[db] implement Get/Put/Version() for BoltDBVersioned

db/db_versioned.go

@@ -7,9 +7,23 @@
 package db
 
 import (
+	"bytes"
 	"context"
+	"fmt"
 
+	"github.com/pkg/errors"
+	bolt "go.etcd.io/bbolt"
+
+	"github.com/iotexproject/go-pkgs/hash"
+	"github.com/iotexproject/iotex-core/db/batch"
 	"github.com/iotexproject/iotex-core/pkg/lifecycle"
+	"github.com/iotexproject/iotex-core/pkg/util/byteutil"
+)
+
+var (
+	ErrInvalidKeyLength = errors.New("invalid key length")
+	ErrDeleted          = errors.New("deleted in DB")
+	_minKey             = []byte{0} // the minimum key, used to store namespace's metadata
 )
 
 type (
@@ -52,12 +66,25 @@ type (
 
 	// BoltDBVersioned is KvVersioned implementation based on bolt DB
 	BoltDBVersioned struct {
-		db *BoltDB
+		db     *BoltDB
+		hasher Hasher
 	}
 )
 
-// Option sets an option
-type Option func(b *BoltDBVersioned)
+type (
+	// Option sets an option
+	Option func(b *BoltDBVersioned)
+
+	// Hasher is a function to compute hash
+	Hasher func([]byte) []byte
+)
+
+// HasherOption sets the hasher
+func HasherOption(h Hasher) Option {
+	return func(b *BoltDBVersioned) {
+		b.hasher = h
+	}
+}
 
 // NewBoltDBVersioned instantiates an BoltDB which implements KvVersioned
 func NewBoltDBVersioned(cfg Config, opts ...Option) *BoltDBVersioned {
@@ -67,6 +94,12 @@ func NewBoltDBVersioned(cfg Config, opts ...Option) *BoltDBVersioned {
 	for _, opt := range opts {
 		opt(b)
 	}
+	if b.hasher == nil {
+		b.hasher = func(in []byte) []byte {
+			h := hash.Hash160b(in)
+			return h[:]
+		}
+	}
 	return b
 }
 
@@ -85,17 +118,97 @@ func (b *BoltDBVersioned) Put(ns string, version uint64, key, value []byte) erro
 	if !b.db.IsReady() {
 		return ErrDBNotStarted
 	}
-	// TODO: implement Put
-	return nil
+	// check namespace
+	vn, err := b.checkNamespace(ns)
+	if err != nil {
+		return err
+	}
+	buf := batch.NewBatch()
+	if vn == nil {
+		// namespace not yet created
+		buf.Put(ns, _minKey, (&versionedNamespace{
+			name:   ns,
+			keyLen: uint32(len(key)),
+		}).serialize(), "failed to create metadata")
+	} else {
+		if len(key) != int(vn.keyLen) {
+			return errors.Wrapf(ErrInvalidKeyLength, "expecting %d, got %d", vn.keyLen, len(key))
+		}
+	}
+	// check key's metadata
+	km, err := b.checkKey(ns, key)
+	if err != nil {
+		return err
+	}
+	km, exit := km.update(version, b.hasher(value))
+	if exit {
+		return nil
+	}
+	buf.Put(ns, append(key, 0), km.serialize(), fmt.Sprintf("failed to put key %x's metadata", key))
+	buf.Put(ns, versionedKey(key, version), value, fmt.Sprintf("failed to put key %x", key))
+	return b.db.WriteBatch(buf)
 }
 
