Faster DevTools launch (#747)

- No longer wait for `CreateIsolate` to complete or the debugger to be enabled before creating the `ChromeProxyService`
- Get rid of the `correctTab` evals as they are no longer necessary
- No longer return a `RunResponse` as the run state is now properly stored in the `AppConnection`

Author: grouma

dwds/CHANGELOG.md

@@ -3,6 +3,7 @@
 - The injected client's connection is now based off the request URI.
 - Fix an issue where resuming while paused at the start would cause an error.
 - Expose the `ChromeDebugException` class for error handling purposes.
+- DevTools will now launch immediately and lazily sets up necessary state.
 
 ## 0.7.4
 

dwds/lib/data/run_request.dart

@@ -14,11 +14,3 @@ abstract class RunRequest implements Built<RunRequest, RunRequestBuilder> {
 
   RunRequest._();
 }
-
-abstract class RunResponse implements Built<RunResponse, RunResponseBuilder> {
-  static Serializer<RunResponse> get serializer => _$runResponseSerializer;
-
-  factory RunResponse([Function(RunResponseBuilder) updates]) = _$RunResponse;
-
-  RunResponse._();
-}

dwds/lib/data/run_request.g.dart

@@ -20,7 +20,6 @@ part 'serializers.g.dart';
   DevToolsResponse,
   ConnectRequest,
   RunRequest,
-  RunResponse,
   DefaultBuildResult,
   IsolateExit,
   IsolateStart,

dwds/lib/data/serializers.dart

@@ -50,6 +50,7 @@ class Dwds {
   Future<DebugConnection> debugConnection(AppConnection appConnection) async {
     if (!_enableDebugging) throw StateError('Debugging is not enabled.');
     var appDebugServices = await _devHandler.loadAppServices(appConnection);
+    await appDebugServices.chromeProxyService.isInitialized;
     return DebugConnection(appDebugServices);
   }
 

dwds/lib/data/serializers.g.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:async';
 import 'dart:convert';
 
 import 'package:sse/server/sse_handler.dart';
@@ -14,17 +15,19 @@ import '../../data/serializers.dart';
 class AppConnection {
   /// The initial connection request sent from the application in the browser.
   final ConnectRequest request;
-
+  final _startedCompleter = Completer<void>();
   final SseConnection _connection;
-  var _isStarted = false;
 
   AppConnection(this.request, this._connection);
 
-  bool get isStarted => _isStarted;
+  bool get isStarted => _startedCompleter.isCompleted;
+  Future<void> get onStart => _startedCompleter.future;
 
   void runMain() {
-    if (_isStarted) throw StateError('Main has already started.');
+    if (_startedCompleter.isCompleted) {
+      throw StateError('Main has already started.');
+    }
     _connection.sink.add(jsonEncode(serializers.serialize(RunRequest())));
-    _isStarted = true;
+    _startedCompleter.complete();
   }
 }

dwds/lib/dwds.dart

@@ -10,7 +10,6 @@ import 'package:build_daemon/data/serializers.dart' as build_daemon;
 import 'package:dwds/data/error_response.dart';
 import 'package:dwds/data/run_request.dart';
 import 'package:dwds/src/connections/debug_connection.dart';
-import 'package:dwds/src/debugging/remote_debugger.dart';
 import 'package:dwds/src/debugging/webkit_debugger.dart';
 import 'package:dwds/src/servers/extension_backend.dart';
 import 'package:logging/logging.dart';
@@ -148,9 +147,6 @@ class DevHandler {
             await startDebugService(await _chromeConnection(), appConnection);
         var appServices = await _createAppDebugServices(
             appConnection.request.appId, debugService);
-        if (appConnection.isStarted) {
-          await appServices.chromeProxyService.resumeFromStart();
-        }
         unawaited(appServices.chromeProxyService.remoteDebugger.onClose.first
             .whenComplete(() {
           appServices.close();
@@ -187,8 +183,6 @@ class DevHandler {
             await _handleIsolateExit(appConnection);
           } else if (message is IsolateStart) {
             await _handleIsolateStart(appConnection, injectedConnection);
-          } else if (message is RunResponse) {
-            await _handleRunResponse(appConnection);
           }
         }
       } catch (e, s) {
@@ -262,15 +256,6 @@ class DevHandler {
       return;
     }
 
-    // If you load the same app in a different tab then we need to throw
-    // away our old services and start new ones.
-    if (!(await _isCorrectTab(appConnection.request.instanceId,
-        appServices.chromeProxyService.remoteDebugger))) {
-      unawaited(appServices.close());
-      unawaited(_servicesByAppId.remove(appConnection.request.appId));
-      appServices = await loadAppServices(appConnection);
-    }
-
     sseConnection.sink.add(jsonEncode(
         serializers.serialize(DevToolsResponse((b) => b..success = true))));
 
@@ -293,13 +278,9 @@ class DevHandler {
     var services = await _servicesByAppId[message.appId];
     var connection = AppConnection(message, sseConnection);
     if (services != null && services.connectedInstanceId == null) {
-      // Re-connect to the previous instance if its in the same tab,
-      // otherwise do nothing for now.
-      if (await _isCorrectTab(
-          message.instanceId, services.chromeProxyService.remoteDebugger)) {
-        services.connectedInstanceId = message.instanceId;
-        await services.chromeProxyService.createIsolate(connection);
-      }
+      // Reconnect to existing service.
+      services.connectedInstanceId = message.instanceId;
+      await services.chromeProxyService.createIsolate(connection);
     }
     _appConnectionByAppId[message.appId] = connection;
     _connectedApps.add(connection);
@@ -322,12 +303,6 @@ class DevHandler {
     sseConnection.sink.add(jsonEncode(serializers.serialize(RunRequest())));
   }
 
-  Future<void> _handleRunResponse(AppConnection appConnection) async {
-    await (await _servicesByAppId[appConnection.request.appId])
-        ?.chromeProxyService
-        ?.resumeFromStart();
-  }
-
   void _listen() async {
     var injectedConnections = _sseHandler.connections;
     while (await injectedConnections.hasNext) {
@@ -406,10 +381,3 @@ class DevHandler {
     });
   }
 }
-
-/// Checks if connection of [remoteDebugger] is running the app with [instanceId].
-Future<bool> _isCorrectTab(
-    String instanceId, RemoteDebugger remoteDebugger) async {
-  var result = await remoteDebugger.evaluate(r'window["$dartAppInstanceId"];');
-  return result.value == instanceId;
-}