Add leases api

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

metadata/leases.go

@@ -0,0 +1,201 @@
+package metadata
+
+import (
+	"context"
+	"time"
+
+	"github.com/boltdb/bolt"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/leases"
+	"github.com/containerd/containerd/metadata/boltutil"
+	"github.com/containerd/containerd/namespaces"
+	digest "github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+)
+
+// Lease retains resources to prevent garbage collection before
+// the resources can be fully referenced.
+type Lease struct {
+	ID        string
+	CreatedAt time.Time
+	Labels    map[string]string
+
+	Content   []string
+	Snapshots map[string][]string
+}
+
+// LeaseManager manages the create/delete lifecyle of leases
+// and also returns existing leases
+type LeaseManager struct {
+	tx *bolt.Tx
+}
+
+// NewLeaseManager creates a new lease manager for managing leases using
+// the provided database transaction.
+func NewLeaseManager(tx *bolt.Tx) *LeaseManager {
+	return &LeaseManager{
+		tx: tx,
+	}
+}
+
+// Create creates a new lease using the provided lease
+func (lm *LeaseManager) Create(ctx context.Context, lid string, labels map[string]string) (Lease, error) {
+	namespace, err := namespaces.NamespaceRequired(ctx)
+	if err != nil {
+		return Lease{}, err
+	}
+
+	topbkt, err := createBucketIfNotExists(lm.tx, bucketKeyVersion, []byte(namespace), bucketKeyObjectLeases)
+	if err != nil {
+		return Lease{}, err
+	}
+
+	txbkt, err := topbkt.CreateBucket([]byte(lid))
+	if err != nil {
+		if err == bolt.ErrBucketExists {
+			err = errdefs.ErrAlreadyExists
+		}
+		return Lease{}, err
+	}
+
+	t := time.Now().UTC()
+	createdAt, err := t.MarshalBinary()
+	if err != nil {
+		return Lease{}, err
+	}
+	if err := txbkt.Put(bucketKeyCreatedAt, createdAt); err != nil {
+		return Lease{}, err
+	}
+
+	if labels != nil {
+		if err := boltutil.WriteLabels(txbkt, labels); err != nil {
+			return Lease{}, err
+		}
+	}
+
+	return Lease{
+		ID:        lid,
+		CreatedAt: t,
+		Labels:    labels,
+	}, nil
+}
+
+// Delete delets the lease with the provided lease ID
+func (lm *LeaseManager) Delete(ctx context.Context, lid string) error {
+	namespace, err := namespaces.NamespaceRequired(ctx)
+	if err != nil {
+		return err
+	}
+
+	topbkt := getBucket(lm.tx, bucketKeyVersion, []byte(namespace), bucketKeyObjectLeases)
+	if topbkt == nil {
+		return nil
+	}
+	if err := topbkt.DeleteBucket([]byte(lid)); err != nil && err != bolt.ErrBucketNotFound {
+		return err
+	}
+	return nil
+}
+
+// List lists all active leases
+func (lm *LeaseManager) List(ctx context.Context, includeResources bool, filter ...string) ([]Lease, error) {
+	namespace, err := namespaces.NamespaceRequired(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	var leases []Lease
+
+	topbkt := getBucket(lm.tx, bucketKeyVersion, []byte(namespace), bucketKeyObjectLeases)
+	if topbkt == nil {
+		return leases, nil
+	}
+
+	if err := topbkt.ForEach(func(k, v []byte) error {
+		if v != nil {
+			return nil
+		}
+		txbkt := topbkt.Bucket(k)
+
+		l := Lease{
+			ID: string(k),
+		}
+
+		if v := txbkt.Get(bucketKeyCreatedAt); v != nil {
+			t := &l.CreatedAt
+			if err := t.UnmarshalBinary(v); err != nil {
+				return err
+			}
+		}
+
+		labels, err := boltutil.ReadLabels(txbkt)
+		if err != nil {
+			return err
+		}
+		l.Labels = labels
+
+		// TODO: Read Snapshots
+		// TODO: Read Content
+
+		leases = append(leases, l)
+
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	return leases, nil
+}
+
+func addSnapshotLease(ctx context.Context, tx *bolt.Tx, snapshotter, key string) error {
+	lid, ok := leases.Lease(ctx)
+	if !ok {
+		return nil
+	}
+
+	namespace, ok := namespaces.Namespace(ctx)
+	if !ok {
+		panic("namespace must already be required")
+	}
+
+	bkt := getBucket(tx, bucketKeyVersion, []byte(namespace), bucketKeyObjectLeases, []byte(lid))
+	if bkt == nil {
+		return errors.Wrap(errdefs.ErrNotFound, "lease does not exist")
+	}
+
+	bkt, err := bkt.CreateBucketIfNotExists(bucketKeyObjectSnapshots)
+	if err != nil {
+		return err
+	}
+
+	bkt, err = bkt.CreateBucketIfNotExists([]byte(snapshotter))
+	if err != nil {
+		return err
+	}
+
+	return bkt.Put([]byte(key), nil)
+}
+
+func addContentLease(ctx context.Context, tx *bolt.Tx, dgst digest.Digest) error {
+	lid, ok := leases.Lease(ctx)
+	if !ok {
+		return nil
+	}
+
+	namespace, ok := namespaces.Namespace(ctx)
+	if !ok {
+		panic("namespace must already be required")
+	}
+
+	bkt := getBucket(tx, bucketKeyVersion, []byte(namespace), bucketKeyObjectLeases, []byte(lid))
+	if bkt == nil {
+		return errors.Wrap(errdefs.ErrNotFound, "lease does not exist")
+	}
+
+	bkt, err := bkt.CreateBucketIfNotExists(bucketKeyObjectContent)
+	if err != nil {
+		return err
+	}
+
+	return bkt.Put([]byte(dgst.String()), nil)
+}