openethereum/util/src/trie/triedb.rs

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// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity 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 General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
use common::*;
use hashdb::*;
use nibbleslice::*;
use rlp::*;
use super::node::Node;
use super::recorder::{Recorder, NoOp};
use super::{Trie, TrieItem, TrieError};
/// A `Trie` implementation using a generic `HashDB` backing database.
///
/// Use it as a `Trie` trait object. You can use `db()` to get the backing database object, `keys`
/// to get the keys belonging to the trie in the backing database, and `db_items_remaining()` to get
/// which items in the backing database do not belong to this trie. If this is the only trie in the
/// backing database, then `db_items_remaining()` should be empty.
///
/// # Example
/// ```
/// extern crate ethcore_util as util;
///
/// use util::trie::*;
/// use util::hashdb::*;
/// use util::memorydb::*;
/// use util::hash::*;
///
/// fn main() {
/// let mut memdb = MemoryDB::new();
/// let mut root = H256::new();
/// TrieDBMut::new(&mut memdb, &mut root).insert(b"foo", b"bar").unwrap();
/// let t = TrieDB::new(&memdb, &root).unwrap();
/// assert!(t.contains(b"foo").unwrap());
/// assert_eq!(t.get(b"foo").unwrap().unwrap(), b"bar");
/// assert!(t.db_items_remaining().unwrap().is_empty());
/// }
/// ```
pub struct TrieDB<'db> {
db: &'db HashDB,
root: &'db H256,
/// The number of hashes performed so far in operations on this trie.
pub hash_count: usize,
}
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#[cfg_attr(feature="dev", allow(wrong_self_convention))]
impl<'db> TrieDB<'db> {
/// Create a new trie with the backing database `db` and `root`
/// Returns an error if `root` does not exist
pub fn new(db: &'db HashDB, root: &'db H256) -> super::Result<Self> {
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if !db.contains(root) {
Err(Box::new(TrieError::InvalidStateRoot(*root)))
} else {
Ok(TrieDB {
db: db,
root: root,
hash_count: 0
})
}
}
/// Get the backing database.
pub fn db(&'db self) -> &'db HashDB {
self.db
}
/// Determine all the keys in the backing database that belong to the trie.
pub fn keys(&self) -> super::Result<Vec<H256>> {
let mut ret: Vec<H256> = Vec::new();
ret.push(self.root.clone());
try!(self.accumulate_keys(try!(self.root_node(&mut NoOp)), &mut ret));
Ok(ret)
}
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/// Convert a vector of hashes to a hashmap of hash to occurrences.
pub fn to_map(hashes: Vec<H256>) -> HashMap<H256, u32> {
let mut r: HashMap<H256, u32> = HashMap::new();
for h in hashes.into_iter() {
*r.entry(h).or_insert(0) += 1;
}
r
}
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/// Determine occurrences of items in the backing database which are not related to this
/// trie.
pub fn db_items_remaining(&self) -> super::Result<HashMap<H256, i32>> {
let mut ret = self.db.keys();
for (k, v) in Self::to_map(try!(self.keys())).into_iter() {
let keycount = *ret.get(&k).unwrap_or(&0);
match keycount <= v as i32 {
true => ret.remove(&k),
_ => ret.insert(k, keycount - v as i32),
};
}
Ok(ret)
}
/// Recursion helper for `keys`.
fn accumulate_keys(&self, node: Node, acc: &mut Vec<H256>) -> super::Result<()> {
let mut handle_payload = |payload| {
let p = Rlp::new(payload);
if p.is_data() && p.size() == 32 {
acc.push(p.as_val());
}
self.accumulate_keys(try!(self.get_node(payload, &mut NoOp, 0)), acc)
};
match node {
Node::Extension(_, payload) => try!(handle_payload(payload)),
Node::Branch(payloads, _) => for payload in &payloads { try!(handle_payload(payload)) },
_ => {},
}
Ok(())
}
/// Get the root node's RLP.
fn root_node<'a, R: 'a + Recorder>(&self, r: &'a mut R) -> super::Result<Node> {
self.root_data(r).map(Node::decoded)
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}
/// Get the data of the root node.
fn root_data<'a, R: 'a + Recorder>(&self, r: &'a mut R) -> super::Result<&[u8]> {
self.db.get(self.root).ok_or_else(|| Box::new(TrieError::InvalidStateRoot(*self.root)))
.map(|node| { r.record(self.root, node, 0); node })
}
/// Get the root node as a `Node`.
