Add DevicePortForwarder

packages/flutter_tools/lib/src/android/android_device.dart

@@ -51,6 +51,7 @@ class AndroidDevice extends Device {
   bool get isLocalEmulator => false;
 
   _AdbLogReader _logReader;
+  _AndroidDevicePortForwarder _portForwarder;
 
   List<String> adbCommandForDevice(List<String> args) {
     return <String>[androidSdk.adbPath, '-s', id]..addAll(args);
@@ -169,19 +170,10 @@ class AndroidDevice extends Device {
   Future _forwardObservatoryPort(int port) async {
     bool portWasZero = port == 0;
 
-    if (port == 0) {
-      // Auto-bind to a port. Set up forwarding for that port. Emit a stdout
-      // message similar to the command-line VM so that tools can parse the output.
-      // "Observatory listening on http://127.0.0.1:52111"
-      port = await findAvailablePort();
-    }
-
     try {
       // Set up port forwarding for observatory.
-      runCheckedSync(adbCommandForDevice(<String>[
-        'forward', 'tcp:$port', 'tcp:$observatoryDefaultPort'
-      ]));
-
+      port = await portForwarder.forward(observatoryDefaultPort,
+                                         hostPort: port);
       if (portWasZero)
         printStatus('Observatory listening on http://127.0.0.1:$port');
     } catch (e) {
@@ -292,6 +284,13 @@ class AndroidDevice extends Device {
     return _logReader;
   }
 
+  DevicePortForwarder get portForwarder {
+    if (_portForwarder == null)
+      _portForwarder = new _AndroidDevicePortForwarder(this);
+
+    return _portForwarder;
+  }
+
   void startTracing(AndroidApk apk) {
     runCheckedSync(adbCommandForDevice(<String>[
       'shell',
@@ -537,3 +536,74 @@ class _AdbLogReader extends DeviceLogReader {
     return other.device.id == device.id;
   }
 }
+
+class _AndroidDevicePortForwarder extends DevicePortForwarder {
+  _AndroidDevicePortForwarder(this.device);
+
+  final AndroidDevice device;
+
+  static int _extractPort(String portString) {
+    return int.parse(portString.trim(), onError: (_) => null);
+  }
+
+  List<ForwardedPort> get forwardedPorts {
+    final List<ForwardedPort> ports = <ForwardedPort>[];
+
+    String stdout = runCheckedSync(
+      <String>[
+        androidSdk.adbPath,
+        'forward',
+        '--list'
+      ]);
+
+    List<String> lines = LineSplitter.split(stdout).toList();
+    for (String line in lines) {
+      if (line.startsWith(device.id)) {
+        List<String> splitLine = line.split("tcp:");
+
+        // Sanity check splitLine.
+        if (splitLine.length != 3)
+          continue;
+
+        // Attempt to extract ports.
+        int hostPort = _extractPort(splitLine[1]);
+        int devicePort = _extractPort(splitLine[2]);
+
+        // Failed, skip.
+        if ((hostPort == null) || (devicePort == null))
+          continue;
+
+        ports.add(new ForwardedPort(hostPort, devicePort));
+      }
+    }
+
+    return ports;
+  }
+
+  Future<int> forward(int devicePort, {int hostPort: null}) async {
+    if ((hostPort == null) || (hostPort == 0)) {
+      // Auto select host port.
+      hostPort = await findAvailablePort();
+    }
+
+    runCheckedSync(
+      <String>[
+        androidSdk.adbPath,
+        'forward',
+        hostPort.toString(),
+        devicePort.toString()
+      ]);
+
+    return hostPort;
+  }
+
+  Future unforward(ForwardedPort forwardedPort) async {
+    runCheckedSync(
+      <String>[
+        androidSdk.adbPath,
+        'forward',
+        '--remove',
+        forwardedPort.hostPort.toString()
+      ]);
+  }
+}

packages/flutter_tools/lib/src/device.dart

@@ -151,6 +151,9 @@ abstract class Device {
   /// Get the log reader for this device.
   DeviceLogReader get logReader;
 
+  /// Get the port forwarder for this device.
+  DevicePortForwarder get portForwarder;
+
   /// Clear the device's logs.
   void clearLogs();
 
@@ -186,6 +189,30 @@ abstract class Device {
   String toString() => '$runtimeType $id';
 }
 
