Cleanup the kernel service implementation and avoid printing on the console when no tracing flags a…

runtime/tools/kernel-service.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 // This is an interface to the Dart Kernel parser and Kernel binary generator.
 // It is used by the kernel-isolate to load Dart source code and generate
 // Kernel binary format.
 
 import 'dart:isolate';
 import 'dart:async';
-import "dart:io";
-import "dart:typed_data";
+import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:kernel/binary/ast_to_binary.dart';
 import 'package:kernel/analyzer/loader.dart';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/target/targets.dart';
 
-bool verbose = false;
+const verbose = false;
 
-final RawReceivePort scriptLoadPort = new RawReceivePort();
+class DataSink implements Sink<List<int>> {
+  final BytesBuilder builder = new BytesBuilder();
 
+  void add(List<int> data) {
+    builder.add(data);
+  }
 
-bool checkIsFile(String path) {
-  var stat = new File(path).statSync();
-  switch (stat.type) {
-    case FileSystemEntityType.DIRECTORY:
-      return false;
-    case FileSystemEntityType.NOT_FOUND:
-      return false;
-  }
-  return true;
-}
-
-
-void checkSdkDirectory(String path) {
-  var stat = new File(path).statSync();
-  switch (stat.type) {
-    case FileSystemEntityType.DIRECTORY:
-    case FileSystemEntityType.LINK:
-      return true;
-    default:
-      return false;
-  }
-}
-
-
-class DataSink implements StreamSink<List<int>> {
-  var buffer = [];
-  add(List<int> data) {
-    buffer.addAll(data);
-  }
-  close() {
+  void close() {
     // Nothing to do.
   }
 }
 
-
-List writeProgramToBuffer(Program program) {
-  var sink = new DataSink();
-  try {
-    new BinaryPrinter(sink).writeProgramFile(program);
-  } finally {
-    sink.close();
-  }
-  return new Uint8List.fromList(sink.buffer);
-}
-
-
-Future parseScript(Uri fileName, String packageConfig, String sdkPath) async {
-
-  if (!checkIsFile(fileName.path)) {
+Future<Uint8List> parseScript(
+    Uri fileName, String packageConfig, String sdkPath) async {
+  if (!FileSystemEntity.isFileSync(fileName.path)) {
     throw "Input file '${fileName.path}' does not exist.";
   }
 
-  if (!checkSdkDirectory(sdkPath)) {
+  if (!FileSystemEntity.isDirectorySync(sdkPath)) {
     throw "Patched sdk directory not found at $sdkPath";
   }
 
   Target target = getTarget("vm", new TargetFlags(strongMode: false));
   DartOptions dartOptions = new DartOptions(
-        strongMode: false,
-        strongModeSdk: false,
-        sdk: sdkPath,
-        packagePath: packageConfig,
-        customUriMappings: {},
-        declaredVariables: {});
+      strongMode: false,
+      strongModeSdk: false,
+      sdk: sdkPath,
+      packagePath: packageConfig,
+      customUriMappings: const {},
+      declaredVariables: const {});
   DartLoader loader =
       await new DartLoaderBatch().getLoader(new Repository(), dartOptions);
   var program = loader.loadProgram(fileName, target: target);
 
   var errors = loader.errors;
   if (errors.isNotEmpty) {
     throw loader.errors.first;
   }
 
-  // Link program into one file, cf. --link option in dartk
+  // Link program into one file, cf. --link option in dartk.
   target.transformProgram(program);
 
-  return writeProgramToBuffer(program);
+  // Write the program to a list of bytes and return it.
+  var sink = new DataSink();
+  new BinaryPrinter(sink).writeProgramFile(program);
+  return sink.builder.takeBytes();
 }
 
-
-_processLoadRequest(request) {
+Future _processLoadRequest(request) async {
   if (verbose) {
     print("FROM DART KERNEL: load request: $request");
     print("FROM DART KERNEL: package: ${Platform.packageConfig}");
     print("FROM DART KERNEL: exec: ${Platform.resolvedExecutable}");
   }
+
   int tag = request[0];
-  SendPort sp = request[1];
+  SendPort port = request[1];
   String inputFileUrl = request[2];
   Uri scriptUri = Uri.parse(inputFileUrl);
   Uri packagesUri = Uri.parse(Platform.packageConfig ?? ".packages");
-  Uri patched_sdk = Uri.parse(Platform.resolvedExecutable).resolve("patched_sdk");
+  Uri patchedSdk =
+      Uri.parse(Platform.resolvedExecutable).resolve("patched_sdk");
 
-  var parsingDone = parseScript(scriptUri, packagesUri.path, patched_sdk.path);
+  var result;
+  try {
+    result = await parseScript(scriptUri, packagesUri.path, patchedSdk.path);
+  } catch (error) {
+    tag = -tag; // Mark reply as an exception.
+    result = error.toString();
+  }
 
-  parsingDone
-    .then((data) {
-        var msg = new List(5);
-        msg[0] = tag;
-        msg[1] = inputFileUrl;
-        msg[2] = inputFileUrl;
-        msg[3] = null;
-        msg[4] = data;
-        sp.send(msg);
-        return;
-    })
-    .catchError((e) {
-        var msg = new List(5);
-        msg[0] = -tag;
-        msg[1] = inputFileUrl;
-        msg[2] = inputFileUrl;
-        msg[3] = null;
-        msg[4] = e.toString();
-        sp.send(msg);
-    });
+  port.send([tag, inputFileUrl, inputFileUrl, null, result]);
 }
 
-
-main() {
-  scriptLoadPort.handler = _processLoadRequest;
-  Timer.run(() {});
-  return scriptLoadPort;
-}
+main() => new RawReceivePort()..handler = _processLoadRequest;