adddefault_executor.rs

version-meld/discv5/examples/default_executor.rs

@@ -0,0 +1,74 @@
+//! Demonstrates how to run a basic Discovery v5 Service with the default Tokio executor.
+//!
+//! Discv5 requires a Tokio executor with all features. If none is passed, it will use the current
+//! runtime that built the `Discv5` struct.
+//!
+//! To run this example simply run:
+//! ```
+//! $ cargo run --example default_executor <BASE64ENR>
+//! ```
+
+use discv5::{enr, enr::CombinedKey, Discv5, Discv5ConfigBuilder, Discv5Event};
+use std::net::SocketAddr;
+use tokio::runtime::Runtime;
+
+#[tokio::main]
+async fn main() {
+    // allows detailed logging with the RUST_LOG env variable
+    let filter_layer = tracing_subscriber::EnvFilter::try_from_default_env()
+        .or_else(|_| tracing_subscriber::EnvFilter::try_new("info"))
+        .unwrap();
+    let _ = tracing_subscriber::fmt()
+        .with_env_filter(filter_layer)
+        .try_init();
+
+    // listening address and port
+    let listen_addr = "0.0.0.0:9000".parse::<SocketAddr>().unwrap();
+
+    let enr_key = CombinedKey::generate_secp256k1();
+    // construct a local ENR
+    let enr = enr::EnrBuilder::new("v4").build(&enr_key).unwrap();
+
+    // default configuration - uses the current executor
+    let config = Discv5ConfigBuilder::new().build();
+
+    // construct the discv5 server
+    let mut discv5 = Discv5::new(enr, enr_key, config).unwrap();
+
+    // if we know of another peer's ENR, add it known peers
+    if let Some(base64_enr) = std::env::args().nth(1) {
+        match base64_enr.parse::<enr::Enr<enr::CombinedKey>>() {
+            Ok(enr) => {
+                println!(
+                    "ENR Read. ip: {:?}, udp_port {:?}, tcp_port: {:?}",
+                    enr.ip(),
+                    enr.udp(),
+                    enr.tcp()
+                );
+                if let Err(e) = discv5.add_enr(enr) {
+                    println!("ENR was not added: {}", e);
+                }
+            }
+            Err(e) => panic!("Decoding ENR failed: {}", e),
+        }
+    }
+
+    // start the discv5 service
+    discv5.start(listen_addr).await.unwrap();
+    println!("Server started");
+
+    // get an event stream
+    let mut event_stream = discv5.event_stream().await.unwrap();
+
+    loop {
+        match event_stream.recv().await {
+            Some(Discv5Event::SocketUpdated(addr)) => {
+                println!("Nodes ENR socket address has been updated to: {:?}", addr);
+            }
+            Some(Discv5Event::Discovered(enr)) => {
+                println!("A peer has been discovered: {}", enr.node_id());
+            }
+            _ => {}
+        }
+    }
+}