metadata: merge storage into package

The implementations for the storage of metadata have been merged into a
single metadata package where they can share storage primitives and
techniques. The is a requisite for the addition of namespaces, which
will require a coordinated layout for records to be organized by
namespace.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

metadata/containers.go

@@ -0,0 +1,171 @@
+package metadata
+
+import (
+	"context"
+
+	"github.com/boltdb/bolt"
+	"github.com/containerd/containerd/containers"
+	"github.com/pkg/errors"
+)
+
+type containerStore struct {
+	tx *bolt.Tx
+}
+
+func NewContainerStore(tx *bolt.Tx) containers.Store {
+	return &containerStore{
+		tx: tx,
+	}
+}
+
+func (s *containerStore) Get(ctx context.Context, id string) (containers.Container, error) {
+	bkt := getContainerBucket(s.tx, id)
+	if bkt == nil {
+		return containers.Container{}, errors.Wrap(ErrNotFound, "bucket does not exist")
+	}
+
+	container := containers.Container{ID: id}
+	if err := readContainer(&container, bkt); err != nil {
+		return containers.Container{}, errors.Wrap(err, "failed to read container")
+	}
+
+	return container, nil
+}
+
+func (s *containerStore) List(ctx context.Context, filter string) ([]containers.Container, error) {
+	var (
+		m   = []containers.Container{}
+		bkt = getContainersBucket(s.tx)
+	)
+	if bkt == nil {
+		return m, nil
+	}
+	err := bkt.ForEach(func(k, v []byte) error {
+		cbkt := bkt.Bucket(k)
+		if cbkt == nil {
+			return nil
+		}
+		container := containers.Container{ID: string(k)}
+
+		if err := readContainer(&container, cbkt); err != nil {
+			return errors.Wrap(err, "failed to read container")
+		}
+		m = append(m, container)
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return m, nil
+}
+
+func (s *containerStore) Create(ctx context.Context, container containers.Container) (containers.Container, error) {
+	bkt, err := createContainersBucket(s.tx)
+	if err != nil {
+		return containers.Container{}, err
+	}
+
+	cbkt, err := bkt.CreateBucket([]byte(container.ID))
+	if err != nil {
+		if err == bolt.ErrBucketExists {
+			err = errors.Wrap(ErrExists, "content for id already exists")
+		}
+		return containers.Container{}, err
+	}
+
+	if err := writeContainer(&container, cbkt); err != nil {
+		return containers.Container{}, errors.Wrap(err, "failed to write container")
+	}
+
+	return container, nil
+}
+
+func (s *containerStore) Update(ctx context.Context, container containers.Container) (containers.Container, error) {
+	bkt := getContainersBucket(s.tx)
+	if bkt == nil {
+		return containers.Container{}, errors.Wrap(ErrNotFound, "no containers")
+	}
+
+	cbkt := bkt.Bucket([]byte(container.ID))
+	if cbkt == nil {
+		return containers.Container{}, errors.Wrap(ErrNotFound, "no content for id")
+	}
+
+	if err := writeContainer(&container, cbkt); err != nil {
+		return containers.Container{}, errors.Wrap(err, "failed to write container")
+	}
+
+	return container, nil
+}
+
+func (s *containerStore) Delete(ctx context.Context, id string) error {
+	bkt := getContainersBucket(s.tx)
+	if bkt == nil {
+		return errors.Wrap(ErrNotFound, "no containers")
+	}
+
+	err := bkt.DeleteBucket([]byte(id))
+	if err == bolt.ErrBucketNotFound {
+		return errors.Wrap(ErrNotFound, "no content for id")
+	}
+	return err
+}
+
+func readContainer(container *containers.Container, bkt *bolt.Bucket) error {
+	return bkt.ForEach(func(k, v []byte) error {
+		switch string(k) {
+		case string(bucketKeyImage):
+			container.Image = string(v)
+		case string(bucketKeyRuntime):
+			container.Runtime = string(v)
+		case string(bucketKeySpec):
+			container.Spec = v
+		case string(bucketKeyRootFS):
+			container.RootFS = string(v)
+		case string(bucketKeyLabels):
+			lbkt := bkt.Bucket(bucketKeyLabels)
+			if lbkt == nil {
+				return nil
+			}
+			container.Labels = map[string]string{}
+			if err := lbkt.ForEach(func(k, v []byte) error {
+				container.Labels[string(k)] = string(v)
+				return nil
+			}); err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+}
+
+func writeContainer(container *containers.Container, bkt *bolt.Bucket) error {
+	for _, v := range [][2][]byte{
+		{bucketKeyImage, []byte(container.Image)},
+		{bucketKeyRuntime, []byte(container.Runtime)},
+		{bucketKeySpec, container.Spec},
+		{bucketKeyRootFS, []byte(container.RootFS)},
+	} {
+		if err := bkt.Put(v[0], v[1]); err != nil {
+			return err
+		}
+	}
+	// Remove existing labels to keep from merging
+	if lbkt := bkt.Bucket(bucketKeyLabels); lbkt != nil {
+		if err := bkt.DeleteBucket(bucketKeyLabels); err != nil {
+			return err
+		}
+	}
+	lbkt, err := bkt.CreateBucket(bucketKeyLabels)
+	if err != nil {
+		return err
+	}
+	for k, v := range container.Labels {
+		if err := lbkt.Put([]byte(k), []byte(v)); err != nil {
+			return err
+		}
+	}
+	return nil
+}