utils/prometheus: Make crate spawn onto global executor

With 6ee1244 the Substrate green threading executor is now configurable. The Substrate Prometheus crate can use this executor to spawn futures per connection (scrape request).
nodebreaker0-0 · Jan 23, 2020 · ea9278a · ea9278a
1 parent 32c04b4
commit ea9278a
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Showing 5 changed files with 30 additions and 94 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/client/service/src/builder.rs b/client/service/src/builder.rs
@@ -1029,7 +1029,7 @@ ServiceBuilder<
 			let metrics = ServiceMetrics::register(&registry)?;
 
 			let future = select(
-				prometheus_exporter::init_prometheus(port, registry).boxed(),
+				prometheus_exporter::init_prometheus(port, registry, to_spawn_tx.clone()).boxed(),
 				exit.clone()
 			).map(drop);
 

diff --git a/utils/prometheus/Cargo.toml b/utils/prometheus/Cargo.toml
@@ -8,10 +8,10 @@ edition = "2018"
 
 [dependencies]
 log = "0.4.8"
-hyper = { version = "0.13.1", default-features = false, features = ["stream"] }
+hyper = { version = "0.13.1", default-features = false, features = ["tcp"] }
 prometheus = { version = "0.7", features = ["nightly", "process"]}
 tokio = "0.2"
-futures-util = { version = "0.3.1", default-features = false, features = ["io"] }
+futures = "0.3.1"
 derive_more = "0.99"
 
 [target.'cfg(not(target_os = "unknown"))'.dependencies]

diff --git a/utils/prometheus/src/lib.rs b/utils/prometheus/src/lib.rs
@@ -14,13 +14,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-use futures_util::{FutureExt, future::Future};
-use hyper::http::StatusCode;
-use hyper::{Server, Body, Response, service::{service_fn, make_service_fn}};
+use futures::{channel::mpsc, prelude::*};
+use hyper::{Body, http::StatusCode, Response, Server, service::{service_fn, make_service_fn}};
 use prometheus::{Encoder, Opts, TextEncoder, core::Atomic};
-use std::net::SocketAddr;
-#[cfg(not(target_os = "unknown"))]
-mod networking;
+use std::{net::SocketAddr, pin::Pin};
 
 pub use prometheus::{
 	Registry, Error as PrometheusError,
@@ -70,29 +67,28 @@ async fn request_metrics(registry: Registry) -> Result<Response<Body>, Error> {
 }
 
 #[derive(Clone)]
-pub struct Executor;
+pub struct Executor {
+	to_spawn_tx: mpsc::UnboundedSender<Pin<Box<dyn Future<Output = ()> + Send>>>,
+}
 
 #[cfg(not(target_os = "unknown"))]
 impl<T> hyper::rt::Executor<T> for Executor
-	where
-		T: Future + Send + 'static,
-		T::Output: Send + 'static,
+where
+	T: Future + Send + 'static,
 {
-	fn execute(&self, future: T) {
-		async_std::task::spawn(future);
+	fn execute(&self, fut: T) {
+		self.to_spawn_tx.unbounded_send(Box::pin(fut.map(drop)))
+			.expect("sending on unbounded channel never fails; qed");
 	}
 }
 /// Initializes the metrics context, and starts an HTTP server
 /// to serve metrics.
 #[cfg(not(target_os = "unknown"))]
-pub async fn init_prometheus(prometheus_addr: SocketAddr, registry: Registry) -> Result<(), Error>{
-	use networking::Incoming;
-	let listener = async_std::net::TcpListener::bind(&prometheus_addr)
-		.await
-		.map_err(|_| Error::PortInUse(prometheus_addr))?;
-
-	log::info!("Prometheus server started at {}", prometheus_addr);
-
+pub async fn init_prometheus(
+	prometheus_addr: SocketAddr,
+	registry: Registry,
+	to_spawn_tx: mpsc::UnboundedSender<Pin<Box<dyn Future<Output = ()> + Send>>>,
+) -> Result<(), Error>{
 	let service = make_service_fn(move |_| {
 		let registry = registry.clone();
 
@@ -103,14 +99,16 @@ pub async fn init_prometheus(prometheus_addr: SocketAddr, registry: Registry) ->
 		}
 	});
 
-	let server = Server::builder(Incoming(listener.incoming()))
-		.executor(Executor)
+	let executor = Executor { to_spawn_tx };
+
+	let server = hyper::server::Server::try_bind(&prometheus_addr)?
+		.executor(executor)
 		.serve(service)
 		.boxed();
 
-	let result = server.await.map_err(Into::into);
+	log::info!("Prometheus metrics served at {}/metrics", prometheus_addr);
 
-	result
+	server.await.map_err(Into::into)
 }
 
 #[cfg(target_os = "unknown")]

diff --git a/utils/prometheus/src/networking.rs b/utils/prometheus/src/networking.rs