Changed how relay loops are started (#840)

* slightly changed relay loop initialization

* git mv

* clippy

* more clippy

* loop_run -> run_loop

* review and clippy

* clippy

bridges/relays/utils/src/metrics/global.rs

@@ -0,0 +1,109 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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 Bridges Common 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 Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Global system-wide Prometheus metrics exposed by relays.
+
+use crate::metrics::{Metrics, StandaloneMetrics};
+
+use async_std::sync::{Arc, Mutex};
+use async_trait::async_trait;
+use std::time::Duration;
+use substrate_prometheus_endpoint::{register, Gauge, GaugeVec, Opts, Registry, F64, U64};
+use sysinfo::{ProcessExt, RefreshKind, System, SystemExt};
+
+/// Global metrics update interval.
+const UPDATE_INTERVAL: Duration = Duration::from_secs(10);
+
+/// Global Prometheus metrics.
+#[derive(Debug, Clone)]
+pub struct GlobalMetrics {
+	system: Arc<Mutex<System>>,
+	system_average_load: GaugeVec<F64>,
+	process_cpu_usage_percentage: Gauge<F64>,
+	process_memory_usage_bytes: Gauge<U64>,
+}
+
+impl Metrics for GlobalMetrics {
+	fn register(&self, registry: &Registry) -> Result<(), String> {
+		register(self.system_average_load.clone(), registry).map_err(|e| e.to_string())?;
+		register(self.process_cpu_usage_percentage.clone(), registry).map_err(|e| e.to_string())?;
+		register(self.process_memory_usage_bytes.clone(), registry).map_err(|e| e.to_string())?;
+		Ok(())
+	}
+}
+
+#[async_trait]
+impl StandaloneMetrics for GlobalMetrics {
+	async fn update(&self) {
+		// update system-wide metrics
+		let mut system = self.system.lock().await;
+		let load = system.get_load_average();
+		self.system_average_load.with_label_values(&["1min"]).set(load.one);
+		self.system_average_load.with_label_values(&["5min"]).set(load.five);
+		self.system_average_load.with_label_values(&["15min"]).set(load.fifteen);
+
+		// update process-related metrics
+		let pid = sysinfo::get_current_pid().expect(
+			"only fails where pid is unavailable (os=unknown || arch=wasm32);\
+				relay is not supposed to run in such MetricsParamss;\
+				qed",
+		);
+		let is_process_refreshed = system.refresh_process(pid);
+		match (is_process_refreshed, system.get_process(pid)) {
+			(true, Some(process_info)) => {
+				let cpu_usage = process_info.cpu_usage() as f64;
+				let memory_usage = process_info.memory() * 1024;
+				log::trace!(
+					target: "bridge-metrics",
+					"Refreshed process metrics: CPU={}, memory={}",
+					cpu_usage,
+					memory_usage,
+				);
+
+				self.process_cpu_usage_percentage
+					.set(if cpu_usage.is_finite() { cpu_usage } else { 0f64 });
+				self.process_memory_usage_bytes.set(memory_usage);
+			}
+			_ => {
+				log::warn!(
+					target: "bridge",
+					"Failed to refresh process information. Metrics may show obsolete values",
+				);
+			}
+		}
+	}
+
+	fn update_interval(&self) -> Duration {
+		UPDATE_INTERVAL
+	}
+}
+
+impl Default for GlobalMetrics {
+	fn default() -> Self {
+		GlobalMetrics {
+			system: Arc::new(Mutex::new(System::new_with_specifics(RefreshKind::everything()))),
+			system_average_load: GaugeVec::new(Opts::new("system_average_load", "System load average"), &["over"])
+				.expect("metric is static and thus valid; qed"),
+			process_cpu_usage_percentage: Gauge::new("process_cpu_usage_percentage", "Process CPU usage")
+				.expect("metric is static and thus valid; qed"),
+			process_memory_usage_bytes: Gauge::new(
+				"process_memory_usage_bytes",
+				"Process memory (resident set size) usage",
+			)
+			.expect("metric is static and thus valid; qed"),
+		}
+	}
+}