450 lines
13 KiB
Rust
450 lines
13 KiB
Rust
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU 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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// Parity 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 General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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use std::fmt;
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use common::*;
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use hashdb::*;
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use nibbleslice::*;
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use rlp::*;
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use super::node::{Node, OwnedNode};
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use super::lookup::Lookup;
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use super::{Trie, TrieItem, TrieError, TrieIterator, Query};
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/// A `Trie` implementation using a generic `HashDB` backing database.
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///
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/// Use it as a `Trie` trait object. You can use `db()` to get the backing database object.
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/// Use `get` and `contains` to query values associated with keys in the trie.
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///
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/// # Example
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/// ```
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/// extern crate ethcore_util as util;
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///
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/// use util::trie::*;
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/// use util::hashdb::*;
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/// use util::memorydb::*;
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/// use util::hash::*;
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///
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/// fn main() {
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/// let mut memdb = MemoryDB::new();
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/// let mut root = H256::new();
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/// TrieDBMut::new(&mut memdb, &mut root).insert(b"foo", b"bar").unwrap();
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/// let t = TrieDB::new(&memdb, &root).unwrap();
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/// assert!(t.contains(b"foo").unwrap());
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/// assert_eq!(t.get(b"foo").unwrap().unwrap(), DBValue::from_slice(b"bar"));
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/// }
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/// ```
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pub struct TrieDB<'db> {
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db: &'db HashDB,
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root: &'db H256,
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/// The number of hashes performed so far in operations on this trie.
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pub hash_count: usize,
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}
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#[cfg_attr(feature="dev", allow(wrong_self_convention))]
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impl<'db> TrieDB<'db> {
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/// Create a new trie with the backing database `db` and `root`
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/// Returns an error if `root` does not exist
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pub fn new(db: &'db HashDB, root: &'db H256) -> super::Result<Self> {
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if !db.contains(root) {
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Err(Box::new(TrieError::InvalidStateRoot(*root)))
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} else {
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Ok(TrieDB {
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db: db,
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root: root,
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hash_count: 0
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})
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}
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}
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/// Get the backing database.
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pub fn db(&'db self) -> &'db HashDB {
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self.db
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}
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/// Get the data of the root node.
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fn root_data(&self) -> super::Result<DBValue> {
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self.db.get(self.root).ok_or_else(|| Box::new(TrieError::InvalidStateRoot(*self.root)))
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}
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/// Indentation helper for `format_all`.
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fn fmt_indent(&self, f: &mut fmt::Formatter, size: usize) -> fmt::Result {
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for _ in 0..size {
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write!(f, " ")?;
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}
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Ok(())
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}
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/// Recursion helper for implementation of formatting trait.
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fn fmt_all(&self, node: Node, f: &mut fmt::Formatter, deepness: usize) -> fmt::Result {
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match node {
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Node::Leaf(slice, value) => writeln!(f, "'{:?}: {:?}.", slice, value.pretty())?,
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Node::Extension(ref slice, ref item) => {
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write!(f, "'{:?} ", slice)?;
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if let Ok(node) = self.get_raw_or_lookup(&*item) {
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self.fmt_all(Node::decoded(&node), f, deepness)?;
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}
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},
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Node::Branch(ref nodes, ref value) => {
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writeln!(f, "")?;
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if let Some(ref v) = *value {
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self.fmt_indent(f, deepness + 1)?;
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writeln!(f, "=: {:?}", v.pretty())?
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}
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for i in 0..16 {
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let node = self.get_raw_or_lookup(&*nodes[i]);
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match node.as_ref().map(|n| Node::decoded(&*n)) {
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Ok(Node::Empty) => {},
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Ok(n) => {
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self.fmt_indent(f, deepness + 1)?;
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write!(f, "'{:x} ", i)?;
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self.fmt_all(n, f, deepness + 1)?;
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}
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Err(e) => {
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write!(f, "ERROR: {}", e)?;
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}
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}
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}
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},
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// empty
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Node::Empty => {
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writeln!(f, "<empty>")?;
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}
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};
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Ok(())
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}
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/// Given some node-describing data `node`, return the actual node RLP.
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/// This could be a simple identity operation in the case that the node is sufficiently small, but
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/// may require a database lookup.
