in midst of refactor

stdio-perftest/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "stdio-perftest"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

stdio-perftest/src/main.rs

@@ -0,0 +1,44 @@
+use std::env::{self, args};
+use std::io::{stdin, BufRead, BufReader, Read, Write};
+use std::process::{self, Child};
+use std::time::SystemTime;
+
+fn main() {
+  let is_child = env::args().any(|arg| arg == "child");
+  if is_child {
+    loop {
+      let mut input = String::new();
+      stdin().read_line(&mut input).unwrap();
+      if input == "ping\n" {
+        println!("pong");
+      } else if input.is_empty() {
+        process::exit(0);
+      } else {
+        panic!("Unrecognized input {input:?}");
+      }
+    }
+  } else {
+    let steps = 10_000;
+    let mut child = process::Command::new(args().next().unwrap())
+      .arg("child")
+      .stdin(process::Stdio::piped())
+      .stdout(process::Stdio::piped())
+      .spawn()
+      .unwrap();
+    let mut bufr = BufReader::new(child.stdout.take().unwrap());
+    let mut child_stdin = child.stdin.take().unwrap();
+    let time = SystemTime::now();
+    for _ in 0..steps {
+      writeln!(child_stdin, "ping");
+      let mut buf = String::new();
+      bufr.read_line(&mut buf).unwrap();
+      if buf != "pong\n" {
+        panic!("Unrecognized output {buf:?}")
+      }
+    }
+    child.kill();
+    let elapsed = time.elapsed().unwrap();
+    let avg = elapsed / steps;
+    println!("A roundtrip takes {avg:?}, {}ms on average", (avg.as_nanos() as f64) / 1_000_000f64);
+  }
+}