225 lines
6.3 KiB
Rust
225 lines
6.3 KiB
Rust
//! Disk-backed HashDB implementation.
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use std::env;
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use common::*;
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use rlp::*;
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use hashdb::*;
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use overlaydb::*;
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use rocksdb::{DB, Writable};
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#[derive(Clone)]
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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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forward: OverlayDB,
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backing: Arc<DB>,
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inserts: Vec<H256>,
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removes: Vec<H256>,
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}
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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 {
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forward: OverlayDB::new_with_arc(db.clone()),
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backing: db,
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inserts: vec![],
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removes: vec![],
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}
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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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JournalDB {
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forward: OverlayDB::new_with_arc(backing.clone()),
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backing: backing,
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inserts: vec![],
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removes: vec![],
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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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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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/// Get a clone of the overlay db portion of this.
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pub fn to_overlaydb(&self) -> OverlayDB { self.forward.clone() }
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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 last_era, 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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// record new commit's details.
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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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r.append(id);
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r.append(&self.inserts);
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r.append(&self.removes);
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try!(self.backing.put(&last, r.as_raw()));
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self.inserts.clear();
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self.removes.clear();
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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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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 to_remove: Vec<H256> = rlp.val_at(if canon_id == rlp.val_at(0) {2} else {1});
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for i in &to_remove {
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self.forward.remove(i);
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}
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try!(self.backing.delete(&last));
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trace!("JournalDB: delete journal for time #{}.{}, (canon was {}): {} entries", end_era, index, canon_id, to_remove.len());
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index += 1;
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}
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}
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self.forward.commit()
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}
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/// Revert all operations on this object (i.e. `insert()`s and `removes()`s) since the
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/// last `commit()`.
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pub fn revert(&mut self) { self.forward.revert(); self.removes.clear(); }
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}
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impl HashDB for JournalDB {
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fn keys(&self) -> HashMap<H256, i32> { self.forward.keys() }
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fn lookup(&self, key: &H256) -> Option<&[u8]> { self.forward.lookup(key) }
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fn exists(&self, key: &H256) -> bool { self.forward.exists(key) }
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fn insert(&mut self, value: &[u8]) -> H256 { let r = self.forward.insert(value); self.inserts.push(r.clone()); r }
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fn emplace(&mut self, key: H256, value: Bytes) { self.inserts.push(key.clone()); self.forward.emplace(key, value); }
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fn kill(&mut self, key: &H256) { self.removes.push(key.clone()); }
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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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}
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