openethereum/parity/db/rocksdb/migration.rs

// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum 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 Ethereum 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 Ethereum.  If not, see <http://www.gnu.org/licenses/>.

use super::{
    kvdb_rocksdb::{CompactionProfile, DatabaseConfig},
    migration_rocksdb::{ChangeColumns, Config as MigrationConfig, Manager as MigrationManager},
};
use ethcore::{self, client::DatabaseCompactionProfile};
use std::{
    fmt::{Display, Error as FmtError, Formatter},
    fs,
    io::{Error as IoError, ErrorKind, Read, Write},
    path::{Path, PathBuf},
};

use super::{blooms::migrate_blooms, helpers};

/// The migration from v10 to v11.
/// Adds a column for node info.
pub const TO_V11: ChangeColumns = ChangeColumns {
    pre_columns: Some(6),
    post_columns: Some(7),
    version: 11,
};

/// The migration from v11 to v12.
/// Adds a column for light chain storage.
pub const TO_V12: ChangeColumns = ChangeColumns {
    pre_columns: Some(7),
    post_columns: Some(8),
    version: 12,
};

/// 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 = 13;
/// A version of database at which blooms-db was introduced
const BLOOMS_DB_VERSION: u32 = 13;
/// 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,
    /// Existing DB is newer than the known one.
    FutureDBVersion,
    /// Migration is not possible.
    MigrationImpossible,
    /// Blooms-db migration error.
    BloomsDB(ethcore::error::Error),
    /// 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::FutureDBVersion => "Database was created with newer client version. Upgrade your client or delete DB and resync.".into(),
			Error::MigrationImpossible => format!("Database migration to version {} is not possible.", CURRENT_VERSION),
			Error::BloomsDB(ref err) => format!("blooms-db migration error: {}", err),
			Error::Io(ref err) => format!("Unexpected io error on DB migration: {}.", 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: &Path) -> PathBuf {
    let mut file_path = path.to_owned();
    file_path.push(VERSION_FILE_NAME);
    file_path
}

/// Reads current database version from the file at given path.
/// If the file does not exist returns `DEFAULT_VERSION`.
fn current_version(path: &Path) -> Result<u32, Error> {
    match fs::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();
            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: &Path) -> Result<(), Error> {
    fs::create_dir_all(path)?;
    let mut file = fs::File::create(version_file_path(path))?;
    file.write_all(format!("{}", CURRENT_VERSION).as_bytes())?;
    Ok(())
}

/// Consolidated database path
fn consolidated_database_path(path: &Path) -> PathBuf {
    let mut state_path = path.to_owned();
    state_path.push("db");
    state_path
}

/// Database backup
fn backup_database_path(path: &Path) -> PathBuf {
    let mut backup_path = path.to_owned();
    backup_path.pop();
    backup_path.push("temp_backup");
    backup_path
}

/// Default migration settings.
pub fn default_migration_settings(compaction_profile: &CompactionProfile) -> MigrationConfig {
    MigrationConfig {
        batch_size: BATCH_SIZE,
        compaction_profile: *compaction_profile,
    }
}

/// Migrations on the consolidated database.
fn consolidated_database_migrations(
    compaction_profile: &CompactionProfile,
) -> Result<MigrationManager, Error> {
    let mut manager = MigrationManager::new(default_migration_settings(compaction_profile));
    manager
        .add_migration(TO_V11)
        .map_err(|_| Error::MigrationImpossible)?;
    manager
        .add_migration(TO_V12)
        .map_err(|_| Error::MigrationImpossible)?;
    Ok(manager)
}

/// Migrates database at given position with given migration rules.
fn migrate_database(
    version: u32,
    db_path: &Path,
    mut migrations: MigrationManager,
) -> Result<(), Error> {
    // check if migration is needed
    if !migrations.is_needed(version) {
        return Ok(());
    }

    let backup_path = backup_database_path(&db_path);
    // remove the backup dir if it exists
    let _ = fs::remove_dir_all(&backup_path);

    // migrate old database to the new one
    let temp_path = migrations.execute(&db_path, version)?;

    // completely in-place migration leads to the paths being equal.
    // in that case, no need to shuffle directories.
    if temp_path == db_path {
        return Ok(());
    }

    // create backup
    fs::rename(&db_path, &backup_path)?;

    // replace the old database with the new one
    if let Err(err) = fs::rename(&temp_path, &db_path) {
        // if something went wrong, bring back backup
        fs::rename(&backup_path, &db_path)?;
        return Err(err.into());
    }

    // remove backup
    fs::remove_dir_all(&backup_path).map_err(Into::into)
}

fn exists(path: &Path) -> bool {
    fs::metadata(path).is_ok()
}

/// Migrates the database.
pub fn migrate(path: &Path, compaction_profile: &DatabaseCompactionProfile) -> Result<(), Error> {
    let compaction_profile = helpers::compaction_profile(&compaction_profile, path);

    // read version file.
    let version = current_version(path)?;

    // migrate the databases.
    // main db directory may already exists, so let's check if we have blocks dir
    if version > CURRENT_VERSION {
        return Err(Error::FutureDBVersion);
    }

    // We are in the latest version, yay!
    if version == CURRENT_VERSION {
        return Ok(());
    }

    let db_path = consolidated_database_path(path);

    // Further migrations
    if version < CURRENT_VERSION && exists(&db_path) {
        println!(
            "Migrating database from version {} to {}",
            version, CURRENT_VERSION
        );
        migrate_database(
            version,
            &db_path,
            consolidated_database_migrations(&compaction_profile)?,
        )?;

        if version < BLOOMS_DB_VERSION {
            println!("Migrating blooms to blooms-db...");
            let db_config = DatabaseConfig {
                max_open_files: 64,
                memory_budget: None,
                compaction: compaction_profile,
                columns: ethcore_db::NUM_COLUMNS,
            };

            migrate_blooms(&db_path, &db_config).map_err(Error::BloomsDB)?;
        }

        println!("Migration finished");
    }

    // update version file.
    update_version(path)
}