fix(server): count http calls in connection guard

server/src/server.rs

@@ -1146,12 +1146,19 @@ where
 				RpcServiceCfg::OnlyCalls,
 			));
 
-			Box::pin(
-				http::call_with_service(request, batch_config, max_request_size, rpc_service, max_response_size)
-					.map(Ok),
-			)
+			Box::pin(async move {
+				let rp =
+					http::call_with_service(request, batch_config, max_request_size, rpc_service, max_response_size)
+						.await;
+				// NOTE: The `conn guard` must be held until the response is processed
+				// to respect the `max_connections` limit.
+				drop(conn);
+				Ok(rp)
+			})
 		} else {
-			Box::pin(async { http::response::denied() }.map(Ok))
+			// NOTE: the `conn guard` is dropped when this function which is fine
+			// because it doesn't rely on any async operations.
+			Box::pin(async { Ok(http::response::denied()) })
 		}
 	}
 }

server/src/tests/ws.rs

@@ -569,16 +569,17 @@ async fn custom_subscription_id_works() {
 	let addr = server.local_addr().unwrap();
 	let mut module = RpcModule::new(());
 	module
-		.register_subscription("subscribe_hello", "subscribe_hello", "unsubscribe_hello", |_, sink, _, _| async {
-			let sink = sink.accept().await.unwrap();
-
-			assert!(matches!(sink.subscription_id(), SubscriptionId::Str(id) if id == "0xdeadbeef"));
-
-			loop {
-				let _ = &sink;
-				tokio::time::sleep(std::time::Duration::from_secs(30)).await;
-			}
-		})
+		.register_subscription::<(), _, _>(
+			"subscribe_hello",
+			"subscribe_hello",
+			"unsubscribe_hello",
+			|_, sink, _, _| async {
+				let sink = sink.accept().await.unwrap();
+				assert!(matches!(sink.subscription_id(), SubscriptionId::Str(id) if id == "0xdeadbeef"));
+				// Keep idle until it's unsubscribed.
+				futures_util::future::pending::<()>().await;
+			},
+		)
 		.unwrap();
 	let _handle = server.start(module);
 

tests/tests/integration_tests.rs

@@ -50,7 +50,7 @@ use jsonrpsee::core::server::SubscriptionMessage;
 use jsonrpsee::core::{JsonValue, StringError};
 use jsonrpsee::http_client::HttpClientBuilder;
 use jsonrpsee::server::middleware::http::HostFilterLayer;
-use jsonrpsee::server::{ServerBuilder, ServerHandle};
+use jsonrpsee::server::{ConnectionGuard, ServerBuilder, ServerHandle};
 use jsonrpsee::types::error::{ErrorObject, UNKNOWN_ERROR_CODE};
 use jsonrpsee::ws_client::WsClientBuilder;
 use jsonrpsee::{rpc_params, ResponsePayload, RpcModule};
@@ -1543,3 +1543,71 @@ async fn server_ws_low_api_works() {
 		Ok(local_addr)
 	}
 }
+
+#[tokio::test]
+async fn http_connection_guard_works() {
+	use jsonrpsee::{server::ServerBuilder, RpcModule};
+	use tokio::sync::mpsc;
+
+	init_logger();
+
+	let (tx, mut rx) = mpsc::channel::<()>(1);
+
+	let server_url = {
+		let server = ServerBuilder::default().build("127.0.0.1:0").await.unwrap();
+		let server_url = format!("http://{}", server.local_addr().unwrap());
+		let mut module = RpcModule::new(tx);
+
+		module
+			.register_async_method("wait_until", |_, wait, _| async move {
+				wait.send(()).await.unwrap();
+				wait.closed().await;
+				true
+			})
+			.unwrap();
+
+		module
+			.register_async_method("connection_count", |_, _, ctx| async move {
+				let conn = ctx.get::<ConnectionGuard>().unwrap();
+				conn.max_connections() - conn.available_connections()
+			})
+			.unwrap();
+
+		let handle = server.start(module);
+
+		tokio::spawn(handle.stopped());
+
+		server_url
+	};
+
+	let waiting_calls: Vec<_> = (0..2)
+		.map(|_| {
+			let client = HttpClientBuilder::default().build(&server_url).unwrap();
+			tokio::spawn(async move {
+				let _ = client.request::<bool, ArrayParams>("wait_until", rpc_params!()).await;
+			})
+		})
+		.collect();
+
+	// Wait until both calls are ACK:ed by the server.
+	rx.recv().await.unwrap();
+	rx.recv().await.unwrap();
+
+	// Assert that two calls are waiting to be answered and the current one.
+	{
+		let client = HttpClientBuilder::default().build(&server_url).unwrap();
+		let conn_count = client.request::<usize, ArrayParams>("connection_count", rpc_params!()).await.unwrap();
+		assert_eq!(conn_count, 3);
+	}
+
+	// Complete the waiting calls.
+	drop(rx);
+	futures::future::join_all(waiting_calls).await;
+
+	// Assert that connection count is back to 1.
+	{
+		let client = HttpClientBuilder::default().build(&server_url).unwrap();
+		let conn_count = client.request::<usize, ArrayParams>("connection_count", rpc_params!()).await.unwrap();
+		assert_eq!(conn_count, 1);
+	}
+}