Relaying tx/blocks by light clients (#190)

* do not import external transactions into light tx pool

* do not announce blocks on light clients

* blocks_are_not_announced_by_light_nodes

polkadot/cli/src/informant.rs

@@ -18,7 +18,7 @@
 
 use std::time::{Duration, Instant};
 use futures::stream::Stream;
-use service::Service;
+use service::{Service, Components};
 use tokio_core::reactor;
 use network::{SyncState, SyncProvider};
 use polkadot_primitives::Block;
@@ -28,11 +28,10 @@ use client::{self, BlockchainEvents};
 const TIMER_INTERVAL_MS: u64 = 5000;
 
 /// Spawn informant on the event loop
-pub fn start<B, E>(service: &Service<B, E>, handle: reactor::Handle)
+pub fn start<C>(service: &Service<C>, handle: reactor::Handle)
 	where
-		B: client::backend::Backend<Block> + Send + Sync + 'static,
-		E: client::CallExecutor<Block> + Send + Sync + 'static,
-		client::error::Error: From<<<B as client::backend::Backend<Block>>::State as state_machine::backend::Backend>::Error>
+		C: Components,
+		client::error::Error: From<<<<C as Components>::Backend as client::backend::Backend<Block>>::State as state_machine::Backend>::Error>,
 {
 	let interval = reactor::Interval::new_at(Instant::now(), Duration::from_millis(TIMER_INTERVAL_MS), &handle)
 		.expect("Error creating informant timer");

polkadot/cli/src/lib.rs

@@ -262,11 +262,10 @@ pub fn run<I, T>(args: I) -> error::Result<()> where
 	}
 }
 
-fn run_until_exit<B, E>(mut core: reactor::Core, service: service::Service<B, E>, matches: &clap::ArgMatches, sys_conf: SystemConfiguration) -> error::Result<()>
+fn run_until_exit<C>(mut core: reactor::Core, service: service::Service<C>, matches: &clap::ArgMatches, sys_conf: SystemConfiguration) -> error::Result<()>
 	where
-		B: client::backend::Backend<Block> + Send + Sync + 'static,
-		E: client::CallExecutor<Block> + Send + Sync + 'static,
-		client::error::Error: From<<<B as client::backend::Backend<Block>>::State as state_machine::backend::Backend>::Error>
+		C: service::Components,
+		client::error::Error: From<<<<C as service::Components>::Backend as client::backend::Backend<Block>>::State as state_machine::Backend>::Error>,
 {
 	let exit = {
 		// can't use signal directly here because CtrlC takes only `Fn`.

