[#2210] pilorama: Reduce the amount of keys per node

Under high load we are limited by the _amount_ of keys we need to update
in a single transaction. In this commit we try storing all state
with a single key.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/local_object_storage/pilorama/boltdb.go

@@ -156,8 +156,7 @@ func (t *boltForest) TreeMove(d CIDDescriptor, treeID string, m *Move) (*LogMove
 		return nil, ErrReadOnlyMode
 	}
 
-	var lm LogMove
-	lm.Move = *m
+	lm := *m
 	return &lm, t.db.Batch(func(tx *bbolt.Tx) error {
 		bLog, bTree, err := t.getTreeBuckets(tx, d.CID, treeID)
 		if err != nil {
@@ -227,7 +226,7 @@ func (t *boltForest) TreeAddByPath(d CIDDescriptor, treeID string, attr string,
 		ts := t.getLatestTimestamp(bLog, d.Position, d.Size)
 		lm = make([]LogMove, len(path)-i+1)
 		for j := i; j < len(path); j++ {
-			lm[j-i].Move = Move{
+			lm[j-i] = Move{
 				Parent: node,
 				Meta: Meta{
 					Time:  ts,
@@ -245,7 +244,7 @@ func (t *boltForest) TreeAddByPath(d CIDDescriptor, treeID string, attr string,
 			node = lm[j-i].Child
 		}
 
-		lm[len(lm)-1].Move = Move{
+		lm[len(lm)-1] = Move{
 			Parent: node,
 			Meta: Meta{
 				Time:  ts,
@@ -274,17 +273,14 @@ func (t *boltForest) getLatestTimestamp(bLog *bbolt.Bucket, pos, size int) uint6
 // findSpareID returns random unused ID.
 func (t *boltForest) findSpareID(bTree *bbolt.Bucket) uint64 {
 	id := uint64(rand.Int63())
-
-	var key [9]byte
-	key[0] = 't'
-	binary.LittleEndian.PutUint64(key[1:], id)
+	key := make([]byte, 9)
 
 	for {
-		if bTree.Get(key[:]) == nil {
+		_, _, _, ok := t.getState(bTree, stateKey(key, id))
+		if !ok {
 			return id
 		}
 		id = uint64(rand.Int63())
-		binary.LittleEndian.PutUint64(key[1:], id)
 	}
 }
 
@@ -420,8 +416,12 @@ func (t *boltForest) applyOperation(logBucket, treeBucket *bbolt.Bucket, ms []*M
 	// 1. Undo up until the desired timestamp is here.
 	for len(key) == 8 && ms[0].Time < binary.BigEndian.Uint64(key) {
 		b.Reset(value)
-		if err := t.logFromBytes(&tmp, r); err != nil {
-			return err
+
+		tmp.Child = r.ReadU64LE()
+		tmp.Parent = r.ReadU64LE()
+		tmp.Time = r.ReadVarUint()
+		if r.Err != nil {
+			return r.Err
 		}
 		if err := t.undo(&tmp, treeBucket, cKey[:]); err != nil {
 			return err
@@ -433,7 +433,7 @@ func (t *boltForest) applyOperation(logBucket, treeBucket *bbolt.Bucket, ms []*M
 		// Loop invariant: key represents the next stored timestamp after ms[i].Time.
 
 		// 2. Insert the operation.
-		lm.Move = *ms[i]
+		*lm = *ms[i]
 		if err := t.do(logBucket, treeBucket, cKey[:], lm); err != nil {
 			return err
 		}
@@ -445,11 +445,10 @@ func (t *boltForest) applyOperation(logBucket, treeBucket *bbolt.Bucket, ms []*M
 
