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node.go
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node.go
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package iavl
// NOTE: This file favors int64 as opposed to int for size/counts.
// The Tree on the other hand favors int. This is intentional.
import (
"bytes"
"fmt"
"io"
"github.com/tendermint/go-amino"
"github.com/tendermint/iavl/sha256truncated"
cmn "github.com/tendermint/tmlibs/common"
)
// Node represents a node in a Tree.
type Node struct {
key []byte
value []byte
version int64
height int8
size int64
hash []byte
leftHash []byte
leftNode *Node
rightHash []byte
rightNode *Node
persisted bool
}
// NewNode returns a new node from a key, value and version.
func NewNode(key []byte, value []byte, version int64) *Node {
return &Node{
key: key,
value: value,
height: 0,
size: 1,
version: version,
}
}
// MakeNode constructs an *Node from an encoded byte slice.
//
// The new node doesn't have its hash saved or set. The caller must set it
// afterwards.
func MakeNode(buf []byte) (node *Node, err cmn.Error) {
node = &Node{}
n := 0
cause := error(nil)
// Read node header.
node.height, n, cause = amino.DecodeInt8(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.height")
}
buf = buf[n:]
node.size, n, cause = amino.DecodeVarint(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.size")
}
buf = buf[n:]
node.version, n, cause = amino.DecodeVarint(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.version")
}
buf = buf[n:]
node.key, n, cause = amino.DecodeByteSlice(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.key")
}
buf = buf[n:]
// Read node body.
if node.isLeaf() {
node.value, _, cause = amino.DecodeByteSlice(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.value")
}
} else { // Read children.
leftHash, n, cause := amino.DecodeByteSlice(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "deocding node.leftHash")
}
buf = buf[n:]
rightHash, _, cause := amino.DecodeByteSlice(buf)
if cause != nil {
return nil, cmn.ErrorWrap(cause, "decoding node.rightHash")
}
node.leftHash = leftHash
node.rightHash = rightHash
}
return node, nil
}
// String returns a string representation of the node.
func (node *Node) String() string {
hashstr := "<no hash>"
if len(node.hash) > 0 {
hashstr = fmt.Sprintf("%X", node.hash)
}
return fmt.Sprintf("Node{%s:%s@%d %X;%X}#%s",
cmn.ColoredBytes(node.key, cmn.Green, cmn.Blue),
cmn.ColoredBytes(node.value, cmn.Cyan, cmn.Blue),
node.version,
node.leftHash, node.rightHash,
hashstr)
}
// clone creates a shallow copy of a node with its hash set to nil.
func (node *Node) clone(version int64) *Node {
if node.isLeaf() {
panic("Attempt to copy a leaf node")
}
return &Node{
key: node.key,
height: node.height,
version: version,
size: node.size,
hash: nil,
leftHash: node.leftHash,
leftNode: node.leftNode,
rightHash: node.rightHash,
rightNode: node.rightNode,
persisted: false,
}
}
func (node *Node) isLeaf() bool {
return node.height == 0
}
// Check if the node has a descendant with the given key.
func (node *Node) has(t *Tree, key []byte) (has bool) {
if bytes.Equal(node.key, key) {
return true
}
if node.isLeaf() {
return false
}
if bytes.Compare(key, node.key) < 0 {
return node.getLeftNode(t).has(t, key)
} else {
return node.getRightNode(t).has(t, key)
}
}
// Get a key under the node.
func (node *Node) get(t *Tree, key []byte) (index int64, value []byte) {
if node.isLeaf() {
switch bytes.Compare(node.key, key) {
case -1:
return 1, nil
case 1:
return 0, nil
default:
return 0, node.value
}
}
if bytes.Compare(key, node.key) < 0 {
return node.getLeftNode(t).get(t, key)
} else {
rightNode := node.getRightNode(t)
index, value = rightNode.get(t, key)
index += node.size - rightNode.size
return index, value
}
}
func (node *Node) getByIndex(t *Tree, index int64) (key []byte, value []byte) {
if node.isLeaf() {
if index == 0 {
return node.key, node.value
} else {
return nil, nil
}
} 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)
} else {
return node.getRightNode(t).getByIndex(t, index-leftNode.size)
}
}
}
// Computes the hash of the node without computing its descendants. Must be
// called on nodes which have descendant node hashes already computed.
func (node *Node) _hash() []byte {
if node.hash != nil {
return node.hash
}
h := sha256truncated.New()
buf := new(bytes.Buffer)
if err := node.writeHashBytes(buf); err != nil {
panic(err)
}
h.Write(buf.Bytes())
node.hash = h.Sum(nil)
return node.hash
}
// Hash the node and its descendants recursively. This usually mutates all
// descendant nodes. Returns the node hash and number of nodes hashed.
