399 lines
8.3 KiB
Go
399 lines
8.3 KiB
Go
package merkle
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import (
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"bytes"
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"crypto/sha256"
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. "github.com/tendermint/tendermint/binary"
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"io"
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)
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// Node
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type IAVLNode struct {
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key []byte
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value []byte
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size uint64
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height uint8
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hash []byte
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left *IAVLNode
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right *IAVLNode
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// volatile
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flags byte
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}
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const (
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IAVLNODE_FLAG_PERSISTED = byte(0x01)
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IAVLNODE_FLAG_PLACEHOLDER = byte(0x02)
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)
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func NewIAVLNode(key []byte, value []byte) *IAVLNode {
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return &IAVLNode{
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key: key,
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value: value,
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size: 1,
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}
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}
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func (self *IAVLNode) Copy() *IAVLNode {
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if self.height == 0 {
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panic("Why are you copying a value node?")
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}
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return &IAVLNode{
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key: self.key,
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size: self.size,
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height: self.height,
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left: self.left,
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right: self.right,
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hash: nil,
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flags: byte(0),
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}
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}
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func (self *IAVLNode) Size() uint64 {
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return self.size
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}
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func (self *IAVLNode) Height() uint8 {
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return self.height
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}
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func (self *IAVLNode) has(db Db, key []byte) (has bool) {
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if bytes.Equal(self.key, key) {
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return true
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}
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if self.height == 0 {
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return false
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} else {
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if bytes.Compare(key, self.key) == -1 {
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return self.leftFilled(db).has(db, key)
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} else {
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return self.rightFilled(db).has(db, key)
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}
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}
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}
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func (self *IAVLNode) get(db Db, key []byte) (value []byte) {
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if self.height == 0 {
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if bytes.Equal(self.key, key) {
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return self.value
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} else {
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return nil
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}
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} else {
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if bytes.Compare(key, self.key) == -1 {
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return self.leftFilled(db).get(db, key)
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} else {
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return self.rightFilled(db).get(db, key)
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}
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}
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}
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func (self *IAVLNode) HashWithCount() ([]byte, uint64) {
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if self.hash != nil {
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return self.hash, 0
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}
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hasher := sha256.New()
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_, hashCount, err := self.saveToCountHashes(hasher)
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if err != nil {
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panic(err)
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}
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self.hash = hasher.Sum(nil)
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return self.hash, hashCount + 1
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}
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func (self *IAVLNode) Save(db Db) {
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if self.hash == nil {
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panic("savee.hash can't be nil")
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}
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if self.flags&IAVLNODE_FLAG_PERSISTED > 0 ||
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self.flags&IAVLNODE_FLAG_PLACEHOLDER > 0 {
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return
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}
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// children
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if self.height > 0 {
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self.left.Save(db)
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self.right.Save(db)
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}
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// save self
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buf := bytes.NewBuffer(nil)
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_, err := self.WriteTo(buf)
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if err != nil {
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panic(err)
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}
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db.Set([]byte(self.hash), buf.Bytes())
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self.flags |= IAVLNODE_FLAG_PERSISTED
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}
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func (self *IAVLNode) set(db Db, key []byte, value []byte) (_ *IAVLNode, updated bool) {
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if self.height == 0 {
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if bytes.Compare(key, self.key) == -1 {
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return &IAVLNode{
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key: self.key,
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height: 1,
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size: 2,
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left: NewIAVLNode(key, value),
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right: self,
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}, false
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} else if bytes.Equal(self.key, key) {
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return NewIAVLNode(key, value), true
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} else {
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return &IAVLNode{
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key: key,
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height: 1,
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size: 2,
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left: self,
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right: NewIAVLNode(key, value),
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}, false
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}
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} else {
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self = self.Copy()
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if bytes.Compare(key, self.key) == -1 {
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self.left, updated = self.leftFilled(db).set(db, key, value)
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} else {
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self.right, updated = self.rightFilled(db).set(db, key, value)
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}
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if updated {
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return self, updated
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} else {
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self.calcHeightAndSize(db)
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return self.balance(db), updated
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}
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}
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}
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// newKey: new leftmost leaf key for tree after successfully removing 'key' if changed.
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func (self *IAVLNode) remove(db Db, key []byte) (newSelf *IAVLNode, newKey []byte, value []byte, err error) {
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if self.height == 0 {
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if bytes.Equal(self.key, key) {
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return nil, nil, self.value, nil
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} else {
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return self, nil, nil, NotFound(key)
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}
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} else {
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if bytes.Compare(key, self.key) == -1 {
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var newLeft *IAVLNode
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newLeft, newKey, value, err = self.leftFilled(db).remove(db, key)
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if err != nil {
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return self, nil, value, err
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} else if newLeft == nil { // left node held value, was removed
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return self.right, self.key, value, nil
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}
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self = self.Copy()
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self.left = newLeft
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} else {
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var newRight *IAVLNode
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newRight, newKey, value, err = self.rightFilled(db).remove(db, key)
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if err != nil {
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return self, nil, value, err
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} else if newRight == nil { // right node held value, was removed
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return self.left, nil, value, nil
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}
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self = self.Copy()
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self.right = newRight
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if newKey != nil {
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self.key = newKey
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newKey = nil
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}
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}
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self.calcHeightAndSize(db)
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return self.balance(db), newKey, value, err
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}
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}
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func (self *IAVLNode) WriteTo(w io.Writer) (n int64, err error) {
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n, _, err = self.saveToCountHashes(w)
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return
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}
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func (self *IAVLNode) saveToCountHashes(w io.Writer) (n int64, hashCount uint64, err error) {
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// height & size & key
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WriteUInt8(w, self.height, &n, &err)
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WriteUInt64(w, self.size, &n, &err)
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WriteByteSlice(w, self.key, &n, &err)
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if err != nil {
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return
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}
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// value or children
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if self.height == 0 {
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// value
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WriteByteSlice(w, self.value, &n, &err)
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} else {
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// left
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leftHash, leftCount := self.left.HashWithCount()
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hashCount += leftCount
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WriteByteSlice(w, leftHash, &n, &err)
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// right
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rightHash, rightCount := self.right.HashWithCount()
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hashCount += rightCount
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WriteByteSlice(w, rightHash, &n, &err)
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}
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return
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}
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// Given a placeholder node which has only the hash set,
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// load the rest of the data from db.
