104 lines
2.9 KiB
Rust
104 lines
2.9 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 std::default::Default;
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use sha3::*;
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use hash::H256;
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use bytes::*;
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use rlp::*;
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use hashdb::*;
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/// Type of operation for the backing database - either a new node or a node deletion.
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#[derive(Debug)]
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enum Operation {
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New(H256, DBValue),
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Delete(H256),
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}
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/// How many insertions and removals were done in an `apply` operation.
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pub struct Score {
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/// Number of insertions.
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pub inserts: usize,
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/// Number of removals.
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pub removes: usize,
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}
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/// A journal of operations on the backing database.
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#[derive(Debug)]
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pub struct Journal (Vec<Operation>);
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impl Default for Journal {
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fn default() -> Self {
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Journal::new()
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}
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}
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impl Journal {
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/// Create a new, empty, object.
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pub fn new() -> Journal { Journal(vec![]) }
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/// Given the RLP that encodes a node, append a reference to that node `out` and leave `journal`
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/// such that the reference is valid, once applied.
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pub fn new_node(&mut self, rlp: DBValue, out: &mut RlpStream) {
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if rlp.len() >= 32 {
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let rlp_sha3 = rlp.sha3();
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trace!("new_node: reference node {:?} => {:?}", rlp_sha3, &*rlp);
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out.append(&rlp_sha3);
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self.0.push(Operation::New(rlp_sha3, rlp));
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}
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else {
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trace!("new_node: inline node {:?}", &*rlp);
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out.append_raw(&rlp, 1);
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}
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}
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/// Given the RLP that encodes a now-unused node, leave `journal` in such a state that it is noted.
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pub fn delete_node_sha3(&mut self, old_sha3: H256) {
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trace!("delete_node: {:?}", old_sha3);
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self.0.push(Operation::Delete(old_sha3));
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}
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/// Register an RLP-encoded node for deletion (given a slice), if it needs to be deleted.
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pub fn delete_node(&mut self, old: &[u8]) {
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let r = Rlp::new(old);
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if r.is_data() && r.size() == 32 {
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self.delete_node_sha3(r.as_val());
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}
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}
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/// Apply this journal to the HashDB `db` and return the number of insertions and removals done.
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pub fn apply(self, db: &mut HashDB) -> Score {
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trace!("applying {:?} changes", self.0.len());
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let mut ret = Score{inserts: 0, removes: 0};
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for d in self.0.into_iter() {
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match d {
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Operation::Delete(h) => {
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trace!("TrieDBMut::apply --- {:?}", &h);
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db.remove(&h);
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ret.removes += 1;
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},
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Operation::New(h, d) => {
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trace!("TrieDBMut::apply +++ {:?} -> {:?}", &h, d.pretty());
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db.emplace(h, d);
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ret.inserts += 1;
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}
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}
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}
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ret
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}
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}
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