Function spawn_kernel

rust/py_repl_host/src/main.rs:248–306

()

}

fn spawn_kernel() -> io::Result<KernelProcess> {
    let python = resolve_python_executable()?;
    let kernel_dir = create_kernel_runtime_dir()?;
    let kernel_path = kernel_dir.join("kernel.py");
    fs::write(&kernel_path, KERNEL_SOURCE)?;

    let mut command = Command::new(python);
    command.arg(&kernel_path);
    command.current_dir(env::current_dir()?);
    command.stdin(Stdio::piped());
    command.stdout(Stdio::piped());
    command.stderr(Stdio::piped());
    command.env(
      "CODEX_PY_TMP_DIR",
      env::temp_dir().to_string_lossy().to_string(),
    );
    if let Some(module_dirs) = resolve_python_module_dirs() {
        command.env("CODEX_PY_REPL_PYTHON_MODULE_DIRS", module_dirs);
    }

    let mut child = command.spawn()?;
    let child_stdin = child
        .stdin
        .take()
        .ok_or_else(|| io::Error::new(io::ErrorKind::BrokenPipe, "missing py_repl stdin"))?;
    let child_stdout = child
        .stdout
        .take()
        .ok_or_else(|| io::Error::new(io::ErrorKind::BrokenPipe, "missing py_repl stdout"))?;
    let child_stderr = child
        .stderr
        .take()
        .ok_or_else(|| io::Error::new(io::ErrorKind::BrokenPipe, "missing py_repl stderr"))?;

    let stderr_tail = Arc::new(Mutex::new(VecDeque::new()));
    let stderr_tail_writer = Arc::clone(&stderr_tail);
    std::thread::spawn(move || {
        let reader = BufReader::new(child_stderr);
        for line in reader.lines() {
            let Ok(line) = line else {
                break;
            };
            let trimmed = line.trim();
            if trimmed.is_empty() {
                continue;
            }
            if let Ok(mut tail) = stderr_tail_writer.lock() {
                push_stderr_tail_line(&mut tail, trimmed);
            }
        }
    });

    Ok(KernelProcess {
        _child: child,
        stdin: BufWriter::new(child_stdin),
        stdout: BufReader::new(child_stdout),
        stderr_tail,
    })