package ethutil
import (
"fmt"
"reflect"
)
// TODO
// A StateObject is an object that has a state root
// This is goig to be the object for the second level caching (the caching of object which have a state such as contracts)
type StateObject interface {
State() *Trie
Sync()
Undo()
}
type Node struct {
Key []byte
Value *Value
Dirty bool
}
func NewNode(key []byte, val *Value, dirty bool) *Node {
return &Node{Key: key, Value: val, Dirty: dirty}
}
func (n *Node) Copy() *Node {
return NewNode(n.Key, n.Value, n.Dirty)
}
type Cache struct {
nodes map[string]*Node
db Database
IsDirty bool
}
func NewCache(db Database) *Cache {
return &Cache{db: db, nodes: make(map[string]*Node)}
}
func (cache *Cache) Put(v interface{}) interface{} {
value := NewValue(v)
enc := value.Encode()
if len(enc) >= 32 {
sha := Sha3Bin(enc)
cache.nodes[string(sha)] = NewNode(sha, value, true)
cache.IsDirty = true
return sha
}
return v
}
func (cache *Cache) Get(key []byte) *Value {
// First check if the key is the cache
if cache.nodes[string(key)] != nil {
return cache.nodes[string(key)].Value
}
// Get the key of the database instead and cache it
data, _ := cache.db.Get(key)
// Create the cached value
value := NewValueFromBytes(data)
// Create caching node
cache.nodes[string(key)] = NewNode(key, value, false)
return value
}
func (cache *Cache) Commit() {
// Don't try to commit if it isn't dirty
if !cache.IsDirty {
return
}
for key, node := range cache.nodes {
if node.Dirty {
cache.db.Put([]byte(key), node.Value.Encode())
node.Dirty = false
}
}
cache.IsDirty = false
// If the nodes grows beyond the 200 entries we simple empty it
// FIXME come up with something better
if len(cache.nodes) > 200 {
cache.nodes = make(map[string]*Node)
}
}
func (cache *Cache) Undo() {
for key, node := range cache.nodes {
if node.Dirty {
delete(cache.nodes, key)
}
}
cache.IsDirty = false
}
// A (modified) Radix Trie implementation. The Trie implements
// a caching mechanism and will used cached values if they are
// present. If a node is not present in the cache it will try to
// fetch it from the database and store the cached value.
// Please note that the data isn't persisted unless `Sync` is
// explicitly called.
type Trie struct {
prevRoot interface{}
Root interface{}
//db Database
cache *Cache
}
func NewTrie(db Database, Root interface{}) *Trie {
return &Trie{cache: NewCache(db), Root: Root, prevRoot: Root}
}
// Save the cached value to the database.
func (t *Trie) Sync() {
t.cache.Commit()
t.prevRoot = t.Root
}
func (t *Trie) Undo() {
t.cache.Undo()
t.Root = t.prevRoot
}
func (t *Trie) Cache() *Cache {
return t.cache
}
/*
* Public (query) interface functions
*/
func (t *Trie) Update(key string, value string) {
k := CompactHexDecode(key)
t.Root = t.UpdateState(t.Root, k, value)
}
func (t *Trie) Get(key string) string {
k := CompactHexDecode(key)
c := NewValue(t.GetState(t.Root, k))
return c.Str()
}
func (t *Trie) GetState(node interface{}, key []int) interface{} {
n := NewValue(node)
// Return the node if key is empty (= found)
if len(key) == 0 || n.IsNil() || n.Len() == 0 {
return node
}
currentNode := t.GetNode(node)
length := currentNode.Len()
if length == 0 {
return ""
} else if length == 2 {
// Decode the key
k := CompactDecode(currentNode.Get(0).Str())
v := currentNode.Get(1).Raw()
if len(key) >= len(k) && CompareIntSlice(k, key[:len(k)]) {
return t.GetState(v, key[len(k):])
} else {
return ""
}
} else if length == 17 {
return t.GetState(currentNode.Get(key[0]).Raw(), key[1:])
}
// It shouldn't come this far
fmt.Println("GetState unexpected return")
return ""
}
func (t *Trie) GetNode(node interface{}) *Value {
n := NewValue(node)
if !n.Get(0).IsNil() {
return n
}
str := n.Str()
if len(str) == 0 {
return n
} else if len(str) < 32 {
return NewValueFromBytes([]byte(str))
}
return t.cache.Get(n.Bytes())
}
func (t *Trie) UpdateState(node interface{}, key []int, value string) interface{} {
if value != "" {
return t.InsertState(node, key, value)
} else {
// delete it
}
return ""
}
func (t *Trie) Put(node interface{}) interface{} {
/*
enc := Encode(node)
if len(enc) >= 32 {
var sha []byte
sha = Sha3Bin(enc)
//t.db.Put([]byte(sha), enc)
return sha
}
return node
*/
/*
TODO?
c := Conv(t.Root)
fmt.Println(c.Type(), c.Length())
if c.Type() == reflect.String && c.AsString() == "" {
return enc
}
*/
return t.cache.Put(node)
}
func EmptyStringSlice(l int) []interface{} {
slice := make([]interface{}, l)
for i := 0; i < l; i++ {
slice[i] = ""
}
return slice
}
func (t *Trie) InsertState(node interface{}, key []int, value interface{}) interface{} {
if len(key) == 0 {
return value
}
// New node
n := NewValue(node)
if node == nil || (n.Type() == reflect.String && (n.Str() == "" || n.Get(0).IsNil())) || n.Len() == 0 {
newNode := []interface{}{CompactEncode(key), value}
return t.Put(newNode)
}
currentNode := t.GetNode(node)
// Check for "special" 2 slice type node
if currentNode.Len() == 2 {
// Decode the key
k := CompactDecode(currentNode.Get(0).Str())
v := currentNode.Get(1).Raw()
// Matching key pair (ie. there's already an object with this key)
if CompareIntSlice(k, key) {
newNode := []interface{}{CompactEncode(key), value}
return t.Put(newNode)
}
var newHash interface{}
matchingLength := MatchingNibbleLength(key, k)
if matchingLength == len(k) {
// Insert the hash, creating a new node
newHash = t.InsertState(v, key[matchingLength:], value)
} else {
// Expand the 2 length slice to a 17 length slice
oldNode := t.InsertState("", k[matchingLength+1:], v)
newNode := t.InsertState("", key[matchingLength+1:], value)
// Create an expanded slice
scaledSlice := EmptyStringSlice(17)
// Set the copied and new node
scaledSlice[k[matchingLength]] = oldNode
scaledSlice[key[matchingLength]] = newNode
newHash = t.Put(scaledSlice)
}
if matchingLength == 0 {
// End of the chain, return
return newHash
} else {
newNode := []interface{}{CompactEncode(key[:matchingLength]), newHash}
return t.Put(newNode)
}
} else {
// Copy the current node over to the new node and replace the first nibble in the key
newNode := EmptyStringSlice(17)
for i := 0; i < 17; i++ {
cpy := currentNode.Get(i).Raw()
if cpy != nil {
newNode[i] = cpy
}
}
newNode[key[0]] = t.InsertState(currentNode.Get(key[0]).Raw(), key[1:], value)
return t.Put(newNode)
}
return ""
}
// Simple compare function which creates a rlp value out of the evaluated objects
func (t *Trie) Cmp(trie *Trie) bool {
return NewValue(t.Root).Cmp(NewValue(trie.Root))
}
// Returns a copy of this trie
func (t *Trie) Copy() *Trie {
trie := NewTrie(t.cache.db, t.Root)
for key, node := range t.cache.nodes {
trie.cache.nodes[key] = node.Copy()
}
return trie
}
