package mpt import ( "bytes" "sort" ) // Batch is batch of storage changes. // It stores key-value pairs in a sorted state. type Batch struct { kv []keyValue } type keyValue struct { key []byte value []byte } // Add adds key-value pair to batch. // If there is an item with the specified key, it is replaced. func (b *Batch) Add(key []byte, value []byte) { path := toNibbles(key) i := sort.Search(len(b.kv), func(i int) bool { return bytes.Compare(path, b.kv[i].key) <= 0 }) if i == len(b.kv) { b.kv = append(b.kv, keyValue{path, value}) } else if bytes.Equal(b.kv[i].key, path) { b.kv[i].value = value } else { b.kv = append(b.kv, keyValue{}) copy(b.kv[i+1:], b.kv[i:]) b.kv[i].key = path b.kv[i].value = value } } // PutBatch puts batch to trie. // It is not atomic (and probably cannot be without substantial slow-down) // and returns number of elements processed. // If an error is returned, the trie may be in the inconsistent state in case of storage failures. // This is due to the fact that we can remove multiple children from the branch node simultaneously // and won't strip the resulting branch node. // However it is used mostly after the block processing to update MPT and error is not expected. func (t *Trie) PutBatch(b Batch) (int, error) { r, n, err := t.putBatch(b.kv) t.root = r return n, err } func (t *Trie) putBatch(kv []keyValue) (Node, int, error) { return t.putBatchIntoNode(t.root, kv) } func (t *Trie) putBatchIntoNode(curr Node, kv []keyValue) (Node, int, error) { switch n := curr.(type) { case *LeafNode: return t.putBatchIntoLeaf(n, kv) case *BranchNode: return t.putBatchIntoBranch(n, kv) case *ExtensionNode: return t.putBatchIntoExtension(n, kv) case *HashNode: return t.putBatchIntoHash(n, kv) case EmptyNode: return t.putBatchIntoEmpty(kv) default: panic("invalid MPT node type") } } func (t *Trie) putBatchIntoLeaf(curr *LeafNode, kv []keyValue) (Node, int, error) { t.removeRef(curr.Hash(), curr.Bytes()) return t.newSubTrieMany(nil, kv, curr.value) } func (t *Trie) putBatchIntoBranch(curr *BranchNode, kv []keyValue) (Node, int, error) { return t.addToBranch(curr, kv, true) } func (t *Trie) mergeExtension(prefix []byte, sub Node) (Node, error) { switch sn := sub.(type) { case *ExtensionNode: t.removeRef(sn.Hash(), sn.bytes) sn.key = append(prefix, sn.key...) sn.invalidateCache() t.addRef(sn.Hash(), sn.bytes) return sn, nil case EmptyNode: return sn, nil case *HashNode: n, err := t.getFromStore(sn.Hash()) if err != nil { return sn, err } return t.mergeExtension(prefix, n) default: if len(prefix) != 0 { e := NewExtensionNode(prefix, sub) t.addRef(e.Hash(), e.bytes) return e, nil } return sub, nil } } func (t *Trie) putBatchIntoExtension(curr *ExtensionNode, kv []keyValue) (Node, int, error) { t.removeRef(curr.Hash(), curr.bytes) common := lcpMany(kv) pref := lcp(common, curr.key) if len(pref) == len(curr.key) { // Extension must be split into new nodes. stripPrefix(len(curr.key), kv) sub, n, err := t.putBatchIntoNode(curr.next, kv) if err == nil { sub, err = t.mergeExtension(pref, sub) } return sub, n, err } if len(pref) != 0 { stripPrefix(len(pref), kv) sub, n, err := t.putBatchIntoExtensionNoPrefix(curr.key[len(pref):], curr.next, kv) if err == nil { sub, err = t.mergeExtension(pref, sub) } return sub, n, err } return t.putBatchIntoExtensionNoPrefix(curr.key, curr.next, kv) } func (t *Trie) putBatchIntoExtensionNoPrefix(key []byte, next Node, kv []keyValue) (Node, int, error) { b := NewBranchNode() if len(key) > 1 { b.Children[key[0]] = t.newSubTrie(key[1:], next, false) } else { b.Children[key[0]] = next } return t.addToBranch(b, kv, false) } func isEmpty(n Node) bool { _, ok := n.