feat: load model from oci image

vendor/oras.land/oras-go/v2/internal/cas/memory.go

@@ -0,0 +1,88 @@
+/*
+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 cas
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"sync"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	contentpkg "oras.land/oras-go/v2/content"
+	"oras.land/oras-go/v2/errdef"
+	"oras.land/oras-go/v2/internal/descriptor"
+)
+
+// Memory is a memory based CAS.
+type Memory struct {
+	content sync.Map // map[descriptor.Descriptor][]byte
+}
+
+// NewMemory creates a new Memory CAS.
+func NewMemory() *Memory {
+	return &Memory{}
+}
+
+// Fetch fetches the content identified by the descriptor.
+func (m *Memory) Fetch(_ context.Context, target ocispec.Descriptor) (io.ReadCloser, error) {
+	key := descriptor.FromOCI(target)
+	content, exists := m.content.Load(key)
+	if !exists {
+		return nil, fmt.Errorf("%s: %s: %w", key.Digest, key.MediaType, errdef.ErrNotFound)
+	}
+	return io.NopCloser(bytes.NewReader(content.([]byte))), nil
+}
+
+// Push pushes the content, matching the expected descriptor.
+func (m *Memory) Push(_ context.Context, expected ocispec.Descriptor, content io.Reader) error {
+	key := descriptor.FromOCI(expected)
+
+	// check if the content exists in advance to avoid reading from the content.
+	if _, exists := m.content.Load(key); exists {
+		return fmt.Errorf("%s: %s: %w", key.Digest, key.MediaType, errdef.ErrAlreadyExists)
+	}
+
+	// read and try to store the content.
+	value, err := contentpkg.ReadAll(content, expected)
+	if err != nil {
+		return err
+	}
+	if _, exists := m.content.LoadOrStore(key, value); exists {
+		return fmt.Errorf("%s: %s: %w", key.Digest, key.MediaType, errdef.ErrAlreadyExists)
+	}
+	return nil
+}
+
+// Exists returns true if the described content exists.
+func (m *Memory) Exists(_ context.Context, target ocispec.Descriptor) (bool, error) {
+	key := descriptor.FromOCI(target)
+	_, exists := m.content.Load(key)
+	return exists, nil
+}
+
+// Map dumps the memory into a built-in map structure.
+// Like other operations, calling Map() is go-routine safe. However, it does not
+// necessarily correspond to any consistent snapshot of the storage contents.
+func (m *Memory) Map() map[descriptor.Descriptor][]byte {
+	res := make(map[descriptor.Descriptor][]byte)
+	m.content.Range(func(key, value interface{}) bool {
+		res[key.(descriptor.Descriptor)] = value.([]byte)
+		return true
+	})
+	return res
+}

vendor/oras.land/oras-go/v2/internal/cas/proxy.go

@@ -0,0 +1,125 @@
+/*
+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 cas
+
+import (
+	"context"
+	"io"
+	"sync"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"oras.land/oras-go/v2/content"
+	"oras.land/oras-go/v2/internal/ioutil"
+)
+
+// Proxy is a caching proxy for the storage.
+// The first fetch call of a described content will read from the remote and
+// cache the fetched content.
+// The subsequent fetch call will read from the local cache.
+type Proxy struct {
+	content.ReadOnlyStorage
+	Cache       content.Storage
+	StopCaching bool
+}
+
+// NewProxy creates a proxy for the `base` storage, using the `cache` storage as
+// the cache.
+func NewProxy(base content.ReadOnlyStorage, cache content.Storage) *Proxy {
+	return &Proxy{
+		ReadOnlyStorage: base,
+		Cache:           cache,
+	}
+}
+
+// NewProxyWithLimit creates a proxy for the `base` storage, using the `cache`
+// storage with a push size limit as the cache.
+func NewProxyWithLimit(base content.ReadOnlyStorage, cache content.Storage, pushLimit int64) *Proxy {
+	limitedCache := content.LimitStorage(cache, pushLimit)
+	return &Proxy{
+		ReadOnlyStorage: base,
+		Cache:           limitedCache,
+	}
+}
+
+// Fetch fetches the content identified by the descriptor.
+func (p *Proxy) Fetch(ctx context.Context, target ocispec.Descriptor) (io.ReadCloser, error) {
+	if p.StopCaching {
+		return p.FetchCached(ctx, target)
+	}
+
+	rc, err := p.Cache.Fetch(ctx, target)
+	if err == nil {
+		return rc, nil
+	}
+
+	rc, err = p.ReadOnlyStorage.Fetch(ctx, target)
+	if err != nil {
+		return nil, err
+	}
+	pr, pw := io.Pipe()
+	var wg sync.WaitGroup
+	wg.Add(1)
+	var pushErr error
+	go func() {
+		defer wg.Done()
+		pushErr = p.Cache.Push(ctx, target, pr)
+		if pushErr != nil {
+			pr.CloseWithError(pushErr)
+		}
+	}()
+	closer := ioutil.CloserFunc(func() error {
+		rcErr := rc.Close()
+		if err := pw.Close(); err != nil {
+			return err
+		}
+		wg.Wait()
+		if pushErr != nil {
+			return pushErr
+		}
+		return rcErr
+	})
+
+	return struct {
+		io.Reader
+		io.Closer
+	}{
+		Reader: io.TeeReader(rc, pw),
+		Closer: closer,
+	}, nil
+}
+
+// FetchCached fetches the content identified by the descriptor.
+// If the content is not cached, it will be fetched from the remote without
+// caching.
+func (p *Proxy) FetchCached(ctx context.Context, target ocispec.Descriptor) (io.ReadCloser, error) {
+	exists, err := p.Cache.Exists(ctx, target)
+	if err != nil {
+		return nil, err
+	}
+	if exists {
+		return p.Cache.Fetch(ctx, target)
+	}
+	return p.ReadOnlyStorage.Fetch(ctx, target)
+}
+
+// Exists returns true if the described content exists.
+func (p *Proxy) Exists(ctx context.Context, target ocispec.Descriptor) (bool, error) {
+	exists, err := p.Cache.Exists(ctx, target)
+	if err == nil && exists {
+		return true, nil
+	}
+	return p.ReadOnlyStorage.Exists(ctx, target)
+}