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460 lines
12 KiB
460 lines
12 KiB
package merkle
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import (
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"bytes"
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"crypto/sha256"
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"io"
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"github.com/tendermint/tendermint/binary"
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)
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// Node
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type IAVLNode struct {
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key interface{}
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value interface{}
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height int8
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size int
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hash []byte
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leftHash []byte
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leftNode *IAVLNode
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rightHash []byte
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rightNode *IAVLNode
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persisted bool
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}
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func NewIAVLNode(key interface{}, value interface{}) *IAVLNode {
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return &IAVLNode{
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key: key,
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value: value,
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height: 0,
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size: 1,
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}
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}
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// NOTE: The hash is not saved or set. The caller should set the hash afterwards.
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// (Presumably the caller already has the hash)
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func ReadIAVLNode(t *IAVLTree, r io.Reader, n *int64, err *error) *IAVLNode {
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node := &IAVLNode{}
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// node header
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node.height = binary.ReadInt8(r, n, err)
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node.size = binary.ReadVarint(r, n, err)
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node.key = decodeByteSlice(t.keyCodec, r, n, err)
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if node.height == 0 {
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// value
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node.value = decodeByteSlice(t.valueCodec, r, n, err)
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} else {
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// children
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node.leftHash = binary.ReadByteSlice(r, n, err)
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node.rightHash = binary.ReadByteSlice(r, n, err)
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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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return node
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}
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func (node *IAVLNode) _copy() *IAVLNode {
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if node.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: node.key,
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height: node.height,
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size: node.size,
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hash: nil, // Going to be mutated anyways.
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leftHash: node.leftHash,
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leftNode: node.leftNode,
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rightHash: node.rightHash,
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rightNode: node.rightNode,
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persisted: false, // Going to be mutated, so it can't already be persisted.
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}
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}
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func (node *IAVLNode) has(t *IAVLTree, key interface{}) (has bool) {
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if t.keyCodec.Compare(node.key, key) == 0 {
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return true
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}
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if node.height == 0 {
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return false
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} else {
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if t.keyCodec.Compare(key, node.key) < 0 {
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return node.getLeftNode(t).has(t, key)
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} else {
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return node.getRightNode(t).has(t, key)
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}
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}
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}
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func (node *IAVLNode) get(t *IAVLTree, key interface{}) (index int, value interface{}) {
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if node.height == 0 {
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if t.keyCodec.Compare(node.key, key) == 0 {
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return 0, node.value
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} else {
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return 0, nil
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}
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} else {
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if t.keyCodec.Compare(key, node.key) < 0 {
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return node.getLeftNode(t).get(t, key)
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} else {
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rightNode := node.getRightNode(t)
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index, value = rightNode.get(t, key)
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index += node.size - rightNode.size
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return index, value
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}
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}
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}
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func (node *IAVLNode) getByIndex(t *IAVLTree, index int) (key interface{}, value interface{}) {
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if node.height == 0 {
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if index == 0 {
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return node.key, node.value
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} else {
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panic("getByIndex asked for invalid index")
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}
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} else {
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// TODO: could improve this by storing the
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// sizes as well as left/right hash.
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leftNode := node.getLeftNode(t)
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if index < leftNode.size {
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return leftNode.getByIndex(t, index)
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} else {
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return node.getRightNode(t).getByIndex(t, index-leftNode.size)
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}
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}
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}
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// NOTE: sets hashes recursively
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func (node *IAVLNode) hashWithCount(t *IAVLTree) ([]byte, int) {
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if node.hash != nil {
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return node.hash, 0
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}
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hasher := sha256.New()
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buf := new(bytes.Buffer)
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_, hashCount, err := node.writeHashBytes(t, buf)
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if err != nil {
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panic(err)
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}
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// fmt.Printf("Wrote IAVL hash bytes: %X\n", buf.Bytes())
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hasher.Write(buf.Bytes())
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node.hash = hasher.Sum(nil)
