path: root/trie/trie.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package trie implements Merkle Patricia Tries.
package trie

import (
    "bytes"
    "container/list"
    "fmt"
    "sync"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
)

func ParanoiaCheck(t1 *Trie, backend Backend) (bool, *Trie) {
    t2 := New(nil, backend)

    it := t1.Iterator()
    for it.Next() {
        t2.Update(it.Key, it.Value)
    }

    return bytes.Equal(t2.Hash(), t1.Hash()), t2
}

type Trie struct {
    mu       sync.Mutex
    root     Node
    roothash []byte
    cache    *Cache

    revisions *list.List
}

func New(root []byte, backend Backend) *Trie {
    trie := &Trie{}
    trie.revisions = list.New()
    trie.roothash = root
    if backend != nil {
        trie.cache = NewCache(backend)
    }

    if root != nil {
        value := common.NewValueFromBytes(trie.cache.Get(root))
        trie.root = trie.mknode(value)
    }

    return trie
}

func (self *Trie) Iterator() *Iterator {
    return NewIterator(self)
}

func (self *Trie) Copy() *Trie {
    cpy := make([]byte, 32)
    copy(cpy, self.roothash) // NOTE: cpy isn't being used anywhere?
    trie := New(nil, nil)
    trie.cache = self.cache.Copy()
    if self.root != nil {
        trie.root = self.root.Copy(trie)
    }

    return trie
}

// Legacy support
func (self *Trie) Root() []byte { return self.Hash() }
func (self *Trie) Hash() []byte {
    var hash []byte
    if self.root != nil {
        t := self.root.Hash()
        if byts, ok := t.([]byte); ok && len(byts) > 0 {
            hash = byts
        } else {
            hash = crypto.Sha3(common.Encode(self.root.RlpData()))
        }
    } else {
        hash = crypto.Sha3(common.Encode(""))
    }

    if !bytes.Equal(hash, self.roothash) {
        self.revisions.PushBack(self.roothash)
        self.roothash = hash
    }

    return hash
}
func (self *Trie) Commit() {
    self.mu.Lock()
    defer self.mu.Unlock()

    // Hash first
    self.Hash()

    self.cache.Flush()
}

// Reset should only be called if the trie has been hashed
func (self *Trie) Reset() {
    self.mu.Lock()
    defer self.mu.Unlock()

    self.cache.Reset()

    if self.revisions.Len() > 0 {
        revision := self.revisions.Remove(self.revisions.Back()).([]byte)
        self.roothash = revision
    }
    value := common.NewValueFromBytes(self.cache.Get(self.roothash))
    self.root = self.mknode(value)
}

func (self *Trie) UpdateString(key, value string) Node { return self.Update([]byte(key), []byte(value)) }
func (self *Trie) Update(key, value []byte) Node {
    self.mu.Lock()
    defer self.mu.Unlock()

    k := CompactHexDecode(key)

    if len(value) != 0 {
        node := NewValueNode(self, value)
        node.dirty = true
        self.root = self.insert(self.root, k, node)
    } else {
        self.root = self.delete(self.root, k)
    }

    return self.root
}

func (self *Trie) GetString(key string) []byte { return self.Get([]byte(key)) }
func (self *Trie) Get(key []byte) []byte {
    self.mu.Lock()
    defer self.mu.Unlock()

    k := CompactHexDecode(key)

    n := self.get(self.root, k)
    if n != nil {
        return n.(*ValueNode).Val()
    }

    return nil
}

func (self *Trie) DeleteString(key string) Node { return self.Delete([]byte(key)) }
func (self *Trie) Delete(key []byte) Node {
    self.mu.Lock()
    defer self.mu.Unlock()

    k := CompactHexDecode(key)
    self.root = self.delete(self.root, k)

    return self.root
}

func (self *Trie) insert(node Node, key []byte, value Node) Node {
    if len(key) == 0 {
        return value
    }

    if node == nil {
        node := NewShortNode(self, key, value)
        node.dirty = true
        return node
    }

    switch node := node.(type) {
    case *ShortNode:
        k := node.Key()
        cnode := node.Value()
        if bytes.Equal(k, key) {
            node := NewShortNode(self, key, value)
            node.dirty = true
            return node

