openethereum/util/journaldb/src/traits.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Disk-backed `HashDB` implementation.
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use std::sync::Arc;
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use hashdb::*;
use kvdb::{self, DBTransaction};
use ethereum_types::H256;
use error::UtilError;
use bytes::Bytes;
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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.
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
fn mem_used(&self) -> usize;
/// Returns the size of journalled state in memory.
/// This function has a considerable speed requirement --
/// it must be fast enough to call several times per block imported.
fn journal_size(&self) -> usize { 0 }
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/// Check if this database has any commits
fn is_empty(&self) -> bool;
/// Get the earliest era in the DB. None if there isn't yet any data in there.
fn earliest_era(&self) -> Option<u64> { None }
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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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/// Journal recent database operations as being associated with a given era and id.
// TODO: give the overlay to this function so journaldbs don't manage the overlays themeselves.
fn journal_under(&mut self, batch: &mut DBTransaction, now: u64, id: &H256) -> Result<u32, UtilError>;
/// Mark a given block as canonical, indicating that competing blocks' states may be pruned out.
fn mark_canonical(&mut self, batch: &mut DBTransaction, era: u64, id: &H256) -> Result<u32, UtilError>;
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/// Commit all queued insert and delete operations without affecting any journalling -- this requires that all insertions
/// and deletions are indeed canonical and will likely lead to an invalid database if that assumption is violated.
///
/// Any keys or values inserted or deleted must be completely independent of those affected
/// by any previous `commit` operations. Essentially, this means that `inject` can be used
/// either to restore a state to a fresh database, or to insert data which may only be journalled
/// from this point onwards.
fn inject(&mut self, batch: &mut DBTransaction) -> Result<u32, UtilError>;
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/// State data query
fn state(&self, _id: &H256) -> Option<Bytes>;
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/// Whether this database is pruned.
fn is_pruned(&self) -> bool { true }
/// Get backing database.
fn backing(&self) -> &Arc<kvdb::KeyValueDB>;
/// Clear internal strucutres. This should called after changes have been written
/// to the backing strage
fn flush(&self) {}
/// Consolidate all the insertions and deletions in the given memory overlay.
fn consolidate(&mut self, overlay: ::memorydb::MemoryDB);
/// Commit all changes in a single batch
#[cfg(test)]
fn commit_batch(&mut self, now: u64, id: &H256, end: Option<(u64, H256)>) -> Result<u32, UtilError> {
let mut batch = self.backing().transaction();
let mut ops = self.journal_under(&mut batch, now, id)?;
if let Some((end_era, canon_id)) = end {
ops += self.mark_canonical(&mut batch, end_era, &canon_id)?;
}
let result = self.backing().write(batch).map(|_| ops).map_err(Into::into);
self.flush();
result
}
/// Inject all changes in a single batch.
#[cfg(test)]
fn inject_batch(&mut self) -> Result<u32, UtilError> {
let mut batch = self.backing().transaction();
let res = self.inject(&mut batch)?;
self.backing().write(batch).map(|_| res).map_err(Into::into)
}
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}