State pruning (#216)

* Started work on state db

* Updated for a new hash type

* Pruning and tests

* Generalize on the block hash/key type

* Integrate with the client backend

* Merge w master

* CLI options

* Updated for light client refactoring

* Used IntoIterator

* Fixed invalid input hadling

polkadot/service/src/config.rs

@@ -20,6 +20,7 @@ use transaction_pool;
 use runtime_primitives::MakeStorage;
 pub use network::Role;
 pub use network::NetworkConfiguration;
+pub use client_db::PruningMode;
 
 /// Service configuration.
 pub struct Configuration {
@@ -33,6 +34,8 @@ pub struct Configuration {
 	pub keystore_path: String,
 	/// Path to the database.
 	pub database_path: String,
+	/// Pruning settings.
+	pub pruning: PruningMode,
 	/// Additional key seeds.
 	pub keys: Vec<String>,
 	/// The name of the chain.
@@ -58,6 +61,7 @@ impl Default for Configuration {
 			genesis_storage: Box::new(Default::default),
 			telemetry: Default::default(),
 			name: "Anonymous".into(),
+			pruning: PruningMode::ArchiveAll,
 		}
 	}
 }

polkadot/service/src/lib.rs

@@ -68,7 +68,7 @@ use exit_future::Signal;
 
 pub use self::error::{ErrorKind, Error};
 pub use self::components::{Components, FullComponents, LightComponents};
-pub use config::{Configuration, Role};
+pub use config::{Configuration, Role, PruningMode};
 
 /// Polkadot service.
 pub struct Service<Components: components::Components> {
@@ -118,6 +118,7 @@ impl<Components> Service<Components>
 		let db_settings = client_db::DatabaseSettings {
 			cache_size: None,
 			path: config.database_path.into(),
+			pruning: config.pruning,
 		};
 
 		let (client, on_demand) = components.build_client(db_settings, executor, config.genesis_storage)?;