go-ethereum/light/trie.go
Felix Lange a31d268b76 trie: remove Key in MissingNodeError
The key was constructed from nibbles, which isn't possible for all
nodes. Remove the only use of Key in LightTrie by always retrying with
the original key that was looked up.
2017-04-18 14:52:11 +02:00

117 lines
3.4 KiB
Go

// Copyright 2015 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 light
import (
"context"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/trie"
)
// LightTrie is an ODR-capable wrapper around trie.SecureTrie
type LightTrie struct {
trie *trie.SecureTrie
id *TrieID
odr OdrBackend
db ethdb.Database
}
// NewLightTrie creates a new LightTrie instance. It doesn't instantly try to
// access the db or network and retrieve the root node, it only initializes its
// encapsulated SecureTrie at the first actual operation.
func NewLightTrie(id *TrieID, odr OdrBackend, useFakeMap bool) *LightTrie {
return &LightTrie{
// SecureTrie is initialized before first request
id: id,
odr: odr,
db: odr.Database(),
}
}
// retrieveKey retrieves a single key, returns true and stores nodes in local
// database if successful
func (t *LightTrie) retrieveKey(ctx context.Context, key []byte) bool {
r := &TrieRequest{Id: t.id, Key: crypto.Keccak256(key)}
return t.odr.Retrieve(ctx, r) == nil
}
// do tries and retries to execute a function until it returns with no error or
// an error type other than MissingNodeError
func (t *LightTrie) do(ctx context.Context, key []byte, fn func() error) error {
err := fn()
for err != nil {
if _, ok := err.(*trie.MissingNodeError); !ok {
return err
}
if !t.retrieveKey(ctx, key) {
break
}
err = fn()
}
return err
}
// Get returns the value for key stored in the trie.
// The value bytes must not be modified by the caller.
func (t *LightTrie) Get(ctx context.Context, key []byte) (res []byte, err error) {
err = t.do(ctx, key, func() (err error) {
if t.trie == nil {
t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
}
if err == nil {
res, err = t.trie.TryGet(key)
}
return
})
return
}
// Update associates key with value in the trie. Subsequent calls to
// Get will return value. If value has length zero, any existing value
// is deleted from the trie and calls to Get will return nil.
//
// The value bytes must not be modified by the caller while they are
// stored in the trie.
func (t *LightTrie) Update(ctx context.Context, key, value []byte) (err error) {
err = t.do(ctx, key, func() (err error) {
if t.trie == nil {
t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
}
if err == nil {
err = t.trie.TryUpdate(key, value)
}
return
})
return
}
// Delete removes any existing value for key from the trie.
func (t *LightTrie) Delete(ctx context.Context, key []byte) (err error) {
err = t.do(ctx, key, func() (err error) {
if t.trie == nil {
t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
}
if err == nil {
err = t.trie.TryDelete(key)
}
return
})
return
}