+class ForwardedPort {
+  ForwardedPort(this.hostPort, this.devicePort);
+
+  final int hostPort;
+  final int devicePort;
+
+  String toString() => 'ForwardedPort HOST:$hostPort to DEVICE:$devicePort';
+}
+
+/// Forward ports from the host machine to the device.
+abstract class DevicePortForwarder {
+  /// Returns a Future that completes with the current list of forwarded
+  /// ports for this device.
+  List<ForwardedPort> get forwardedPorts;
+
+  /// Forward [hostPort] on the host to [devicePort] on the device.
+  /// If [hostPort] is null, will auto select a host port.
+  /// Returns a Future that completes with the host port.
+  Future<int> forward(int devicePort, {int hostPort: null});
+
+  /// Stops forwarding [forwardedPort].
+  Future unforward(ForwardedPort forwardedPort);
+}
+
 /// Read the log for a particular device. Subclasses must implement `hashCode`
 /// and `operator ==` so that log readers that read from the same location can be
 /// de-duped. For example, two Android devices will both try and log using

packages/flutter_tools/lib/src/ios/devices.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import '../application_package.dart';
 import '../base/common.dart';
+import '../base/os.dart';
 import '../base/process.dart';
 import '../build_configuration.dart';
 import '../device.dart';
@@ -65,6 +66,8 @@ class IOSDevice extends Device {
 
   _IOSDeviceLogReader _logReader;
 
+  _IOSDevicePortForwarder _portForwarder;
+
   bool get isLocalEmulator => false;
 
   bool get supportsStartPaused => false;
@@ -230,6 +233,13 @@ class IOSDevice extends Device {
     return _logReader;
   }
 
+  DevicePortForwarder get portForwarder {
+    if (_portForwarder == null)
+      _portForwarder = new _IOSDevicePortForwarder(this);
+
+    return _portForwarder;
+  }
+
   void clearLogs() {
   }
 }
@@ -310,3 +320,28 @@ class _IOSDeviceLogReader extends DeviceLogReader {
     return other.name == name;
   }
 }
+
+class _IOSDevicePortForwarder extends DevicePortForwarder {
+  _IOSDevicePortForwarder(this.device);
+
+  final IOSDevice device;
+
+  List<ForwardedPort> get forwardedPorts {
+    final List<ForwardedPort> ports = <ForwardedPort>[];
+    // TODO(chinmaygarde): Implement.
+    return ports;
+  }
+
+  Future<int> forward(int devicePort, {int hostPort: null}) async {
+    if ((hostPort == null) || (hostPort == 0)) {
+      // Auto select host port.
+      hostPort = await findAvailablePort();
+    }
+    // TODO(chinmaygarde): Implement.
+    return hostPort;
+  }
+
+  Future unforward(ForwardedPort forwardedPort) async {
+    // TODO(chinmaygarde): Implement.
+  }
+}

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -321,6 +321,7 @@ class IOSSimulator extends Device {
   bool get isLocalEmulator => true;
 
   _IOSSimulatorLogReader _logReader;
+  _IOSSimulatorDevicePortForwarder _portForwarder;
 
   String get xcrunPath => path.join('/usr', 'bin', 'xcrun');
 
@@ -544,6 +545,13 @@ class IOSSimulator extends Device {
     return _logReader;
   }
 
+  DevicePortForwarder get portForwarder {
+    if (_portForwarder == null)
+      _portForwarder = new _IOSSimulatorDevicePortForwarder(this);
+
+    return _portForwarder;
+  }
+
   void clearLogs() {
     File logFile = new File(logFilePath);
     if (logFile.existsSync()) {
@@ -772,3 +780,28 @@ int compareIphoneVersions(String id1, String id2) {
   int q2 = qualifiers.indexOf(m2[2]);
   return q1.compareTo(q2);
 }
+
+class _IOSSimulatorDevicePortForwarder extends DevicePortForwarder {
+  _IOSSimulatorDevicePortForwarder(this.device);
+
+  final IOSSimulator device;
+
+  final List<ForwardedPort> _ports = <ForwardedPort>[];
+
+  List<ForwardedPort> get forwardedPorts {
+    return _ports;
+  }
+
+  Future<int> forward(int devicePort, {int hostPort: null}) async {
+    if ((hostPort == null) || (hostPort == 0)) {
+      hostPort = devicePort;
+    }
+    assert(devicePort == hostPort);
+    _ports.add(new ForwardedPort(devicePort, hostPort));
+    return hostPort;
+  }
+
+  Future unforward(ForwardedPort forwardedPort) async {
+    _ports.remove(forwardedPort);
+  }
+}