123 lines
3.5 KiB
Go
123 lines
3.5 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package light
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import (
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/trie"
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"golang.org/x/net/context"
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)
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// LightTrie is an ODR-capable wrapper around trie.SecureTrie
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type LightTrie struct {
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trie *trie.SecureTrie
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id *TrieID
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odr OdrBackend
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db ethdb.Database
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}
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// NewLightTrie creates a new LightTrie instance. It doesn't instantly try to
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// access the db or network and retrieve the root node, it only initializes its
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// encapsulated SecureTrie at the first actual operation.
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func NewLightTrie(id *TrieID, odr OdrBackend, useFakeMap bool) *LightTrie {
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return &LightTrie{
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// SecureTrie is initialized before first request
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id: id,
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odr: odr,
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db: odr.Database(),
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}
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}
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// retrieveKey retrieves a single key, returns true and stores nodes in local
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// database if successful
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func (t *LightTrie) retrieveKey(ctx context.Context, key []byte) bool {
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r := &TrieRequest{Id: t.id, Key: key}
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return t.odr.Retrieve(ctx, r) == nil
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}
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// do tries and retries to execute a function until it returns with no error or
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// an error type other than MissingNodeError
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func (t *LightTrie) do(ctx context.Context, fallbackKey []byte, fn func() error) error {
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err := fn()
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for err != nil {
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mn, ok := err.(*trie.MissingNodeError)
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if !ok {
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return err
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}
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var key []byte
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if mn.PrefixLen+mn.SuffixLen > 0 {
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key = mn.Key
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} else {
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key = fallbackKey
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}
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if !t.retrieveKey(ctx, key) {
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break
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}
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err = fn()
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}
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return err
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}
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// Get returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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func (t *LightTrie) Get(ctx context.Context, key []byte) (res []byte, err error) {
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err = t.do(ctx, key, func() (err error) {
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if t.trie == nil {
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t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
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}
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if err == nil {
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res, err = t.trie.TryGet(key)
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}
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return
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})
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return
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}
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// Update associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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func (t *LightTrie) Update(ctx context.Context, key, value []byte) (err error) {
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err = t.do(ctx, key, func() (err error) {
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if t.trie == nil {
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t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
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}
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if err == nil {
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err = t.trie.TryUpdate(key, value)
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}
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return
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})
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return
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}
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// Delete removes any existing value for key from the trie.
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func (t *LightTrie) Delete(ctx context.Context, key []byte) (err error) {
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err = t.do(ctx, key, func() (err error) {
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if t.trie == nil {
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t.trie, err = trie.NewSecure(t.id.Root, t.db, 0)
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}
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if err == nil {
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err = t.trie.TryDelete(key)
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}
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return
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})
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return
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}
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