Add an option to dwds to suppress emitting debug events (#1467)

* Add an option to dwds to suppress emitting debug events

Flutter sends a stream of debug events to dwds for profiling information
that can slow down debugging for apps that refresh frames frequently.

Add an option to disable debug events as a workaround until we can improve
performance of communication between the injected client and dwds.

Workaround for: #1466

* Address CR comments

Author: Anna Gringauze

dwds/CHANGELOG.md

@@ -9,6 +9,8 @@
 **Breaking changes:**
 
 - Add `sdkDir` argument to `Dwds.start` to help file resolution for sdk uris.
+- Add `emitDebugEvents` argument to `Dwds.start` to suppress emitting debug
+  events from the injected client.
 
 ## 11.5.1
 

dwds/lib/dwds.dart

@@ -113,6 +113,7 @@ class Dwds {
     bool enableDevtoolsLaunch,
     DevtoolsLauncher devtoolsLauncher,
     Uri sdkDir,
+    bool emitDebugEvents,
   }) async {
     hostname ??= 'localhost';
     enableDebugging ??= true;
@@ -123,6 +124,7 @@ class Dwds {
     enableDevtoolsLaunch ??= true;
     spawnDds ??= true;
     globalLoadStrategy = loadStrategy;
+    emitDebugEvents ??= true;
 
     await DartUri.initialize(sdkDir: sdkDir);
 
@@ -162,6 +164,7 @@ class Dwds {
       useSseForInjectedClient: useSseForInjectedClient,
       extensionUri: extensionUri,
       enableDevtoolsLaunch: enableDevtoolsLaunch,
+      emitDebugEvents: emitDebugEvents,
     );
 
     var devHandler = DevHandler(

dwds/lib/src/handlers/injector.dart

@@ -38,15 +38,18 @@ class DwdsInjector {
   final _logger = Logger('DwdsInjector');
   final bool _enableDevtoolsLaunch;
   final bool _useSseForInjectedClient;
+  final bool _emitDebugEvents;
 
   DwdsInjector(
     this._loadStrategy, {
     Future<String> extensionUri,
     bool enableDevtoolsLaunch,
     bool useSseForInjectedClient,
+    bool emitDebugEvents,
   })  : _extensionUri = extensionUri,
         _enableDevtoolsLaunch = enableDevtoolsLaunch,
-        _useSseForInjectedClient = useSseForInjectedClient ?? true;
+        _useSseForInjectedClient = useSseForInjectedClient ?? true,
+        _emitDebugEvents = emitDebugEvents ?? true;
 
   /// Returns the embedded dev handler paths.
   ///
@@ -107,6 +110,7 @@ class DwdsInjector {
                 await _extensionUri,
                 _loadStrategy,
                 _enableDevtoolsLaunch,
+                _emitDebugEvents,
               );
               body += await _loadStrategy.bootstrapFor(entrypoint);
               _logger.info('Injected debugging metadata for '
@@ -137,6 +141,7 @@ String _injectClientAndHoistMain(
   String extensionUri,
   LoadStrategy loadStrategy,
   bool enableDevtoolsLaunch,
+  bool emitDebugEvents,
 ) {
   var bodyLines = body.split('\n');
   var extensionIndex =
@@ -156,6 +161,7 @@ String _injectClientAndHoistMain(
     extensionUri,
     loadStrategy,
     enableDevtoolsLaunch,
+    emitDebugEvents,
   );
   result += '''
   // Injected by dwds for debugging support.
@@ -189,6 +195,7 @@ String _injectedClientSnippet(
   String extensionUri,
   LoadStrategy loadStrategy,
   bool enableDevtoolsLaunch,
+  bool emitDebugEvents,
 ) {
   var injectedBody = 'window.\$dartAppId = "$appId";\n'
       'window.\$dartReloadConfiguration = "${loadStrategy.reloadConfiguration}";\n'
@@ -198,6 +205,7 @@ String _injectedClientSnippet(
       'window.\$dwdsDevHandlerPath = "$devHandlerPath";\n'
       'window.\$dwdsEnableDevtoolsLaunch = $enableDevtoolsLaunch;\n'
       'window.\$dartEntrypointPath = "$entrypointPath";\n'
+      'window.\$dartEmitDebugEvents = "$emitDebugEvents";\n'
       '${loadStrategy.loadClientSnippet(_clientScript)}';
   if (extensionUri != null) {
     injectedBody += 'window.\$dartExtensionUri = "$extensionUri";\n';