Grafana integration (#3913)

* Very WIP

* record_metrics macro works

* Integrate into service

* Licenses and documentation

* Remove unused Debugs, make respond function clearer

* Conform to line widths, fix service test

* Switch to storing the timestamps as millis instead

* Update core/grafana-data-source/src/lib.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Transform timestamps to i64 in serialization

* Fix license date

* Binary sort to find selection range for metrics

* Obey maxDataPoints

* Run a cleaning future

* Newlines at EOF

* Update core/service/Cargo.toml

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>

* Update core/grafana-data-source/src/lib.rs

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>

* Fix indentation

* Improve select_points

* Made test more accurate

* Inprogress

* Use the same futures version as hyper for now

* Error handling

* Remove dependence on hyper's tokio feature

* Added target_os flag

* Update Cargo.toml

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>

* Simplify example

* Remove compat wildcard

* Updated lock file

* Fix indentation 😉

substrate/client/grafana-data-source/test/src/main.rs

@@ -0,0 +1,40 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use grafana_data_source::{run_server, record_metrics};
+use std::time::Duration;
+use rand::Rng;
+use futures::{future::join, executor};
+
+async fn randomness() {
+	loop {
+		futures_timer::Delay::new(Duration::from_secs(1)).await;
+
+		let random = rand::thread_rng().gen_range(0.0, 1000.0);
+
+		record_metrics!(
+			"random data" => random,
+			"random^2" => random * random
+		);
+	}
+}
+
+fn main() {
+	executor::block_on(join(
+		run_server("127.0.0.1:9955".parse().unwrap()),
+		randomness()
+	)).0.unwrap();
+}