 		// 3. Re-apply all other operations.
 		for len(key) == 8 && (i == len(ms)-1 || binary.BigEndian.Uint64(key) < ms[i+1].Time) {
-			b.Reset(value)
-			if err := t.logFromBytes(&tmp, r); err != nil {
+			if err := t.logFromBytes(&tmp, value); err != nil {
 				return err
 			}
-			if err := t.do(logBucket, treeBucket, cKey[:], &tmp); err != nil {
+			if err := t.redo(treeBucket, cKey[:], &tmp, value[16:]); err != nil {
 				return err
 			}
 			key, value = c.Next()
@@ -460,39 +459,42 @@ func (t *boltForest) applyOperation(logBucket, treeBucket *bbolt.Bucket, ms []*M
 }
 
 func (t *boltForest) do(lb *bbolt.Bucket, b *bbolt.Bucket, key []byte, op *LogMove) error {
-	currParent := b.Get(parentKey(key, op.Child))
-	op.HasOld = currParent != nil
-	if currParent != nil { // node is already in tree
-		op.Old.Parent = binary.LittleEndian.Uint64(currParent)
-		if err := op.Old.Meta.FromBytes(b.Get(metaKey(key, op.Child))); err != nil {
-			return err
-		}
-	} else {
-		op.HasOld = false
-		op.Old = nodeInfo{}
-	}
-
 	binary.BigEndian.PutUint64(key, op.Time)
-	if err := lb.Put(key[:8], t.logToBytes(op)); err != nil {
+	rawLog := t.logToBytes(op)
+	if err := lb.Put(key[:8], rawLog); err != nil {
 		return err
 	}
 
-	if op.Child == op.Parent || t.isAncestor(b, op.Child, op.Parent) {
-		return nil
+	return t.redo(b, key, op, rawLog[16:])
 }
 
-	if currParent == nil {
-		if err := b.Put(timestampKey(key, op.Child), toUint64(op.Time)); err != nil {
-			return err
-		}
+func (t *boltForest) redo(b *bbolt.Bucket, key []byte, op *LogMove, rawMeta []byte) error {
+	var err error
+
+	parent, ts, currMeta, inTree := t.getState(b, stateKey(key, op.Child))
+	if inTree {
+		err = t.putState(b, oldKey(key, op.Time), parent, ts, currMeta)
 	} else {
-		parent := binary.LittleEndian.Uint64(currParent)
+		ts = op.Time
+		err = b.Delete(oldKey(key, op.Time))
+	}
+
+	if err != nil || op.Child == op.Parent || t.isAncestor(b, op.Child, op.Parent) {
+		return err
+	}
+
+	if inTree {
 		if err := b.Delete(childrenKey(key, op.Child, parent)); err != nil {
 			return err
 		}
-		for i := range op.Old.Meta.Items {
-			if isAttributeInternal(op.Old.Meta.Items[i].Key) {
-				key = internalKey(key, op.Old.Meta.Items[i].Key, string(op.Old.Meta.Items[i].Value), parent, op.Child)
+
+		var meta Meta
+		if err := meta.FromBytes(currMeta); err != nil {
+			return err
+		}
+		for i := range meta.Items {
+			if isAttributeInternal(meta.Items[i].Key) {
+				key = internalKey(key, meta.Items[i].Key, string(meta.Items[i].Value), parent, op.Child)
 				err := b.Delete(key)
 				if err != nil {
 					return err
@@ -500,17 +502,16 @@ func (t *boltForest) do(lb *bbolt.Bucket, b *bbolt.Bucket, key []byte, op *LogMo
 			}
 		}
 	}
-	return t.addNode(b, key, op.Child, op.Parent, op.Meta)
+	return t.addNode(b, key, op.Child, op.Parent, ts, op.Meta, rawMeta)
 }
 
 // removeNode removes node keys from the tree except the children key or its parent.
 func (t *boltForest) removeNode(b *bbolt.Bucket, key []byte, node, parent Node) error {
-	if err := b.Delete(parentKey(key, node)); err != nil {
-		return err
-	}
+	k := stateKey(key, node)
+	_, _, rawMeta, _ := t.getState(b, k)
+
 	var meta Meta
-	var k = metaKey(key, node)
-	if err := meta.FromBytes(b.Get(k)); err == nil {
+	if err := meta.FromBytes(rawMeta); err == nil {
 		for i := range meta.Items {
 			if isAttributeInternal(meta.Items[i].Key) {
 				err := b.Delete(internalKey(nil, meta.Items[i].Key, string(meta.Items[i].Value), parent, node))
@@ -520,23 +521,16 @@ func (t *boltForest) removeNode(b *bbolt.Bucket, key []byte, node, parent Node)
 			}
 		}
 	}
-	if err := b.Delete(metaKey(key, node)); err != nil {
-		return err
-	}
-	return b.Delete(timestampKey(key, node))
+	return b.Delete(k)
 }
 
