fix(cli): Racing on playground webserver port binding

cli/Cargo.toml

@@ -35,7 +35,7 @@ rustc-hash = "1"
 semver = "1.0"
 serde = { version = "1.0.130", features = ["derive"] }
 smallbitvec = "2.5.1"
-tiny_http = "0.8"
+tiny_http = "0.12.0"
 walkdir = "2.3"
 webbrowser = "0.5.1"
 which = "4.1.0"

cli/src/playground.rs

@@ -45,20 +45,7 @@ fn get_main_html(tree_sitter_dir: &Option<PathBuf>) -> Cow<'static, [u8]> {
 }
 
 pub fn serve(grammar_path: &Path, open_in_browser: bool) {
-    let port = env::var("TREE_SITTER_PLAYGROUND_PORT")
-        .map(|v| v.parse::<u16>().expect("Invalid port specification"))
-        .unwrap_or_else(
-            |_| get_available_port().expect(
-                "Couldn't find an available port, try providing a port number via the TREE_SITTER_PLAYGROUND_PORT \
-                 environment variable"
-            )
-        );
-    let addr = format!(
-        "{}:{}",
-        env::var("TREE_SITTER_PLAYGROUND_ADDR").unwrap_or("127.0.0.1".to_owned()),
-        port
-    );
-    let server = Server::http(&addr).expect("Failed to start web server");
+    let server = get_server();
     let grammar_name = wasm::get_grammar_name(&grammar_path.join("src"))
         .with_context(|| "Failed to get wasm filename")
         .unwrap();
@@ -71,7 +58,7 @@ pub fn serve(grammar_path: &Path, open_in_browser: bool) {
             )
         })
         .unwrap();
-    let url = format!("http://{}", addr);
+    let url = format!("http://{}", server.server_addr());
     println!("Started playground on: {}", url);
     if open_in_browser {
         if let Err(_) = webbrowser::open(&url) {
@@ -135,10 +122,24 @@ fn response<'a>(data: &'a [u8], header: &Header) -> Response<&'a [u8]> {
         .with_header(header.clone())
 }
 
-fn get_available_port() -> Option<u16> {
-    (8000..12000).find(port_is_available)
+fn get_server() -> Server {
+    let addr = env::var("TREE_SITTER_PLAYGROUND_ADDR").unwrap_or("127.0.0.1".to_owned());
+    let port = env::var("TREE_SITTER_PLAYGROUND_PORT")
+        .map(|v| v.parse::<u16>().expect("Invalid port specification"))
+        .ok();
+    let listener = match port {
+        Some(port) => bind_to(&*addr, port).expect("Can't bind to the specified port"),
+        None => {
+            get_listener_on_available_port(&*addr).expect("Can't find a free port to bind to it")
+        }
+    };
+    Server::from_listener(listener, None).expect("Failed to start web server")
+}
+
+fn get_listener_on_available_port(addr: &str) -> Option<TcpListener> {
+    (8000..12000).find_map(|port| bind_to(addr, port))
 }
 
-fn port_is_available(port: &u16) -> bool {
-    TcpListener::bind(("127.0.0.1", *port)).is_ok()
+fn bind_to(addr: &str, port: u16) -> Option<TcpListener> {
+    TcpListener::bind(format!("{addr}:{port}")).ok()
 }