Expose health status over RPC (#6274)

* Node-health to a separate crate.

* Initialize node_health outside of dapps.

* Expose health over RPC.

* Bring back 412 and fix JS.

* Add health to workspace and tests.

* Fix compilation without default features.

* Fix borked merge.

* Revert to generics to avoid virtual calls.

* Fix node-health tests.

* Add missing trailing comma.

dapps/node-health/src/lib.rs

@@ -0,0 +1,49 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Node Health status reporting.
+
+#![warn(missing_docs)]
+
+extern crate futures;
+extern crate futures_cpupool;
+extern crate ntp;
+extern crate time as time_crate;
+extern crate parity_reactor;
+extern crate parking_lot;
+
+#[macro_use]
+extern crate log;
+#[macro_use]
+extern crate serde_derive;
+
+mod health;
+mod time;
+mod types;
+
+pub use futures_cpupool::CpuPool;
+pub use health::NodeHealth;
+pub use types::{Health, HealthInfo, HealthStatus};
+pub use time::{TimeChecker, Error};
+
+/// Indicates sync status
+pub trait SyncStatus: ::std::fmt::Debug + Send + Sync {
+	/// Returns true if there is a major sync happening.
+	fn is_major_importing(&self) -> bool;
+
+	/// Returns number of connected and ideal peers.
+	fn peers(&self) -> (usize, usize);
+}