 // addNode adds node keys to the tree except the timestamp key.
-func (t *boltForest) addNode(b *bbolt.Bucket, key []byte, child, parent Node, meta Meta) error {
-	err := b.Put(parentKey(key, child), toUint64(parent))
-	if err != nil {
+func (t *boltForest) addNode(b *bbolt.Bucket, key []byte, child, parent Node, time Timestamp, meta Meta, rawMeta []byte) error {
+	if err := t.putState(b, stateKey(key, child), parent, time, rawMeta); err != nil {
 		return err
 	}
-	err = b.Put(childrenKey(key, child, parent), []byte{1})
-	if err != nil {
-		return err
-	}
-	err = b.Put(metaKey(key, child), meta.Bytes())
+
+	err := b.Put(childrenKey(key, child, parent), []byte{1})
 	if err != nil {
 		return err
 	}
@@ -564,22 +558,28 @@ func (t *boltForest) undo(m *LogMove, b *bbolt.Bucket, key []byte) error {
 		return err
 	}
 
-	if !m.HasOld {
+	parent, ts, rawMeta, ok := t.getState(b, oldKey(key, m.Time))
+	if !ok {
 		return t.removeNode(b, key, m.Child, m.Parent)
 	}
-	return t.addNode(b, key, m.Child, m.Old.Parent, m.Old.Meta)
+
+	var meta Meta
+	if err := meta.FromBytes(rawMeta); err != nil {
+		return err
+	}
+	return t.addNode(b, key, m.Child, parent, ts, meta, rawMeta)
 }
 
 func (t *boltForest) isAncestor(b *bbolt.Bucket, parent, child Node) bool {
 	key := make([]byte, 9)
-	key[0] = 'p'
+	key[0] = 's'
 	for node := child; node != parent; {
 		binary.LittleEndian.PutUint64(key[1:], node)
-		rawParent := b.Get(key)
-		if len(rawParent) != 8 {
+		parent, _, _, ok := t.getState(b, key)
+		if !ok {
 			return false
 		}
-		node = binary.LittleEndian.Uint64(rawParent)
+		node = parent
 	}
 	return true
 }
@@ -619,10 +619,7 @@ func (t *boltForest) TreeGetByPath(cid cidSDK.ID, treeID string, attr string, pa
 			return nil
 		}
 
-		var (
-			childID      [9]byte
-			maxTimestamp uint64
-		)
+		var maxTimestamp uint64
 
 		c := b.Cursor()
 
@@ -632,7 +629,7 @@ func (t *boltForest) TreeGetByPath(cid cidSDK.ID, treeID string, attr string, pa
 		for len(childKey) == len(attrKey)+8 && bytes.Equal(attrKey, childKey[:len(childKey)-8]) {
 			child := binary.LittleEndian.Uint64(childKey[len(childKey)-8:])
 			if latest {
-				ts := binary.LittleEndian.Uint64(b.Get(timestampKey(childID[:], child)))
+				_, ts, _, _ := t.getState(b, stateKey(make([]byte, 9), child))
 				if ts >= maxTimestamp {
 					nodes = append(nodes[:0], child)
 					maxTimestamp = ts
@@ -655,7 +652,7 @@ func (t *boltForest) TreeGetMeta(cid cidSDK.ID, treeID string, nodeID Node) (Met
 		return Meta{}, 0, ErrDegradedMode
 	}
 
