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node.go
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/
node.go
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// Copyright Fuzamei Corp. 2018 All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mavl
import (
"bytes"
"fmt"
"github.com/PhenixChain/devchain/common"
"github.com/PhenixChain/devchain/types"
farm "github.com/dgryski/go-farm"
"github.com/golang/protobuf/proto"
)
// Node merkle avl Node
type Node struct {
key []byte
value []byte
height int32
size int32
hash []byte
leftHash []byte
leftNode *Node
rightHash []byte
rightNode *Node
parentNode *Node
persisted bool
}
// NewNode 创建节点;保存数据的是叶子节点
func NewNode(key []byte, value []byte) *Node {
return &Node{
key: key,
value: value,
height: 0,
size: 1,
}
}
// MakeNode 从数据库中读取数据,创建Node
// NOTE: The hash is not saved or set. The caller should set the hash afterwards.
// (Presumably the caller already has the hash)
func MakeNode(buf []byte, t *Tree) (node *Node, err error) {
node = &Node{}
var storeNode types.StoreNode
err = proto.Unmarshal(buf, &storeNode)
if err != nil {
return nil, err
}
// node header
node.height = storeNode.Height
node.size = storeNode.Size
node.key = storeNode.Key
//leaf(叶子节点保存数据)
if node.height == 0 {
node.value = storeNode.Value
} else {
node.leftHash = storeNode.LeftHash
node.rightHash = storeNode.RightHash
}
return node, nil
}
func (node *Node) _copy() *Node {
if node.height == 0 {
panic("Why are you copying a value node?")
}
return &Node{
key: node.key,
height: node.height,
size: node.size,
hash: nil, // Going to be mutated anyways.
leftHash: node.leftHash,
leftNode: node.leftNode,
rightHash: node.rightHash,
rightNode: node.rightNode,
parentNode: node.parentNode,
persisted: false, // Going to be mutated, so it can't already be persisted.
}
}
func (node *Node) has(t *Tree, key []byte) (has bool) {
if bytes.Equal(node.key, key) {
return true
}
if node.height == 0 {
return false
}
if bytes.Compare(key, node.key) < 0 {
return node.getLeftNode(t).has(t, key)
}
return node.getRightNode(t).has(t, key)
}
func (node *Node) get(t *Tree, key []byte) (index int32, value []byte, exists bool) {
if node.height == 0 {
cmp := bytes.Compare(node.key, key)
if cmp == 0 {
return 0, node.value, true
} else if cmp == -1 {
return 1, nil, false
} else {
return 0, nil, false
}
}
if bytes.Compare(key, node.key) < 0 {
return node.getLeftNode(t).get(t, key)
}
rightNode := node.getRightNode(t)
index, value, exists = rightNode.get(t, key)
index += node.size - rightNode.size
return index, value, exists
}
func (node *Node) getHash(t *Tree, key []byte) (index int32, hash []byte, exists bool) {
if node.height == 0 {
cmp := bytes.Compare(node.key, key)
if cmp == 0 {
return 0, node.hash, true
} else if cmp == -1 {
return 1, nil, false
} else {
return 0, nil, false
}
}
if bytes.Compare(key, node.key) < 0 {
return node.getLeftNode(t).getHash(t, key)
}
rightNode := node.getRightNode(t)
index, hash, exists = rightNode.getHash(t, key)
index += node.size - rightNode.size
return index, hash, exists
}
//通过index获取leaf节点信息
func (node *Node) getByIndex(t *Tree, index int32) (key []byte, value []byte) {
if node.height == 0 {
if index == 0 {
return node.key, node.value
}
panic("getByIndex asked for invalid index")
} else {
// TODO: could improve this by storing the sizes as well as left/right hash.