func (node *Node) hashWithCount() ([]byte, int64) {
if node.hash != nil {
return node.hash, 0
}
h := sha256truncated.New()
buf := new(bytes.Buffer)
hashCount, err := node.writeHashBytesRecursively(buf)
if err != nil {
panic(err)
}
h.Write(buf.Bytes())
node.hash = h.Sum(nil)
return node.hash, hashCount + 1
}
// Writes the node's hash to the given io.Writer. This function expects
// child hashes to be already set.
func (node *Node) writeHashBytes(w io.Writer) cmn.Error {
err := amino.EncodeInt8(w, node.height)
if err != nil {
return cmn.ErrorWrap(err, "writing height")
}
err = amino.EncodeVarint(w, node.size)
if err != nil {
return cmn.ErrorWrap(err, "writing size")
}
err = amino.EncodeVarint(w, node.version)
if err != nil {
return cmn.ErrorWrap(err, "writing version")
}
// Key is not written for inner nodes, unlike writeBytes.
if node.isLeaf() {
err = amino.EncodeByteSlice(w, node.key)
if err != nil {
return cmn.ErrorWrap(err, "writing key")
}
// Indirection needed to provide proofs without values.
// (e.g. proofLeafNode.ValueHash)
valueHash := sha256truncated.Hash(node.value)
err = amino.EncodeByteSlice(w, valueHash)
if err != nil {
return cmn.ErrorWrap(err, "writing value")
}
} else {
if node.leftHash == nil || node.rightHash == nil {
panic("Found an empty child hash")
}
err = amino.EncodeByteSlice(w, node.leftHash)
if err != nil {
return cmn.ErrorWrap(err, "writing left hash")
}
err = amino.EncodeByteSlice(w, node.rightHash)
if err != nil {
return cmn.ErrorWrap(err, "writing right hash")
}
}
return nil
}
// Writes the node's hash to the given io.Writer.
// This function has the side-effect of calling hashWithCount.
func (node *Node) writeHashBytesRecursively(w io.Writer) (hashCount int64, err cmn.Error) {
if node.leftNode != nil {
leftHash, leftCount := node.leftNode.hashWithCount()
node.leftHash = leftHash
hashCount += leftCount
}
if node.rightNode != nil {
rightHash, rightCount := node.rightNode.hashWithCount()
node.rightHash = rightHash
hashCount += rightCount
}
err = node.writeHashBytes(w)
return
}
// Writes the node as a serialized byte slice to the supplied io.Writer.
func (node *Node) writeBytes(w io.Writer) cmn.Error {
var cause error
cause = amino.EncodeInt8(w, node.height)
if cause != nil {
return cmn.ErrorWrap(cause, "writing height")
}
cause = amino.EncodeVarint(w, node.size)
if cause != nil {
return cmn.ErrorWrap(cause, "writing size")
}
cause = amino.EncodeVarint(w, node.version)
if cause != nil {
return cmn.ErrorWrap(cause, "writing version")
}
// Unlike writeHashBytes, key is written for inner nodes.
cause = amino.EncodeByteSlice(w, node.key)
if cause != nil {
return cmn.ErrorWrap(cause, "writing key")
}
if node.isLeaf() {
cause = amino.EncodeByteSlice(w, node.value)
if cause != nil {
return cmn.ErrorWrap(cause, "writing value")
}
} else {
if node.leftHash == nil {
panic("node.leftHash was nil in writeBytes")
}
cause = amino.EncodeByteSlice(w, node.leftHash)
if cause != nil {
return cmn.ErrorWrap(cause, "writing left hash")
}
if node.rightHash == nil {
panic("node.rightHash was nil in writeBytes")
}
cause = amino.EncodeByteSlice(w, node.rightHash)
if cause != nil {
return cmn.ErrorWrap(cause, "writing right hash")
}
}
return nil
}
func (node *Node) set(t *Tree, key []byte, value []byte) (
newSelf *Node, updated bool, orphaned []*Node,
) {
version := t.version + 1
if node.isLeaf() {
switch bytes.Compare(key, node.key) {
case -1:
return &Node{
key: node.key,
height: 1,
size: 2,
leftNode: NewNode(key, value, version),
rightNode: node,
version: version,
}, false, []*Node{}
case 1:
return &Node{
key: key,
height: 1,
size: 2,
leftNode: node,
rightNode: NewNode(key, value, version),
version: version,
}, false, []*Node{}
default:
return NewNode(key, value, version), true, []*Node{node}
}
} else {
orphaned = append(orphaned, node)
node = node.clone(version)
if bytes.Compare(key, node.key) < 0 {
var leftOrphaned []*Node
node.leftNode, updated, leftOrphaned = node.getLeftNode(t).set(t, key, value)
node.leftHash = nil // leftHash is yet unknown
orphaned = append(orphaned, leftOrphaned...)
