430 lines
12 KiB
Rust
430 lines
12 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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//! Disk-backed HashDB implementation.
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use common::*;
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use rlp::*;
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use hashdb::*;
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use memorydb::*;
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use rocksdb::{DB, Writable, WriteBatch, IteratorMode};
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#[cfg(test)]
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use std::env;
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/// Implementation of the HashDB trait for a disk-backed database with a memory overlay
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/// and latent-removal semantics.
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///
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/// Like OverlayDB, there is a memory overlay; `commit()` must be called in order to
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/// write operations out to disk. Unlike OverlayDB, `remove()` operations do not take effect
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/// immediately. Rather some age (based on a linear but arbitrary metric) must pass before
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/// the removals actually take effect.
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pub struct JournalDB {
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overlay: MemoryDB,
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backing: Arc<DB>,
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counters: Arc<RwLock<HashMap<H256, i32>>>,
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}
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impl Clone for JournalDB {
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fn clone(&self) -> JournalDB {
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JournalDB {
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overlay: MemoryDB::new(),
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backing: self.backing.clone(),
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counters: self.counters.clone(),
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}
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}
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}
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const LAST_ERA_KEY : [u8; 4] = [ b'l', b'a', b's', b't' ];
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const VERSION_KEY : [u8; 4] = [ b'j', b'v', b'e', b'r' ];
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const DB_VERSION: u32 = 1;
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impl JournalDB {
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/// Create a new instance given a `backing` database.
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pub fn new(backing: DB) -> JournalDB {
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let db = Arc::new(backing);
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JournalDB::new_with_arc(db)
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}
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/// Create a new instance given a shared `backing` database.
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pub fn new_with_arc(backing: Arc<DB>) -> JournalDB {
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if backing.iterator(IteratorMode::Start).next().is_some() {
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match backing.get(&VERSION_KEY).map(|d| d.map(|v| decode::<u32>(&v))) {
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Ok(Some(DB_VERSION)) => {},
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v => panic!("Incompatible DB version, expected {}, got {:?}", DB_VERSION, v)
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}
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} else {
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backing.put(&VERSION_KEY, &encode(&DB_VERSION)).expect("Error writing version to database");
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}
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let counters = JournalDB::read_counters(&backing);
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JournalDB {
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overlay: MemoryDB::new(),
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backing: backing,
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counters: Arc::new(RwLock::new(counters)),
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}
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}
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/// Create a new instance with an anonymous temporary database.
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#[cfg(test)]
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pub fn new_temp() -> JournalDB {
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let mut dir = env::temp_dir();
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dir.push(H32::random().hex());
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Self::new(DB::open_default(dir.to_str().unwrap()).unwrap())
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}
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/// Check if this database has any commits
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pub fn is_empty(&self) -> bool {
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self.backing.get(&LAST_ERA_KEY).expect("Low level database error").is_none()
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}
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/// Commit all recent insert operations and historical removals from the old era
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/// to the backing database.
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pub fn commit(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
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// journal format:
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// [era, 0] => [ id, [insert_0, ...], [remove_0, ...] ]
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// [era, 1] => [ id, [insert_0, ...], [remove_0, ...] ]
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// [era, n] => [ ... ]
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// TODO: store reclaim_period.
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// when we make a new commit, we journal the inserts and removes.
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// for each end_era that we journaled that we are no passing by,
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// we remove all of its removes assuming it is canonical and all
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// of its inserts otherwise.
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//
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// We also keep reference counters for each key inserted in the journal to handle
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// the following cases where key K must not be deleted from the DB when processing removals :
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// Given H is the journal size in eras, 0 <= C <= H.
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// Key K is removed in era A(N) and re-inserted in canonical era B(N + C).
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// Key K is removed in era A(N) and re-inserted in non-canonical era B`(N + C).
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// Key K is added in non-canonical era A'(N) canonical B(N + C).
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//
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// The counter is encreased each time a key is inserted in the journal in the commit. The list of insertions
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// is saved with the era record. When the era becomes end_era and goes out of journal the counter is decreased
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// and the key is safe to delete.
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// record new commit's details.
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let batch = WriteBatch::new();
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let mut counters = self.counters.write().unwrap();
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{
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let mut index = 0usize;
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let mut last;
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while try!(self.backing.get({
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let mut r = RlpStream::new_list(2);
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r.append(&now);
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r.append(&index);
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last = r.drain();
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&last
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})).is_some() {
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index += 1;
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}
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let mut r = RlpStream::new_list(3);
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let inserts: Vec<H256> = self.overlay.keys().iter().filter(|&(_, &c)| c > 0).map(|(key, _)| key.clone()).collect();
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// Increase counter for each inserted key no matter if the block is canonical or not.
