Make device discovery asynchronous (#10803)

Migrates DeviceDiscovery.devices and all device-specific lookup to be
asynchronous.

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

@@ -48,7 +48,7 @@ class AndroidDevices extends PollingDeviceDiscovery {
   bool get canListAnything => androidWorkflow.canListDevices;
 
   @override
-  List<Device> pollingGetDevices() => getAdbDevices();
+  Future<List<Device>> pollingGetDevices() async => getAdbDevices();
 }
 
 class AndroidDevice extends Device {

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -305,7 +305,7 @@ class AppDomain extends Domain {
     final String target = _getStringArg(args, 'target');
     final bool enableHotReload = _getBoolArg(args, 'hot') ?? kHotReloadDefault;
 
-    final Device device = daemon.deviceDomain._getOrLocateDevice(deviceId);
+    final Device device = await daemon.deviceDomain._getOrLocateDevice(deviceId);
     if (device == null)
       throw "device '$deviceId' not found";
 
@@ -493,7 +493,7 @@ class AppDomain extends Domain {
   Future<List<Map<String, dynamic>>> discover(Map<String, dynamic> args) async {
     final String deviceId = _getStringArg(args, 'deviceId', required: true);
 
-    final Device device = daemon.deviceDomain._getDevice(deviceId);
+    final Device device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null)
       throw "device '$deviceId' not found";
 
@@ -575,11 +575,12 @@ class DeviceDomain extends Domain {
 
   final List<PollingDeviceDiscovery> _discoverers = <PollingDeviceDiscovery>[];
 
-  Future<List<Device>> getDevices([Map<String, dynamic> args]) {
-    final List<Device> devices = _discoverers.expand((PollingDeviceDiscovery discoverer) {
-      return discoverer.devices;
-    }).toList();
-    return new Future<List<Device>>.value(devices);
+  Future<List<Device>> getDevices([Map<String, dynamic> args]) async {
+    final List<Device> devices = <Device>[];
+    for (PollingDeviceDiscovery discoverer in _discoverers) {
+      devices.addAll(await discoverer.devices);
+    }
+    return devices;
   }
 
   /// Enable device events.
@@ -602,7 +603,7 @@ class DeviceDomain extends Domain {
     final int devicePort = _getIntArg(args, 'devicePort', required: true);
     int hostPort = _getIntArg(args, 'hostPort');
 
-    final Device device = daemon.deviceDomain._getDevice(deviceId);
+    final Device device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null)
       throw "device '$deviceId' not found";
 
@@ -617,7 +618,7 @@ class DeviceDomain extends Domain {
     final int devicePort = _getIntArg(args, 'devicePort', required: true);
     final int hostPort = _getIntArg(args, 'hostPort', required: true);
 
-    final Device device = daemon.deviceDomain._getDevice(deviceId);
+    final Device device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null)
       throw "device '$deviceId' not found";
 
@@ -631,23 +632,25 @@ class DeviceDomain extends Domain {
   }
 
   /// Return the device matching the deviceId field in the args.
-  Device _getDevice(String deviceId) {
-    final List<Device> devices = _discoverers.expand((PollingDeviceDiscovery discoverer) {
-      return discoverer.devices;
-    }).toList();
-    return devices.firstWhere((Device device) => device.id == deviceId, orElse: () => null);
+  Future<Device> _getDevice(String deviceId) async {
+    for (PollingDeviceDiscovery discoverer in _discoverers) {
+      final Device device = (await discoverer.devices).firstWhere((Device device) => device.id == deviceId, orElse: () => null);
+      if (device != null)
+        return device;
+    }
+    return null;
   }
 
   /// Return a known matching device, or scan for devices if no known match is found.
-  Device _getOrLocateDevice(String deviceId) {
+  Future<Device> _getOrLocateDevice(String deviceId) async {
     // Look for an already known device.
-    final Device device = _getDevice(deviceId);
+    final Device device = await _getDevice(deviceId);
     if (device != null)
       return device;
 
