rpc: backpressured RPC server (bump jsonrpsee 0.20) (#1313)

This is a rather big change in jsonrpsee, the major things in this bump
are:
- Server backpressure (the subscription impls are modified to deal with
that)
- Allow custom error types / return types (remove jsonrpsee::core::Error
and jsonrpee::core::CallError)
- Bug fixes (graceful shutdown in particular not used by substrate
anyway)
   - Less dependencies for the clients in particular
   - Return type requires Clone in method call responses
   - Moved to tokio channels
   - Async subscription API (not used in this PR)

Major changes in this PR:
- The subscriptions are now bounded and if subscription can't keep up
with the server it is dropped
- CLI: add parameter to configure the jsonrpc server bounded message
buffer (default is 64)
- Add our own subscription helper to deal with the unbounded streams in
substrate

The most important things in this PR to review is the added helpers
functions in `substrate/client/rpc/src/utils.rs` and the rest is pretty
much chore.

Regarding the "bounded buffer limit" it may cause the server to handle
the JSON-RPC calls
slower than before.

The message size limit is bounded by "--rpc-response-size" thus "by
default 10MB * 64 = 640MB"
but the subscription message size is not covered by this limit and could
be capped as well.

Hopefully the last release prior to 1.0, sorry in advance for a big PR

Previous attempt: https://github.com/paritytech/substrate/pull/13992

Resolves https://github.com/paritytech/polkadot-sdk/issues/748, resolves
https://github.com/paritytech/polkadot-sdk/issues/627

substrate/client/rpc-servers/src/lib.rs

@@ -22,15 +22,14 @@
 
 pub mod middleware;
 
+use std::{error::Error as StdError, net::SocketAddr, time::Duration};
+
 use http::header::HeaderValue;
 use jsonrpsee::{
-	server::{
-		middleware::proxy_get_request::ProxyGetRequestLayer, AllowHosts, ServerBuilder,
-		ServerHandle,
-	},
+	server::middleware::{HostFilterLayer, ProxyGetRequestLayer},
 	RpcModule,
 };
-use std::{error::Error as StdError, net::SocketAddr};
+use tokio::net::TcpListener;
 use tower_http::cors::{AllowOrigin, CorsLayer};
 
 pub use crate::middleware::RpcMetrics;
@@ -42,7 +41,7 @@ pub use jsonrpsee::core::{
 const MEGABYTE: u32 = 1024 * 1024;
 
 /// Type alias for the JSON-RPC server.
-pub type Server = ServerHandle;
+pub type Server = jsonrpsee::server::ServerHandle;
 
 /// RPC server configuration.
 #[derive(Debug)]
@@ -61,6 +60,8 @@ pub struct Config<'a, M: Send + Sync + 'static> {
 	pub max_payload_out_mb: u32,
 	/// Metrics.
 	pub metrics: Option<RpcMetrics>,
+	/// Message buffer size
+	pub message_buffer_capacity: u32,
 	/// RPC API.
 	pub rpc_api: RpcModule<M>,
 	/// Subscription ID provider.
@@ -72,7 +73,7 @@ pub struct Config<'a, M: Send + Sync + 'static> {
 /// Start RPC server listening on given address.
 pub async fn start_server<M: Send + Sync + 'static>(
 	config: Config<'_, M>,
-) -> Result<ServerHandle, Box<dyn StdError + Send + Sync>> {
+) -> Result<Server, Box<dyn StdError + Send + Sync>> {
 	let Config {
 		addrs,
 		cors,
@@ -81,26 +82,30 @@ pub async fn start_server<M: Send + Sync + 'static>(
 		max_connections,
 		max_subs_per_conn,
 		metrics,
+		message_buffer_capacity,
 		id_provider,
 		tokio_handle,
 		rpc_api,
 	} = config;
 
-	let host_filter = hosts_filtering(cors.is_some(), &addrs);
+	let std_listener = TcpListener::bind(addrs.as_slice()).await?.into_std()?;
+	let local_addr = std_listener.local_addr().ok();
+	let host_filter = hosts_filtering(cors.is_some(), local_addr);
 
 	let middleware = tower::ServiceBuilder::new()
+		.option_layer(host_filter)
 		// Proxy `GET /health` requests to internal `system_health` method.
 		.layer(ProxyGetRequestLayer::new("/health", "system_health")?)
 		.layer(try_into_cors(cors)?);
 
