128 lines
3.9 KiB
Rust
128 lines
3.9 KiB
Rust
// Copyright 2019-2021 Parity Technologies (UK) Ltd.
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//
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// Permission is hereby granted, free of charge, to any
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// person obtaining a copy of this software and associated
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// documentation files (the "Software"), to deal in the
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// Software without restriction, including without
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// limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software
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// is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice
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// shall be included in all copies or substantial portions
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// of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
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// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
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// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
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// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
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// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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use std::net::SocketAddr;
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use std::time::Duration;
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use futures::{Stream, StreamExt};
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use jsonrpsee::core::DeserializeOwned;
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use jsonrpsee::core::client::{Subscription, SubscriptionClientT};
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use jsonrpsee::rpc_params;
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use jsonrpsee::server::{RpcModule, Server};
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use jsonrpsee::ws_client::WsClientBuilder;
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use tokio_stream::wrappers::BroadcastStream;
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use tokio_stream::wrappers::errors::BroadcastStreamRecvError;
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#[tokio::main]
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async fn main() -> anyhow::Result<()> {
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tracing_subscriber::FmtSubscriber::builder()
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.with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
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.try_init()
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.expect("setting default subscriber failed");
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let addr = run_server().await?;
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let url = format!("ws://{}", addr);
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let client = WsClientBuilder::default().build(&url).await?;
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let sub: Subscription<i32> = client.subscribe("subscribe_hello", rpc_params![], "unsubscribe_hello").await?;
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// drop oldest messages from subscription:
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let mut sub = drop_oldest_when_lagging(sub, 10);
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// Simulate that polling takes a long time.
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tokio::time::sleep(Duration::from_secs(1)).await;
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// The subscription starts from zero but you can
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// notice that many items have been replaced
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// because the subscription wasn't polled.
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for _ in 0..10 {
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match sub.next().await.unwrap() {
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Ok(n) => {
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tracing::info!("recv={n}");
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}
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Err(e) => {
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tracing::info!("{e}");
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}
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};
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}
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Ok(())
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}
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fn drop_oldest_when_lagging<T: Clone + DeserializeOwned + Send + Sync + 'static>(
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mut sub: Subscription<T>,
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buffer_size: usize,
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) -> impl Stream<Item = Result<T, BroadcastStreamRecvError>> {
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let (tx, rx) = tokio::sync::broadcast::channel(buffer_size);
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tokio::spawn(async move {
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// Poll the subscription which ignores errors.
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while let Some(n) = sub.next().await {
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let msg = match n {
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Ok(msg) => msg,
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Err(e) => {
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tracing::error!("Failed to decode the subscription message: {e}");
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continue;
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}
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};
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if tx.send(msg).is_err() {
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return;
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}
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}
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});
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BroadcastStream::new(rx)
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}
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async fn run_server() -> anyhow::Result<SocketAddr> {
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let server = Server::builder().build("127.0.0.1:0").await?;
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let mut module = RpcModule::new(());
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module
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.register_subscription("subscribe_hello", "s_hello", "unsubscribe_hello", |_, pending, _, _| async move {
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let sub = pending.accept().await.unwrap();
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for i in 0..usize::MAX {
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let json = serde_json::value::to_raw_value(&i).unwrap();
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sub.send(json).await.unwrap();
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tokio::time::sleep(Duration::from_millis(10)).await;
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}
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Ok(())
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})
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.unwrap();
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let addr = server.local_addr()?;
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let handle = server.start(module);
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// In this example we don't care about doing shutdown so let's it run forever.
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// You may use the `ServerHandle` to shut it down or manage it yourself.
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tokio::spawn(handle.stopped());
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Ok(addr)
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}
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