diff --git a/util/src/journaldb.rs b/util/src/journaldb.rs index 810b06727..e805f0a60 100644 --- a/util/src/journaldb.rs +++ b/util/src/journaldb.rs @@ -92,7 +92,6 @@ impl JournalDB { /// Commit all recent insert operations and historical removals from the old era /// to the backing database. - #[allow(cyclomatic_complexity)] pub fn commit(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result { // journal format: // [era, 0] => [ id, [insert_0, ...], [remove_0, ...] ] @@ -105,6 +104,17 @@ impl JournalDB { // for each end_era that we journaled that we are no passing by, // we remove all of its removes assuming it is canonical and all // of its inserts otherwise. + // + // We also keep reference counters for each key inserted in the journal to handle + // the following cases where key K must not be deleted from the DB when processing removals : + // Given H is the journal size in eras, 0 <= C <= H. + // Key K is removed in era A(N) and re-inserted in canonical era B(N + C). + // Key K is removed in era A(N) and re-inserted in non-canonical era B`(N + C). + // Key K is added in non-canonical era A'(N) canonical B(N + C). + // + // The counter is encreased each time a key is inserted in the journal in the commit. The list of insertions + // is saved with the era record. When the era becomes end_era and goes out of journal the counter is decreased + // and the key is safe to delete. // record new commit's details. let batch = WriteBatch::new(); @@ -125,6 +135,7 @@ impl JournalDB { let mut r = RlpStream::new_list(3); let inserts: Vec = self.overlay.keys().iter().filter(|&(_, &c)| c > 0).map(|(key, _)| key.clone()).collect(); + // Increase counter for each inserted key no matter if the block is canonical or not. for i in &inserts { *counters.entry(i.clone()).or_insert(0) += 1; } @@ -139,6 +150,8 @@ impl JournalDB { if let Some((end_era, canon_id)) = end { let mut index = 0usize; let mut last; + let mut to_remove: Vec = Vec::new(); + let mut canon_inserts: Vec = Vec::new(); while let Some(rlp_data) = try!(self.backing.get({ let mut r = RlpStream::new_list(2); r.append(&end_era); @@ -146,39 +159,33 @@ impl JournalDB { last = r.drain(); &last })) { - let to_add; let rlp = Rlp::new(&rlp_data); - { - to_add = rlp.val_at(1); - for i in &to_add { - let delete_counter = { - if let Some(mut cnt) = counters.get_mut(i) { - *cnt -= 1; - *cnt == 0 - } - else { false } - - }; - if delete_counter { - counters.remove(i); - } - } + let inserts: Vec = rlp.val_at(1); + JournalDB::decrease_counters(&inserts, &mut counters); + // Collect keys to be removed. These are removed keys for canonical block, inserted for non-canonical + if canon_id == rlp.val_at(0) { + to_remove.extend(rlp.at(2).iter().map(|r| r.as_val::())); + canon_inserts = inserts; } - let to_remove: Vec = if canon_id == rlp.val_at(0) {rlp.val_at(2)} else {to_add}; - for i in &to_remove { - if !counters.contains_key(i) { - batch.delete(&i).expect("Low-level database error. Some issue with your hard disk?"); - } + else { + to_remove.extend(inserts); } - try!(batch.delete(&last)); - trace!("JournalDB: delete journal for time #{}.{}, (canon was {}): {} entries", end_era, index, canon_id, to_remove.len()); index += 1; } + let canon_inserts = canon_inserts.drain(..).collect::>(); + // Purge removed keys if they are not referenced and not re-inserted in the canon commit + let mut deletes = 0; + for h in to_remove.iter().filter(|h| !counters.contains_key(h) && !canon_inserts.contains(h)) { + try!(batch.delete(&h)); + deletes += 1; + } try!(batch.put(&LAST_ERA_KEY, &encode(&end_era))); + trace!("JournalDB: delete journal for time #{}.{}, (canon was {}): {} entries", end_era, index, canon_id, deletes); } + // Commit overlay insertions let mut ret = 0u32; let mut deletes = 0usize; for i in self.overlay.drain().into_iter() { @@ -200,6 +207,23 @@ impl JournalDB { Ok(ret) } + + // Decrease counters for given keys. Deletes obsolete counters + fn decrease_counters(keys: &[H256], counters: &mut HashMap) { + for i in keys.iter() { + let delete_counter = { + if let Some(mut cnt) = counters.get_mut(i) { + *cnt -= 1; + *cnt == 0 + } + else { false } + }; + if delete_counter { + counters.remove(i); + } + } + } + fn payload(&self, key: &H256) -> Option { self.backing.get(&key.bytes()).expect("Low-level database error. Some issue with your hard disk?").map(|v| v.to_vec()) } @@ -387,4 +411,21 @@ mod tests { jdb.commit(3, &b"2".sha3(), Some((0, b"2".sha3()))).unwrap(); assert!(jdb.exists(&foo)); } + + #[test] + fn fork_same_key() { + // history is 1 + let mut jdb = JournalDB::new_temp(); + jdb.commit(0, &b"0".sha3(), None).unwrap(); + + let foo = jdb.insert(b"foo"); + jdb.commit(1, &b"1a".sha3(), Some((0, b"0".sha3()))).unwrap(); + + jdb.insert(b"foo"); + jdb.commit(1, &b"1b".sha3(), Some((0, b"0".sha3()))).unwrap(); + assert!(jdb.exists(&foo)); + + jdb.commit(2, &b"2a".sha3(), Some((1, b"1a".sha3()))).unwrap(); + assert!(jdb.exists(&foo)); + } }