     // Scan the different device providers for a match.
     for (PollingDeviceDiscovery discoverer in _discoverers) {
-      final List<Device> devices = discoverer.pollingGetDevices();
+      final List<Device> devices = await discoverer.pollingGetDevices();
       for (Device device in devices)
         if (device.id == deviceId)
           return device;

packages/flutter_tools/lib/src/device.dart

@@ -81,11 +81,17 @@ class DeviceManager {
         : getAllConnectedDevices();
   }
 
+  Iterable<DeviceDiscovery> get _platformDiscoverers {
+    return _deviceDiscoverers.where((DeviceDiscovery discoverer) => discoverer.supportsPlatform);
+  }
+
   /// Return the list of all connected devices.
-  Stream<Device> getAllConnectedDevices() {
-    return new Stream<Device>.fromIterable(_deviceDiscoverers
-      .where((DeviceDiscovery discoverer) => discoverer.supportsPlatform)
-      .expand((DeviceDiscovery discoverer) => discoverer.devices));
+  Stream<Device> getAllConnectedDevices() async* {
+    for (DeviceDiscovery discoverer in _platformDiscoverers) {
+      for (Device device in await discoverer.devices) {
+        yield device;
+      }
+    }
   }
 }
 
@@ -97,7 +103,7 @@ abstract class DeviceDiscovery {
   /// current environment configuration.
   bool get canListAnything;
 
-  List<Device> get devices;
+  Future<List<Device>> get devices;
 }
 
 /// A [DeviceDiscovery] implementation that uses polling to discover device adds
@@ -111,13 +117,13 @@ abstract class PollingDeviceDiscovery extends DeviceDiscovery {
   ItemListNotifier<Device> _items;
   Timer _timer;
 
-  List<Device> pollingGetDevices();
+  Future<List<Device>> pollingGetDevices();
 
   void startPolling() {
     if (_timer == null) {
       _items ??= new ItemListNotifier<Device>();
-      _timer = new Timer.periodic(_pollingDuration, (Timer timer) {
-        _items.updateWithNewList(pollingGetDevices());
+      _timer = new Timer.periodic(_pollingDuration, (Timer timer) async {
+        _items.updateWithNewList(await pollingGetDevices());
       });
     }
   }
@@ -128,8 +134,8 @@ abstract class PollingDeviceDiscovery extends DeviceDiscovery {
   }
 
   @override
-  List<Device> get devices {
-    _items ??= new ItemListNotifier<Device>.from(pollingGetDevices());
+  Future<List<Device>> get devices async {
+    _items ??= new ItemListNotifier<Device>.from(await pollingGetDevices());
     return _items.items;
   }
 

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

@@ -36,7 +36,7 @@ class IOSDevices extends PollingDeviceDiscovery {
   bool get canListAnything => iosWorkflow.canListDevices;
 
   @override
-  List<Device> pollingGetDevices() => IOSDevice.getAttachedDevices();
+  Future<List<Device>> pollingGetDevices() => IOSDevice.getAttachedDevices();
 }
 
 class IOSDevice extends Device {
@@ -81,12 +81,12 @@ class IOSDevice extends Device {
   // iPhone 6s (9.3) [F6CEE7CF-81EB-4448-81B4-1755288C7C11] (Simulator)
   static final RegExp _deviceRegex = new RegExp(r'^(.*) +\((.*)\) +\[(.*)\]$');
 
-  static List<IOSDevice> getAttachedDevices() {
+  static Future<List<IOSDevice>> getAttachedDevices() async {
     if (!xcode.isInstalled)
       return <IOSDevice>[];
 
     final List<IOSDevice> devices = <IOSDevice>[];
-    final Iterable<String> deviceLines = xcode.getAvailableDevices()
+    final Iterable<String> deviceLines = (await xcode.getAvailableDevices())
         .split('\n')
         .map((String line) => line.trim());
     for (String line in deviceLines) {

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

@@ -158,7 +158,12 @@ class Xcode {
     return _xcodeVersionCheckValid(_xcodeMajorVersion, _xcodeMinorVersion);
   }
 
