[#19] transformer: Add a target which sends parts to a channel

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

object/transformer/channel.go

@@ -0,0 +1,44 @@
+package transformer
+
+import (
+	objectSDK "github.com/TrueCloudLab/frostfs-sdk-go/object"
+	"github.com/nspcc-dev/neo-go/pkg/util/slice"
+)
+
+type chanTarget struct {
+	header  *objectSDK.Object
+	payload []byte
+	ch      chan<- *objectSDK.Object
+}
+
+// NewChannelTarget returns ObjectTarget which writes
+// object parts to a provided channel.
+func NewChannelTarget(ch chan<- *objectSDK.Object) ObjectTarget {
+	return &chanTarget{
+		ch: ch,
+	}
+}
+
+// WriteHeader implements the ObjectTarget interface.
+func (c *chanTarget) WriteHeader(object *objectSDK.Object) error {
+	c.header = object
+	return nil
+}
+
+// Write implements the ObjectTarget interface.
+func (c *chanTarget) Write(p []byte) (n int, err error) {
+	c.payload = append(c.payload, p...)
+	return len(p), nil
+}
+
+// Close implements the ObjectTarget interface.
+func (c *chanTarget) Close() (*AccessIdentifiers, error) {
+	if len(c.payload) != 0 {
+		c.header.SetPayload(slice.Copy(c.payload))
+	}
+	c.ch <- c.header
+
+	c.header = nil
+	c.payload = nil
+	return new(AccessIdentifiers), nil
+}

object/transformer/channel_test.go

@@ -0,0 +1,55 @@
+package transformer
+
+import (
+	"crypto/rand"
+	"testing"
+
+	cidtest "github.com/TrueCloudLab/frostfs-sdk-go/container/id/test"
+	objectSDK "github.com/TrueCloudLab/frostfs-sdk-go/object"
+	"github.com/TrueCloudLab/frostfs-sdk-go/version"
+	"github.com/stretchr/testify/require"
+)
+
+func TestChannelTarget(t *testing.T) {
+	const maxSize = 100
+
+	ch := make(chan *objectSDK.Object, 10)
+	tt := new(testTarget)
+
+	chTarget, _ := newPayloadSizeLimiter(maxSize, NewChannelTarget(ch))
+	testTarget, _ := newPayloadSizeLimiter(maxSize, tt)
+
+	ver := version.Current()
+	cnr := cidtest.ID()
+	hdr := objectSDK.New()
+	hdr.SetContainerID(cnr)
+	hdr.SetType(objectSDK.TypeRegular)
+	hdr.SetVersion(&ver)
+
+	payload := make([]byte, maxSize*2+maxSize/2)
+	_, _ = rand.Read(payload)
+
+	expectedIDs := writeObject(t, testTarget, hdr, payload)
+	actualIDs := writeObject(t, chTarget, hdr, payload)
+	_ = expectedIDs
+	_ = actualIDs
+	//require.Equal(t, expectedIDs, actualIDs)
+
+	for i := range tt.objects {
+		select {
+		case obj := <-ch:
+			// Because of the split ID objects can be different.
+			// However, payload and attributes must be the same.
+			require.Equal(t, tt.objects[i].Payload(), obj.Payload())
+			require.Equal(t, tt.objects[i].Attributes(), obj.Attributes())
+		default:
+			require.FailNow(t, "received less parts than expected")
+		}
+	}
+
+	select {
+	case <-ch:
+		require.FailNow(t, "received more parts than expected")
+	default:
+	}
+}