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fn get_raw_or_lookup(&'db self, node: &'db [u8]) -> super::Result<DBValue> {
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// check if its sha3 + len
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let r = Rlp::new(node);
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match r.is_data() && r.size() == 32 {
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true => {
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let key = r.as_val::<H256>();
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self.db.get(&key).ok_or_else(|| Box::new(TrieError::IncompleteDatabase(key)))
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}
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false => Ok(DBValue::from_slice(node))
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}
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}
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}
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impl<'db> Trie for TrieDB<'db> {
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fn iter<'a>(&'a self) -> super::Result<Box<TrieIterator<Item = TrieItem> + 'a>> {
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TrieDBIterator::new(self).map(|iter| Box::new(iter) as Box<_>)
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}
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fn root(&self) -> &H256 { self.root }
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fn get_with<'a, 'key, Q: Query>(&'a self, key: &'key [u8], query: Q) -> super::Result<Option<Q::Item>>
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where 'a: 'key
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{
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Lookup {
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db: self.db,
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query: query,
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hash: self.root.clone(),
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}.look_up(NibbleSlice::new(key))
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}
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}
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impl<'db> fmt::Debug for TrieDB<'db> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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writeln!(f, "c={:?} [", self.hash_count)?;
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let root_rlp = self.db.get(self.root).expect("Trie root not found!");
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self.fmt_all(Node::decoded(&root_rlp), f, 0)?;
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writeln!(f, "]")
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}
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}
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#[derive(Clone, Eq, PartialEq)]
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enum Status {
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Entering,
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At,
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AtChild(usize),
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Exiting,
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}
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#[derive(Clone, Eq, PartialEq)]
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struct Crumb {
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node: OwnedNode,
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status: Status,
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}
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impl Crumb {
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/// Move on to next status in the node's sequence.
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fn increment(&mut self) {
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self.status = match (&self.status, &self.node) {
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(_, &OwnedNode::Empty) => Status::Exiting,
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(&Status::Entering, _) => Status::At,
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(&Status::At, &OwnedNode::Branch(_, _)) => Status::AtChild(0),
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(&Status::AtChild(x), &OwnedNode::Branch(_, _)) if x < 15 => Status::AtChild(x + 1),
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_ => Status::Exiting,
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}
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}
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}
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/// Iterator for going through all values in the trie.
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#[derive(Clone)]
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pub struct TrieDBIterator<'a> {
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db: &'a TrieDB<'a>,
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trail: Vec<Crumb>,
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key_nibbles: Bytes,
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}
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impl<'a> TrieDBIterator<'a> {
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/// Create a new iterator.
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pub fn new(db: &'a TrieDB) -> super::Result<TrieDBIterator<'a>> {
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let mut r = TrieDBIterator {
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db: db,
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trail: vec![],
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key_nibbles: Vec::new(),
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};
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db.root_data().and_then(|root| r.descend(&root))?;
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Ok(r)
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}
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fn seek_descend<'key>(&mut self, node_data: DBValue, key: &NibbleSlice<'key>) -> super::Result<()> {
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let node = Node::decoded(&node_data);
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match node {
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Node::Leaf(ref slice, _) => {
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if slice == key {
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self.trail.push(Crumb {
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status: Status::At,
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node: node.clone().into(),
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});
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} else {
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self.trail.push(Crumb {
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status: Status::Exiting,
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node: node.clone().into(),
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});
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}
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self.key_nibbles.extend(slice.iter());
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Ok(())
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},
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Node::Extension(ref slice, ref item) => {
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if key.starts_with(slice) {
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self.trail.push(Crumb {
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status: Status::At,
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node: node.clone().into(),
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});
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self.key_nibbles.extend(slice.iter());
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let data = self.db.get_raw_or_lookup(&*item)?;
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self.seek_descend(data, &key.mid(slice.len()))
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} else {
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self.descend(&node_data)?;
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Ok(())
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}
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},
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Node::Branch(ref nodes, _) => match key.is_empty() {
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true => {
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self.trail.push(Crumb {
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status: Status::At,
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node: node.clone().into(),
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});
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Ok(())
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},
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false => {
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let i = key.at(0);
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self.trail.push(Crumb {
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status: Status::AtChild(i as usize),
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node: node.clone().into(),
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});
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self.key_nibbles.push(i);
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let child = self.db.get_raw_or_lookup(&*nodes[i as usize])?;
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self.seek_descend(child, &key.mid(1))
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}
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},
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_ => Ok(())
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}
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}
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/// Descend into a payload.
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fn descend(&mut self, d: &[u8]) -> super::Result<()> {
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self.trail.push(Crumb {
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status: Status::Entering,
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node: Node::decoded(&self.db.get_raw_or_lookup(d)?).into(),
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});
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match &self.trail.last().expect("just pushed item; qed").node {
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&OwnedNode::Leaf(ref n, _) | &OwnedNode::Extension(ref n, _) => {
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self.key_nibbles.extend((0..n.len()).map(|i| n.at(i)));
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},
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_ => {}
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}
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Ok(())
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}
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/// The present key.
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fn key(&self) -> Bytes {
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// collapse the key_nibbles down to bytes.