-  String getAvailableDevices() => runSync(<String>['/usr/bin/instruments', '-s', 'devices']);
+  Future<String> getAvailableDevices() async {
+    final RunResult result = await runAsync(<String>['/usr/bin/instruments', '-s', 'devices']);
+    if (result.exitCode != 0)
+      throw new ToolExit('Failed to invoke /usr/bin/instruments. Is Xcode installed?');
+    return result.stdout;
+  }
 }
 
 bool _xcodeVersionCheckValid(int major, int minor) {

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

@@ -37,7 +37,7 @@ class IOSSimulators extends PollingDeviceDiscovery {
   bool get canListAnything => iosWorkflow.canListDevices;
 
   @override
-  List<Device> pollingGetDevices() => IOSSimulatorUtils.instance.getAttachedDevices();
+  Future<List<Device>> pollingGetDevices() async => IOSSimulatorUtils.instance.getAttachedDevices();
 }
 
 class IOSSimulatorUtils {

packages/flutter_tools/test/ios/devices_test.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:file/file.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/ios/devices.dart';
@@ -30,15 +32,15 @@ void main() {
 
     testUsingContext('return no devices if Xcode is not installed', () async {
       when(mockXcode.isInstalled).thenReturn(false);
-      expect(IOSDevice.getAttachedDevices(), isEmpty);
+      expect(await IOSDevice.getAttachedDevices(), isEmpty);
     }, overrides: <Type, Generator>{
       Xcode: () => mockXcode,
     });
 
     testUsingContext('returns no devices if none are attached', () async {
       when(mockXcode.isInstalled).thenReturn(true);
-      when(mockXcode.getAvailableDevices()).thenReturn('');
-      final List<IOSDevice> devices = IOSDevice.getAttachedDevices();
+      when(mockXcode.getAvailableDevices()).thenReturn(new Future<String>.value(''));
+      final List<IOSDevice> devices = await IOSDevice.getAttachedDevices();
       expect(devices, isEmpty);
     }, overrides: <Type, Generator>{
       Xcode: () => mockXcode,
@@ -46,7 +48,7 @@ void main() {
 
     testUsingContext('returns attached devices', () async {
       when(mockXcode.isInstalled).thenReturn(true);
-      when(mockXcode.getAvailableDevices()).thenReturn('''
+      when(mockXcode.getAvailableDevices()).thenReturn(new Future<String>.value('''
 Known Devices:
 je-mappelle-horse [ED6552C4-B774-5A4E-8B5A-606710C87C77]
 La tele me regarde (10.3.2) [98206e7a4afd4aedaff06e687594e089dede3c44]
@@ -55,8 +57,8 @@ iPhone 6 Plus (9.3) [FBA880E6-4020-49A5-8083-DCD50CA5FA09] (Simulator)
 iPhone 6s (11.0) [E805F496-FC6A-4EA4-92FF-B7901FF4E7CC] (Simulator)
 iPhone 7 (11.0) + Apple Watch Series 2 - 38mm (4.0) [60027FDD-4A7A-42BF-978F-C2209D27AD61] (Simulator)
 iPhone SE (11.0) [667E8DCD-5DCD-4C80-93A9-60D1D995206F] (Simulator)
-''');
-      final List<IOSDevice> devices = IOSDevice.getAttachedDevices();
+'''));
+      final List<IOSDevice> devices = await IOSDevice.getAttachedDevices();
       expect(devices, hasLength(2));
       expect(devices[0].id, '98206e7a4afd4aedaff06e687594e089dede3c44');
       expect(devices[0].name, 'La tele me regarde');

packages/flutter_tools/test/src/mocks.dart

@@ -37,7 +37,7 @@ class MockPollingDeviceDiscovery extends PollingDeviceDiscovery {
   MockPollingDeviceDiscovery() : super('mock');
 
   @override
-  List<Device> pollingGetDevices() => _devices;
+  Future<List<Device>> pollingGetDevices() async => _devices;
 
   @override
   bool get supportsPlatform => true;
@@ -52,7 +52,7 @@ class MockPollingDeviceDiscovery extends PollingDeviceDiscovery {
   }
 
   @override
-  List<Device> get devices => _devices;
+  Future<List<Device>> get devices async => _devices;
 
   @override
   Stream<Device> get onAdded => _onAddedController.stream;