Optimize url encoding, use default port for debugger service (#1402)

Author: Anna Gringauze

dwds/CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 11.3.1-dev
 
+- Encode extension url asynchronously.
+- Use default constant port for debug service.
+  - If we fail binding to the port, fall back to previous strategy
+    of finding unbound ports.
 - Add metrics measuring DevTools Initial Page Load time.
 - Add `ext.dwds.sendEvent` service extension to dwds so other tools
   can send events to the debugger.

dwds/lib/dwds.dart

@@ -121,7 +121,7 @@ class Dwds {
     globalLoadStrategy = loadStrategy;
 
     DevTools devTools;
-    String extensionUri;
+    Future<String> extensionUri;
     ExtensionBackend extensionBackend;
     if (enableDebugExtension) {
       final handler = useSseForDebugBackend
@@ -134,13 +134,13 @@ class Dwds {
           : WebSocketSocketHandler();
 
       extensionBackend = await ExtensionBackend.start(handler, hostname);
-      extensionUri = Uri(
+      extensionUri = Future.value(Uri(
               scheme: useSseForDebugBackend ? 'http' : 'ws',
               host: extensionBackend.hostname,
               port: extensionBackend.port,
               path: r'$debug')
-          .toString();
-      if (urlEncoder != null) extensionUri = await urlEncoder(extensionUri);
+          .toString());
+      if (urlEncoder != null) extensionUri = urlEncoder(await extensionUri);
     }
 
     var serveDevTools = devtoolsLauncher != null;

dwds/lib/src/handlers/injector.dart

@@ -33,15 +33,15 @@ const _clientScript = 'dwds/src/injected/client';
 /// information.
 class DwdsInjector {
   final LoadStrategy _loadStrategy;
-  final String _extensionUri;
+  final Future<String> _extensionUri;
   final _devHandlerPaths = StreamController<String>();
   final _logger = Logger('DwdsInjector');
   final bool _enableDevtoolsLaunch;
   final bool _useSseForInjectedClient;
 
   DwdsInjector(
     this._loadStrategy, {
-    String extensionUri,
+    Future<String> extensionUri,
     bool enableDevtoolsLaunch,
     bool useSseForInjectedClient,
   })  : _extensionUri = extensionUri,
@@ -104,7 +104,7 @@ class DwdsInjector {
                 appId,
                 devHandlerPath,
                 entrypoint,
-                _extensionUri,
+                await _extensionUri,
                 _loadStrategy,
                 _enableDevtoolsLaunch,
               );