Make migration api more friendly

ethcore/src/migrations/state/v7.rs

@@ -24,6 +24,7 @@ use util::{Address, FixedHash, H256};
 use util::kvdb::Database;
 use util::migration::{Batch, Config, Error, Migration, SimpleMigration, Progress};
 use util::sha3::Hashable;
+use std::sync::Arc;
 
 use rlp::{decode, Rlp, RlpStream, Stream, View};
 
@@ -107,7 +108,7 @@ pub struct OverlayRecentV7 {
 impl OverlayRecentV7 {
 	// walk all journal entries in the database backwards.
 	// find migrations for any possible inserted keys.
-	fn walk_journal(&mut self, source: &Database) -> Result<(), Error> {
+	fn walk_journal(&mut self, source: Arc<Database>) -> Result<(), Error> {
 		if let Some(val) = try!(source.get(None, V7_LATEST_ERA_KEY).map_err(Error::Custom)) {
 			let mut era = decode::<u64>(&val);
 			loop {
@@ -151,7 +152,7 @@ impl OverlayRecentV7 {
 	// walk all journal entries in the database backwards.
 	// replace all possible inserted/deleted keys with their migrated counterparts
 	// and commit the altered entries.
-	fn migrate_journal(&self, source: &Database, mut batch: Batch, dest: &mut Database) -> Result<(), Error> {
+	fn migrate_journal(&self, source: Arc<Database>, mut batch: Batch, dest: &mut Database) -> Result<(), Error> {
 		if let Some(val) = try!(source.get(None, V7_LATEST_ERA_KEY).map_err(Error::Custom)) {
 			try!(batch.insert(V7_LATEST_ERA_KEY.into(), val.to_owned(), dest));
 
@@ -228,7 +229,7 @@ impl Migration for OverlayRecentV7 {
 	// walk all records in the database, attempting to migrate any possible and
 	// keeping records of those that we do. then migrate the journal using
 	// this information.
-	fn migrate(&mut self, source: &Database, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
+	fn migrate(&mut self, source: Arc<Database>, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
 		let mut batch = Batch::new(config, col);
 
 		// check version metadata.
@@ -257,7 +258,7 @@ impl Migration for OverlayRecentV7 {
 			try!(batch.insert(key, value.into_vec(), dest));
 		}
 
-		try!(self.walk_journal(source));
+		try!(self.walk_journal(source.clone()));
 		self.migrate_journal(source, batch, dest)
 	}
 }

ethcore/src/migrations/v9.rs

@@ -20,6 +20,7 @@
 use rlp::{Rlp, RlpStream, View, Stream};
 use util::kvdb::Database;
 use util::migration::{Batch, Config, Error, Migration, Progress};
+use std::sync::Arc;
 
 /// Which part of block to preserve
 pub enum Extract {
@@ -55,7 +56,7 @@ impl Migration for ToV9 {
 
 	fn version(&self) -> u32 { 9 }
 
-	fn migrate(&mut self, source: &Database, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
+	fn migrate(&mut self, source: Arc<Database>, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
 		let mut batch = Batch::new(config, self.column);
 
 		for (key, value) in source.iter(col) {

parity/migration.rs

@@ -19,6 +19,7 @@ use std::fs::File;
 use std::io::{Read, Write, Error as IoError, ErrorKind};
 use std::path::{Path, PathBuf};
 use std::fmt::{Display, Formatter, Error as FmtError};
+use std::sync::Arc;
 use util::journaldb::Algorithm;
 use util::migration::{Manager as MigrationManager, Config as MigrationConfig, Error as MigrationError, Migration};
 use util::kvdb::{CompactionProfile, Database, DatabaseConfig};
@@ -172,13 +173,13 @@ fn consolidate_database(
 	let old_path_str = try!(old_db_path.to_str().ok_or(Error::MigrationImpossible));
 	let new_path_str = try!(new_db_path.to_str().ok_or(Error::MigrationImpossible));
 
-	let cur_db = try!(Database::open(&db_config, old_path_str).map_err(db_error));
+	let cur_db = Arc::new(try!(Database::open(&db_config, old_path_str).map_err(db_error)));
 	// open new DB with proper number of columns
 	db_config.columns = migration.columns();
 	let mut new_db = try!(Database::open(&db_config, new_path_str).map_err(db_error));
 
 	// Migrate to new database (default column only)
-	try!(migration.migrate(&cur_db, &config, &mut new_db, None));
+	try!(migration.migrate(cur_db, &config, &mut new_db, None));
 
 	Ok(())
 }

util/src/migration/mod.rs

@@ -22,6 +22,7 @@ use std::collections::BTreeMap;
 use std::fs;
 use std::fmt;
 use std::path::{Path, PathBuf};
+use std::sync::Arc;
 
 use ::kvdb::{CompactionProfile, Database, DatabaseConfig, DBTransaction};
 
@@ -123,7 +124,7 @@ pub trait Migration: 'static {
 	/// Version of the database after the migration.
 	fn version(&self) -> u32;
 	/// Migrate a source to a destination.
-	fn migrate(&mut self, source: &Database, config: &Config, destination: &mut Database, col: Option<u32>) -> Result<(), Error>;
+	fn migrate(&mut self, source: Arc<Database>, config: &Config, destination: &mut Database, col: Option<u32>) -> Result<(), Error>;
 }
 
 /// A simple migration over key-value pairs.
@@ -142,7 +143,7 @@ impl<T: SimpleMigration> Migration for T {
 
 	fn version(&self) -> u32 { SimpleMigration::version(self) }
 
-	fn migrate(&mut self, source: &Database, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
+	fn migrate(&mut self, source: Arc<Database>, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
 		let mut batch = Batch::new(config, col);
 
 		for (key, value) in source.iter(col) {
@@ -239,7 +240,7 @@ impl Manager {
 
 		// start with the old db.
 		let old_path_str = try!(old_path.to_str().ok_or(Error::MigrationImpossible));
-		let mut cur_db = try!(Database::open(&db_config, old_path_str).map_err(Error::Custom));
+		let mut cur_db = Arc::new(try!(Database::open(&db_config, old_path_str).map_err(Error::Custom)));
 
 		for migration in migrations {
 			// Change number of columns in new db
@@ -254,16 +255,16 @@ impl Manager {
 			// perform the migration from cur_db to new_db.
 			match current_columns {
 				// migrate only default column
-				None => try!(migration.migrate(&cur_db, &config, &mut new_db, None)),
+				None => try!(migration.migrate(cur_db.clone(), &config, &mut new_db, None)),
 				Some(v) => {
 					// Migrate all columns in previous DB
 					for col in 0..v {
-						try!(migration.migrate(&cur_db, &config, &mut new_db, Some(col)))
+						try!(migration.migrate(cur_db.clone(), &config, &mut new_db, Some(col)))
 					}
 				}
 			}
 			// next iteration, we will migrate from this db into the other temp.
-			cur_db = new_db;
+			cur_db = Arc::new(new_db);
 			temp_idx.swap();
 
 			// remove the other temporary migration database.

util/src/migration/tests.rs

@@ -91,7 +91,7 @@ impl Migration for AddsColumn {
 
 	fn version(&self) -> u32 { 1 }
 
-	fn migrate(&mut self, source: &Database, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
+	fn migrate(&mut self, source: Arc<Database>, config: &Config, dest: &mut Database, col: Option<u32>) -> Result<(), Error> {
 		let mut batch = Batch::new(config, col);
 
 		for (key, value) in source.iter(col) {