fn get_node<'a, R: 'a + Recorder>(&'db self, node: &'db [u8], r: &'a mut R, depth: u32) -> super::Result<Node> {
self.get_raw_or_lookup(node, r, depth).map(Node::decoded)
}
/// Indentation helper for `formal_all`.
fn fmt_indent(&self, f: &mut fmt::Formatter, size: usize) -> fmt::Result {
for _ in 0..size {
try!(write!(f, " "));
}
Ok(())
}
/// Recursion helper for implementation of formatting trait.
fn fmt_all(&self, node: Node, f: &mut fmt::Formatter, deepness: usize) -> fmt::Result {
match node {
Node::Leaf(slice, value) => try!(writeln!(f, "'{:?}: {:?}.", slice, value.pretty())),
Node::Extension(ref slice, item) => {
try!(write!(f, "'{:?} ", slice));
if let Ok(node) = self.get_node(item, &mut NoOp, 0) {
try!(self.fmt_all(node, f, deepness));
}
},
Node::Branch(ref nodes, ref value) => {
try!(writeln!(f, ""));
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if let Some(v) = *value {
try!(self.fmt_indent(f, deepness + 1));
try!(writeln!(f, "=: {:?}", v.pretty()))
}
for i in 0..16 {
match self.get_node(nodes[i], &mut NoOp, 0) {
Ok(Node::Empty) => {},
Ok(n) => {
try!(self.fmt_indent(f, deepness + 1));
try!(write!(f, "'{:x} ", i));
try!(self.fmt_all(n, f, deepness + 1));
}
Err(e) => {
try!(write!(f, "ERROR: {}", e));
}
}
}
},
// empty
Node::Empty => {
try!(writeln!(f, "<empty>"));
}
};
Ok(())
}
/// Return optional data for a key given as a `NibbleSlice`. Returns `None` if no data exists.
fn do_lookup<'key, R: 'key>(&'db self, key: &NibbleSlice<'key>, r: &'key mut R) -> super::Result<Option<&'db [u8]>>
where 'db: 'key, R: Recorder
{
let root_rlp = try!(self.root_data(r));
self.get_from_node(root_rlp, key, r, 1)
}
/// Recursible function to retrieve the value given a `node` and a partial `key`. `None` if no
/// value exists for the key.
///
/// Note: Not a public API; use Trie trait functions.
fn get_from_node<'key, R: 'key>(
&'db self,
node: &'db [u8],
key: &NibbleSlice<'key>,
r: &'key mut R,
d: u32
) -> super::Result<Option<&'db [u8]>> where 'db: 'key, R: Recorder {
match Node::decoded(node) {
Node::Leaf(ref slice, value) if key == slice => Ok(Some(value)),
Node::Extension(ref slice, item) if key.starts_with(slice) => {
let data = try!(self.get_raw_or_lookup(item, r, d));
self.get_from_node(data, &key.mid(slice.len()), r, d + 1)
},
Node::Branch(ref nodes, value) => match key.is_empty() {
true => Ok(value),
false => {
let node = try!(self.get_raw_or_lookup(nodes[key.at(0) as usize], r, d));
self.get_from_node(node, &key.mid(1), r, d + 1)
}
},
_ => Ok(None)
}
}
/// Given some node-describing data `node`, return the actual node RLP.
/// This could be a simple identity operation in the case that the node is sufficiently small, but
/// may require a database lookup.
fn get_raw_or_lookup<R: Recorder>(&'db self, node: &'db [u8], rec: &mut R, d: u32) -> super::Result<&'db [u8]> {
// check if its sha3 + len
let r = Rlp::new(node);
match r.is_data() && r.size() == 32 {
true => {
let key = r.as_val::<H256>();
self.db.get(&key).ok_or_else(|| Box::new(TrieError::IncompleteDatabase(key)))
.map(|raw| { rec.record(&key, raw, d); raw })
}
false => Ok(node)
}
}
}
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#[derive(Clone, Eq, PartialEq)]
enum Status {
Entering,
At,
AtChild(usize),
Exiting,
}
#[derive(Clone, Eq, PartialEq)]
struct Crumb<'a> {
node: Node<'a>,
status: Status,
}
impl<'a> Crumb<'a> {
/// Move on to next status in the node's sequence.
fn increment(&mut self) {
self.status = match (&self.status, &self.node) {
(_, &Node::Empty) => Status::Exiting,
(&Status::Entering, _) => Status::At,
(&Status::At, &Node::Branch(_, _)) => Status::AtChild(0),
(&Status::AtChild(x), &Node::Branch(_, _)) if x < 15 => Status::AtChild(x + 1),
_ => Status::Exiting,
}
}
}
/// Iterator for going through all values in the trie.
