147 lines
4.3 KiB
Rust
147 lines
4.3 KiB
Rust
// Copyright 2015-2018 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 hashdb::{HashDB, Hasher};
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use super::{Result, DBValue, TrieDBMut, TrieMut};
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use node_codec::NodeCodec;
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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, H, C>
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where
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H: Hasher + 'db,
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C: NodeCodec<H>
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{
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raw: TrieDBMut<'db, H, C>,
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}
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impl<'db, H, C> FatDBMut<'db, H, C>
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where
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H: Hasher,
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C: NodeCodec<H>
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{
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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<H, DBValue>, root: &'db mut H::Out) -> 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<H, DBValue>, root: &'db mut H::Out) -> Result<Self, H::Out, C::Error> {
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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<H, DBValue> {
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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<H, DBValue> {
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self.raw.db_mut()
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}
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}
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impl<'db, H, C> TrieMut<H, C> for FatDBMut<'db, H, C>
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where
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H: Hasher,
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C: NodeCodec<H>
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{
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fn root(&mut self) -> &H::Out { self.raw.root() }
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fn is_empty(&self) -> bool { self.raw.is_empty() }
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fn contains(&self, key: &[u8]) -> Result<bool, H::Out, C::Error> {
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self.raw.contains(H::hash(key).as_ref())
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}
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fn get<'a, 'key>(&'a self, key: &'key [u8]) -> Result<Option<DBValue>, H::Out, C::Error>
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where 'a: 'key
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{
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self.raw.get(H::hash(key).as_ref())
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}
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fn insert(&mut self, key: &[u8], value: &[u8]) -> Result<Option<DBValue>, H::Out, C::Error> {
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let hash = H::hash(key);
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let out = self.raw.insert(hash.as_ref(), value)?;
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let db = self.raw.db_mut();
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// insert if it doesn't exist.
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if out.is_none() {
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let aux_hash = H::hash(hash.as_ref());
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db.emplace(aux_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]) -> Result<Option<DBValue>, H::Out, C::Error> {
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let hash = H::hash(key);
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let out = self.raw.remove(hash.as_ref())?;
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// remove if it already exists.
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if out.is_some() {
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let aux_hash = H::hash(hash.as_ref());
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self.raw.db_mut().remove(&aux_hash);
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}
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Ok(out)
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}
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}
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#[cfg(test)]
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mod test {
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use DBValue;
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use memorydb::MemoryDB;
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use ethtrie::trie::{Trie, TrieMut};
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use ethtrie::{TrieDB, FatDBMut};
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use keccak_hasher::KeccakHasher;
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use keccak;
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use ethereum_types::H256;
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#[test]
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fn fatdbmut_to_trie() {
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let mut memdb = MemoryDB::<KeccakHasher, DBValue>::new();
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let mut root = H256::new();
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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(&keccak::keccak(&[0x01u8, 0x23])), Ok(Some(DBValue::from_slice(&[0x01u8, 0x23]))));
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}
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#[test]
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fn fatdbmut_insert_remove_key_mapping() {
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let mut memdb = MemoryDB::<KeccakHasher, DBValue>::new();
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let mut root = H256::new();
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let key = [0x01u8, 0x23];
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let val = [0x01u8, 0x24];
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let key_hash = keccak::keccak(&key);
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let aux_hash = keccak::keccak(&key_hash);
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let mut t = FatDBMut::new(&mut memdb, &mut root);
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t.insert(&key, &val).unwrap();
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assert_eq!(t.get(&key), Ok(Some(DBValue::from_slice(&val))));
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assert_eq!(t.db().get(&aux_hash), Some(DBValue::from_slice(&key)));
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t.remove(&key).unwrap();
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assert_eq!(t.db().get(&aux_hash), None);
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}
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}
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