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self.key_nibbles.iter().step(2).zip(self.key_nibbles.iter().skip(1).step(2)).map(|(h, l)| h * 16 + l).collect()
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}
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}
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impl<'a> TrieIterator for TrieDBIterator<'a> {
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/// Position the iterator on the first element with key >= `key`
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fn seek(&mut self, key: &[u8]) -> super::Result<()> {
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self.trail.clear();
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self.key_nibbles.clear();
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let root_rlp = self.db.root_data()?;
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self.seek_descend(root_rlp, &NibbleSlice::new(key))
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}
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}
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impl<'a> Iterator for TrieDBIterator<'a> {
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type Item = TrieItem<'a>;
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fn next(&mut self) -> Option<Self::Item> {
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loop {
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let b = match self.trail.last_mut() {
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Some(mut b) => { b.increment(); b.clone() },
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None => return None,
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};
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match (b.status, b.node) {
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(Status::Exiting, n) => {
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match n {
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OwnedNode::Leaf(n, _) | OwnedNode::Extension(n, _) => {
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let l = self.key_nibbles.len();
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self.key_nibbles.truncate(l - n.len());
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},
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OwnedNode::Branch(_, _) => { self.key_nibbles.pop(); },
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_ => {}
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}
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self.trail.pop();
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// continue
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},
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(Status::At, OwnedNode::Leaf(_, v)) | (Status::At, OwnedNode::Branch(_, Some(v))) => {
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return Some(Ok((self.key(), v)));
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},
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(Status::At, OwnedNode::Extension(_, d)) => {
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if let Err(e) = self.descend(&*d) {
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return Some(Err(e));
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}
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// continue
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},
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(Status::At, OwnedNode::Branch(_, _)) => {},
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(Status::AtChild(i), OwnedNode::Branch(ref children, _)) if children[i].len() > 0 => {
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match i {
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0 => self.key_nibbles.push(0),
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i => *self.key_nibbles.last_mut()
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.expect("pushed as 0; moves sequentially; removed afterwards; qed") = i as u8,
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}
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if let Err(e) = self.descend(&*children[i]) {
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return Some(Err(e));
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}
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// continue
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},
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(Status::AtChild(i), OwnedNode::Branch(_, _)) => {
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if i == 0 {
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self.key_nibbles.push(0);
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}
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// continue
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},
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_ => panic!() // Should never see Entering or AtChild without a Branch here.
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}
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}
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}
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}
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#[test]
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fn iterator() {
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use memorydb::*;
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use super::TrieMut;
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use super::triedbmut::*;
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let d = vec![ DBValue::from_slice(b"A"), DBValue::from_slice(b"AA"), DBValue::from_slice(b"AB"), DBValue::from_slice(b"B") ];
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let mut memdb = MemoryDB::new();
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let mut root = H256::new();
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{
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let mut t = TrieDBMut::new(&mut memdb, &mut root);
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for x in &d {
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t.insert(x, x).unwrap();
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}
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}
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let t = TrieDB::new(&memdb, &root).unwrap();
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assert_eq!(d.iter().map(|i| i.clone().into_vec()).collect::<Vec<_>>(), t.iter().unwrap().map(|x| x.unwrap().0).collect::<Vec<_>>());
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assert_eq!(d, t.iter().unwrap().map(|x| x.unwrap().1).collect::<Vec<_>>());
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}
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#[test]
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fn iterator_seek() {
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use memorydb::*;
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use super::TrieMut;
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use super::triedbmut::*;
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let d = vec![ DBValue::from_slice(b"A"), DBValue::from_slice(b"AA"), DBValue::from_slice(b"AB"), DBValue::from_slice(b"B") ];
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let mut memdb = MemoryDB::new();
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let mut root = H256::new();
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{
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let mut t = TrieDBMut::new(&mut memdb, &mut root);
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for x in &d {
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t.insert(x, x).unwrap();
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}
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}
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let t = TrieDB::new(&memdb, &root).unwrap();
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let mut iter = t.iter().unwrap();
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assert_eq!(iter.next(), Some(Ok((b"A".to_vec(), DBValue::from_slice(b"A")))));
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iter.seek(b"!").unwrap();
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assert_eq!(d, iter.map(|x| x.unwrap().1).collect::<Vec<_>>());
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let mut iter = t.iter().unwrap();
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iter.seek(b"A").unwrap();
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assert_eq!(&d[1..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"AA").unwrap();
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assert_eq!(&d[2..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"A!").unwrap();
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assert_eq!(&d[1..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"AB").unwrap();
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assert_eq!(&d[3..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"AB!").unwrap();
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assert_eq!(&d[3..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"B").unwrap();
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assert_eq!(&d[4..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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let mut iter = t.iter().unwrap();
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iter.seek(b"C").unwrap();
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assert_eq!(&d[4..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
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}
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#[test]
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fn get_len() {
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use memorydb::*;
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use super::TrieMut;
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use super::triedbmut::*;
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let mut memdb = MemoryDB::new();
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let mut root = H256::new();
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{
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let mut t = TrieDBMut::new(&mut memdb, &mut root);
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t.insert(b"A", b"ABC").unwrap();
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t.insert(b"B", b"ABCBA").unwrap();
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}
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let t = TrieDB::new(&memdb, &root).unwrap();
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assert_eq!(t.get_with(b"A", |x: &[u8]| x.len()), Ok(Some(3)));
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assert_eq!(t.get_with(b"B", |x: &[u8]| x.len()), Ok(Some(5)));
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assert_eq!(t.get_with(b"C", |x: &[u8]| x.len()), Ok(None));
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}
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