-	key := parentKey(make([]byte, 9), nodeID)
+	key := stateKey(make([]byte, 9), nodeID)
 
 	var m Meta
 	var parentID uint64
@@ -667,10 +664,11 @@ func (t *boltForest) TreeGetMeta(cid cidSDK.ID, treeID string, nodeID Node) (Met
 		}
 
 		b := treeRoot.Bucket(dataBucket)
-		if data := b.Get(key); len(data) == 8 {
+		if data := b.Get(key); len(data) != 0 {
 			parentID = binary.LittleEndian.Uint64(data)
 		}
-		return m.FromBytes(b.Get(metaKey(key, nodeID)))
+		_, _, meta, _ := t.getState(b, stateKey(key, nodeID))
+		return m.FromBytes(meta)
 	})
 
 	return m, parentID, err
@@ -828,41 +826,31 @@ loop:
 }
 
 func (t *boltForest) moveFromBytes(m *Move, data []byte) error {
-	r := io.NewBinReaderFromBuf(data)
-	m.Child = r.ReadU64LE()
-	m.Parent = r.ReadU64LE()
-	m.Meta.DecodeBinary(r)
-	return r.Err
+	return t.logFromBytes(m, data)
 }
 
-func (t *boltForest) logFromBytes(lm *LogMove, r *io.BinReader) error {
-	lm.Child = r.ReadU64LE()
-	lm.Parent = r.ReadU64LE()
-	lm.Meta.DecodeBinary(r)
-	lm.HasOld = r.ReadBool()
-	if lm.HasOld {
-		lm.Old.Parent = r.ReadU64LE()
-		lm.Old.Meta.DecodeBinary(r)
-	}
-	return r.Err
+func (t *boltForest) logFromBytes(lm *LogMove, data []byte) error {
+	lm.Child = binary.LittleEndian.Uint64(data)
+	lm.Parent = binary.LittleEndian.Uint64(data[8:])
+	return lm.Meta.FromBytes(data[16:])
 }
 
 func (t *boltForest) logToBytes(lm *LogMove) []byte {
 	w := io.NewBufBinWriter()
 	size := 8 + 8 + lm.Meta.Size() + 1
-	if lm.HasOld {
-		size += 8 + lm.Old.Meta.Size()
-	}
+	//if lm.HasOld {
+	//	size += 8 + lm.Old.Meta.Size()
+	//}
 
 	w.Grow(size)
 	w.WriteU64LE(lm.Child)
 	w.WriteU64LE(lm.Parent)
 	lm.Meta.EncodeBinary(w.BinWriter)
-	w.WriteBool(lm.HasOld)
-	if lm.HasOld {
-		w.WriteU64LE(lm.Old.Parent)
-		lm.Old.Meta.EncodeBinary(w.BinWriter)
-	}
+	//w.WriteBool(lm.HasOld)
+	//if lm.HasOld {
+	//	w.WriteU64LE(lm.Old.Parent)
+	//	lm.Old.Meta.EncodeBinary(w.BinWriter)
+	//}
 	return w.Bytes()
 }
 
@@ -870,25 +858,37 @@ func bucketName(cid cidSDK.ID, treeID string) []byte {
 	return []byte(cid.String() + treeID)
 }
 
-// 't' + node (id) -> timestamp when the node first appeared.
-func timestampKey(key []byte, child Node) []byte {
-	key[0] = 't'
+// 'o' + time -> old meta.
+func oldKey(key []byte, ts Timestamp) []byte {
+	key[0] = 'o'
+	binary.LittleEndian.PutUint64(key[1:], ts)
+	return key[:9]
+}
+
+// 's' + child ID -> parent + timestamp of the first appearance + meta.
+func stateKey(key []byte, child Node) []byte {
+	key[0] = 's'
 	binary.LittleEndian.PutUint64(key[1:], child)
 	return key[:9]
 }
 
-// 'p' + node (id) -> parent (id).
-func parentKey(key []byte, child Node) []byte {
-	key[0] = 'p'
-	binary.LittleEndian.PutUint64(key[1:], child)
-	return key[:9]
+func (t *boltForest) putState(b *bbolt.Bucket, key []byte, parent Node, timestamp Timestamp, meta []byte) error {
+	data := make([]byte, len(meta)+8+8)
+	binary.LittleEndian.PutUint64(data, parent)
+	binary.LittleEndian.PutUint64(data[8:], timestamp)
+	copy(data[16:], meta)
+	return b.Put(key, data)
 }
 