#[derive(Clone)]
pub struct TrieDBIterator<'a> {
db: &'a TrieDB<'a>,
trail: Vec<Crumb<'a>>,
key_nibbles: Bytes,
}
impl<'a> TrieDBIterator<'a> {
/// Create a new iterator.
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pub fn new(db: &'a TrieDB) -> TrieDBIterator<'a> {
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let mut r = TrieDBIterator {
db: db,
trail: vec![],
key_nibbles: Vec::new(),
};
r.descend(db.root_data(&mut NoOp).unwrap());
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r
}
/// Descend into a payload.
fn descend(&mut self, d: &'a [u8]) {
self.trail.push(Crumb {
status: Status::Entering,
node: self.db.get_node(d, &mut NoOp, 0).unwrap(),
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});
match self.trail.last().unwrap().node {
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Node::Leaf(n, _) | Node::Extension(n, _) => { self.key_nibbles.extend(n.iter()); },
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_ => {}
}
}
/// Descend into a payload and get the next item.
fn descend_next(&mut self, d: &'a [u8]) -> Option<(Bytes, &'a [u8])> { self.descend(d); self.next() }
/// The present key.
fn key(&self) -> Bytes {
// collapse the key_nibbles down to bytes.
self.key_nibbles.iter().step(2).zip(self.key_nibbles.iter().skip(1).step(2)).map(|(h, l)| h * 16 + l).collect()
}
}
impl<'a> Iterator for TrieDBIterator<'a> {
type Item = (Bytes, &'a [u8]);
fn next(&mut self) -> Option<Self::Item> {
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
};
match (b.status, b.node) {
(Status::Exiting, n) => {
match n {
Node::Leaf(n, _) | Node::Extension(n, _) => {
let l = self.key_nibbles.len();
self.key_nibbles.truncate(l - n.len());
},
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Node::Branch(_, _) => { self.key_nibbles.pop(); },
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_ => {}
}
self.trail.pop();
self.next()
},
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(Status::At, Node::Leaf(_, v)) | (Status::At, Node::Branch(_, Some(v))) => Some((self.key(), v)),
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(Status::At, Node::Extension(_, d)) => self.descend_next(d),
(Status::At, Node::Branch(_, _)) => self.next(),
(Status::AtChild(i), Node::Branch(children, _)) if children[i].len() > 0 => {
match i {
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0 => self.key_nibbles.push(0),
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i => *self.key_nibbles.last_mut().unwrap() = i as u8,
}
self.descend_next(children[i])
},
(Status::AtChild(i), Node::Branch(_, _)) => {
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if i == 0 { self.key_nibbles.push(0); }
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self.next()
},
_ => panic!() // Should never see Entering or AtChild without a Branch here.
}
}
}
impl<'db> Trie for TrieDB<'db> {
fn iter<'a>(&'a self) -> Box<Iterator<Item = TrieItem> + 'a> {
Box::new(TrieDBIterator::new(self))
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}
fn root(&self) -> &H256 { self.root }
fn get_recorded<'a, 'b, R: 'b>(&'a self, key: &'b [u8], rec: &'b mut R) -> super::Result<Option<&'a [u8]>>
where 'a: 'b, R: Recorder
{
self.do_lookup(&NibbleSlice::new(key), rec)
}
}
impl<'db> fmt::Debug for TrieDB<'db> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(writeln!(f, "c={:?} [", self.hash_count));
let root_rlp = self.db.get(self.root).expect("Trie root not found!");
try!(self.fmt_all(Node::decoded(root_rlp), f, 0));
writeln!(f, "]")
}
}
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#[test]
fn iterator() {
use memorydb::*;
use super::TrieMut;
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use super::triedbmut::*;
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let d = vec![ &b"A"[..], &b"AA"[..], &b"AB"[..], &b"B"[..] ];
let mut memdb = MemoryDB::new();
let mut root = H256::new();
{
let mut t = TrieDBMut::new(&mut memdb, &mut root);
for x in &d {
t.insert(x, x).unwrap();
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}
}
let t = TrieDB::new(&memdb, &root).unwrap();
assert_eq!(d.iter().map(|i|i.to_vec()).collect::<Vec<_>>(), t.iter().map(|x|x.0).collect::<Vec<_>>());
assert_eq!(d, t.iter().map(|x|x.1).collect::<Vec<_>>());
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}