c213fd1fd8
There is no need to depend on the old context package now that the minimum Go version is 1.7. The move to "context" eliminates our weird vendoring setup. Some vendored code still uses golang.org/x/net/context and it is now vendored in the normal way. This change triggered new vet checks around context.WithTimeout which didn't fire with golang.org/x/net/context.
124 lines
3.5 KiB
Go
124 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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"context"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/trie"
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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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