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for i in &inserts {
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*counters.entry(i.clone()).or_insert(0) += 1;
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}
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let removes: Vec<H256> = self.overlay.keys().iter().filter(|&(_, &c)| c < 0).map(|(key, _)| key.clone()).collect();
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r.append(id);
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r.append(&inserts);
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r.append(&removes);
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try!(batch.put(&last, r.as_raw()));
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}
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// apply old commits' details
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if let Some((end_era, canon_id)) = end {
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let mut index = 0usize;
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let mut last;
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let mut to_remove: Vec<H256> = Vec::new();
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let mut canon_inserts: Vec<H256> = Vec::new();
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while let Some(rlp_data) = try!(self.backing.get({
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let mut r = RlpStream::new_list(2);
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r.append(&end_era);
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r.append(&index);
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last = r.drain();
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&last
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})) {
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let rlp = Rlp::new(&rlp_data);
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let inserts: Vec<H256> = rlp.val_at(1);
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JournalDB::decrease_counters(&inserts, &mut counters);
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// Collect keys to be removed. These are removed keys for canonical block, inserted for non-canonical
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if canon_id == rlp.val_at(0) {
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to_remove.extend(rlp.at(2).iter().map(|r| r.as_val::<H256>()));
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canon_inserts = inserts;
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}
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else {
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to_remove.extend(inserts);
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}
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try!(batch.delete(&last));
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index += 1;
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}
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let canon_inserts = canon_inserts.drain(..).collect::<HashSet<_>>();
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// Purge removed keys if they are not referenced and not re-inserted in the canon commit
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let mut deletes = 0;
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for h in to_remove.iter().filter(|h| !counters.contains_key(h) && !canon_inserts.contains(h)) {
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try!(batch.delete(&h));
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deletes += 1;
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}
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try!(batch.put(&LAST_ERA_KEY, &encode(&end_era)));
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trace!("JournalDB: delete journal for time #{}.{}, (canon was {}): {} entries", end_era, index, canon_id, deletes);
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}
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// Commit overlay insertions
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let mut ret = 0u32;
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let mut deletes = 0usize;
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for i in self.overlay.drain().into_iter() {
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let (key, (value, rc)) = i;
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if rc > 0 {
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assert!(rc == 1);
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batch.put(&key.bytes(), &value).expect("Low-level database error. Some issue with your hard disk?");
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ret += 1;
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}
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if rc < 0 {
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assert!(rc == -1);
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ret += 1;
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deletes += 1;
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}
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}
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try!(self.backing.write(batch));
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trace!("JournalDB::commit() deleted {} nodes", deletes);
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Ok(ret)
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}
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// Decrease counters for given keys. Deletes obsolete counters
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fn decrease_counters(keys: &[H256], counters: &mut HashMap<H256, i32>) {
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for i in keys.iter() {
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let delete_counter = {
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let cnt = counters.get_mut(i).expect("Missing key counter");
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*cnt -= 1;
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*cnt == 0
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};
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if delete_counter {
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counters.remove(i);
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}
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}
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}
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fn payload(&self, key: &H256) -> Option<Bytes> {
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self.backing.get(&key.bytes()).expect("Low-level database error. Some issue with your hard disk?").map(|v| v.to_vec())
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}
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fn read_counters(db: &DB) -> HashMap<H256, i32> {
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let mut res = HashMap::new();
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if let Some(val) = db.get(&LAST_ERA_KEY).expect("Low-level database error.") {
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let mut era = decode::<u64>(&val) + 1;
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loop {
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let mut index = 0usize;
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while let Some(rlp_data) = db.get({
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let mut r = RlpStream::new_list(2);
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r.append(&era);
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r.append(&index);
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&r.drain()
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}).expect("Low-level database error.") {
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let rlp = Rlp::new(&rlp_data);
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let to_add: Vec<H256> = rlp.val_at(1);
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for h in to_add {
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*res.entry(h).or_insert(0) += 1;
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}
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index += 1;
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};
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if index == 0 {
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break;
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}
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era += 1;
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}
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}
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trace!("Recovered {} counters", res.len());
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res
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}
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}
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impl HashDB for JournalDB {
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fn keys(&self) -> HashMap<H256, i32> {
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let mut ret: HashMap<H256, i32> = HashMap::new();
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for (key, _) in self.backing.iterator(IteratorMode::Start) {
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let h = H256::from_slice(key.deref());
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ret.insert(h, 1);
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}
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for (key, refs) in self.overlay.keys().into_iter() {
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let refs = *ret.get(&key).unwrap_or(&0) + refs;
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ret.insert(key, refs);
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}
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ret
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}
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fn lookup(&self, key: &H256) -> Option<&[u8]> {
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let k = self.overlay.raw(key);
