Update package server to use the port file. (#137)

* Update package server to use the port file.

This is to simplify the package server removing the logic to get the
port from stdout.

https://github.com/flutter/flutter/issues/43285

* Add missing dash to flag.

* Import path with path alias.

packages/fuchsia_ctl/lib/src/package_server.dart

@@ -6,8 +6,12 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:file/file.dart';
+import 'package:file/local.dart';
 import 'package:fuchsia_ctl/fuchsia_ctl.dart';
 import 'package:process/process.dart';
+import 'package:path/path.dart' as path;
+import 'package:uuid/uuid.dart';
 
 /// A wrapper around the Fuchsia SDK `pm` tool.
 class PackageServer {
@@ -15,8 +19,10 @@ class PackageServer {
   PackageServer(
     this.pmPath, {
     this.processManager = const LocalProcessManager(),
+    this.fileSystem = const LocalFileSystem(),
   })  : assert(pmPath != null),
-        assert(processManager != null);
+        assert(processManager != null),
+        assert(fileSystem != null);
 
   /// The path on the file system to the `pm` executable.
   final String pmPath;
@@ -24,8 +30,14 @@ class PackageServer {
   /// The process manager to use for launching `pm`.
   final ProcessManager processManager;
 
+  /// The file sytem for the package server.
+  final FileSystem fileSystem;
+
   Process _pmServerProcess;
 
+  /// Path to the port file generated by `pm`.
+  String portPath;
+
   /// The port the server is listening on, if the server is running.
   ///
   /// Throws a [StateError] if accessed when the server is not running.
@@ -84,33 +96,38 @@ class PackageServer {
     String repo, {
     String address = '',
     int port = 0,
+    String portFilePath,
   }) async {
     assert(repo != null);
     assert(port != null);
+
+    final String uuid = Uuid().v4();
+    portPath = portFilePath ??
+        path.join(fileSystem.systemTempDirectory.path, '${uuid}_port.txt');
     final List<String> pmCommand = <String>[
       pmPath,
       'serve',
-      '-repo', repo, //
-      '-l', '$address:$port',
+      '-repo',
+      repo,
+      '-l',
+      '$address:$port',
+      '-f',
+      portPath,
     ];
     stdout.writeln('Running ${pmCommand.join(' ')}');
     _pmServerProcess = await processManager.start(pmCommand);
-    final Completer<void> serverPortCompleter = Completer<void>();
+    await Future<void>.delayed(const Duration(seconds: 5), () async {
+      final String portString = await fileSystem.file(portPath).readAsString();
+      _serverPort = int.parse(portString);
+    });
     _pmServerProcess.stdout
         .transform(utf8.decoder)
         .transform(const LineSplitter())
-        .listen((String line) {
-      if (line.contains('serving $repo at http://')) {
-        _serverPort = int.parse(line.substring(line.lastIndexOf(':') + 1));
-        serverPortCompleter.complete();
-      }
-      stdout.writeln(line);
-    });
+        .listen(stdout.writeln);
     _pmServerProcess.stderr
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .listen(stderr.writeln);
-    await serverPortCompleter.future;
   }
 
   /// Closes a running server.
@@ -120,6 +137,7 @@ class PackageServer {
     if (_pmServerProcess == null) {
       throw StateError('Must call serveRepo before calling close.');
     }
+    await fileSystem.file(portPath).delete();
     _pmServerProcess.kill();
     final int exitCode = await _pmServerProcess.exitCode;
     _pmServerProcess = null;

packages/fuchsia_ctl/test/package_server_test.dart

@@ -5,6 +5,8 @@
 import 'dart:io' show ProcessResult;
 import 'dart:math' show Random;
 
+import 'package:file/file.dart';
+import 'package:file/memory.dart';
 import 'package:fuchsia_ctl/fuchsia_ctl.dart';
 import 'package:fuchsia_ctl/src/package_server.dart';
 import 'package:fuchsia_ctl/src/operation_result.dart';
@@ -67,8 +69,10 @@ void main() {
       pmBin,
       'publish',
       '-a',
-      '-repo', repoPath, //
-      '-f', farFile,
+      '-repo',
+      repoPath,
+      '-f',
+      farFile,
     ]);
     expect(result.success, true);
   });
@@ -80,8 +84,6 @@ void main() {
       0,
       <String>[
         '',
-        'YYYY-MM-DD HH:mm:ss [pm serve] serving $repoPath at http://:$randomPort',
-        'YYYY-MM-DD HH:mm:ss [pm serve] 200 /',
       ],
       <String>[''],
     );
@@ -90,14 +92,28 @@ void main() {
       return serverProcess;
     });
 
+    final MemoryFileSystem fs = MemoryFileSystem();
+
     final PackageServer server = PackageServer(
       pmBin,
       processManager: processManager,
+      fileSystem: fs,
     );
 
     expect(server.serving, false);
+    final File portFile = fs.file(
+      'port.txt',
+    )
+      ..create()
+      ..writeAsString(
+        randomPort.toString(),
+      );
 
-    await server.serveRepo(repoPath, port: 0);
+    await server.serveRepo(
+      repoPath,
+      port: 0,
+      portFilePath: portFile.path,
+    );
     expect(server.serving, true);
 
     final List<String> capturedStartArgs =
@@ -109,8 +125,12 @@ void main() {
     expect(capturedStartArgs, <String>[
       pmBin,
       'serve',
-      '-repo', repoPath, //
-      '-l', ':0',
+      '-repo',
+      repoPath,
+      '-l',
+      ':0',
+      '-f',
+      'port.txt',
     ]);
     expect(server.serverPort, randomPort);