feat: load model from oci image

vendor/oras.land/oras-go/v2/internal/status/tracker.go

@@ -0,0 +1,43 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package status
+
+import (
+	"sync"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"oras.land/oras-go/v2/internal/descriptor"
+)
+
+// Tracker tracks content status described by a descriptor.
+type Tracker struct {
+	status sync.Map // map[descriptor.Descriptor]chan struct{}
+}
+
+// NewTracker creates a new content status tracker.
+func NewTracker() *Tracker {
+	return &Tracker{}
+}
+
+// TryCommit tries to commit the work for the target descriptor.
+// Returns true if committed. A channel is also returned for sending
+// notifications. Once the work is done, the channel should be closed.
+// Returns false if the work is done or still in progress.
+func (t *Tracker) TryCommit(target ocispec.Descriptor) (chan struct{}, bool) {
+	key := descriptor.FromOCI(target)
+	status, exists := t.status.LoadOrStore(key, make(chan struct{}))
+	return status.(chan struct{}), !exists
+}