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// Not threadsafe.
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func (self *IAVLNode) fill(db Db) {
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if self.hash == nil {
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panic("placeholder.hash can't be nil")
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}
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buf := db.Get(self.hash)
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r := bytes.NewReader(buf)
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var n int64
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var err error
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// node header & key
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self.height = ReadUInt8(r, &n, &err)
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self.size = ReadUInt64(r, &n, &err)
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self.key = ReadByteSlice(r, &n, &err)
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if err != nil {
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panic(err)
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}
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// node value or children.
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if self.height == 0 {
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// value
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self.value = ReadByteSlice(r, &n, &err)
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} else {
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// left
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leftHash := ReadByteSlice(r, &n, &err)
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self.left = &IAVLNode{
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hash: leftHash,
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flags: IAVLNODE_FLAG_PERSISTED | IAVLNODE_FLAG_PLACEHOLDER,
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}
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// right
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rightHash := ReadByteSlice(r, &n, &err)
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self.right = &IAVLNode{
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hash: rightHash,
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flags: IAVLNODE_FLAG_PERSISTED | IAVLNODE_FLAG_PLACEHOLDER,
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}
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if r.Len() != 0 {
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panic("buf not all consumed")
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}
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}
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if err != nil {
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panic(err)
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}
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self.flags &= ^IAVLNODE_FLAG_PLACEHOLDER
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}
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func (self *IAVLNode) leftFilled(db Db) *IAVLNode {
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if self.left.flags&IAVLNODE_FLAG_PLACEHOLDER > 0 {
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self.left.fill(db)
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}
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return self.left
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}
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func (self *IAVLNode) rightFilled(db Db) *IAVLNode {
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if self.right.flags&IAVLNODE_FLAG_PLACEHOLDER > 0 {
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self.right.fill(db)
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}
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return self.right
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}
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func (self *IAVLNode) rotateRight(db Db) *IAVLNode {
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self = self.Copy()
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sl := self.leftFilled(db).Copy()
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slr := sl.right
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sl.right = self
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self.left = slr
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self.calcHeightAndSize(db)
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sl.calcHeightAndSize(db)
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return sl
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}
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func (self *IAVLNode) rotateLeft(db Db) *IAVLNode {
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self = self.Copy()
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sr := self.rightFilled(db).Copy()
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srl := sr.left
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sr.left = self
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self.right = srl
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self.calcHeightAndSize(db)
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sr.calcHeightAndSize(db)
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return sr
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}
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func (self *IAVLNode) calcHeightAndSize(db Db) {
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self.height = maxUint8(self.leftFilled(db).Height(), self.rightFilled(db).Height()) + 1
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self.size = self.leftFilled(db).Size() + self.rightFilled(db).Size()
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}
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func (self *IAVLNode) calcBalance(db Db) int {
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return int(self.leftFilled(db).Height()) - int(self.rightFilled(db).Height())
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}
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func (self *IAVLNode) balance(db Db) (newSelf *IAVLNode) {
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balance := self.calcBalance(db)
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if balance > 1 {
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if self.leftFilled(db).calcBalance(db) >= 0 {
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// Left Left Case
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return self.rotateRight(db)
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} else {
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// Left Right Case
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self = self.Copy()
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self.left = self.leftFilled(db).rotateLeft(db)
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//self.calcHeightAndSize()
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return self.rotateRight(db)
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}
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}
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if balance < -1 {
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if self.rightFilled(db).calcBalance(db) <= 0 {
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// Right Right Case
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return self.rotateLeft(db)
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} else {
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// Right Left Case
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self = self.Copy()
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self.right = self.rightFilled(db).rotateRight(db)
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//self.calcHeightAndSize()
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return self.rotateLeft(db)
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}
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}
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// Nothing changed
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return self
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}
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func (self *IAVLNode) lmd(db Db) *IAVLNode {
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if self.height == 0 {
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return self
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}
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return self.leftFilled(db).lmd(db)
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}
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func (self *IAVLNode) rmd(db Db) *IAVLNode {
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if self.height == 0 {
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return self
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}
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return self.rightFilled(db).rmd(db)
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}
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func (self *IAVLNode) traverse(db Db, cb func(*IAVLNode) bool) bool {
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stop := cb(self)
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if stop {
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return stop
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}
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if self.height > 0 {
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stop = self.leftFilled(db).traverse(db, cb)
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if stop {
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return stop
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}
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stop = self.rightFilled(db).traverse(db, cb)
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if stop {
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return stop
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}
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}
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return false
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}
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