builder.rs

				SUBSTRATE_INFO;
				"system.network_state";
				"state" => network_state,
			);
			Ok(())
		}).select(exit.clone()).then(|_| Ok(()));
		let _ = to_spawn_tx.unbounded_send(Box::new(tel_task_2));

		// RPC
		let (system_rpc_tx, system_rpc_rx) = futures03::channel::mpsc::unbounded();
		let gen_handler = || {
			use rpc::{chain, state, author, system};

			let system_info = rpc::system::SystemInfo {
				chain_name: config.chain_spec.name().into(),
				impl_name: config.impl_name.into(),
				impl_version: config.impl_version.into(),
				properties: config.chain_spec.properties().clone(),
			};

			let subscriptions = rpc::Subscriptions::new(Arc::new(SpawnTaskHandle {
				sender: to_spawn_tx.clone(),
				on_exit: exit.clone()
			}));

			let (chain, state) = if let (Some(remote_backend), Some(on_demand)) =
				(remote_backend.as_ref(), on_demand.as_ref()) {
				// Light clients
				let chain = rpc::chain::new_light(
					client.clone(),
					subscriptions.clone(),
					remote_backend.clone(),
					on_demand.clone()
				);
				let state = rpc::state::new_light(
					client.clone(),
					subscriptions.clone(),
					remote_backend.clone(),
					on_demand.clone()
				);
				(chain, state)

			} else {
				// Full nodes
				let chain = rpc::chain::new_full(client.clone(), subscriptions.clone());
				let state = rpc::state::new_full(client.clone(), subscriptions.clone());
				(chain, state)
			};

			let author = rpc::author::Author::new(
				client.clone(),
				transaction_pool.clone(),
				subscriptions,
				keystore.clone(),
			);
			let system = system::System::new(system_info, system_rpc_tx.clone());

			rpc_servers::rpc_handler((
				state::StateApi::to_delegate(state),
				chain::ChainApi::to_delegate(chain),
				author::AuthorApi::to_delegate(author),
				system::SystemApi::to_delegate(system),
				rpc_extensions.clone(),
			))
		};
		let rpc_handlers = gen_handler();
		let rpc = start_rpc_servers(&config, gen_handler)?;


		let _ = to_spawn_tx.unbounded_send(Box::new(build_network_future(
			config.roles,
			network_mut,
			client.clone(),
			network_status_sinks.clone(),
			system_rpc_rx,
			has_bootnodes,
			dht_event_tx,
		)
			.map_err(|_| ())
			.select(exit.clone())
			.then(|_| Ok(()))));

		let telemetry_connection_sinks: Arc<Mutex<Vec<mpsc::UnboundedSender<()>>>> = Default::default();

		// Telemetry
		let telemetry = config.telemetry_endpoints.clone().map(|endpoints| {
			let is_authority = config.roles.is_authority();
			let network_id = network.local_peer_id().to_base58();
			let name = config.name.clone();
			let impl_name = config.impl_name.to_owned();
			let version = version.clone();
			let chain_name = config.chain_spec.name().to_owned();
			let telemetry_connection_sinks_ = telemetry_connection_sinks.clone();
			let telemetry = tel::init_telemetry(tel::TelemetryConfig {
				endpoints,
				wasm_external_transport: config.telemetry_external_transport.take(),
			});
			let future = telemetry.clone()
				.map(|ev| Ok::<_, ()>(ev))
				.compat()
				.for_each(move |event| {
					// Safe-guard in case we add more events in the future.
					let tel::TelemetryEvent::Connected = event;

					telemetry!(SUBSTRATE_INFO; "system.connected";
						"name" => name.clone(),
						"implementation" => impl_name.clone(),
						"version" => version.clone(),
						"config" => "",
						"chain" => chain_name.clone(),
						"authority" => is_authority,
						"network_id" => network_id.clone()
					);

					telemetry_connection_sinks_.lock().retain(|sink| {
						sink.unbounded_send(()).is_ok()
					});
					Ok(())
				});
			let _ = to_spawn_tx.unbounded_send(Box::new(future
				.select(exit.clone())
				.then(|_| Ok(()))));
			telemetry
		});

		Ok(Service {
			client,
			network,
			network_status_sinks,
			select_chain,
			transaction_pool,
			exit,
			signal: Some(signal),
			essential_failed: Arc::new(AtomicBool::new(false)),
			to_spawn_tx,
			to_spawn_rx,
			to_poll: Vec::new(),
			rpc_handlers,
			_rpc: rpc,
			_telemetry: telemetry,
			_offchain_workers: offchain_workers,
			_telemetry_on_connect_sinks: telemetry_connection_sinks.clone(),
			keystore,
			marker: PhantomData::<TBl>,
		})
	}
}

