87 lines
3.0 KiB
Rust
87 lines
3.0 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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//! `JournalDB` interface and implementation.
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use common::*;
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/// Export the journaldb module.
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pub mod traits;
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mod archivedb;
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mod earlymergedb;
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mod overlayrecentdb;
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mod refcounteddb;
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/// Export the `JournalDB` trait.
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pub use self::traits::JournalDB;
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/// A journal database algorithm.
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#[derive(Debug, Clone, Copy)]
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pub enum Algorithm {
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/// Keep all keys forever.
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Archive,
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/// Ancient and recent history maintained separately; recent history lasts for particular
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/// number of blocks.
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///
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/// Inserts go into backing database, journal retains knowledge of whether backing DB key is
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/// ancient or recent. Non-canon inserts get explicitly reverted and removed from backing DB.
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EarlyMerge,
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/// Ancient and recent history maintained separately; recent history lasts for particular
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/// number of blocks.
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///
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/// Inserts go into memory overlay, which is tried for key fetches. Memory overlay gets
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/// flushed in backing only at end of recent history.
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OverlayRecent,
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/// Ancient and recent history maintained separately; recent history lasts for particular
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/// number of blocks.
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///
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/// References are counted in disk-backed DB.
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RefCounted,
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}
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impl Default for Algorithm {
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fn default() -> Algorithm { Algorithm::Archive }
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}
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impl fmt::Display for Algorithm {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{}", match self {
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&Algorithm::Archive => "archive",
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&Algorithm::EarlyMerge => "earlymerge",
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&Algorithm::OverlayRecent => "overlayrecent",
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&Algorithm::RefCounted => "refcounted",
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})
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}
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}
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/// Create a new `JournalDB` trait object.
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pub fn new(path: &str, algorithm: Algorithm, cache_size: Option<usize>) -> Box<JournalDB> {
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match algorithm {
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Algorithm::Archive => Box::new(archivedb::ArchiveDB::new(path, cache_size)),
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Algorithm::EarlyMerge => Box::new(earlymergedb::EarlyMergeDB::new(path, cache_size)),
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Algorithm::OverlayRecent => Box::new(overlayrecentdb::OverlayRecentDB::new(path, cache_size)),
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Algorithm::RefCounted => Box::new(refcounteddb::RefCountedDB::new(path, cache_size)),
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}
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}
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// all keys must be at least 12 bytes
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const DB_PREFIX_LEN : usize = 12;
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const LATEST_ERA_KEY : [u8; DB_PREFIX_LEN] = [ b'l', b'a', b's', b't', 0, 0, 0, 0, 0, 0, 0, 0 ];
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const VERSION_KEY : [u8; DB_PREFIX_LEN] = [ b'j', b'v', b'e', b'r', 0, 0, 0, 0, 0, 0, 0, 0 ];
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