ReadCloser, error)
+	rc     io.ReadCloser
+	closed bool
+}
+
+func newDelayedReader(open func() (io.ReadCloser, error)) (io.ReadCloser, error) {
+	return &delayedReader{
+		open: open,
+	}, nil
+}
+
+func (d *delayedReader) Read(p []byte) (n int, err error) {
+	if d.closed {
+		return 0, io.EOF
+	}
+
+	reader, err := d.reader()
+	if err != nil {
+		return 0, err
+
+	}
+
+	return reader.Read(p)
+}
+
+func (d *delayedReader) reader() (io.ReadCloser, error) {
+	if d.rc != nil {
+		return d.rc, nil
+	}
+
+	rc, err := d.open()
+	if err != nil {
+		return nil, err
+	}
+
+	d.rc = rc
+	return rc, nil
+}
+
+func (d *delayedReader) Close() error {
+	if d.closed {
+		return nil
+	}
+
+	// we close regardless of an error
+	d.closed = true
+	return d.rc.Close()
+}

api/utils/accessobj/accessstate.go

@@ -153,7 +153,6 @@ func newState(mode AccessMode, a StateAccess, p StateHandler) (*state, error) {
 			return nil, fmt.Errorf("failed to get blob data: %w", err)
 		}
 
-		fmt.Println("data: ", blob.MimeType())
 		blob = blobaccess.ForData(blob.MimeType(), data) // cache original data
 		current, err = p.Decode(data)
 		if err != nil {

examples/lib/tour/07-resource-management/example.go

@@ -160,7 +160,6 @@ func HandleResources(resources []Resource) error {
 // --- end handle ---
 
 func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, error) {
-	fmt.Println("BEGIN GATHERING")
 	var resources []Resource
 
 	spec := ocireg.NewRepositorySpec("ghcr.io/open-component-model/ocm")
@@ -173,7 +172,6 @@ func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, erro
 	if err != nil {
 		return nil, errors.Wrapf(err, "cannot setup repository")
 	}
-	fmt.Println("GOT REPO:", spec)
 
 	// to release potentially allocated temporary resources,
 	// many objects must be closed, if they should not be used
@@ -187,15 +185,11 @@ func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, erro
 	// All kinds of repositories, regardless of their type
 	// feature the same interface to work with OCM content.
 	// --- begin lookup component ---
-	fmt.Println("Looking up component...")
 	c, err := repo.LookupComponent("ocm.software/ocmcli")
 	if err != nil {
 		return nil, errors.Wrapf(err, "cannot lookup component")
 	}
 	defer c.Close()
-
-	fmt.Println("Lookued up Component: ", c)
-
 	// --- end lookup component ---
 
 	// Now we look for the versions of the component
@@ -205,8 +199,6 @@ func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, erro
 		return nil, errors.Wrapf(err, "cannot query version names")
 	}
 
-	fmt.Println("Versions:", versions)
-
 	// OCM version names must follow the SemVer rules.
 	// Therefore, we can simply order the versions and print them.
 	err = semverutils.SortVersions(versions)
@@ -221,8 +213,6 @@ func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, erro
 	// --- begin lookup version ---
 	// to retrieve the latest version use
 	// cv, err := c.LookupVersion(versions[len(versions)-1])
-
-	fmt.Println("looking up component version: v0.17.0")
 	cv, err := c.LookupVersion("0.17.0")
 	if err != nil {
 		return nil, errors.Wrapf(err, "cannot get latest version")
@@ -242,7 +232,6 @@ func GatherResources(ctx ocm.Context, factory ResourceFactory) ([]Resource, erro
 	// like the repository specification.
 	// --- begin resources ---
 	for _, r := range cv.GetResources() {
-		fmt.Println("trying to fetch resource: ", r.Meta())
 		res := factory.Create(
 			r.Meta().GetIdentity(cv.GetDescriptor().Resources),
 			r.Meta().GetType(),

hack/generate.sh

@@ -4,4 +4,4 @@ set -e
 
 echo "> Generate"
 
-GO111MODULE=on go generate -v -mod=mod $@
+GO111MODULE=on go generate -mod=mod $@