Updates

reference_jsonrpsee_crate_examples/ws_pubsub_broadcast.rs

@@ -0,0 +1,149 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+//
+// Permission is hereby granted, free of charge, to any
+// person obtaining a copy of this software and associated
+// documentation files (the "Software"), to deal in the
+// Software without restriction, including without
+// limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software
+// is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice
+// shall be included in all copies or substantial portions
+// of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+//! Example that shows how to broadcast to all active subscriptions using `tokio::sync::broadcast`.
+
+use std::net::SocketAddr;
+
+use futures::StreamExt;
+use futures::future::{self, Either};
+use jsonrpsee::PendingSubscriptionSink;
+use jsonrpsee::core::client::{Subscription, SubscriptionClientT};
+use jsonrpsee::core::middleware::RpcServiceBuilder;
+use jsonrpsee::rpc_params;
+use jsonrpsee::server::{RpcModule, Server, ServerConfig};
+use jsonrpsee::ws_client::WsClientBuilder;
+use tokio::sync::broadcast;
+use tokio_stream::wrappers::BroadcastStream;
+
+const NUM_SUBSCRIPTION_RESPONSES: usize = 5;
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+	tracing_subscriber::FmtSubscriber::builder()
+		.with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+		.try_init()
+		.expect("setting default subscriber failed");
+
+	let addr = run_server().await?;
+	let url = format!("ws://{}", addr);
+
+	let client1 =
+		WsClientBuilder::default().set_rpc_middleware(RpcServiceBuilder::new().rpc_logger(1024)).build(&url).await?;
+	let client2 =
+		WsClientBuilder::default().set_rpc_middleware(RpcServiceBuilder::new().rpc_logger(1024)).build(&url).await?;
+	let sub1: Subscription<i32> = client1.subscribe("subscribe_hello", rpc_params![], "unsubscribe_hello").await?;
+	let sub2: Subscription<i32> = client2.subscribe("subscribe_hello", rpc_params![], "unsubscribe_hello").await?;
+
+	let fut1 = sub1.take(NUM_SUBSCRIPTION_RESPONSES).for_each(|r| async move { tracing::info!("sub1 rx: {:?}", r) });
+	let fut2 = sub2.take(NUM_SUBSCRIPTION_RESPONSES).for_each(|r| async move { tracing::info!("sub2 rx: {:?}", r) });
+
+	future::join(fut1, fut2).await;
+
+	Ok(())
+}
+
+async fn run_server() -> anyhow::Result<SocketAddr> {
+	// let's configure the server only hold 5 messages in memory.
+	let config = ServerConfig::builder().set_message_buffer_capacity(5).build();
+	let server = Server::builder()
+		.set_config(config)
+		.set_rpc_middleware(RpcServiceBuilder::new().rpc_logger(1024))
+		.build("127.0.0.1:0")
+		.await?;
+	let (tx, _rx) = broadcast::channel::<usize>(16);
+
+	let mut module = RpcModule::new(tx.clone());
+
+	std::thread::spawn(move || produce_items(tx));
+
+	module
+		.register_subscription("subscribe_hello", "s_hello", "unsubscribe_hello", |_, pending, tx, _| async move {
+			let rx = tx.subscribe();
+			let stream = BroadcastStream::new(rx);
+			pipe_from_stream_with_bounded_buffer(pending, stream).await?;
+			Ok(())
+		})
+		.unwrap();
+	let addr = server.local_addr()?;
+	let handle = server.start(module);
+
+	// In this example we don't care about doing shutdown so let's it run forever.
+	// You may use the `ServerHandle` to shut it down or manage it yourself.
+	tokio::spawn(handle.stopped());
+
+	Ok(addr)
+}
+
+async fn pipe_from_stream_with_bounded_buffer(
+	pending: PendingSubscriptionSink,
+	stream: BroadcastStream<usize>,
+) -> Result<(), anyhow::Error> {
+	let sink = pending.accept().await?;
+	let closed = sink.closed();
+
+	futures::pin_mut!(closed, stream);
+
+	loop {
+		match future::select(closed, stream.next()).await {
+			// subscription closed.
+			Either::Left((_, _)) => break Ok(()),
+
+			// received new item from the stream.
+			Either::Right((Some(Ok(item)), c)) => {
+				let msg = serde_json::value::to_raw_value(&item)?;
+
+				// NOTE: this will block until there a spot in the queue
+				// and you might want to do something smarter if it's
+				// critical that "the most recent item" must be sent when it is produced.
+				if sink.send(msg).await.is_err() {
+					break Ok(());
+				}
+
+				closed = c;
+			}
+
+			// Send back back the error.
+			Either::Right((Some(Err(e)), _)) => break Err(e.into()),
+
+			// Stream is closed.
+			Either::Right((None, _)) => break Ok(()),
+		}
+	}
+}
+
+// Naive example that broadcasts the produced values to all active subscribers.
+fn produce_items(tx: broadcast::Sender<usize>) {
+	for c in 1..=100 {
+		std::thread::sleep(std::time::Duration::from_millis(1));
+
+		// This might fail if no receivers are alive, could occur if no subscriptions are active...
+		// Also be aware that this will succeed when at least one receiver is alive
+		// Thus, clients connecting at different point in time will not receive
+		// the items sent before the subscription got established.
+		let _ = tx.send(c);
+	}
+}