Add status tracker for Docker remote push

Update push client to use status tracker

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

remotes/docker/status.go

@@ -0,0 +1,46 @@
+package docker
+
+import (
+	"sync"
+
+	"github.com/containerd/containerd/content"
+)
+
+type Status struct {
+	content.Status
+
+	// UploadUUID is used by the Docker registry to reference blob uploads
+	UploadUUID string
+}
+
+type StatusTracker interface {
+	GetStatus(string) (Status, error)
+	SetStatus(string, Status)
+}
+
+type memoryStatusTracker struct {
+	statuses map[string]Status
+	m        sync.Mutex
+}
+
+func NewInMemoryTracker() StatusTracker {
+	return &memoryStatusTracker{
+		statuses: map[string]Status{},
+	}
+}
+
+func (t *memoryStatusTracker) GetStatus(ref string) (Status, error) {
+	t.m.Lock()
+	defer t.m.Unlock()
+	status, ok := t.statuses[ref]
+	if !ok {
+		return Status{}, content.ErrNotFound
+	}
+	return status, nil
+}
+
+func (t *memoryStatusTracker) SetStatus(ref string, status Status) {
+	t.m.Lock()
+	t.statuses[ref] = status
+	t.m.Unlock()
+}