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match k {
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Some(&(ref d, rc)) if rc > 0 => Some(d),
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_ => {
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if let Some(x) = self.payload(key) {
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Some(&self.overlay.denote(key, x).0)
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}
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else {
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None
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}
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}
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}
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}
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fn exists(&self, key: &H256) -> bool {
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self.lookup(key).is_some()
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}
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fn insert(&mut self, value: &[u8]) -> H256 {
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self.overlay.insert(value)
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}
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fn emplace(&mut self, key: H256, value: Bytes) {
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self.overlay.emplace(key, value);
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}
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fn kill(&mut self, key: &H256) {
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self.overlay.kill(key);
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}
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}
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#[cfg(test)]
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mod tests {
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use common::*;
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use super::*;
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use hashdb::*;
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#[test]
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fn long_history() {
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// history is 3
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let mut jdb = JournalDB::new_temp();
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let h = jdb.insert(b"foo");
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jdb.commit(0, &b"0".sha3(), None).unwrap();
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assert!(jdb.exists(&h));
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jdb.remove(&h);
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jdb.commit(1, &b"1".sha3(), None).unwrap();
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assert!(jdb.exists(&h));
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jdb.commit(2, &b"2".sha3(), None).unwrap();
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assert!(jdb.exists(&h));
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jdb.commit(3, &b"3".sha3(), Some((0, b"0".sha3()))).unwrap();
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assert!(jdb.exists(&h));
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jdb.commit(4, &b"4".sha3(), Some((1, b"1".sha3()))).unwrap();
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assert!(!jdb.exists(&h));
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}
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#[test]
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fn complex() {
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// history is 1
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let mut jdb = JournalDB::new_temp();
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let foo = jdb.insert(b"foo");
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let bar = jdb.insert(b"bar");
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jdb.commit(0, &b"0".sha3(), None).unwrap();
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assert!(jdb.exists(&foo));
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assert!(jdb.exists(&bar));
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jdb.remove(&foo);
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jdb.remove(&bar);
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let baz = jdb.insert(b"baz");
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jdb.commit(1, &b"1".sha3(), Some((0, b"0".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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assert!(jdb.exists(&bar));
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assert!(jdb.exists(&baz));
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let foo = jdb.insert(b"foo");
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jdb.remove(&baz);
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jdb.commit(2, &b"2".sha3(), Some((1, b"1".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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assert!(!jdb.exists(&bar));
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assert!(jdb.exists(&baz));
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jdb.remove(&foo);
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jdb.commit(3, &b"3".sha3(), Some((2, b"2".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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assert!(!jdb.exists(&bar));
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assert!(!jdb.exists(&baz));
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jdb.commit(4, &b"4".sha3(), Some((3, b"3".sha3()))).unwrap();
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assert!(!jdb.exists(&foo));
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assert!(!jdb.exists(&bar));
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assert!(!jdb.exists(&baz));
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}
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#[test]
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fn fork() {
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// history is 1
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let mut jdb = JournalDB::new_temp();
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let foo = jdb.insert(b"foo");
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let bar = jdb.insert(b"bar");
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jdb.commit(0, &b"0".sha3(), None).unwrap();
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assert!(jdb.exists(&foo));
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assert!(jdb.exists(&bar));
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jdb.remove(&foo);
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let baz = jdb.insert(b"baz");
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jdb.commit(1, &b"1a".sha3(), Some((0, b"0".sha3()))).unwrap();
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jdb.remove(&bar);
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jdb.commit(1, &b"1b".sha3(), Some((0, b"0".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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assert!(jdb.exists(&bar));
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assert!(jdb.exists(&baz));
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jdb.commit(2, &b"2b".sha3(), Some((1, b"1b".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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assert!(!jdb.exists(&baz));
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assert!(!jdb.exists(&bar));
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}
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#[test]
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fn overwrite() {
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// history is 1
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let mut jdb = JournalDB::new_temp();
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let foo = jdb.insert(b"foo");
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jdb.commit(0, &b"0".sha3(), None).unwrap();
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assert!(jdb.exists(&foo));
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jdb.remove(&foo);
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jdb.commit(1, &b"1".sha3(), Some((0, b"0".sha3()))).unwrap();
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jdb.insert(b"foo");
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assert!(jdb.exists(&foo));
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jdb.commit(2, &b"2".sha3(), Some((1, b"1".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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jdb.commit(3, &b"2".sha3(), Some((0, b"2".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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}
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#[test]
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fn fork_same_key() {
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// history is 1
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let mut jdb = JournalDB::new_temp();
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jdb.commit(0, &b"0".sha3(), None).unwrap();
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let foo = jdb.insert(b"foo");
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jdb.commit(1, &b"1a".sha3(), Some((0, b"0".sha3()))).unwrap();
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jdb.insert(b"foo");
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jdb.commit(1, &b"1b".sha3(), Some((0, b"0".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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jdb.commit(2, &b"2a".sha3(), Some((1, b"1a".sha3()))).unwrap();
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assert!(jdb.exists(&foo));
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}
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}
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