polkadot/service/src/components.rs

@@ -0,0 +1,219 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot 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.
+
+// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+
+//! Polkadot service components.
+
+use std::collections::HashMap;
+use std::sync::Arc;
+use client::{self, Client};
+use client_db;
+use codec::{self, Slicable};
+use consensus;
+use keystore::Store as Keystore;
+use network;
+use polkadot_api;
+use runtime_primitives::MakeStorage;
+use polkadot_executor::Executor as LocalDispatch;
+use polkadot_primitives::{Block, BlockId, Hash};
+use state_machine;
+use substrate_executor::NativeExecutor;
+use transaction_pool::{self, TransactionPool};
+use error;
+
+/// Code executor.
+pub type CodeExecutor = NativeExecutor<LocalDispatch>;
+
+/// Polkadot service components.
+pub trait Components {
+	/// Client backend type.
+	type Backend: 'static + client::backend::Backend<Block>;
+
+	/// Polkadot API type.
+	type Api: 'static + polkadot_api::PolkadotApi + Send + Sync;
+
+	/// Code executor type.
+	type Executor: 'static + client::CallExecutor<Block> + Send + Sync;
+
+	/// Create client.
+	fn build_client(&self, settings: client_db::DatabaseSettings, executor: CodeExecutor, genesis_storage: MakeStorage)
+		-> Result<(Arc<Client<Self::Backend, Self::Executor, Block>>, Option<Arc<network::OnDemand<Block, network::Service<Block>>>>), error::Error>;
+
+	/// Create api.
+	fn build_api(&self, client: Arc<Client<Self::Backend, Self::Executor, Block>>) -> Arc<Self::Api>;
+
+	/// Create network transaction pool adapter.
+	fn build_network_tx_pool(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>, api: Arc<Self::Api>, tx_pool: Arc<TransactionPool>)
+		-> Arc<network::TransactionPool<Block>>;
+
+	/// Create consensus service.
+	fn build_consensus(&self, client: Arc<Client<Self::Backend, Self::Executor, Block>>, network: Arc<network::Service<Block>>, tx_pool: Arc<TransactionPool>, keystore: &Keystore)
+		-> Result<Option<consensus::Service>, error::Error>;
+}
+
+/// Components for full Polkadot service.
+pub struct FullComponents {
+	/// Is this a validator node?
+	pub is_validator: bool,
+}
+
+impl Components for FullComponents {
+	type Backend = client_db::Backend<Block>;
+	type Api = Client<Self::Backend, Self::Executor, Block>;
+	type Executor = client::LocalCallExecutor<client_db::Backend<Block>, NativeExecutor<LocalDispatch>>;
+
+	fn build_client(&self, db_settings: client_db::DatabaseSettings, executor: CodeExecutor, genesis_storage: MakeStorage)
+		-> Result<(Arc<client::Client<Self::Backend, Self::Executor, Block>>, Option<Arc<network::OnDemand<Block, network::Service<Block>>>>), error::Error> {
+		Ok((Arc::new(client_db::new_client(db_settings, executor, genesis_storage)?), None))
+	}
+
+	fn build_api(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>) -> Arc<Self::Api> {
+		client
+	}
+
+	fn build_network_tx_pool(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>, api: Arc<Self::Api>, pool: Arc<TransactionPool>)
+		-> Arc<network::TransactionPool<Block>> {
+		Arc::new(TransactionPoolAdapter {
+			imports_external_transactions: true,
+			pool,
+			client,
+			api,
+		})
+	}
+
+	fn build_consensus(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>, network: Arc<network::Service<Block>>, tx_pool: Arc<TransactionPool>, keystore: &Keystore)
+		-> Result<Option<consensus::Service>, error::Error> {
+		if !self.is_validator {
+			return Ok(None);
+		}
+
+		// Load the first available key
+		let key = keystore.load(&keystore.contents()?[0], "")?;
+		info!("Using authority key {:?}", key.public());
+		Ok(Some(consensus::Service::new(
+			client.clone(),
+			client.clone(),
+			network.clone(),
+			tx_pool.clone(),
+			::std::time::Duration::from_millis(4000), // TODO: dynamic
+			key,
+		)))
+	}
+}
+
+/// Components for light Polkadot service.
+pub struct LightComponents;
+
+impl Components for LightComponents {
+	type Backend = client::light::Backend<Block>;
+	type Api = polkadot_api::light::RemotePolkadotApiWrapper<Self::Backend, Self::Executor>;
+	type Executor = client::RemoteCallExecutor<client::light::Backend<Block>, network::OnDemand<Block, network::Service<Block>>>;
+
+	fn build_client(&self, _settings: client_db::DatabaseSettings, executor: CodeExecutor, genesis_storage: MakeStorage)
+		-> Result<(Arc<client::Client<Self::Backend, Self::Executor, Block>>, Option<Arc<network::OnDemand<Block, network::Service<Block>>>>), error::Error> {
+		let client_backend = client::light::new_light_backend();
+		let fetch_checker = Arc::new(client::light::new_fetch_checker(client_backend.clone(), executor));
+		let fetcher = Arc::new(network::OnDemand::new(fetch_checker));
+		let client = client::light::new_light(client_backend, fetcher.clone(), genesis_storage)?;
+		Ok((Arc::new(client), Some(fetcher)))
+	}
+
+	fn build_api(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>) -> Arc<Self::Api> {
+		Arc::new(polkadot_api::light::RemotePolkadotApiWrapper(client.clone()))
+	}
+
+	fn build_network_tx_pool(&self, client: Arc<client::Client<Self::Backend, Self::Executor, Block>>, api: Arc<Self::Api>, pool: Arc<TransactionPool>)
+		-> Arc<network::TransactionPool<Block>> {
+		Arc::new(TransactionPoolAdapter {
+			imports_external_transactions: false,
+			pool,
+			client,
+			api,
+		})
+	}
+
+	fn build_consensus(&self, _client: Arc<client::Client<Self::Backend, Self::Executor, Block>>, _network: Arc<network::Service<Block>>, _tx_pool: Arc<TransactionPool>, _keystore: &Keystore)
+		-> Result<Option<consensus::Service>, error::Error> {
+		Ok(None)
+	}
+}
+
+/// Transaction pool adapter.
+pub struct TransactionPoolAdapter<B, E, A> where A: Send + Sync, E: Send + Sync {
+	imports_external_transactions: bool,
+	pool: Arc<TransactionPool>,
+	client: Arc<Client<B, E, Block>>,
+	api: Arc<A>,
+}
+
+impl<B, E, A> network::TransactionPool<Block> for TransactionPoolAdapter<B, E, A>
+	where
+		B: client::backend::Backend<Block> + Send + Sync,
+		E: client::CallExecutor<Block> + Send + Sync,
+		client::error::Error: From<<<B as client::backend::Backend<Block>>::State as state_machine::backend::Backend>::Error>,
+		A: polkadot_api::PolkadotApi + Send + Sync,
+{
+	fn transactions(&self) -> Vec<(Hash, Vec<u8>)> {
+		let best_block = match self.client.info() {
+			Ok(info) => info.chain.best_hash,
+			Err(e) => {
+				debug!("Error getting best block: {:?}", e);
+				return Vec::new();
+			}
+		};
+
+		let id = match self.api.check_id(BlockId::hash(best_block)) {
+			Ok(id) => id,
+			Err(_) => return Vec::new(),
+		};
+
+		let ready = transaction_pool::Ready::create(id, &*self.api);
+
+		self.pool.cull_and_get_pending(ready, |pending| pending
+			.map(|t| {
+				let hash = t.hash().clone();
+				(hash, t.primitive_extrinsic())
+			})
+			.collect()
+		)
+	}
+
+	fn import(&self, transaction: &Vec<u8>) -> Option<Hash> {
+		if !self.imports_external_transactions {
+			return None;
+		}
+
+		let encoded = transaction.encode();
+		if let Some(uxt) = codec::Slicable::decode(&mut &encoded[..]) {
+			match self.pool.import_unchecked_extrinsic(uxt) {
+				Ok(xt) => Some(*xt.hash()),
+				Err(e) => match *e.kind() {
+					transaction_pool::ErrorKind::AlreadyImported(hash) => Some(hash[..].into()),
+					_ => {
+						debug!("Error adding transaction to the pool: {:?}", e);
+						None
+					},
+				}
+			}
+		} else {
+			debug!("Error decoding transaction");
+			None
+		}
+	}
+
+	fn on_broadcasted(&self, propagations: HashMap<Hash, Vec<String>>) {
+		self.pool.on_broadcasted(propagations)
+	}
+}