        }

        var n Node
        matchlength := MatchingNibbleLength(key, k)
        if matchlength == len(k) {
            n = self.insert(cnode, key[matchlength:], value)
        } else {
            pnode := self.insert(nil, k[matchlength+1:], cnode)
            nnode := self.insert(nil, key[matchlength+1:], value)
            fulln := NewFullNode(self)
            fulln.dirty = true
            fulln.set(k[matchlength], pnode)
            fulln.set(key[matchlength], nnode)
            n = fulln
        }
        if matchlength == 0 {
            return n
        }

        snode := NewShortNode(self, key[:matchlength], n)
        snode.dirty = true
        return snode

    case *FullNode:
        cpy := node.Copy(self).(*FullNode)
        cpy.set(key[0], self.insert(node.branch(key[0]), key[1:], value))
        cpy.dirty = true

        return cpy

    default:
        panic(fmt.Sprintf("%T: invalid node: %v", node, node))
    }
}

func (self *Trie) get(node Node, key []byte) Node {
    if len(key) == 0 {
        return node
    }

    if node == nil {
        return nil
    }

    switch node := node.(type) {
    case *ShortNode:
        k := node.Key()
        cnode := node.Value()

        if len(key) >= len(k) && bytes.Equal(k, key[:len(k)]) {
            return self.get(cnode, key[len(k):])
        }

        return nil
    case *FullNode:
        return self.get(node.branch(key[0]), key[1:])
    default:
        panic(fmt.Sprintf("%T: invalid node: %v", node, node))
    }
}

func (self *Trie) delete(node Node, key []byte) Node {
    if len(key) == 0 && node == nil {
        return nil
    }

    switch node := node.(type) {
    case *ShortNode:
        k := node.Key()
        cnode := node.Value()
        if bytes.Equal(key, k) {
            return nil
        } else if bytes.Equal(key[:len(k)], k) {
            child := self.delete(cnode, key[len(k):])

            var n Node
            switch child := child.(type) {
            case *ShortNode:
                nkey := append(k, child.Key()...)
                n = NewShortNode(self, nkey, child.Value())
                n.(*ShortNode).dirty = true
            case *FullNode:
                sn := NewShortNode(self, node.Key(), child)
                sn.dirty = true
                sn.key = node.key
                n = sn
            }

            return n
        } else {
            return node
        }

    case *FullNode:
        n := node.Copy(self).(*FullNode)
        n.set(key[0], self.delete(n.branch(key[0]), key[1:]))
        n.dirty = true

        pos := -1
        for i := 0; i < 17; i++ {
            if n.branch(byte(i)) != nil {
                if pos == -1 {
                    pos = i
                } else {
                    pos = -2
                }
            }
        }

        var nnode Node
        if pos == 16 {
            nnode = NewShortNode(self, []byte{16}, n.branch(byte(pos)))
            nnode.(*ShortNode).dirty = true
        } else if pos >= 0 {
            cnode := n.branch(byte(pos))
            switch cnode := cnode.(type) {
            case *ShortNode:
                // Stitch keys
                k := append([]byte{byte(pos)}, cnode.Key()...)
                nnode = NewShortNode(self, k, cnode.Value())
                nnode.(*ShortNode).dirty = true
            case *FullNode:
                nnode = NewShortNode(self, []byte{byte(pos)}, n.branch(byte(pos)))
                nnode.(*ShortNode).dirty = true
            }
        } else {
            nnode = n
        }

        return nnode
    case nil:
        return nil
    default:
        panic(fmt.Sprintf("%T: invalid node: %v (%v)", node, node, key))
    }
}

// casting functions and cache storing
func (self *Trie) mknode(value *common.Value) Node {
    l := value.Len()
    switch l {
    case 0:
        return nil
    case 2:
        // A value node may consists of 2 bytes.
        if value.Get(0).Len() != 0 {
            key := CompactDecode(value.Get(0).Bytes())
            if key[len(key)-1] == 16 {
                return NewShortNode(self, key, NewValueNode(self, value.Get(1).Bytes()))
            } else {
                return NewShortNode(self, key, self.mknode(value.Get(1)))
            }
        }
    case 17:
        if len(value.Bytes()) != 17 {
            fnode := NewFullNode(self)
            for i := 0; i < 16; i++ {
                fnode.set(byte(i), self.mknode(value.Get(i)))
            }
            return fnode
        }
    case 32:
        return NewHash(value.Bytes(), self)
    }

    return NewValueNode(self, value.Bytes())
}

func (self *Trie) trans(node Node) Node {
    switch node := node.(type) {
    case *HashNode:
        value := common.NewValueFromBytes(self.cache.Get(node.key))
        return self.mknode(value)
    default:
        return node
    }
}

func (self *Trie) store(node Node) interface{} {
    data := common.Encode(node)
    if len(data) >= 32 {
        key := crypto.Sha3(data)
        if node.Dirty() {
            //fmt.Println("save", node)
            //fmt.Println()
            self.cache.Put(key, data)
        }

        return key
    }

    return node.RlpData()
}

func (self *Trie) PrintRoot() {
    fmt.Println(self.root)
    fmt.Printf("root=%x\n", self.Root())
}