Add unstable API for bazel summary worker and move the actual worker out of package:front-end

Bug:
Change-Id: I0a64d3de46ef55e8185e723d6111fa315ad286ca
Reviewed-on: https://dart-review.googlesource.com/30621
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Peter von der Ahé <ahe@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>

pkg/front_end/lib/src/api_unstable/summary_worker.dart

@@ -0,0 +1,61 @@
+// Copyright (c) 2017, 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.
+
+/// API needed by `utils/front_end/summary_worker.dart`, a tool used to compute
+/// summaries in build systems like bazel, pub-build, and package-build.
+
+import 'dart:async' show Future;
+
+import 'package:front_end/src/api_prototype/file_system.dart';
+import 'package:front_end/src/base/processed_options.dart';
+import 'package:front_end/src/kernel_generator_impl.dart';
+import 'package:kernel/target/targets.dart' show Target;
+
+import '../api_prototype/compiler_options.dart';
+import 'compiler_state.dart';
+
+export 'compiler_state.dart';
+
+export '../api_prototype/physical_file_system.dart' show PhysicalFileSystem;
+export '../fasta/fasta_codes.dart' show LocatedMessage;
+export '../fasta/severity.dart' show Severity;
+
+Future<InitializedCompilerState> initializeCompiler(
+    InitializedCompilerState oldState,
+    Uri sdkSummary,
+    Uri packagesFile,
+    List<Uri> inputSummaries,
+    Target target,
+    FileSystem fileSystem) async {
+  // TODO(sigmund): use incremental compiler when it supports our use case.
+  // Note: it is common for the summary worker to invoke the compiler with the
+  // same input summary URIs, but with different contents, so we'd need to be
+  // able to track shas or modification time-stamps to be able to invalidate the
+  // old state appropriately.
+  CompilerOptions options = new CompilerOptions()
+    ..sdkSummary = sdkSummary
+    ..packagesFileUri = packagesFile
+    ..inputSummaries = inputSummaries
+    ..target = target
+    ..fileSystem = fileSystem
+    ..chaseDependencies = true;
+
+  ProcessedOptions processedOpts = new ProcessedOptions(options, true, []);
+
+  return new InitializedCompilerState(options, processedOpts);
+}
+
+Future<List<int>> compile(InitializedCompilerState compilerState,
+    List<Uri> inputs, ProblemHandler problemHandler) async {
+  CompilerOptions options = compilerState.options;
+  options..onProblem = problemHandler;
+
+  ProcessedOptions processedOpts = compilerState.processedOpts;
+  processedOpts.inputs.clear();
+  processedOpts.inputs.addAll(inputs);
+
+  var result = await generateKernel(processedOpts,
+      buildSummary: true, buildProgram: false);
+  return result?.summary;
+}

pkg/front_end/pubspec.yaml

@@ -18,7 +18,6 @@ dependencies:
 dev_dependencies:
   analyzer: '>=0.30.0 <0.32.0'
   args: '>=0.13.0 <2.0.0'
-  bazel_worker: ^0.1.4
   dart_style: '^1.0.7'
   json_rpc_2: ^2.0.4
   mockito: ^2.0.2

sdk/BUILD.gn

@@ -44,7 +44,7 @@ declare_args() {
 # ........dartfmt.dart.snapshot
 # ........dartdevc.dart.snapshot
 # ........dartdevk.dart.snapshot
-# ........front_end_worker.dart.snapshot
+# ........kernel_summary_worker.dart.snapshot
 # ........pub.dart.snapshot
 # ........utils_wrapper.dart.snapshot
 #.........resources/
@@ -163,8 +163,8 @@ _full_sdk_snapshots = [
     "../utils/dartfmt",
   ],
   [
-    "front_end_worker",
-    "../utils/front_end:front_end_worker",
+    "kernel_summary_worker",
+    "../utils/bazel:kernel_summary_worker",
   ],
   [
     "pub",

utils/bazel/BUILD.gn

@@ -4,7 +4,7 @@
 
 import("../application_snapshot.gni")
 
