85 lines
3.3 KiB
Rust
85 lines
3.3 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 hashdb::*;
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use kvdb::{Database, DBTransaction};
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/// A `HashDB` which can manage a short-term journal potentially containing many forks of mutually
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/// exclusive actions.
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pub trait JournalDB: HashDB {
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/// Return a copy of ourself, in a box.
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fn boxed_clone(&self) -> Box<JournalDB>;
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/// Returns heap memory size used
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fn mem_used(&self) -> usize;
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/// Check if this database has any commits
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fn is_empty(&self) -> bool;
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/// Get the latest era in the DB. None if there isn't yet any data in there.
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fn latest_era(&self) -> Option<u64>;
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/// Commit all recent insert operations and canonical historical commits' removals from the
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/// old era to the backing database, reverting any non-canonical historical commit's inserts.
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fn commit(&mut self, batch: &mut DBTransaction, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError>;
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/// Commit all queued insert and delete operations without affecting any journalling -- this requires that all insertions
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/// and deletions are indeed canonical and will likely lead to an invalid database if that assumption is violated.
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///
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/// Any keys or values inserted or deleted must be completely independent of those affected
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/// by any previous `commit` operations. Essentially, this means that `inject` can be used
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/// either to restore a state to a fresh database, or to insert data which may only be journalled
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/// from this point onwards.
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fn inject(&mut self, batch: &mut DBTransaction) -> Result<u32, UtilError>;
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/// State data query
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fn state(&self, _id: &H256) -> Option<Bytes>;
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/// Whether this database is pruned.
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fn is_pruned(&self) -> bool { true }
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/// Get backing database.
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fn backing(&self) -> &Arc<Database>;
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/// Clear internal strucutres. This should called after changes have been written
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/// to the backing strage
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fn flush(&self) {}
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/// Consolidate all the insertions and deletions in the given memory overlay.
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fn consolidate(&mut self, overlay: ::memorydb::MemoryDB);
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/// Commit all changes in a single batch
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#[cfg(test)]
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fn commit_batch(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
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let mut batch = self.backing().transaction();
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let res = try!(self.commit(&mut batch, now, id, end));
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let result = self.backing().write(batch).map(|_| res).map_err(Into::into);
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self.flush();
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result
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}
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/// Inject all changes in a single batch.
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#[cfg(test)]
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fn inject_batch(&mut self) -> Result<u32, UtilError> {
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let mut batch = self.backing().transaction();
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let res = try!(self.inject(&mut batch));
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self.backing().write(batch).map(|_| res).map_err(Into::into)
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}
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}
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