Pass exitCode via message and eagerly exit

lib/src/embedded/compilation_dispatcher.dart

@@ -3,6 +3,7 @@
 // https://opensource.org/licenses/MIT.
 
 import 'dart:convert';
+import 'dart:io' if (dart.library.js) 'js/io.dart';
 import 'dart:isolate' if (dart.library.js) 'js/isolate.dart';
 import 'dart:typed_data';
 
@@ -366,14 +367,14 @@ final class CompilationDispatcher {
     message.writeToCodedBufferWriter(protobufWriter);
 
     // Add one additional byte to the beginning to indicate whether or not the
-    // compilation has finished (1) or encountered a fatal error (2), so the
+    // compilation has finished (1) or encountered a fatal error (exitCode), so the
     // [IsolateDispatcher] knows whether to treat this isolate as inactive or
     // close out entirely.
     var packet = Uint8List(
         1 + _compilationIdVarint.length + protobufWriter.lengthInBytes);
     packet[0] = switch (message.whichMessage()) {
       OutboundMessage_Message.compileResponse => 1,
-      OutboundMessage_Message.error => 2,
+      OutboundMessage_Message.error => exitCode,
       _ => 0
     };
     packet.setAll(1, _compilationIdVarint);

lib/src/embedded/executable.dart

@@ -14,8 +14,7 @@ void main(List<String> args) {
   if (parseOptions(args)) {
     IsolateDispatcher(
             StreamChannel.withGuarantees(stdin, stdout, allowSinkErrors: false)
-                .transform(lengthDelimited),
-            gracefulShutdown: false)
+                .transform(lengthDelimited))
         .listen();
   }
 }

lib/src/embedded/isolate_dispatcher.dart

@@ -23,15 +23,6 @@ class IsolateDispatcher {
   /// The channel of encoded protocol buffers, connected to the host.
   final StreamChannel<Uint8List> _channel;
 
-  /// Whether to wait for all worker isolates to exit before exiting the main
-  /// isolate or not.
-  final bool _gracefulShutdown;
-
-  /// All isolates that have been spawned to dispatch to.
-  ///
-  /// Only used for cleaning up the process when the underlying channel closes.
-  final _allIsolates = StreamController<ReusableIsolate>(sync: true);
-
   /// The isolates that aren't currently running compilations
   final _inactiveIsolates = <ReusableIsolate>{};
 
@@ -42,11 +33,7 @@ class IsolateDispatcher {
   /// may be live at once.
   final _isolatePool = Pool(concurrencyLimit);
 
-  /// Whether [_channel] has been closed or not.
-  var _closed = false;
-
-  IsolateDispatcher(this._channel, {bool gracefulShutdown = true})
-      : _gracefulShutdown = gracefulShutdown;
+  IsolateDispatcher(this._channel);
 
   void listen() {
     _channel.stream.listen((packet) async {
@@ -60,9 +47,6 @@ class IsolateDispatcher {
           var isolate = await _activeIsolates.putIfAbsent(
               compilationId, () => _getIsolate(compilationId!));
 
-          // The shutdown may have started by the time the isolate is spawned
-          if (_closed) return;
-
           try {
             isolate.send(packet);
             return;
@@ -95,12 +79,7 @@ class IsolateDispatcher {
     }, onError: (Object error, StackTrace stackTrace) {
       _handleError(error, stackTrace);
     }, onDone: () {
-      if (_gracefulShutdown) {
-        _closed = true;
-        _allIsolates.stream.listen((isolate) => isolate.kill());
-      } else {
-        exit(exitCode);
-      }
+      exit(exitCode);
     });
   }
 
@@ -120,7 +99,6 @@ class IsolateDispatcher {
         _handleError(error, stackTrace);
       });
       isolate = await future;
-      _allIsolates.add(isolate);
     }
 
     isolate.borrow((message) {
@@ -145,13 +123,10 @@ class IsolateDispatcher {
           _inactiveIsolates.add(isolate);
           resource.release();
           _channel.sink.add(packet);
-        case 2:
+        default:
           _channel.sink.add(packet);
-          if (_gracefulShutdown) {
-            _channel.sink.close();
-          } else {
-            exit(exitCode);
-          }
+          exitCode = category;
+          exit(exitCode);
       }
     });
 
@@ -175,11 +150,7 @@ class IsolateDispatcher {
       {int? compilationId, int? messageId}) {
     sendError(compilationId ?? errorId,
         handleError(error, stackTrace, messageId: messageId));
-    if (_gracefulShutdown) {
-      _channel.sink.close();
-    } else {
-      exit(exitCode);
-    }
+    exit(exitCode);
   }
 
   /// Sends [message] to the host.

lib/src/embedded/js/reusable_isolate.dart

@@ -6,7 +6,6 @@ import 'dart:async';
 import 'dart:js_interop';
 import 'dart:typed_data';
 
-import 'io.dart';
 import 'js.dart';
 import 'sync_message_port.dart';
 import 'worker_threads.dart';
@@ -46,14 +45,6 @@ class ReusableIsolate {
             workerData: channel.port2,
             transferList: [channel.port2].toJS,
             argv: argv));
-    worker.once(
-        'exit',
-        (int code) {
-          // Worker exit code 1 means it is killed by worker.terminate()
-          if (code > exitCode && code != 1) {
-            exitCode = code;
-          }
-        }.toJS);
     var controller = StreamController<dynamic>(sync: true);
     var sendPort = SyncMessagePort(channel.port1);
     var receivePort = channel.port1;