-	let mut builder = ServerBuilder::new()
+	let mut builder = jsonrpsee::server::Server::builder()
 		.max_request_body_size(max_payload_in_mb.saturating_mul(MEGABYTE))
 		.max_response_body_size(max_payload_out_mb.saturating_mul(MEGABYTE))
 		.max_connections(max_connections)
 		.max_subscriptions_per_connection(max_subs_per_conn)
-		.ping_interval(std::time::Duration::from_secs(30))
-		.set_host_filtering(host_filter)
+		.ping_interval(Duration::from_secs(30))
 		.set_middleware(middleware)
+		.set_message_buffer_capacity(message_buffer_capacity)
 		.custom_tokio_runtime(tokio_handle);
 
 	if let Some(provider) = id_provider {
@@ -110,36 +115,34 @@ pub async fn start_server<M: Send + Sync + 'static>(
 	};
 
 	let rpc_api = build_rpc_api(rpc_api);
-	let (handle, addr) = if let Some(metrics) = metrics {
-		let server = builder.set_logger(metrics).build(&addrs[..]).await?;
-		let addr = server.local_addr();
-		(server.start(rpc_api)?, addr)
+	let handle = if let Some(metrics) = metrics {
+		let server = builder.set_logger(metrics).build_from_tcp(std_listener)?;
+		server.start(rpc_api)
 	} else {
-		let server = builder.build(&addrs[..]).await?;
-		let addr = server.local_addr();
-		(server.start(rpc_api)?, addr)
+		let server = builder.build_from_tcp(std_listener)?;
+		server.start(rpc_api)
 	};
 
 	log::info!(
 		"Running JSON-RPC server: addr={}, allowed origins={}",
-		addr.map_or_else(|_| "unknown".to_string(), |a| a.to_string()),
+		local_addr.map_or_else(|| "unknown".to_string(), |a| a.to_string()),
 		format_cors(cors)
 	);
 
 	Ok(handle)
 }
 
-fn hosts_filtering(enabled: bool, addrs: &[SocketAddr]) -> AllowHosts {
+fn hosts_filtering(enabled: bool, addr: Option<SocketAddr>) -> Option<HostFilterLayer> {
+	// If the local_addr failed, fallback to wildcard.
+	let port = addr.map_or("*".to_string(), |p| p.port().to_string());
+
 	if enabled {
-		// NOTE The listening addresses are whitelisted by default.
-		let mut hosts = Vec::with_capacity(addrs.len() * 2);
-		for addr in addrs {
-			hosts.push(format!("localhost:{}", addr.port()).into());
-			hosts.push(format!("127.0.0.1:{}", addr.port()).into());
-		}
-		AllowHosts::Only(hosts)
+		// NOTE: The listening addresses are whitelisted by default.
+		let hosts =
+			[format!("localhost:{port}"), format!("127.0.0.1:{port}"), format!("[::1]:{port}")];
+		Some(HostFilterLayer::new(hosts).expect("Valid hosts; qed"))
 	} else {
-		AllowHosts::Any
+		None
 	}
 }
 
@@ -151,9 +154,9 @@ fn build_rpc_api<M: Send + Sync + 'static>(mut rpc_api: RpcModule<M>) -> RpcModu
 
 	rpc_api
 		.register_method("rpc_methods", move |_, _| {
-			Ok(serde_json::json!({
+			serde_json::json!({
 				"methods": available_methods,
-			}))
+			})
 		})
 		.expect("infallible all other methods have their own address space; qed");
 

substrate/client/rpc-servers/src/middleware.rs

@@ -18,7 +18,9 @@
 
 //! RPC middleware to collect prometheus metrics on RPC calls.
 
-use jsonrpsee::server::logger::{HttpRequest, Logger, MethodKind, Params, TransportProtocol};
+use jsonrpsee::server::logger::{
+	HttpRequest, Logger, MethodKind, Params, SuccessOrError, TransportProtocol,
+};
 use prometheus_endpoint::{
 	register, Counter, CounterVec, HistogramOpts, HistogramVec, Opts, PrometheusError, Registry,
 	U64,
@@ -176,7 +178,7 @@ impl Logger for RpcMetrics {
 	fn on_result(
 		&self,
 		name: &str,
-		success: bool,
+		success_or_error: SuccessOrError,
 		started_at: Self::Instant,
 		transport: TransportProtocol,
 	) {
@@ -197,7 +199,7 @@ impl Logger for RpcMetrics {
 				name,
 				// the label "is_error", so `success` should be regarded as false
 				// and vice-versa to be registrered correctly.
-				if success { "false" } else { "true" },
+				if success_or_error.is_success() { "false" } else { "true" },
 			])
 			.inc();
 	}