openethereum/util/src/trie/fatdbmut.rs

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2016-06-27 10:59:59 +02:00
// 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 hash::H256;
use sha3::Hashable;
use hashdb::HashDB;
use super::{TrieDBMut, Trie, TrieMut, TrieError};
/// A mutable `Trie` implementation which hashes keys and uses a generic `HashDB` backing database.
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/// Additionaly it stores inserted hash-key mappings for later retrieval.
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///
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/// Use it as a `Trie` or `TrieMut` trait object.
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pub struct FatDBMut<'db> {
raw: TrieDBMut<'db>,
}
impl<'db> FatDBMut<'db> {
/// Create a new trie with the backing database `db` and empty `root`
/// Initialise to the state entailed by the genesis block.
/// This guarantees the trie is built correctly.
pub fn new(db: &'db mut HashDB, root: &'db mut H256) -> Self {
FatDBMut { raw: TrieDBMut::new(db, root) }
}
/// Create a new trie with the backing database `db` and `root`.
///
/// Returns an error if root does not exist.
pub fn from_existing(db: &'db mut HashDB, root: &'db mut H256) -> Result<Self, TrieError> {
Ok(FatDBMut { raw: try!(TrieDBMut::from_existing(db, root)) })
}
/// Get the backing database.
pub fn db(&self) -> &HashDB {
self.raw.db()
}
/// Get the backing database.
pub fn db_mut(&mut self) -> &mut HashDB {
self.raw.db_mut()
}
}
impl<'db> TrieMut for FatDBMut<'db> {
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fn root(&self) -> &H256 {
self.raw.root()
}
fn contains(&self, key: &[u8]) -> bool {
self.raw.contains(&key.sha3())
}
fn get<'a, 'key>(&'a self, key: &'key [u8]) -> Option<&'a [u8]> where 'a: 'key {
self.raw.get(&key.sha3())
}
fn insert(&mut self, key: &[u8], value: &[u8]) {
let hash = key.sha3();
self.raw.insert(&hash, value);
let db = self.raw.db_mut();
db.insert_aux(hash.to_vec(), key.to_vec());
}
fn remove(&mut self, key: &[u8]) {
self.raw.remove(&key.sha3());
}
}
#[test]
fn fatdb_to_trie() {
use memorydb::MemoryDB;
use super::TrieDB;
let mut memdb = MemoryDB::new();
let mut root = H256::default();
{
let mut t = FatDBMut::new(&mut memdb, &mut root);
t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
}
let t = TrieDB::new(&memdb, &root).unwrap();
assert_eq!(t.get(&(&[0x01u8, 0x23]).sha3()).unwrap(), &[0x01u8, 0x23]);
}