VM: [Kernel] Fix bootstraping when Kernel isolate is used.

runtime/tools/kernel-service.dart

Index: runtime/tools/kernel-service.dart
diff --git a/runtime/tools/kernel-service.dart b/runtime/tools/kernel-service.dart
index f473c154775f0376174f49614e7eb7ace589ec48..b1b441db2ed5e7d1f6efe595150f09d973bb1c93 100644
--- a/runtime/tools/kernel-service.dart
+++ b/runtime/tools/kernel-service.dart
@@ -1,22 +1,26 @@
 // 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.
+library runtime.tools.kernel_service;
 
 // 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:convert';
 import 'dart:io';
+import 'dart:isolate';
 import 'dart:typed_data';
 
-import 'package:kernel/binary/ast_to_binary.dart';
 import 'package:kernel/analyzer/loader.dart';
+import 'package:kernel/binary/ast_to_binary.dart';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/target/targets.dart';
 
-const verbose = false;
+const bool verbose = const bool.fromEnvironment('DFE_VERBOSE') ?? false;
 
 class DataSink implements Sink<List<int>> {
   final BytesBuilder builder = new BytesBuilder();
@@ -30,7 +34,55 @@ class DataSink implements Sink<List<int>> {
   }
 }
 
-Future<Uint8List> parseScript(
+// Note: these values must match Dart_KernelCompilationStatus in dart_api.h.
+const int STATUS_OK = 0; // Compilation was successful.
+const int STATUS_ERROR = 1; // Compilation failed with a compile time error.
+const int STATUS_CRASH = 2; // Compiler crashed.
+
+abstract class CompilationResult {
+  List toResponse();
+}
+
+class CompilationOk extends CompilationResult {
+  final Uint8List binary;
+
+  CompilationOk(this.binary);
+
+  List toResponse() => [STATUS_OK, binary];
+
+  String toString() => "CompilationOk(${binary.length} bytes)";
+}
+
+abstract class CompilationFail extends CompilationResult {
+  String get errorString;
+}
+
+class CompilationError extends CompilationFail {
+  final List<String> errors;
+
+  CompilationError(this.errors);
+
+  List toResponse() => [STATUS_ERROR, errorString];
+
+  String get errorString => errors.take(10).join('\n');
+
+  String toString() => "CompilationError(${errorString})";
+}
+
+class CompilationCrash extends CompilationFail {
+  final String exception;
+  final String stack;
+
+  CompilationCrash(this.exception, this.stack);
+
+  List toResponse() => [STATUS_CRASH, errorString];
+
+  String get errorString => "${exception}\n${stack}";
+
+  String toString() => "CompilationCrash(${errorString})";
+}
+
+Future<CompilationResult> parseScriptImpl(DartLoaderBatch batch_loader,
     Uri fileName, String packageConfig, String sdkPath) async {
   if (!FileSystemEntity.isFileSync(fileName.path)) {
     throw "Input file '${fileName.path}' does not exist.";
@@ -49,12 +101,12 @@ Future<Uint8List> parseScript(
       customUriMappings: const {},
       declaredVariables: const {});
   DartLoader loader =
-      await new DartLoaderBatch().getLoader(new Repository(), dartOptions);
+      await batch_loader.getLoader(new Repository(), dartOptions);
   var program = loader.loadProgram(fileName, target: target);
 
   var errors = loader.errors;
   if (errors.isNotEmpty) {
-    throw loader.errors.first;
+    return new CompilationError(loader.errors.toList());
   }
 
   // Link program into one file, cf. --link option in dartk.
@@ -63,33 +115,111 @@ Future<Uint8List> parseScript(
   // Write the program to a list of bytes and return it.
   var sink = new DataSink();
   new BinaryPrinter(sink).writeProgramFile(program);
-  return sink.builder.takeBytes();
+  return new CompilationOk(sink.builder.takeBytes());
 }
 
-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}");
+Future<CompilationResult> parseScript(DartLoaderBatch loader, Uri fileName,
+    String packageConfig, String sdkPath) async {
+  try {
+    return await parseScriptImpl(loader, fileName, packageConfig, sdkPath);
+  } catch (err, stack) {
+    return new CompilationCrash(err.toString(), stack.toString());
   }
+}
 
