Add database migrations

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

metadata/db_test.go

@@ -0,0 +1,178 @@
+package metadata
+
+import (
+	"encoding/binary"
+	"testing"
+
+	"github.com/boltdb/bolt"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/pkg/errors"
+)
+
+func TestInit(t *testing.T) {
+	ctx, db, cancel := testEnv(t)
+	defer cancel()
+
+	if err := NewDB(db, nil, nil).Init(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	version, err := readDBVersion(db, bucketKeyVersion)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if version != dbVersion {
+		t.Fatalf("Unexpected version %d, expected %d", version, dbVersion)
+	}
+}
+
+func TestMigrations(t *testing.T) {
+	migrationTests := []struct {
+		name  string
+		init  func(*bolt.Tx) error
+		check func(*bolt.Tx) error
+	}{
+		{
+			name: "ChildrenKey",
+			init: func(tx *bolt.Tx) error {
+				bkt, err := createSnapshotterBucket(tx, "testing", "testing")
+				if err != nil {
+					return err
+				}
+
+				snapshots := []struct {
+					key    string
+					parent string
+				}{
+					{
+						key:    "k1",
+						parent: "",
+					},
+					{
+						key:    "k2",
+						parent: "k1",
+					},
+					{
+						key:    "k2a",
+						parent: "k1",
+					},
+					{
+						key:    "a1",
+						parent: "k2",
+					},
+				}
+
+				for _, s := range snapshots {
+					sbkt, err := bkt.CreateBucket([]byte(s.key))
+					if err != nil {
+						return err
+					}
+					if err := sbkt.Put(bucketKeyParent, []byte(s.parent)); err != nil {
+						return err
+					}
+				}
+
+				return nil
+			},
+			check: func(tx *bolt.Tx) error {
+				bkt := getSnapshotterBucket(tx, "testing", "testing")
+				if bkt == nil {
+					return errors.Wrap(errdefs.ErrNotFound, "snapshots bucket not found")
+				}
+				snapshots := []struct {
+					key      string
+					children []string
+				}{
+					{
+						key:      "k1",
+						children: []string{"k2", "k2a"},
+					},
+					{
+						key:      "k2",
+						children: []string{"a1"},
+					},
+					{
+						key:      "k2a",
+						children: []string{},
+					},
+					{
+						key:      "a1",
+						children: []string{},
+					},
+				}
+
+				for _, s := range snapshots {
+					sbkt := bkt.Bucket([]byte(s.key))
+					if sbkt == nil {
+						return errors.Wrap(errdefs.ErrNotFound, "key does not exist")
+					}
+
+					cbkt := sbkt.Bucket(bucketKeyChildren)
+					var cn int
+					if cbkt != nil {
+						cn = cbkt.Stats().KeyN
+					}
+
+					if cn != len(s.children) {
+						return errors.Errorf("unexpected number of children %d, expected %d", cn, len(s.children))
+					}
+
+					for _, ch := range s.children {
+						if v := cbkt.Get([]byte(ch)); v == nil {
+							return errors.Errorf("missing child record for %s", ch)
+						}
+					}
+				}
+
+				return nil
+			},
+		},
+	}
+
+	if len(migrationTests) != len(migrations) {
+		t.Fatal("Each migration must have a test case")
+	}
+
+	for i, mt := range migrationTests {
+		t.Run(mt.name, runMigrationTest(i, mt.init, mt.check))
+	}
+}
+
+func runMigrationTest(i int, init, check func(*bolt.Tx) error) func(t *testing.T) {
+	return func(t *testing.T) {
+		_, db, cancel := testEnv(t)
+		defer cancel()
+
+		if err := db.Update(init); err != nil {
+			t.Fatal(err)
+		}
+
+		if err := db.Update(migrations[i].migrate); err != nil {
+			t.Fatal(err)
+		}
+
+		if err := db.View(check); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func readDBVersion(db *bolt.DB, schema []byte) (int, error) {
+	var version int
+	if err := db.View(func(tx *bolt.Tx) error {
+		bkt := tx.Bucket(schema)
+		if bkt == nil {
+			return errors.Wrap(errdefs.ErrNotFound, "no version bucket")
+		}
+		vb := bkt.Get(bucketKeyDBVersion)
+		if vb == nil {
+			return errors.Wrap(errdefs.ErrNotFound, "no version value")
+		}
+		v, _ := binary.Varint(vb)
+		version = int(v)
+		return nil
+	}); err != nil {
+		return 0, err
+	}
+	return version, nil
+}