pkg/dartdev/lib/src/dds_runner.dart

// Copyright (c) 2024, 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.

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:path/path.dart';

import 'core.dart';
import 'sdk.dart';

class DDSRunner {
  Uri? ddsUri;

  Future<bool> start({
    required Uri vmServiceUri,
    required String ddsHost,
    required String ddsPort,
    required bool disableServiceAuthCodes,
    required bool enableDevTools,
    required bool debugDds,
    required bool enableServicePortFallback,
  }) async {
    void printError(String details) =>
        log.stderr('Could not start the VM service:\n$details');

    final sdkDir = dirname(sdk.dart);
    final fullSdk = sdkDir.endsWith('bin');
    var execName = fullSdk
        ? sdk.dartAotRuntime
        : absolute(sdkDir, 'dartaotruntime${Platform.isWindows ? '.exe' : ''}');
    var snapshotName = fullSdk
        ? sdk.ddsAotSnapshot
        : absolute(sdkDir, 'dds_aot.dart.snapshot');
    final isAot = checkArtifactExists(snapshotName) ? true : false;
    if (!isAot) {
      printError('Unable to find snapshot for the development server');
      return false;
    }

    final process = await Process.start(execName, [
      if (debugDds) '--enable-vm-service=0',
      snapshotName,
      '--vm-service-uri=$vmServiceUri',
      '--bind-address=$ddsHost',
      '--bind-port=$ddsPort',
      if (disableServiceAuthCodes) '--disable-service-auth-codes',
      if (enableDevTools) '--serve-devtools',
      if (debugDds) '--enable-logging',
      if (enableServicePortFallback) '--enable-service-port-fallback',
    ], mode: ProcessStartMode.detachedWithStdio);

    // NOTE: update pkg/dartdev/lib/src/commands/run.dart if this message
    // is changed to ensure consistency.
    const devToolsMessagePrefix =
        'The Dart DevTools debugger and profiler is available at:';
    if (debugDds) {
      late final StreamSubscription<String> stdoutSub;
      stdoutSub = process.stdout
          .transform(utf8.decoder)
          .transform(const LineSplitter())
          .listen((event) {
            if (event.startsWith(devToolsMessagePrefix)) {
              final ddsDebuggingUri = event.split(' ').last;
              log.stdout(
                'A DevTools debugger for DDS is available at: $ddsDebuggingUri',
              );
              stdoutSub.cancel();
            }
          });
    }

    // DDS will close stderr once it's finished launching.
    final launchResult = await process.stderr.transform(utf8.decoder).join();

    try {
      final result = json.decode(launchResult) as Map<String, dynamic>;
      if (result case {'state': 'started', 'ddsUri': final String ddsUriStr}) {
        ddsUri = Uri.parse(ddsUriStr);
        if (result case {'devToolsUri': String devToolsUri}) {
          log.stdout('$devToolsMessagePrefix $devToolsUri');
        }
      } else {
        final error = result['error'] ?? result;
        final stacktrace = result['stacktrace'] ?? '';
        String message = 'Could not start the VM service: ';
        if (error.contains('Failed to create server socket')) {
          message += '$ddsHost:$ddsPort is already in use.\n';
        } else {
          message += '$error\n$stacktrace\n';
        }
        printError(message);
        return false;
      }
    } catch (_) {
      // Malformed JSON was likely encountered, so output the entirety of
      // stderr in the error message.
      printError(launchResult);
      return false;
    }
    return true;
  }
}