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// fmt.Printf("Write IAVL hash: %X\n", node.hash)
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return node.hash, hashCount + 1
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}
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// NOTE: sets hashes recursively
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func (node *IAVLNode) writeHashBytes(t *IAVLTree, w io.Writer) (n int64, hashCount int, err error) {
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// height & size
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binary.WriteInt8(node.height, w, &n, &err)
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binary.WriteVarint(node.size, w, &n, &err)
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// key is not written for inner nodes, unlike writePersistBytes
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if node.height == 0 {
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// key & value
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encodeByteSlice(node.key, t.keyCodec, w, &n, &err)
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encodeByteSlice(node.value, t.valueCodec, w, &n, &err)
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} else {
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// left
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if node.leftNode != nil {
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leftHash, leftCount := node.leftNode.hashWithCount(t)
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node.leftHash = leftHash
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hashCount += leftCount
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}
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if node.leftHash == nil {
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panic("node.leftHash was nil in writeHashBytes")
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}
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binary.WriteByteSlice(node.leftHash, w, &n, &err)
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// right
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if node.rightNode != nil {
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rightHash, rightCount := node.rightNode.hashWithCount(t)
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node.rightHash = rightHash
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hashCount += rightCount
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}
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if node.rightHash == nil {
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panic("node.rightHash was nil in writeHashBytes")
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}
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binary.WriteByteSlice(node.rightHash, w, &n, &err)
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}
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return
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}
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// NOTE: sets hashes recursively
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// NOTE: clears leftNode/rightNode recursively
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func (node *IAVLNode) save(t *IAVLTree) []byte {
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if node.hash == nil {
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node.hash, _ = node.hashWithCount(t)
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}
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if node.persisted {
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return node.hash
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}
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// save children
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if node.leftNode != nil {
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node.leftHash = node.leftNode.save(t)
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node.leftNode = nil
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}
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if node.rightNode != nil {
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node.rightHash = node.rightNode.save(t)
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node.rightNode = nil
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}
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// save node
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t.ndb.SaveNode(t, node)
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return node.hash
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}
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// NOTE: sets hashes recursively
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func (node *IAVLNode) writePersistBytes(t *IAVLTree, w io.Writer) (n int64, err error) {
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// node header
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binary.WriteInt8(node.height, w, &n, &err)
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binary.WriteVarint(node.size, w, &n, &err)
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// key (unlike writeHashBytes, key is written for inner nodes)
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encodeByteSlice(node.key, t.keyCodec, w, &n, &err)
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if node.height == 0 {
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// value
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encodeByteSlice(node.value, t.valueCodec, w, &n, &err)
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} else {
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// left
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if node.leftHash == nil {
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panic("node.leftHash was nil in writePersistBytes")
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}
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binary.WriteByteSlice(node.leftHash, w, &n, &err)
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// right
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if node.rightHash == nil {
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panic("node.rightHash was nil in writePersistBytes")
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}
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binary.WriteByteSlice(node.rightHash, w, &n, &err)
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}
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return
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}
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func (node *IAVLNode) set(t *IAVLTree, key interface{}, value interface{}) (newSelf *IAVLNode, updated bool) {
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if node.height == 0 {
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cmp := t.keyCodec.Compare(key, node.key)
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if cmp < 0 {
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return &IAVLNode{
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key: node.key,
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height: 1,
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size: 2,
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leftNode: NewIAVLNode(key, value),
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rightNode: node,
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}, false
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} else if cmp == 0 {
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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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leftNode: node,
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rightNode: NewIAVLNode(key, value),
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}, false
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}
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} else {
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node = node._copy()
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if t.keyCodec.Compare(key, node.key) < 0 {
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node.leftNode, updated = node.getLeftNode(t).set(t, key, value)
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node.leftHash = nil
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} else {
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node.rightNode, updated = node.getRightNode(t).set(t, key, value)
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node.rightHash = nil
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}
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if updated {
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return node, updated
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} else {
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node.calcHeightAndSize(t)
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return node.balance(t), updated
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}
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}
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}
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// newHash/newNode: The new hash or node to replace node after remove.
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// newKey: new leftmost leaf key for tree after successfully removing 'key' if changed.
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// value: removed value.