pub(crate) fn maintain_transaction_pool<Api, Backend, Block, Executor, PoolApi>(
	id: &BlockId<Block>,
	client: &Arc<Client<Backend, Executor, Block, Api>>,
	transaction_pool: &TransactionPool<PoolApi>,
	retracted: &[Block::Hash],
) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>> where
	Block: BlockT<Hash = <Blake2Hasher as primitives::Hasher>::Out>,
	Backend: 'static + client::backend::Backend<Block, Blake2Hasher>,
	Client<Backend, Executor, Block, Api>: ProvideRuntimeApi,
	<Client<Backend, Executor, Block, Api> as ProvideRuntimeApi>::Api: runtime_api::TaggedTransactionQueue<Block>,
	Executor: 'static + client::CallExecutor<Block, Blake2Hasher>,
	PoolApi: 'static + txpool::ChainApi<Hash = Block::Hash, Block = Block>,
	Api: 'static,
{
	// Put transactions from retracted blocks back into the pool.
	let client_copy = client.clone();
	let retracted_transactions = retracted.to_vec().into_iter()
		.filter_map(move |hash| client_copy.block(&BlockId::hash(hash)).ok().unwrap_or(None))
		.flat_map(|block| block.block.deconstruct().1.into_iter())
		.filter(|tx| tx.is_signed().unwrap_or(false));
	let resubmit_future = transaction_pool
		.submit_at(id, retracted_transactions, true)
		.then(|resubmit_result| ready(match resubmit_result {
			Ok(_) => Ok(()),
			Err(e) => {
				warn!("Error re-submitting transactions: {:?}", e);
				Ok(())
			}
		}))
		.compat();

	// Avoid calling into runtime if there is nothing to prune from the pool anyway.
	if transaction_pool.status().is_empty() {
		return Ok(Box::new(resubmit_future))
	}

	let block = client.block(id)?;
	Ok(match block {
		Some(block) => {
			let parent_id = BlockId::hash(*block.block.header().parent_hash());
			let prune_future = transaction_pool
				.prune(id, &parent_id, block.block.extrinsics())
				.boxed()
				.compat()
				.map_err(|e| { format!("{:?}", e); });

			Box::new(resubmit_future.and_then(|_| prune_future))
		},
		None => Box::new(resubmit_future),
	})
}

#[cfg(test)]
mod tests {
	use super::*;
	use futures03::executor::block_on;
	use consensus_common::{BlockOrigin, SelectChain};
	use substrate_test_runtime_client::{prelude::*, runtime::Transfer};

	#[test]
	fn should_remove_transactions_from_the_pool() {
		let (client, longest_chain) = TestClientBuilder::new().build_with_longest_chain();
		let client = Arc::new(client);
		let pool = TransactionPool::new(Default::default(), ::transaction_pool::FullChainApi::new(client.clone()));
		let transaction = Transfer {
			amount: 5,
			nonce: 0,
			from: AccountKeyring::Alice.into(),
			to: Default::default(),
		}.into_signed_tx();
		let best = longest_chain.best_chain().unwrap();

		// store the transaction in the pool
		block_on(pool.submit_one(&BlockId::hash(best.hash()), transaction.clone())).unwrap();

		// import the block
		let mut builder = client.new_block(Default::default()).unwrap();
		builder.push(transaction.clone()).unwrap();
		let block = builder.bake().unwrap();
		let id = BlockId::hash(block.header().hash());
		client.import(BlockOrigin::Own, block).unwrap();

		// fire notification - this should clean up the queue
		assert_eq!(pool.status().ready, 1);
		maintain_transaction_pool(
			&id,
			&client,
			&pool,
			&[]
		).unwrap().wait().unwrap();

		// then
		assert_eq!(pool.status().ready, 0);
		assert_eq!(pool.status().future, 0);
	}

	#[test]
	fn should_add_reverted_transactions_to_the_pool() {
		let (client, longest_chain) = TestClientBuilder::new().build_with_longest_chain();
		let client = Arc::new(client);
		let pool = TransactionPool::new(Default::default(), ::transaction_pool::FullChainApi::new(client.clone()));
		let transaction = Transfer {
			amount: 5,
			nonce: 0,
			from: AccountKeyring::Alice.into(),
			to: Default::default(),
		}.into_signed_tx();
		let best = longest_chain.best_chain().unwrap();

		// store the transaction in the pool
		block_on(pool.submit_one(&BlockId::hash(best.hash()), transaction.clone())).unwrap();

		// import the block
		let mut builder = client.new_block(Default::default()).unwrap();
		builder.push(transaction.clone()).unwrap();
		let block = builder.bake().unwrap();
		let block1_hash = block.header().hash();
		let id = BlockId::hash(block1_hash.clone());
		client.import(BlockOrigin::Own, block).unwrap();

		// fire notification - this should clean up the queue
		assert_eq!(pool.status().ready, 1);
		maintain_transaction_pool(
			&id,
			&client,
			&pool,
			&[]
		).unwrap().wait().unwrap();

		// then
		assert_eq!(pool.status().ready, 0);
		assert_eq!(pool.status().future, 0);

		// import second block
		let builder = client.new_block_at(&BlockId::hash(best.hash()), Default::default()).unwrap();
		let block = builder.bake().unwrap();
		let id = BlockId::hash(block.header().hash());
		client.import(BlockOrigin::Own, block).unwrap();

		// fire notification - this should add the transaction back to the pool.
		maintain_transaction_pool(
			&id,
			&client,
			&pool,
			&[block1_hash]
		).unwrap().wait().unwrap();

		// then
		assert_eq!(pool.status().ready, 1);
		assert_eq!(pool.status().future, 0);
	}
}