Basic informant (#118)

* Informant

* Pass Handle instead of Core

polkadot/cli/src/informant.rs

@@ -0,0 +1,66 @@
+// 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/>.
+
+//! Console informant. Prints sync progress and block events. Runs on the calling thread.
+
+use std::time::{Duration, Instant};
+use futures::stream::Stream;
+use service::Service;
+use tokio_core::reactor;
+use network::{SyncState, SyncProvider};
+use runtime_support::Hashable;
+use primitives::block::HeaderHash;
+use client::BlockchainEvents;
+
+const TIMER_INTERVAL_MS: u64 = 5000;
+
+/// Spawn informant on the event loop
+pub fn start(service: &Service, handle: reactor::Handle) {
+	let interval = reactor::Interval::new_at(Instant::now(), Duration::from_millis(TIMER_INTERVAL_MS), &handle)
+		.expect("Error creating informant timer");
+
+	let network = service.network();
+	let client = service.client();
+
+	let display_notifications = interval.map_err(|e| debug!("Timer error: {:?}", e)).for_each(move |_| {
+		let sync_status = network.status();
+
+		if let Ok(best_block) = client.best_block_header() {
+			let hash: HeaderHash = best_block.blake2_256().into();
+			let status = match (sync_status.sync.state, sync_status.sync.best_seen_block) {
+				(SyncState::Idle, _) => "Idle".into(),
+				(SyncState::Downloading, None) => "Syncing".into(),
+				(SyncState::Downloading, Some(n)) => format!("Syncing, target=#{}", n),
+			};
+			println!("{} ({} peers), best: #{} ({})", status, sync_status.num_peers, best_block.number, hash)
+		} else {
+			warn!("Error getting best block information");
+		}
+		Ok(())
+	});
+
+	let client = service.client();
+	let display_block_import = client.import_notification_stream().for_each(|n| {
+		info!(target: "polkadot", "Imported #{} ({})", n.header.number, n.hash);
+		Ok(())
+	});
+
+	handle.spawn(display_notifications);
+	handle.spawn(display_block_import);
+}
+
+
+