-// 'm' + node (id) -> serialized meta.
-func metaKey(key []byte, child Node) []byte {
-	key[0] = 'm'
-	binary.LittleEndian.PutUint64(key[1:], child)
-	return key[:9]
+func (t *boltForest) getState(b *bbolt.Bucket, key []byte) (Node, Timestamp, []byte, bool) {
+	data := b.Get(key)
+	if data == nil {
+		return 0, 0, nil, false
+	}
+
+	parent := binary.LittleEndian.Uint64(data)
+	timestamp := binary.LittleEndian.Uint64(data[8:])
+	return parent, timestamp, data[16:], true
 }
 
 // 'c' + parent (id) + child (id) -> 0/1.

pkg/local_object_storage/pilorama/forest.go

@@ -44,7 +44,7 @@ func (f *memoryForest) TreeMove(d CIDDescriptor, treeID string, op *Move) (*LogM
 
 	lm := s.do(op)
 	s.operations = append(s.operations, lm)
-	return &lm, nil
+	return &lm.Move, nil
 }
 
 // TreeAddByPath implements the Forest interface.
@@ -66,20 +66,21 @@ func (f *memoryForest) TreeAddByPath(d CIDDescriptor, treeID string, attr string
 	i, node := s.getPathPrefix(attr, path)
 	lm := make([]LogMove, len(path)-i+1)
 	for j := i; j < len(path); j++ {
-		lm[j-i] = s.do(&Move{
+		op := s.do(&Move{
 			Parent: node,
 			Meta: Meta{
 				Time:  s.timestamp(d.Position, d.Size),
 				Items: []KeyValue{{Key: attr, Value: []byte(path[j])}}},
 			Child: s.findSpareID(),
 		})
-		node = lm[j-i].Child
-		s.operations = append(s.operations, lm[j-i])
+		lm[j-i] = op.Move
+		node = op.Child
+		s.operations = append(s.operations, op)
 	}
 
 	mCopy := make([]KeyValue, len(m))
 	copy(mCopy, m)
-	lm[len(lm)-1] = s.do(&Move{
+	op := s.do(&Move{
 		Parent: node,
 		Meta: Meta{
 			Time:  s.timestamp(d.Position, d.Size),
@@ -87,6 +88,7 @@ func (f *memoryForest) TreeAddByPath(d CIDDescriptor, treeID string, attr string
 		},
 		Child: s.findSpareID(),
 	})
+	lm[len(lm)-1] = op.Move
 	return lm, nil
 }
 

pkg/local_object_storage/pilorama/inmemory.go

@@ -6,9 +6,15 @@ type nodeInfo struct {
 	Meta   Meta
 }
 
+type move struct {
+	Move
+	HasOld bool
+	Old    nodeInfo
+}
+
 // state represents state being replicated.
 type state struct {
-	operations []LogMove
+	operations []move
 	tree
 }
 
@@ -20,7 +26,7 @@ func newState() *state {
 }
 
 // undo un-does op and changes s in-place.
-func (s *state) undo(op *LogMove) {
+func (s *state) undo(op *move) {
 	children := s.tree.childMap[op.Parent]
 	for i := range children {
 		if children[i] == op.Child {
@@ -76,8 +82,8 @@ func (s *state) Apply(op *Move) error {
 }
 
 // do performs a single move operation on a tree.
-func (s *state) do(op *Move) LogMove {
-	lm := LogMove{
+func (s *state) do(op *Move) move {
+	lm := move{
 		Move: Move{
 			Parent: op.Parent,
 			Meta:   op.Meta,

pkg/local_object_storage/pilorama/types.go

@@ -36,11 +36,7 @@ type Move struct {
 }
 
 // LogMove represents log record for a single move operation.
-type LogMove struct {
-	Move
-	HasOld bool
-	Old    nodeInfo
-}
+type LogMove = Move
 
 const (
 	// RootID represents the ID of a root node.