(EmptyNode) return ok } // addToBranch puts items into the branch node assuming b is not yet in trie. func (t *Trie) addToBranch(b *BranchNode, kv []keyValue, inTrie bool) (Node, int, error) { if inTrie { t.removeRef(b.Hash(), b.bytes) } // Error during iterate means some storage failure (i.e. some hash node cannot be // retrieved from storage). This can leave trie in inconsistent state, because // it can be impossible to strip branch node after it has been changed. // Consider a branch with 10 children, first 9 of which are deleted and the remaining one // is a leaf node replaced by a hash node missing from storage. // This can't be fixed easily because we need to _revert_ changes in reference counts // for children which were updated successfully. But storage access errors means we are // in a bad state anyway. n, err := t.iterateBatch(kv, func(c byte, kv []keyValue) (int, error) { child, n, err := t.putBatchIntoNode(b.Children[c], kv) b.Children[c] = child return n, err }) if inTrie && n != 0 { b.invalidateCache() } // Even if some of the children can't be put, we need to try to strip branch // and possibly update refcounts. nd, bErr := t.stripBranch(b) if err == nil { err = bErr } return nd, n, err } // stripsBranch strips branch node after incomplete batch put. // It assumes there is no reference to b in trie. func (t *Trie) stripBranch(b *BranchNode) (Node, error) { var n int var lastIndex byte for i := range b.Children { if !isEmpty(b.Children[i]) { n++ lastIndex = byte(i) } } switch { case n == 0: return EmptyNode{}, nil case n == 1: if lastIndex != lastChild { return t.mergeExtension([]byte{lastIndex}, b.Children[lastIndex]) } return b.Children[lastIndex], nil default: t.addRef(b.Hash(), b.bytes) return b, nil } } func (t *Trie) iterateBatch(kv []keyValue, f func(c byte, kv []keyValue) (int, error)) (int, error) { var n int for len(kv) != 0 { c, i := getLastIndex(kv) if c != lastChild { stripPrefix(1, kv[:i]) } sub, err := f(c, kv[:i]) n += sub if err != nil { return n, err } kv = kv[i:] } return n, nil } func (t *Trie) putBatchIntoEmpty(kv []keyValue) (Node, int, error) { common := lcpMany(kv) stripPrefix(len(common), kv) return t.newSubTrieMany(common, kv, nil) } func (t *Trie) putBatchIntoHash(curr *HashNode, kv []keyValue) (Node, int, error) { result, err := t.getFromStore(curr.hash) if err != nil { return curr, 0, err } return t.putBatchIntoNode(result, kv) } // Creates new subtrie from provided key-value pairs. // Items in kv must have no common prefix. // If there are any deletions in kv, return error. // kv is not empty. // kv is sorted by key. // value is current value stored by prefix. func (t *Trie) newSubTrieMany(prefix []byte, kv []keyValue, value []byte) (Node, int, error) { if len(kv[0].key) == 0 { if kv[0].value == nil { if len(kv) == 1 { return EmptyNode{}, 1, nil } node, n, err := t.newSubTrieMany(prefix, kv[1:], nil) return node, n + 1, err } if len(kv) == 1 { return t.newSubTrie(prefix, NewLeafNode(kv[0].value), true), 1, nil } value = kv[0].value } // Prefix is empty and we have at least 2 children. b := NewBranchNode() if value != nil { // Empty key is always first. leaf := NewLeafNode(value) t.addRef(leaf.Hash(), leaf.bytes) b.Children[lastChild] = leaf } nd, n, err := t.addToBranch(b, kv, false) if err == nil { nd, err = t.mergeExtension(prefix, nd) } return nd, n, err } func stripPrefix(n int, kv []keyValue) { for i := range kv { kv[i].key = kv[i].key[n:] } } func getLastIndex(kv []keyValue) (byte, int) { if len(kv[0].key) == 0 { return lastChild, 1 } c := kv[0].key[0] for i := range kv[1:] { if kv[i+1].key[0] != c { return c, i + 1 } } return c, len(kv) }