Use tokio runtime handle instead of TaskExecutor abstraction (#9737)

* Use tokio runtime handle instead of TaskExecutor abstraction

Before this pr we had the `TaskExecutor` abstraction which theoretically
allowed that any futures executor could have been used. However, this
was never tested and is currently not really required. Anyone running a
node currently only used tokio and nothing else (because this was hard
coded in CLI). So, this pr removes the `TaskExecutor` abstraction and
relies directly on the tokio runtime handle.

Besides this changes, this pr also makes sure that the http and ws rpc
server use the same tokio runtime. This fixes a panic that occurred when
you drop the rpc servers inside an async function (tokio doesn't like
that a tokio runtime is dropped in the async context of another tokio
runtime).

As we don't use any custom runtime in the http rpc server anymore, this
pr also removes the `rpc-http-threads` cli argument. If external parties
complain that there aren't enough threads for the rpc server, we could
bring support for increasing the thread count of the tokio runtime.

* FMT

* Fix try runtime

* Fix integration tests and some other optimizations

* Remove warnings

substrate/client/service/src/task_manager/mod.rs

@@ -18,23 +18,20 @@
 
 //! Substrate service tasks management module.
 
-use crate::{
-	config::{JoinFuture, TaskExecutor, TaskType},
-	Error,
-};
+use crate::{config::TaskType, Error};
 use exit_future::Signal;
 use futures::{
 	future::{join_all, pending, select, try_join_all, BoxFuture, Either},
-	sink::SinkExt,
 	Future, FutureExt, StreamExt,
 };
-use log::{debug, error};
+use log::debug;
 use prometheus_endpoint::{
 	exponential_buckets, register, CounterVec, HistogramOpts, HistogramVec, Opts, PrometheusError,
 	Registry, U64,
 };
 use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedReceiver, TracingUnboundedSender};
 use std::{panic, pin::Pin, result::Result};
+use tokio::{runtime::Handle, task::JoinHandle};
 use tracing_futures::Instrument;
 
 mod prometheus_future;
@@ -45,9 +42,9 @@ mod tests;
 #[derive(Clone)]
 pub struct SpawnTaskHandle {
 	on_exit: exit_future::Exit,
-	executor: TaskExecutor,
+	tokio_handle: Handle,
 	metrics: Option<Metrics>,
-	task_notifier: TracingUnboundedSender<JoinFuture>,
+	task_notifier: TracingUnboundedSender<JoinHandle<()>>,
 }
 
 impl SpawnTaskHandle {
@@ -126,19 +123,20 @@ impl SpawnTaskHandle {
 				futures::pin_mut!(task);
 				let _ = select(on_exit, task).await;
 			}
+		}
+		.in_current_span();
+
+		let join_handle = match task_type {
+			TaskType::Async => self.tokio_handle.spawn(future),
+			TaskType::Blocking => {
+				let handle = self.tokio_handle.clone();
+				self.tokio_handle.spawn_blocking(move || {
+					handle.block_on(future);
+				})
+			},
 		};
 
-		let join_handle = self.executor.spawn(future.in_current_span().boxed(), task_type);
-
-		let mut task_notifier = self.task_notifier.clone();
-		self.executor.spawn(
-			Box::pin(async move {
-				if let Err(err) = task_notifier.send(join_handle).await {
-					error!("Could not send spawned task handle to queue: {}", err);
-				}
-			}),
-			TaskType::Async,
-		);
+		let _ = self.task_notifier.unbounded_send(join_handle);
 	}
 }
 
@@ -222,8 +220,8 @@ pub struct TaskManager {
 	on_exit: exit_future::Exit,
 	/// A signal that makes the exit future above resolve, fired on service drop.
 	signal: Option<Signal>,
-	/// How to spawn background tasks.
-	executor: TaskExecutor,
+	/// Tokio runtime handle that is used to spawn futures.
+	tokio_handle: Handle,
 	/// Prometheus metric where to report the polling times.
 	metrics: Option<Metrics>,
 	/// Send a signal when a spawned essential task has concluded. The next time
@@ -234,9 +232,9 @@ pub struct TaskManager {
 	/// Things to keep alive until the task manager is dropped.
 	keep_alive: Box<dyn std::any::Any + Send>,
 	/// A sender to a stream of background tasks. This is used for the completion future.
-	task_notifier: TracingUnboundedSender<JoinFuture>,
+	task_notifier: TracingUnboundedSender<JoinHandle<()>>,
 	/// This future will complete when all the tasks are joined and the stream is closed.
-	completion_future: JoinFuture,
+	completion_future: JoinHandle<()>,
 	/// A list of other `TaskManager`'s to terminate and gracefully shutdown when the parent
 	/// terminates and gracefully shutdown. Also ends the parent `future()` if a child's essential
 	/// task fails.
@@ -247,7 +245,7 @@ impl TaskManager {
 	/// If a Prometheus registry is passed, it will be used to report statistics about the
 	/// service tasks.
 	pub fn new(
-		executor: TaskExecutor,
+		tokio_handle: Handle,
 		prometheus_registry: Option<&Registry>,
 	) -> Result<Self, PrometheusError> {
 		let (signal, on_exit) = exit_future::signal();
@@ -261,13 +259,15 @@ impl TaskManager {
 		// NOTE: for_each_concurrent will await on all the JoinHandle futures at the same time. It
 		// is possible to limit this but it's actually better for the memory foot print to await
 		// them all to not accumulate anything on that stream.
-		let completion_future = executor
-			.spawn(Box::pin(background_tasks.for_each_concurrent(None, |x| x)), TaskType::Async);
+		let completion_future =
+			tokio_handle.spawn(background_tasks.for_each_concurrent(None, |x| async move {
+				let _ = x.await;
+			}));
 
 		Ok(Self {
 			on_exit,
 			signal: Some(signal),
-			executor,
+			tokio_handle,
 			metrics,
 			essential_failed_tx,
 			essential_failed_rx,
@@ -282,7 +282,7 @@ impl TaskManager {
 	pub fn spawn_handle(&self) -> SpawnTaskHandle {
 		SpawnTaskHandle {
 			on_exit: self.on_exit.clone(),
-			executor: self.executor.clone(),
+			tokio_handle: self.tokio_handle.clone(),
 			metrics: self.metrics.clone(),
 			task_notifier: self.task_notifier.clone(),
 		}
@@ -310,14 +310,9 @@ impl TaskManager {
 
 		Box::pin(async move {
 			join_all(children_shutdowns).await;
-			completion_future.await;
+			let _ = completion_future.await;
 
-			// The keep_alive stuff is holding references to some RPC handles etc. These
-			// RPC handles spawn their own tokio stuff and that doesn't like to be closed in an
-			// async context. So, we move the deletion to some other thread.
-			std::thread::spawn(move || {
-				let _ = keep_alive;
-			});
+			let _ = keep_alive;
 		})
 	}