leftNode := node.getLeftNode(t)
if index < leftNode.size {
return leftNode.getByIndex(t, index)
}
return node.getRightNode(t).getByIndex(t, index-leftNode.size)
}
}
// Hash 计算节点的hash
func (node *Node) Hash(t *Tree) []byte {
if node.hash != nil {
return node.hash
}
//leafnode
if node.height == 0 {
var leafnode types.LeafNode
leafnode.Height = node.height
leafnode.Key = node.key
leafnode.Size = node.size
leafnode.Value = node.value
node.hash = leafnode.Hash()
if enableMavlPrefix && node.height != t.root.height {
hashKey := genPrefixHashKey(node, t.blockHeight)
hashKey = append(hashKey, node.hash...)
node.hash = hashKey
}
} else {
var innernode types.InnerNode
innernode.Height = node.height
innernode.Size = node.size
// left
if node.leftNode != nil {
leftHash := node.leftNode.Hash(t)
node.leftHash = leftHash
}
if node.leftHash == nil {
panic("node.leftHash was nil in writeHashBytes")
}
innernode.LeftHash = node.leftHash
// right
if node.rightNode != nil {
rightHash := node.rightNode.Hash(t)
node.rightHash = rightHash
}
if node.rightHash == nil {
panic("node.rightHash was nil in writeHashBytes")
}
innernode.RightHash = node.rightHash
node.hash = innernode.Hash()
if enableMavlPrefix && node.height != t.root.height {
hashKey := genPrefixHashKey(node, t.blockHeight)
hashKey = append(hashKey, node.hash...)
node.hash = hashKey
}
if enablePrune {
//加入parentNode
if node.leftNode != nil && node.leftNode.height != t.root.height {
node.leftNode.parentNode = node
}
if node.rightNode != nil && node.rightNode.height != t.root.height {
node.rightNode.parentNode = node
}
}
}
if enableMemTree {
updateLocalMemTree(t, node)
}
return node.hash
}
// NOTE: clears leftNode/rigthNode recursively sets hashes recursively
func (node *Node) save(t *Tree) int64 {
if node.hash == nil {
node.hash = node.Hash(t)
}
if node.persisted {
return 0
}
var leftsaveNodeNo int64
var rightsaveNodeNo int64
// save children
if node.leftNode != nil {
leftsaveNodeNo = node.leftNode.save(t)
node.leftNode = nil
}
if node.rightNode != nil {
rightsaveNodeNo = node.rightNode.save(t)
node.rightNode = nil
}
// save node
t.ndb.SaveNode(t, node)
return leftsaveNodeNo + rightsaveNodeNo + 1
}
// 保存root节点hash以及区块高度
func (node *Node) saveRootHash(t *Tree) (err error) {
if node.hash == nil || t.ndb == nil || t.ndb.db == nil {
return
}
h := &types.Int64{}
h.Data = t.blockHeight
value, err := proto.Marshal(h)
if err != nil {
return err
}
t.ndb.batch.Set(genRootHashHeight(t.blockHeight, node.hash), value)
return nil
}
//将内存中的node转换成存储到db中的格式
func (node *Node) storeNode(t *Tree) []byte {
var storeNode types.StoreNode
// node header
storeNode.Height = node.height
storeNode.Size = node.size
storeNode.Key = node.key
storeNode.Value = nil
storeNode.LeftHash = nil
storeNode.RightHash = nil
//leafnode
if node.height == 0 {
if !enableMvcc {
storeNode.Value = node.value
}
} else {
// left
if node.leftHash == nil {
panic("node.leftHash was nil in writePersistBytes")
}
storeNode.LeftHash = node.leftHash
// right
if node.rightHash == nil {
panic("node.rightHash was nil in writePersistBytes")
}
storeNode.RightHash = node.rightHash
}
storeNodebytes, err := proto.Marshal(&storeNode)
if err != nil {
panic(err)
}
return storeNodebytes
}
//从指定node开始插入一个新的node,updated表示是否有叶子结点的value更新
func (node *Node) set(t *Tree, key []byte, value []byte) (newSelf *Node, updated bool) {
if node.height == 0 {
cmp := bytes.Compare(key, node.key)
if cmp < 0 {
return &Node{