-  int tag = request[0];
-  SendPort port = request[1];
-  String inputFileUrl = request[2];
+Future _processLoadRequestImpl(String inputFileUrl) async {
   Uri scriptUri = Uri.parse(inputFileUrl);
-  Uri packagesUri = Uri.parse(Platform.packageConfig ?? ".packages");
-  Uri patchedSdk =
+
+  // Because we serve both Loader and bootstrapping requests we need to
+  // duplicate the logic from _resolveScriptUri(...) here and attempt to
+  // resolve schemaless uris using current working directory.
+  if (scriptUri.scheme == '') {
+    // Script does not have a scheme, assume that it is a path,
+    // resolve it against the working directory.
+    scriptUri = Directory.current.uri.resolveUri(scriptUri);
+  }
+
+  if (scriptUri.scheme != 'file') {
+    // TODO: reuse loader code to support other schemes.
+    throw "Expected 'file' scheme for a script uri: got ${scriptUri.scheme}";
+  }
+
+  final Uri packagesUri = (Platform.packageConfig != null)
+      ? Uri.parse(Platform.packageConfig)
+      : await _findPackagesFile(scriptUri);
+  if (packagesUri == null) {
+    throw "Could not find .packages";
+  }
+
+  final Uri patchedSdk =
       Uri.parse(Platform.resolvedExecutable).resolve("patched_sdk");
 
+  if (verbose) {
+    print("""DFE: Requesting compilation {
+  scriptUri: ${scriptUri}
+  packagesUri: ${packagesUri}
+  patchedSdk: ${patchedSdk}
+}""");
+  }
+
+  return await parseScript(
+      new DartLoaderBatch(), scriptUri, packagesUri.path, patchedSdk.path);
+}
+
+// Process a request from the runtime. See KernelIsolate::CompileToKernel in
+// kernel_isolate.cc and Loader::SendKernelRequest in loader.cc.
+Future _processLoadRequest(request) async {
+  if (verbose) {
+    print("DFE: request: $request");
+    print("DFE: Platform.packageConfig: ${Platform.packageConfig}");
+    print("DFE: Platform.resolvedExecutable: ${Platform.resolvedExecutable}");
+  }
+
+  final int tag = request[0];
+  final SendPort port = request[1];
+  final String inputFileUrl = request[2];
+
   var result;
   try {
-    result = await parseScript(scriptUri, packagesUri.path, patchedSdk.path);
-  } catch (error) {
-    tag = -tag; // Mark reply as an exception.
-    result = error.toString();
+    result = await _processLoadRequestImpl(inputFileUrl);
+  } catch (error, stack) {
+    result = new CompilationCrash(error.toString(), stack.toString());
   }
 
-  port.send([tag, inputFileUrl, inputFileUrl, null, result]);
+  if (verbose) {
+    print("DFE:> ${result}");
+  }
+
+  // Check whether this is a Loader request or a bootstrapping request from
+  // KernelIsolate::CompileToKernel.
+  final isBootstrapRequest = tag == null;
+  if (isBootstrapRequest) {
+    port.send(result.toResponse());
+  } else {
+    // See loader.cc for the code that handles these replies.
+    if (result is CompilationOk) {
+      port.send([tag, inputFileUrl, inputFileUrl, null, result]);
+    } else {
+      port.send([-tag, inputFileUrl, inputFileUrl, null, result.errorString]);
+    }
+  }
 }
 
 main() => new RawReceivePort()..handler = _processLoadRequest;
+
+// This duplicates functionality from the Loader which we can't easily
+// access from here.
+Uri _findPackagesFile(Uri base) async {
+  var dir = new File.fromUri(base).parent;
+  while (true) {
+    final packagesFile = dir.uri.resolve(".packages");
+    if (await new File.fromUri(packagesFile).exists()) {
+      return packagesFile;
+    }
+    if (dir.parent == dir) {
+      break;
+    }
+    dir = dir.parent;
+  }
+  return null;
+}