-application_snapshot("front_end_worker") {
-  main_dart = "../../pkg/front_end/tool/bazel/worker.dart"
+application_snapshot("kernel_summary_worker") {
+  main_dart = "kernel_summary_worker.dart"
   training_args = [ "--help" ]
 }

utils/bazel/kernel_summary_worker.dart

@@ -1,16 +1,21 @@
 // Copyright (c) 2017, 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.
+
+/// A tool that invokes the CFE to compute kernel summary files.
+///
+/// This script can be used as a command-line command or a persistent server.
+/// The server is implemented using the bazel worker protocol, so it can be used
+/// within bazel as is. Other tools (like pub-build and package-build) also
+/// use this persistent worker via the same protocol.
+
 import 'dart:async';
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:bazel_worker/bazel_worker.dart';
-import 'package:front_end/src/api_prototype/front_end.dart'
-    hide FileSystemException;
-import 'package:front_end/src/fasta/command_line_reporting.dart';
+import 'package:front_end/src/api_unstable/summary_worker.dart' as fe;
 import 'package:front_end/src/multi_root_file_system.dart';
-import 'package:front_end/src/api_prototype/physical_file_system.dart';
 import 'package:kernel/target/targets.dart';
 
 main(List<String> args) async {
@@ -108,42 +113,38 @@ Future<bool> computeSummary(List<String> args,
   var fileSystem = new MultiRootFileSystem(
       'org-dartlang-multi-root',
       parsedArgs['multi-root'].map(Uri.parse).toList(),
-      PhysicalFileSystem.instance);
-  var options = new CompilerOptions()
-    ..packagesFileUri = Uri.parse(parsedArgs['packages-file'])
-    ..inputSummaries = parsedArgs['input-summary'].map(Uri.parse).toList()
-    ..sdkSummary = Uri.parse(parsedArgs['dart-sdk-summary'])
-    ..fileSystem = fileSystem
-    ..target = new NoneTarget(new TargetFlags());
+      fe.PhysicalFileSystem.instance);
 
-  options.onError = (CompilationMessage error) {
-    var message = new StringBuffer()
-      ..write(severityName(error.severity, capitalized: true))
-      ..write(': ');
-    if (error.span != null) {
-      message.writeln(error.span.message(error.message));
-    } else {
-      message.writeln(error.message);
-    }
-    if (error.tip != null) {
-      message.writeln(error.tip);
-    }
+  var state = await fe.initializeCompiler(
+      // TODO(sigmund): pass an old state once we can make use of it.
+      null,
+      Uri.parse(parsedArgs['dart-sdk-summary']),
+      Uri.parse(parsedArgs['packages-file']),
+      parsedArgs['input-summary'].map(Uri.parse).toList(),
+      new NoneTarget(new TargetFlags()),
+      fileSystem);
+
+  void onProblem(problem, severity, String formatted, line, column) {
     if (outputBuffer != null) {
-      outputBuffer.writeln(message);
+      outputBuffer.writeln(formatted);
     } else {
-      print(message);
+      stderr.writeln(formatted);
     }
-    if (error.severity != Severity.nit) {
+    if (severity != fe.Severity.nit) {
       succeeded = false;
     }
-  };
+  }
 
   var sources = parsedArgs['source'].map(Uri.parse).toList();
-  var program = await summaryFor(sources, options);
+  var summary = await fe.compile(state, sources, onProblem);
 
-  var outputFile = new File(parsedArgs['output']);
-  outputFile.createSync(recursive: true);
-  outputFile.writeAsBytesSync(program);
+  if (summary != null) {
+    var outputFile = new File(parsedArgs['output']);
+    outputFile.createSync(recursive: true);
+    outputFile.writeAsBytesSync(summary);
+  } else {
+    assert(!succeeded);
+  }
 
   return succeeded;
 }