key: node.key,
height: 1,
size: 2,
leftNode: NewNode(key, value),
rightNode: node,
}, false
} else if cmp == 0 {
removeOrphan(t, node)
return NewNode(key, value), true
} else {
return &Node{
key: key,
height: 1,
size: 2,
leftNode: node,
rightNode: NewNode(key, value),
}, false
}
} else {
removeOrphan(t, node)
node = node._copy()
if bytes.Compare(key, node.key) < 0 {
node.leftNode, updated = node.getLeftNode(t).set(t, key, value)
node.leftHash = nil // leftHash is yet unknown
} else {
node.rightNode, updated = node.getRightNode(t).set(t, key, value)
node.rightHash = nil // rightHash is yet unknown
}
if updated {
return node, updated
}
//有节点插入,需要重新计算height和size以及tree的平衡
node.calcHeightAndSize(t)
return node.balance(t), updated
}
}
func (node *Node) getLeftNode(t *Tree) *Node {
if node.leftNode != nil {
return node.leftNode
}
leftNode, err := t.ndb.GetNode(t, node.leftHash)
if err != nil {
panic(fmt.Sprintln("left hash", common.ToHex(node.leftHash), err)) //数据库已经损坏
}
return leftNode
}
func (node *Node) getRightNode(t *Tree) *Node {
if node.rightNode != nil {
return node.rightNode
}
rightNode, err := t.ndb.GetNode(t, node.rightHash)
if err != nil {
panic(fmt.Sprintln("right hash", common.ToHex(node.rightHash), err))
}
return rightNode
}
// NOTE: overwrites node TODO: optimize balance & rotate
func (node *Node) rotateRight(t *Tree) *Node {
node = node._copy()
l := node.getLeftNode(t)
removeOrphan(t, l)
_l := l._copy()
_lrHash, _lrCached := _l.rightHash, _l.rightNode
_l.rightHash, _l.rightNode = node.hash, node
node.leftHash, node.leftNode = _lrHash, _lrCached
node.calcHeightAndSize(t)
_l.calcHeightAndSize(t)
return _l
}
// NOTE: overwrites node TODO: optimize balance & rotate
func (node *Node) rotateLeft(t *Tree) *Node {
node = node._copy()
r := node.getRightNode(t)
removeOrphan(t, r)
_r := r._copy()
_rlHash, _rlCached := _r.leftHash, _r.leftNode
_r.leftHash, _r.leftNode = node.hash, node
node.rightHash, node.rightNode = _rlHash, _rlCached
node.calcHeightAndSize(t)
_r.calcHeightAndSize(t)
return _r
}
// NOTE: mutates height and size
func (node *Node) calcHeightAndSize(t *Tree) {
leftN := node.getLeftNode(t)
rightN := node.getRightNode(t)
node.height = maxInt32(leftN.height, rightN.height) + 1
node.size = leftN.size + rightN.size
}
func (node *Node) calcBalance(t *Tree) int {
return int(node.getLeftNode(t).height) - int(node.getRightNode(t).height)
}
// NOTE: assumes that node can be modified TODO: optimize balance & rotate
func (node *Node) balance(t *Tree) (newSelf *Node) {
if node.persisted {
panic("Unexpected balance() call on persisted node")
}
balance := node.calcBalance(t)
if balance > 1 {
if node.getLeftNode(t).calcBalance(t) >= 0 {
// Left Left Case
return node.rotateRight(t)
}
// Left Right Case
// node = node._copy()
left := node.getLeftNode(t)
removeOrphan(t, left)
node.leftHash, node.leftNode = nil, left.rotateLeft(t)
//node.calcHeightAndSize()
return node.rotateRight(t)
}
if balance < -1 {
if node.getRightNode(t).calcBalance(t) <= 0 {
// Right Right Case
return node.rotateLeft(t)
}
// Right Left Case
// node = node._copy()
right := node.getRightNode(t)
removeOrphan(t, right)
node.rightHash, node.rightNode = nil, right.rotateRight(t)
//node.calcHeightAndSize()
return node.rotateLeft(t)
}
// Nothing changed
return node
}
// newHash/newNode: The new hash or node to replace node after remove.
// newKey: new leftmost leaf key for tree after successfully removing 'key' if changed.
