119 lines
3.2 KiB
Rust
119 lines
3.2 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 hash::H256;
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use sha3::Hashable;
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use hashdb::{HashDB, DBValue};
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use super::{TrieDBMut, TrieMut};
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/// 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> {
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raw: TrieDBMut<'db>,
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}
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impl<'db> FatDBMut<'db> {
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/// Create a new trie with the backing database `db` and empty `root`
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/// Initialise to the state entailed by the genesis block.
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/// This guarantees the trie is built correctly.
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pub fn new(db: &'db mut HashDB, root: &'db mut H256) -> Self {
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FatDBMut { raw: TrieDBMut::new(db, root) }
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}
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/// Create a new trie with the backing database `db` and `root`.
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///
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/// Returns an error if root does not exist.
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pub fn from_existing(db: &'db mut HashDB, root: &'db mut H256) -> super::Result<Self> {
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Ok(FatDBMut { raw: TrieDBMut::from_existing(db, root)? })
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}
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/// Get the backing database.
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pub fn db(&self) -> &HashDB {
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self.raw.db()
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}
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/// Get the backing database.
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pub fn db_mut(&mut self) -> &mut HashDB {
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self.raw.db_mut()
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}
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fn to_aux_key(key: &[u8]) -> H256 {
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key.sha3()
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}
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}
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impl<'db> TrieMut for FatDBMut<'db> {
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fn root(&mut self) -> &H256 {
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self.raw.root()
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}
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fn is_empty(&self) -> bool {
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self.raw.is_empty()
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}
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fn contains(&self, key: &[u8]) -> super::Result<bool> {
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self.raw.contains(&key.sha3())
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}
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fn get<'a, 'key>(&'a self, key: &'key [u8]) -> super::Result<Option<DBValue>>
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where 'a: 'key
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{
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self.raw.get(&key.sha3())
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}
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fn insert(&mut self, key: &[u8], value: &[u8]) -> super::Result<Option<DBValue>> {
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let hash = key.sha3();
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let out = self.raw.insert(&hash, value)?;
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let db = self.raw.db_mut();
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// don't insert if it doesn't exist.
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if out.is_none() {
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db.emplace(Self::to_aux_key(&hash), DBValue::from_slice(key));
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}
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Ok(out)
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}
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fn remove(&mut self, key: &[u8]) -> super::Result<Option<DBValue>> {
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let hash = key.sha3();
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let out = self.raw.remove(&hash)?;
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// don't remove if it already exists.
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if out.is_some() {
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self.raw.db_mut().remove(&Self::to_aux_key(&hash));
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}
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Ok(out)
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}
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}
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#[test]
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fn fatdb_to_trie() {
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use memorydb::MemoryDB;
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use super::TrieDB;
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use super::Trie;
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let mut memdb = MemoryDB::new();
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let mut root = H256::default();
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{
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let mut t = FatDBMut::new(&mut memdb, &mut root);
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]).unwrap();
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}
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let t = TrieDB::new(&memdb, &root).unwrap();
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assert_eq!(t.get(&(&[0x01u8, 0x23]).sha3()).unwrap().unwrap(), DBValue::from_slice(&[0x01u8, 0x23]));
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}
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