[go/tokio] set SO_REUSE{ADDR,PORT} sockopts

And format both.

servers/go-echo-server/echo.go

 package main
 
 import (
+	"context"
 	"flag"
 	"log"
 	"net"
 	"os"
 	"strconv"
+	"syscall"
 	"time"
 )
 
+// Taken from https://pkg.go.dev/golang.org/x/sys/unix#pkg-constants
+const (
+	SOL_SOCKET   = 0x1
+	SO_REUSEADDR = 0x2
+	SO_REUSEPORT = 0xf
+)
+
 func main() {
 	port := flag.Int("port", 12345, "Port to accept connections on.")
 	host := flag.String("host", "0.0.0.0", "Host or IP to bind to")
 	computation := flag.Uint("computation", 0, "Computation done before sending a responce in microseconds")
 	flag.Parse()
 
-	l, err := net.Listen("tcp", *host+":"+strconv.Itoa(*port))
+	lc := net.ListenConfig{
+		Control: func(network, address string, conn syscall.RawConn) error {
+			var operr error
+			err := conn.Control(func(fd uintptr) {
+				operr = syscall.SetsockoptInt(int(fd), SOL_SOCKET, SO_REUSEADDR, 1)
+				if operr != nil {
+					return
+				}
+				operr = syscall.SetsockoptInt(int(fd), SOL_SOCKET, SO_REUSEPORT, 1)
+			})
+			if err != nil {
+				return err
+			}
+			return operr
+		},
+	}
+
+	l, err := lc.Listen(context.Background(), "tcp", *host+":"+strconv.Itoa(*port))
 	if err != nil {
 		log.Panicln(err)
 	}
+
 	log.Println("Listening to connections at '"+*host+"' on port", strconv.Itoa(*port), "with", *computation, "microseconds computation")
 	defer l.Close()
 

servers/tokio-echo/Cargo.lock

 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "autocfg"
 version = "1.0.1"
@@ -18,6 +20,12 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b700ce4376041dcd0a327fd0097c41095743c4c8af8887265942faf1100bd040"
 
+[[package]]
+name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -39,7 +47,7 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bee0328b1209d157ef001c94dd85b4f8f64139adb0eac2659f4b08382b2f474d"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]
 
 [[package]]
@@ -63,7 +71,7 @@ version = "0.4.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]
 
 [[package]]
@@ -94,6 +102,17 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "net2"
+version = "0.2.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "391630d12b68002ae1e25e8f974306474966550ad82dac6886fb8910c19568ae"
+dependencies = [
+ "cfg-if 0.1.10",
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "ntapi"
 version = "0.3.6"
@@ -136,7 +155,7 @@ version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fa7a782938e745763fe6907fc6ba86946d72f49fe7e21de074e08128a99fb018"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
  "instant",
  "libc",
  "redox_syscall",
@@ -233,6 +252,7 @@ dependencies = [
 name = "tokio-echo"
 version = "0.1.0"
 dependencies = [
+ "net2",
  "tokio",
 ]
 

servers/tokio-echo/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2018"
 
 [dependencies]
 tokio = { version = "1", features = ["full"] }
+net2 = { version = "0.2"}

servers/tokio-echo/src/main.rs

 use std::env;
 use std::time::{Duration, Instant};
 
-use tokio::net::TcpListener;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::TcpListener;
+
+extern crate net2;
+
+use net2::{unix::UnixTcpBuilderExt, TcpBuilder};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let args: Vec<String> = env::args().collect();
@@ -11,7 +15,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
         2 => args[1].parse()?,
 
-        _=> {
+        _ => {
             let prog = &args[0];
             panic!("Usage: {} [computation in us]", prog);
         }
@@ -28,43 +32,55 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         None => {}
     };
 
-    runtime_builder.enable_all().build().unwrap().block_on(async {
-        let listener = TcpListener::bind("[::]:12345").await.unwrap();
-        println!("Echoserver listening on :::12345 with {} microseconds computation", computation);
+    runtime_builder
+        .enable_all()
+        .build()
+        .unwrap()
+        .block_on(async {
+            let std_listener = TcpBuilder::new_v6()?
+                .reuse_address(true)?
+                .reuse_port(true)?
+                .bind("[::]:12345")?
+                .listen(4096)?;
+            let listener = TcpListener::from_std(std_listener).unwrap();
+            println!(
+                "Echoserver listening on :::12345 with {} microseconds computation",
+                computation
+            );
 
-        loop {
-            let (mut socket, _) = listener.accept().await.unwrap();
+            loop {
+                let (mut socket, _) = listener.accept().await.unwrap();
 
-            tokio::spawn(async move {
-                let mut buf = [0; 1024];
+                tokio::spawn(async move {
+                    let mut buf = [0; 1024];
 
-                // In a loop, read data from the socket and write the data back.
-                loop {
-                    let n = match socket.read(&mut buf).await {
-                        // socket closed
-                        Ok(n) if n == 0 => return,
-                        Ok(n) => n,
-                        Err(e) => {
-                            eprintln!("failed to read from socket; err = {:?}", e);
-                            return;
-                        }
-                    };
+                    // In a loop, read data from the socket and write the data back.
+                    loop {
+                        let n = match socket.read(&mut buf).await {
+                            // socket closed
+                            Ok(n) if n == 0 => return,
+                            Ok(n) => n,
+                            Err(e) => {
+                                eprintln!("failed to read from socket; err = {:?}", e);
+                                return;
+                            }
+                        };
 
-                    if n == 5 && &buf[0..n] == "quit\n".as_bytes() {
-                        std::process::exit(0);
-                    }
+                        if n == 5 && &buf[0..n] == "quit\n".as_bytes() {
+                            std::process::exit(0);
+                        }
 
-                    let now = Instant::now();
-                    let execution_duartion = Duration::from_micros(computation);
-                    while now.elapsed() < execution_duartion {}
+                        let now = Instant::now();
+                        let execution_duartion = Duration::from_micros(computation);
+                        while now.elapsed() < execution_duartion {}
 
-                    // Write the data back
-                    if let Err(e) = socket.write_all(&buf[0..n]).await {
-                        eprintln!("failed to write to socket; err = {:?}", e);
-                        return;
+                        // Write the data back
+                        if let Err(e) = socket.write_all(&buf[0..n]).await {
+                            eprintln!("failed to write to socket; err = {:?}", e);
+                            return;
+                        }
                     }
-                }
-            });
-        }
-   })
+                });
+            }
+        })
 }