 // Get retrieves the most recent version
 func (b *BoltDBVersioned) Get(ns string, version uint64, key []byte) ([]byte, error) {
 	if !b.db.IsReady() {
 		return nil, ErrDBNotStarted
 	}
-	// TODO: implement Get
-	return nil, nil
+	// check namespace
+	vn, err := b.checkNamespace(ns)
+	if err != nil {
+		return nil, err
+	}
+	if vn == nil {
+		return nil, errors.Wrapf(ErrNotExist, "key = %x doesn't exist", key)
+	}
+	if len(key) != int(vn.keyLen) {
+		return nil, errors.Wrapf(ErrInvalidKeyLength, "expecting %d, got %d", vn.keyLen, len(key))
+	}
+	// check key's metadata
+	km, err := b.checkKey(ns, key)
+	if err != nil {
+		return nil, err
+	}
+	if km == nil || version < km.firstVersion {
+		return nil, errors.Wrapf(ErrNotExist, "key = %x doesn't exist", key)
+	}
+	if version >= km.deleteVersion {
+		return nil, errors.Wrapf(ErrDeleted, "key = %x already deleted", key)
+	}
+	return b.get(ns, version, key)
+}
+
+func (b *BoltDBVersioned) get(ns string, version uint64, key []byte) ([]byte, error) {
+	// construct the actual key = key + version (represented in 8-bytes)
+	// and read from DB
+	key = versionedKey(key, version)
+	var value []byte
+	err := b.db.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte(ns))
+		if bucket == nil {
+			return errors.Wrapf(ErrBucketNotExist, "bucket = %x doesn't exist", []byte(ns))
+		}
+		c := bucket.Cursor()
+		k, v := c.Seek(key)
+		if k == nil || bytes.Compare(k, key) == 1 {
+			k, v = c.Prev()
+			if k == nil || bytes.Compare(k, append(key[:len(key)-8], 0)) <= 0 {
+				// cursor is at the beginning/end of the bucket or smaller than minimum key
+				return errors.Wrapf(ErrNotExist, "key = %x doesn't exist", key[:len(key)-8])
+			}
+		}
+		value = make([]byte, len(v))
+		copy(value, v)
+		return nil
+	})
+	if err == nil {
+		return value, nil
+	}
+	if cause := errors.Cause(err); cause == ErrNotExist || cause == ErrBucketNotExist {
+		return nil, err
+	}
+	return nil, errors.Wrap(ErrIO, err.Error())
 }
 
 // Delete deletes a record,if key is nil,this will delete the whole bucket
@@ -112,8 +225,27 @@ func (b *BoltDBVersioned) Version(ns string, key []byte) (uint64, error) {
 	if !b.db.IsReady() {
 		return 0, ErrDBNotStarted
 	}
-	// TODO: implement Version
-	return 0, nil
+	// check namespace
+	vn, err := b.checkNamespace(ns)
+	if err != nil {
+		return 0, err
+	}
+	if vn == nil {
+		return 0, errors.Wrapf(ErrNotExist, "key = %x doesn't exist", key)
+	}
+	if len(key) != int(vn.keyLen) {
+		return 0, errors.Wrapf(ErrInvalidKeyLength, "expecting %d, got %d", vn.keyLen, len(key))
+	}
+	// check key's metadata
+	km, err := b.checkKey(ns, key)
+	if err != nil {
+		return 0, err
+	}
+	if km == nil {
+		// key not yet written
+		return 0, errors.Wrapf(ErrNotExist, "key = %x doesn't exist", key)
+	}
+	return km.lastVersion, nil
 }
 
 // SetVersion sets the version, and returns a KVStore to call Put()/Get()
@@ -124,6 +256,42 @@ func (b *BoltDBVersioned) SetVersion(v uint64) KVStoreBasic {
 	}
 }
 
+func versionedKey(key []byte, v uint64) []byte {
+	return append(key, byteutil.Uint64ToBytesBigEndian(v)...)
+}
+
+func (b *BoltDBVersioned) checkNamespace(ns string) (*versionedNamespace, error) {
+	data, err := b.db.Get(ns, _minKey)
+	switch errors.Cause(err) {
+	case nil:
+		vn, err := deserializeVersionedNamespace(data)
+		if err != nil {
+			return nil, err
+		}
+		return vn, nil
+	case ErrNotExist, ErrBucketNotExist:
+		return nil, nil
+	default:
+		return nil, err
+	}
+}
+
+func (b *BoltDBVersioned) checkKey(ns string, key []byte) (*keyMeta, error) {
+	data, err := b.db.Get(ns, append(key, 0))
+	switch errors.Cause(err) {
+	case nil:
+		km, err := deserializeKeyMeta(data)
+		if err != nil {
+			return nil, err
+		}
+		return km, nil
+	case ErrNotExist, ErrBucketNotExist:
+		return nil, nil
+	default:
+		return nil, err
+	}
+}
+
 // KvWithVersion wraps the BoltDBVersioned with a certain version
 type KvWithVersion struct {
 	db      *BoltDBVersioned