Database backend (#133)

* DB backend

* DB backend

* Cleanup

* Clean build files after running tests

* Fixed comment

* add OOM lang item to runtime-io

polkadot/service/src/config.rs

@@ -39,6 +39,8 @@ pub struct Configuration {
 	pub network: NetworkConfiguration,
 	/// Path to key files.
 	pub keystore_path: String,
+	/// Path to the database.
+	pub database_path: String,
 	/// Additional key seeds.
 	pub keys: Vec<String>,
 	/// Chain specification.
@@ -52,6 +54,7 @@ impl Default for Configuration {
 			transaction_pool: Default::default(),
 			network: Default::default(),
 			keystore_path: Default::default(),
+			database_path: Default::default(),
 			keys: Default::default(),
 			chain_spec: ChainSpec::Development,
 		}

polkadot/service/src/lib.rs

@@ -33,6 +33,7 @@ extern crate substrate_runtime_io as runtime_io;
 extern crate substrate_primitives as primitives;
 extern crate substrate_network as network;
 extern crate substrate_codec as codec;
+extern crate substrate_client_db as client_db;
 extern crate substrate_executor;
 
 extern crate exit_future;
@@ -64,14 +65,13 @@ use polkadot_api::PolkadotApi;
 use polkadot_runtime::{GenesisConfig, ConsensusConfig, CouncilConfig, DemocracyConfig,
 	SessionConfig, StakingConfig, BuildExternalities};
 use client::{genesis, BlockchainEvents};
-use client::in_mem::Backend as InMemory;
 use network::ManageNetwork;
 use exit_future::Signal;
 
 pub use self::error::{ErrorKind, Error};
 pub use config::{Configuration, Role, ChainSpec};
 
-type Client = client::Client<InMemory, NativeExecutor<LocalDispatch>>;
+type Client = client::Client<client_db::Backend, NativeExecutor<LocalDispatch>>;
 
 /// Polkadot service.
 pub struct Service {
@@ -275,7 +275,12 @@ impl Service {
 			(primitives::block::Header::decode(&mut block.header.encode().as_ref()).expect("to_vec() always gives a valid serialisation; qed"), storage.into_iter().collect())
 		};
 
-		let client = Arc::new(client::new_in_mem(executor, prepare_genesis)?);
+		let db_settings = client_db::DatabaseSettings {
+			cache_size: None,
+			path: config.database_path.into(),
+		};
+
+		let client = Arc::new(client_db::new_client(db_settings, executor, prepare_genesis)?);
 		let best_header = client.best_block_header()?;
 		info!("Starting Polkadot. Best block is #{}", best_header.number);
 		let transaction_pool = Arc::new(Mutex::new(TransactionPool::new(config.transaction_pool)));