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func (node *IAVLNode) remove(t *IAVLTree, key interface{}) (
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newHash []byte, newNode *IAVLNode, newKey interface{}, value interface{}, removed bool) {
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if node.height == 0 {
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if t.keyCodec.Compare(key, node.key) == 0 {
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return nil, nil, nil, node.value, true
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} else {
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return nil, node, nil, nil, false
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}
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} else {
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if t.keyCodec.Compare(key, node.key) < 0 {
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var newLeftHash []byte
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var newLeftNode *IAVLNode
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newLeftHash, newLeftNode, newKey, value, removed = node.getLeftNode(t).remove(t, key)
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if !removed {
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return nil, node, nil, value, false
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} else if newLeftHash == nil && newLeftNode == nil { // left node held value, was removed
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return node.rightHash, node.rightNode, node.key, value, true
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}
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node = node._copy()
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node.leftHash, node.leftNode = newLeftHash, newLeftNode
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node.calcHeightAndSize(t)
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return nil, node.balance(t), newKey, value, true
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} else {
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var newRightHash []byte
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var newRightNode *IAVLNode
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newRightHash, newRightNode, newKey, value, removed = node.getRightNode(t).remove(t, key)
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if !removed {
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return nil, node, nil, value, false
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} else if newRightHash == nil && newRightNode == nil { // right node held value, was removed
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return node.leftHash, node.leftNode, nil, value, true
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}
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node = node._copy()
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node.rightHash, node.rightNode = newRightHash, newRightNode
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if newKey != nil {
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node.key = newKey
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newKey = nil
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}
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node.calcHeightAndSize(t)
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return nil, node.balance(t), newKey, value, true
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}
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}
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}
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func (node *IAVLNode) getLeftNode(t *IAVLTree) *IAVLNode {
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if node.leftNode != nil {
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return node.leftNode
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} else {
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return t.ndb.GetNode(t, node.leftHash)
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}
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}
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func (node *IAVLNode) getRightNode(t *IAVLTree) *IAVLNode {
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if node.rightNode != nil {
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return node.rightNode
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} else {
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return t.ndb.GetNode(t, node.rightHash)
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}
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}
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func (node *IAVLNode) rotateRight(t *IAVLTree) *IAVLNode {
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node = node._copy()
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sl := node.getLeftNode(t)._copy()
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slrHash, slrCached := sl.rightHash, sl.rightNode
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sl.rightHash, sl.rightNode = nil, node
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node.leftHash, node.leftNode = slrHash, slrCached
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node.calcHeightAndSize(t)
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sl.calcHeightAndSize(t)
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return sl
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}
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func (node *IAVLNode) rotateLeft(t *IAVLTree) *IAVLNode {
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node = node._copy()
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sr := node.getRightNode(t)._copy()
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srlHash, srlCached := sr.leftHash, sr.leftNode
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sr.leftHash, sr.leftNode = nil, node
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node.rightHash, node.rightNode = srlHash, srlCached
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node.calcHeightAndSize(t)
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sr.calcHeightAndSize(t)
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return sr
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}
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// NOTE: mutates height and size
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func (node *IAVLNode) calcHeightAndSize(t *IAVLTree) {
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node.height = maxInt8(node.getLeftNode(t).height, node.getRightNode(t).height) + 1
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node.size = node.getLeftNode(t).size + node.getRightNode(t).size
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}
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func (node *IAVLNode) calcBalance(t *IAVLTree) int {
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return int(node.getLeftNode(t).height) - int(node.getRightNode(t).height)
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}
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func (node *IAVLNode) balance(t *IAVLTree) (newSelf *IAVLNode) {
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balance := node.calcBalance(t)
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if balance > 1 {
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if node.getLeftNode(t).calcBalance(t) >= 0 {
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// Left Left Case
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return node.rotateRight(t)
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} else {
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// Left Right Case
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node = node._copy()
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node.leftHash, node.leftNode = nil, node.getLeftNode(t).rotateLeft(t)
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//node.calcHeightAndSize()
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return node.rotateRight(t)
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}
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}
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if balance < -1 {
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if node.getRightNode(t).calcBalance(t) <= 0 {
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// Right Right Case
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return node.rotateLeft(t)
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} else {
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// Right Left Case
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node = node._copy()
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node.rightHash, node.rightNode = nil, node.getRightNode(t).rotateRight(t)
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//node.calcHeightAndSize()
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return node.rotateLeft(t)
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}
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}
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// Nothing changed
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return node
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}
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func (node *IAVLNode) traverse(t *IAVLTree, cb func(*IAVLNode) bool) bool {
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stop := cb(node)
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if stop {
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return stop
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}
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if node.height > 0 {
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stop = node.getLeftNode(t).traverse(t, cb)
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if stop {
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return stop
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}
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stop = node.getRightNode(t).traverse(t, 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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// Only used in testing...
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func (node *IAVLNode) lmd(t *IAVLTree) *IAVLNode {
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if node.height == 0 {
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return node
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}
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return node.getLeftNode(t).lmd(t)
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}
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// Only used in testing...
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func (node *IAVLNode) rmd(t *IAVLTree) *IAVLNode {
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if node.height == 0 {
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return node
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}
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return node.getRightNode(t).rmd(t)
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}
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//--------------------------------------------------------------------------------
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// Read a (length prefixed) byteslice then decode the object using the codec
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func decodeByteSlice(codec binary.Codec, r io.Reader, n *int64, err *error) interface{} {
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bytez := binary.ReadByteSlice(r, n, err)
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if *err != nil {
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return nil
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}
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n_ := new(int64)
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return codec.Decode(bytes.NewBuffer(bytez), n_, err)
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}
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// Encode object using codec, then write a (length prefixed) byteslice.
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func encodeByteSlice(o interface{}, codec binary.Codec, w io.Writer, n *int64, err *error) {
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buf, n_ := new(bytes.Buffer), new(int64)
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codec.Encode(o, buf, n_, err)
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if *err != nil {
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return
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}
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binary.WriteByteSlice(buf.Bytes(), w, n, err)
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}
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