} else {
var rightOrphaned []*Node
node.rightNode, updated, rightOrphaned = node.getRightNode(t).set(t, key, value)
node.rightHash = nil // rightHash is yet unknown
orphaned = append(orphaned, rightOrphaned...)
}
if updated {
return node, updated, orphaned
} else {
node.calcHeightAndSize(t)
newNode, balanceOrphaned := node.balance(t)
return newNode, updated, append(orphaned, balanceOrphaned...)
}
}
}
// 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, orphaned []*Node,
) {
version := t.version + 1
if node.isLeaf() {
if bytes.Equal(key, node.key) {
return nil, nil, nil, node.value, []*Node{node}
}
return node.hash, node, nil, nil, orphaned
}
if bytes.Compare(key, node.key) < 0 {
var newLeftHash []byte
var newLeftNode *Node
newLeftHash, newLeftNode, newKey, value, orphaned =
node.getLeftNode(t).remove(t, key)
if len(orphaned) == 0 {
return node.hash, node, nil, value, orphaned
} else if newLeftHash == nil && newLeftNode == nil { // left node held value, was removed
return node.rightHash, node.rightNode, node.key, value, orphaned
}
orphaned = append(orphaned, node)
newNode := node.clone(version)
newNode.leftHash, newNode.leftNode = newLeftHash, newLeftNode
newNode.calcHeightAndSize(t)
newNode, balanceOrphaned := newNode.balance(t)
return newNode.hash, newNode, newKey, value, append(orphaned, balanceOrphaned...)
} else {
var newRightHash []byte
var newRightNode *Node
newRightHash, newRightNode, newKey, value, orphaned =
node.getRightNode(t).remove(t, key)
if len(orphaned) == 0 {
return node.hash, node, nil, value, orphaned
} else if newRightHash == nil && newRightNode == nil { // right node held value, was removed
return node.leftHash, node.leftNode, nil, value, orphaned
}
orphaned = append(orphaned, node)
newNode := node.clone(version)
newNode.rightHash, newNode.rightNode = newRightHash, newRightNode
if newKey != nil {
newNode.key = newKey
}
newNode.calcHeightAndSize(t)
newNode, balanceOrphaned := newNode.balance(t)
return newNode.hash, newNode, nil, value, append(orphaned, balanceOrphaned...)
}
}
func (node *Node) getLeftNode(t *Tree) *Node {
if node.leftNode != nil {
return node.leftNode
}
return t.ndb.GetNode(node.leftHash)
}
func (node *Node) getRightNode(t *Tree) *Node {
if node.rightNode != nil {
return node.rightNode
}
return t.ndb.GetNode(node.rightHash)
}
// Rotate right and return the new node and orphan.
func (node *Node) rotateRight(t *Tree) (newNode *Node, orphan *Node) {
version := t.version + 1
// TODO: optimize balance & rotate.
node = node.clone(version)
l := node.getLeftNode(t)
_l := l.clone(version)
_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, l
}
// Rotate left and return the new node and orphan.
func (node *Node) rotateLeft(t *Tree) (newNode *Node, orphan *Node) {
version := t.version + 1
// TODO: optimize balance & rotate.
node = node.clone(version)
r := node.getRightNode(t)
_r := r.clone(version)
_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, r
}
// NOTE: mutates height and size
func (node *Node) calcHeightAndSize(t *Tree) {
node.height = maxInt8(node.getLeftNode(t).height, node.getRightNode(t).height) + 1
node.size = node.getLeftNode(t).size + node.getRightNode(t).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, orphaned []*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
newNode, orphaned := node.rotateRight(t)
return newNode, []*Node{orphaned}
} else {
// Left Right Case
var leftOrphaned *Node
left := node.getLeftNode(t)
node.leftHash = nil
node.leftNode, leftOrphaned = left.rotateLeft(t)
newNode, rightOrphaned := node.rotateRight(t)
return newNode, []*Node{left, leftOrphaned, rightOrphaned}
}
}
if balance < -1 {
if node.getRightNode(t).calcBalance(t) <= 0 {
// Right Right Case
newNode, orphaned := node.rotateLeft(t)
return newNode, []*Node{orphaned}
} else {
// Right Left Case
var rightOrphaned *Node
right := node.getRightNode(t)
node.rightHash = nil
node.rightNode, rightOrphaned = right.rotateRight(t)
newNode, leftOrphaned := node.rotateLeft(t)
return newNode, []*Node{right, leftOrphaned, rightOrphaned}
}
}
// Nothing changed
return node, []*Node{}
}
// traverse is a wrapper over traverseInRange when we want the whole tree
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
startOrAfter := 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
}
// Run callback per inner/leaf node.
stop := false
if !node.isLeaf() || startOrAfter {
stop = cb(node, depth)
if stop {
return stop
}
}
if node.isLeaf() {
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.isLeaf() {
return node
}
return node.getLeftNode(t).lmd(t)
}