115 lines
3.0 KiB
Rust
115 lines
3.0 KiB
Rust
// Copyright 2015, 2016 Ethcore (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;
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use super::{TrieDB, Trie, TrieDBIterator, TrieItem};
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/// A `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 FatDB<'db> {
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raw: TrieDB<'db>,
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}
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impl<'db> FatDB<'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 HashDB, root: &'db H256) -> super::Result<Self> {
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let fatdb = FatDB {
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raw: try!(TrieDB::new(db, root))
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};
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Ok(fatdb)
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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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/// Iterator over all key / vlaues in the trie.
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pub fn iter(&self) -> FatDBIterator {
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FatDBIterator::new(&self.raw)
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}
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}
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impl<'db> Trie for FatDB<'db> {
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fn iter<'a>(&'a self) -> Box<Iterator<Item = TrieItem> + 'a> {
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Box::new(FatDB::iter(self))
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}
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fn root(&self) -> &H256 {
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self.raw.root()
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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<&'a [u8]>>
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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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}
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/// Itarator over inserted pairs of key values.
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pub struct FatDBIterator<'db> {
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trie_iterator: TrieDBIterator<'db>,
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trie: &'db TrieDB<'db>,
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}
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impl<'db> FatDBIterator<'db> {
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/// Creates new iterator.
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pub fn new(trie: &'db TrieDB) -> Self {
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FatDBIterator {
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trie_iterator: TrieDBIterator::new(trie),
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trie: trie,
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}
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}
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}
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impl<'db> Iterator for FatDBIterator<'db> {
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type Item = (Vec<u8>, &'db [u8]);
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fn next(&mut self) -> Option<Self::Item> {
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self.trie_iterator.next()
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.map(|(hash, value)| {
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(self.trie.db().get_aux(&hash).expect("Missing fatdb hash"), value)
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})
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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 trie::{FatDBMut, TrieMut};
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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 = FatDB::new(&memdb, &root).unwrap();
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assert_eq!(t.get(&[0x01u8, 0x23]).unwrap().unwrap(), &[0x01u8, 0x23]);
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assert_eq!(t.iter().collect::<Vec<_>>(), vec![(vec![0x01u8, 0x23], &[0x01u8, 0x23] as &[u8])]);
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}
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