openethereum/parity/migration.rs

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// Copyright 2015, 2016 Ethcore (UK) Ltd.
// 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/>.
use std::fs;
use std::fs::File;
use std::io::{Read, Write, Error as IoError, ErrorKind};
use std::path::PathBuf;
use std::fmt::{Display, Formatter, Error as FmtError};
use util::migration::{Manager as MigrationManager, Config as MigrationConfig, MigrationIterator};
use util::kvdb::{Database, DatabaseConfig};
use ethcore::migrations;
/// Database is assumed to be at default version, when no version file is found.
const DEFAULT_VERSION: u32 = 5;
/// Current version of database models.
const CURRENT_VERSION: u32 = 6;
/// Defines how many items are migrated to the new version of database at once.
const BATCH_SIZE: usize = 1024;
/// Version file name.
const VERSION_FILE_NAME: &'static str = "db_version";
/// Migration related erorrs.
#[derive(Debug)]
pub enum Error {
/// Returned when current version cannot be read or guessed.
UnknownDatabaseVersion,
/// Returned when migration is not possible.
MigrationImpossible,
/// Returned when migration unexpectadly failed.
MigrationFailed,
/// Returned when migration was completed succesfully,
/// but there was a problem with io.
Io(IoError),
}
impl Display for Error {
fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
let out = match *self {
Error::UnknownDatabaseVersion => "Current database version cannot be read".into(),
Error::MigrationImpossible => format!("Migration to version {} is not possible", CURRENT_VERSION),
Error::MigrationFailed => "Migration unexpectedly failed".into(),
Error::Io(ref err) => format!("Unexpected io error: {}", err),
};
write!(f, "{}", out)
}
}
impl From<IoError> for Error {
fn from(err: IoError) -> Self {
Error::Io(err)
}
}
/// Returns the version file path.
fn version_file_path(path: &PathBuf) -> PathBuf {
let mut file_path = path.clone();
file_path.push(VERSION_FILE_NAME);
file_path
}
/// Reads current database version from the file at given path.
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/// If the file does not exist returns `DEFAULT_VERSION`.
fn current_version(path: &PathBuf) -> Result<u32, Error> {
match File::open(version_file_path(path)) {
Err(ref err) if err.kind() == ErrorKind::NotFound => Ok(DEFAULT_VERSION),
Err(_) => Err(Error::UnknownDatabaseVersion),
Ok(mut file) => {
let mut s = String::new();
try!(file.read_to_string(&mut s).map_err(|_| Error::UnknownDatabaseVersion));
u32::from_str_radix(&s, 10).map_err(|_| Error::UnknownDatabaseVersion)
},
}
}
/// Writes current database version to the file.
/// Creates a new file if the version file does not exist yet.
fn update_version(path: &PathBuf) -> Result<(), Error> {
let mut file = try!(File::create(version_file_path(path)));
try!(file.write_all(format!("{}", CURRENT_VERSION).as_bytes()));
Ok(())
}
/// Blocks database path.
fn blocks_database_path(path: &PathBuf) -> PathBuf {
let mut blocks_path = path.clone();
blocks_path.push("blocks");
blocks_path
}
/// Extras database path.
fn extras_database_path(path: &PathBuf) -> PathBuf {
let mut extras_path = path.clone();
extras_path.push("extras");
extras_path
}
/// Temporary database path used for migration.
fn temp_database_path(path: &PathBuf) -> PathBuf {
let mut temp_path = path.clone();
temp_path.pop();
temp_path.push("temp_migration");
temp_path
}
/// Database backup
fn backup_database_path(path: &PathBuf) -> PathBuf {
let mut backup_path = path.clone();
backup_path.pop();
backup_path.push("temp_backup");
backup_path
}
/// Default migration settings.
fn default_migration_settings() -> MigrationConfig {
MigrationConfig {
batch_size: BATCH_SIZE,
}
}
/// Migrations on blocks database.
fn blocks_database_migrations() -> Result<MigrationManager, Error> {
let manager = MigrationManager::new(default_migration_settings());
Ok(manager)
}
/// Migrations on extras database.
fn extras_database_migrations() -> Result<MigrationManager, Error> {
let mut manager = MigrationManager::new(default_migration_settings());
try!(manager.add_migration(migrations::extras::ToV6).map_err(|_| Error::MigrationImpossible));
Ok(manager)
}
/// Migrates database at given position with given migration rules.
fn migrate_database(version: u32, path: PathBuf, migrations: MigrationManager) -> Result<(), Error> {
// check if migration is needed
if !migrations.is_needed(version) {
return Ok(())
}
let temp_path = temp_database_path(&path);
let backup_path = backup_database_path(&path);
// remote the dir if it exists
let _ = fs::remove_dir_all(&temp_path);
let _ = fs::remove_dir_all(&backup_path);
{
let db_config = DatabaseConfig {
prefix_size: None,
max_open_files: 64,
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cache_size: None,
};
// open old database
let old = try!(Database::open(&db_config, path.to_str().unwrap()).map_err(|_| Error::MigrationFailed));
// create new database
let mut temp = try!(Database::open(&db_config, temp_path.to_str().unwrap()).map_err(|_| Error::MigrationFailed));
// migrate old database to the new one
try!(migrations.execute(MigrationIterator::from(old.iter()), version, &mut temp).map_err(|_| Error::MigrationFailed));
}
// create backup
try!(fs::rename(&path, &backup_path));
// replace the old database with the new one
if let Err(err) = fs::rename(&temp_path, &path) {
// if something went wrong, bring back backup
try!(fs::rename(&backup_path, path));
return Err(From::from(err));
}
// remove backup
try!(fs::remove_dir_all(&backup_path));
Ok(())
}
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fn exists(path: &PathBuf) -> bool {
fs::metadata(path).is_ok()
}
/// Migrates the database.
pub fn migrate(path: &PathBuf) -> Result<(), Error> {
// read version file.
let version = try!(current_version(path));
// migrate the databases.
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// main db directory may already exists, so let's check if we have blocks dir
if version != CURRENT_VERSION && exists(&blocks_database_path(path)) {
println!("Migrating database from version {} to {}", version, CURRENT_VERSION);
try!(migrate_database(version, blocks_database_path(path), try!(blocks_database_migrations())));
try!(migrate_database(version, extras_database_path(path), try!(extras_database_migrations())));
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println!("Migration finished");
}
// update version file.
update_version(path)
}