// value: removed value.
func (node *Node) remove(t *Tree, key []byte) (
newHash []byte, newNode *Node, newKey []byte, value []byte, removed bool) {
if node.height == 0 {
if bytes.Equal(key, node.key) {
removeOrphan(t, node)
return nil, nil, nil, node.value, true
}
return node.hash, node, nil, nil, false
}
if bytes.Compare(key, node.key) < 0 {
var newLeftHash []byte
var newLeftNode *Node
newLeftHash, newLeftNode, newKey, value, removed = node.getLeftNode(t).remove(t, key)
if !removed {
return node.hash, node, nil, value, false
} else if newLeftHash == nil && newLeftNode == nil { // left node held value, was removed
return node.rightHash, node.rightNode, node.key, value, true
}
removeOrphan(t, node)
node = node._copy()
node.leftHash, node.leftNode = newLeftHash, newLeftNode
node.calcHeightAndSize(t)
node = node.balance(t)
return node.hash, node, newKey, value, true
}
var newRightHash []byte
var newRightNode *Node
newRightHash, newRightNode, newKey, value, removed = node.getRightNode(t).remove(t, key)
if !removed {
return node.hash, node, nil, value, false
} else if newRightHash == nil && newRightNode == nil { // right node held value, was removed
return node.leftHash, node.leftNode, nil, value, true
}
removeOrphan(t, node)
node = node._copy()
node.rightHash, node.rightNode = newRightHash, newRightNode
if newKey != nil {
node.key = newKey
}
node.calcHeightAndSize(t)
node = node.balance(t)
return node.hash, node, nil, value, true
}
func removeOrphan(t *Tree, node *Node) {
if !node.persisted {
return
}
if t.ndb == nil {
return
}
if enableMemTree && t != nil {
t.obsoleteNode[uintkey(farm.Hash64(node.hash))] = struct{}{}
}
t.ndb.RemoveNode(t, node)
}
// 迭代整个树
func (node *Node) traverse(t *Tree, ascending bool, cb func(*Node) bool) bool {
return node.traverseInRange(t, nil, nil, ascending, false, 0, func(node *Node, depth uint8) bool {
return cb(node)
})
}
func (node *Node) traverseWithDepth(t *Tree, ascending bool, cb func(*Node, uint8) bool) bool {
return node.traverseInRange(t, nil, nil, ascending, false, 0, cb)
}
func (node *Node) traverseInRange(t *Tree, start, end []byte, ascending bool, inclusive bool, depth uint8, cb func(*Node, uint8) bool) bool {
afterStart := start == nil || bytes.Compare(start, node.key) <= 0
beforeEnd := end == nil || bytes.Compare(node.key, end) < 0
if inclusive {
beforeEnd = end == nil || bytes.Compare(node.key, end) <= 0
}
stop := false
if afterStart && beforeEnd {
// IterateRange ignores this if not leaf
stop = cb(node, depth)
}
if stop {
return stop
}
if node.height == 0 {
return stop
}
if ascending {
// check lower nodes, then higher
if afterStart {
stop = node.getLeftNode(t).traverseInRange(t, start, end, ascending, inclusive, depth+1, cb)
}
if stop {
return stop
}
if beforeEnd {
stop = node.getRightNode(t).traverseInRange(t, start, end, ascending, inclusive, depth+1, cb)
}
} else {
// check the higher nodes first
if beforeEnd {
stop = node.getRightNode(t).traverseInRange(t, start, end, ascending, inclusive, depth+1, cb)
}
if stop {
return stop
}
if afterStart {
stop = node.getLeftNode(t).traverseInRange(t, start, end, ascending, inclusive, depth+1, cb)
}
}
return stop
}
// Only used in testing...
func (node *Node) lmd(t *Tree) *Node {
if node.height == 0 {
return node
}
return node.getLeftNode(t).lmd(t)
}
// Only used in testing...
func (node *Node) rmd(t *Tree) *Node {
if node.height == 0 {
return node
}
return node.getRightNode(t).rmd(t)
}