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250 lines
5.3 KiB
250 lines
5.3 KiB
package merkle
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import (
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"bytes"
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"container/list"
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"sync"
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. "github.com/tendermint/tendermint/binary"
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. "github.com/tendermint/tendermint/db"
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)
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/*
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Immutable AVL Tree (wraps the Node root)
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This tree is not goroutine safe.
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*/
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type IAVLTree struct {
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keyCodec Codec
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valueCodec Codec
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root *IAVLNode
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ndb *nodeDB
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}
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func NewIAVLTree(keyCodec, valueCodec Codec, cacheSize int, db DB) *IAVLTree {
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if db == nil {
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// In-memory IAVLTree
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return &IAVLTree{
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keyCodec: keyCodec,
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valueCodec: valueCodec,
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}
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} else {
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// Persistent IAVLTree
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return &IAVLTree{
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keyCodec: keyCodec,
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valueCodec: valueCodec,
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ndb: newNodeDB(cacheSize, db),
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}
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}
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}
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// The returned tree and the original tree are goroutine independent.
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// That is, they can each run in their own goroutine.
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func (t *IAVLTree) Copy() Tree {
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if t.root == nil {
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return &IAVLTree{
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keyCodec: t.keyCodec,
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valueCodec: t.valueCodec,
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root: nil,
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ndb: t.ndb,
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}
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}
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if t.ndb != nil && !t.root.persisted {
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// Saving a tree finalizes all the nodes.
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// It sets all the hashes recursively,
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// clears all the leftNode/rightNode values recursively,
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// and all the .persisted flags get set.
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panic("It is unsafe to Copy() an unpersisted tree.")
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} else if t.ndb == nil && t.root.hash == nil {
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// An in-memory IAVLTree is finalized when the hashes are
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// calculated.
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t.root.hashWithCount(t)
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}
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return &IAVLTree{
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keyCodec: t.keyCodec,
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valueCodec: t.valueCodec,
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root: t.root,
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ndb: t.ndb,
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}
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}
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func (t *IAVLTree) Size() uint64 {
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if t.root == nil {
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return 0
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}
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return t.root.size
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}
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func (t *IAVLTree) Height() uint8 {
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if t.root == nil {
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return 0
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}
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return t.root.height
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}
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func (t *IAVLTree) Has(key interface{}) bool {
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if t.root == nil {
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return false
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}
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return t.root.has(t, key)
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}
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func (t *IAVLTree) Set(key interface{}, value interface{}) (updated bool) {
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if t.root == nil {
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t.root = NewIAVLNode(key, value)
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return false
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}
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t.root, updated = t.root.set(t, key, value)
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return updated
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}
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func (t *IAVLTree) Hash() []byte {
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if t.root == nil {
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return nil
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}
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hash, _ := t.root.hashWithCount(t)
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return hash
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}
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func (t *IAVLTree) HashWithCount() ([]byte, uint64) {
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if t.root == nil {
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return nil, 0
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}
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return t.root.hashWithCount(t)
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}
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func (t *IAVLTree) Save() []byte {
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if t.root == nil {
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return nil
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}
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return t.root.save(t)
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}
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func (t *IAVLTree) Load(hash []byte) {
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t.root = t.ndb.GetNode(t, hash)
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}
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func (t *IAVLTree) Get(key interface{}) (index uint64, value interface{}) {
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if t.root == nil {
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return 0, nil
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}
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return t.root.get(t, key)
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}
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func (t *IAVLTree) GetByIndex(index uint64) (key interface{}, value interface{}) {
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if t.root == nil {
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return nil, nil
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}
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return t.root.getByIndex(t, index)
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}
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func (t *IAVLTree) Remove(key interface{}) (value interface{}, removed bool) {
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if t.root == nil {
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return nil, false
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}
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newRootHash, newRoot, _, value, removed := t.root.remove(t, key)
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if !removed {
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return nil, false
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}
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if newRoot == nil && newRootHash != nil {
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t.root = t.ndb.GetNode(t, newRootHash)
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} else {
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t.root = newRoot
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}
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return value, true
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}
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func (t *IAVLTree) Iterate(fn func(key interface{}, value interface{}) bool) (stopped bool) {
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if t.root == nil {
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return false
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}
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return t.root.traverse(t, func(node *IAVLNode) bool {
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if node.height == 0 {
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return fn(node.key, node.value)
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} else {
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return false
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}
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})
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}
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//-----------------------------------------------------------------------------
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type nodeElement struct {
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node *IAVLNode
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elem *list.Element
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}
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type nodeDB struct {
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mtx sync.Mutex
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cache map[string]nodeElement
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cacheSize int
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cacheQueue *list.List
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db DB
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}
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func newNodeDB(cacheSize int, db DB) *nodeDB {
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return &nodeDB{
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cache: make(map[string]nodeElement),
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cacheSize: cacheSize,
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cacheQueue: list.New(),
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db: db,
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}
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}
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func (ndb *nodeDB) GetNode(t *IAVLTree, hash []byte) *IAVLNode {
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ndb.mtx.Lock()
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defer ndb.mtx.Unlock()
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// Check the cache.
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nodeElem, ok := ndb.cache[string(hash)]
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if ok {
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// Already exists. Move to back of cacheQueue.
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ndb.cacheQueue.MoveToBack(nodeElem.elem)
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return nodeElem.node
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} else {
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// Doesn't exist, load.
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buf := ndb.db.Get(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 := ReadIAVLNode(t, 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.persisted = true
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ndb.cacheNode(node)
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return node
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}
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}
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func (ndb *nodeDB) SaveNode(t *IAVLTree, node *IAVLNode) {
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ndb.mtx.Lock()
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defer ndb.mtx.Unlock()
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if node.hash == nil {
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panic("Expected to find node.hash, but none found.")
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}
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if node.persisted {
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panic("Shouldn't be calling save on an already persisted node.")
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}
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if _, ok := ndb.cache[string(node.hash)]; ok {
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panic("Shouldn't be calling save on an already cached node.")
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}
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// Save node bytes to db
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buf := bytes.NewBuffer(nil)
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_, _, err := node.writeToCountHashes(t, buf)
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if err != nil {
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panic(err)
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}
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ndb.db.Set(node.hash, buf.Bytes())
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node.persisted = true
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ndb.cacheNode(node)
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}
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func (ndb *nodeDB) cacheNode(node *IAVLNode) {
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// Create entry in cache and append to cacheQueue.
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elem := ndb.cacheQueue.PushBack(node.hash)
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ndb.cache[string(node.hash)] = nodeElement{node, elem}
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// Maybe expire an item.
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if ndb.cacheQueue.Len() > ndb.cacheSize {
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hash := ndb.cacheQueue.Remove(ndb.cacheQueue.Front()).([]byte)
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delete(ndb.cache, string(hash))
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}
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}
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