blob: b85c79c91ce632ac5d5895f5e561bb4d04b7b575 [file] [log] [blame]
// Copyright 2014 The Flutter Authors. 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:file/file.dart' as f;
import 'package:fuchsia_remote_debug_protocol/fuchsia_remote_debug_protocol.dart' as fuchsia;
import 'package:json_rpc_2/json_rpc_2.dart' as rpc;
import 'package:meta/meta.dart';
import 'package:path/path.dart' as p;
import 'package:vm_service_client/vm_service_client.dart';
import 'package:webdriver/async_io.dart' as async_io;
import 'package:web_socket_channel/io.dart';
import '../../flutter_driver.dart';
import '../common/error.dart';
import '../common/frame_sync.dart';
import '../common/fuchsia_compat.dart';
import '../common/health.dart';
import '../common/message.dart';
import 'common.dart';
import 'driver.dart';
import 'timeline.dart';
/// An implementation of the Flutter Driver over the vmservice protocol.
class VMServiceFlutterDriver extends FlutterDriver {
/// Creates a driver that uses a connection provided by the given
/// [serviceClient], [_peer] and [appIsolate].
this._appIsolate, {
bool printCommunication = false,
bool logCommunicationToFile = true,
}) : _printCommunication = printCommunication,
_logCommunicationToFile = logCommunicationToFile,
_driverId = _nextDriverId++;
/// Connects to a Flutter application.
/// See [FlutterDriver.connect] for more documentation.
static Future<FlutterDriver> connect({
String dartVmServiceUrl,
bool printCommunication = false,
bool logCommunicationToFile = true,
int isolateNumber,
Pattern fuchsiaModuleTarget,
Map<String, dynamic> headers,
}) async {
// If running on a Fuchsia device, connect to the first isolate whose name
// If the user has already supplied an isolate number/URL to the Dart VM
// service, then this won't be run as it is unnecessary.
if (Platform.isFuchsia && isolateNumber == null) {
// TODO(awdavies): Use something other than print. On fuchsia
// `stderr`/`stdout` appear to have issues working correctly.
driverLog = (String source, String message) {
print('$source: $message');
fuchsiaModuleTarget ??= Platform.environment['FUCHSIA_MODULE_TARGET'];
if (fuchsiaModuleTarget == null) {
throw DriverError(
'No Fuchsia module target has been specified.\n'
'Please make sure to specify the FUCHSIA_MODULE_TARGET '
'environment variable.'
final fuchsia.FuchsiaRemoteConnection fuchsiaConnection =
await FuchsiaCompat.connect();
final List<fuchsia.IsolateRef> refs =
await fuchsiaConnection.getMainIsolatesByPattern(fuchsiaModuleTarget);
final fuchsia.IsolateRef ref = refs.first;
isolateNumber = ref.number;
dartVmServiceUrl = ref.dartVm.uri.toString();
await fuchsiaConnection.stop();
dartVmServiceUrl ??= Platform.environment['VM_SERVICE_URL'];
if (dartVmServiceUrl == null) {
throw DriverError(
'Could not determine URL to connect to application.\n'
'Either the VM_SERVICE_URL environment variable should be set, or an explicit '
'URL should be provided to the FlutterDriver.connect() method.'
// Connect to Dart VM services
_log('Connecting to Flutter application at $dartVmServiceUrl');
final VMServiceClientConnection connection =
await vmServiceConnectFunction(dartVmServiceUrl, headers: headers);
final VMServiceClient client = connection.client;
final VM vm = await client.getVM();
final VMIsolateRef isolateRef = isolateNumber ==
null ? vm.isolates.first :
(VMIsolateRef isolate) => isolate.number == isolateNumber);
_log('Isolate found with number: ${isolateRef.number}');
VMIsolate isolate = await isolateRef.loadRunnable();
// TODO(yjbanov): vm_service_client does not support "None" pause event yet.
// It is currently reported as null, but we cannot rely on it because
// eventually the event will be reported as a non-null object. For now,
// list all the events we know about. Later we'll check for "None" event
// explicitly.
// See:
if (isolate.pauseEvent is! VMPauseStartEvent &&
isolate.pauseEvent is! VMPauseExitEvent &&
isolate.pauseEvent is! VMPauseBreakpointEvent &&
isolate.pauseEvent is! VMPauseExceptionEvent &&
isolate.pauseEvent is! VMPauseInterruptedEvent &&
isolate.pauseEvent is! VMResumeEvent) {
isolate = await isolateRef.loadRunnable();
final VMServiceFlutterDriver driver = VMServiceFlutterDriver.connectedTo(
client, connection.peer, isolate,
printCommunication: printCommunication,
logCommunicationToFile: logCommunicationToFile,
driver._dartVmReconnectUrl = dartVmServiceUrl;
// Attempts to resume the isolate, but does not crash if it fails because
// the isolate is already resumed. There could be a race with other tools,
// such as a debugger, any of which could have resumed the isolate.
Future<dynamic> resumeLeniently() {
_log('Attempting to resume isolate');
return isolate.resume().catchError((dynamic e) {
const int vmMustBePausedCode = 101;
if (e is rpc.RpcException && e.code == vmMustBePausedCode) {
// No biggie; something else must have resumed the isolate
'Attempted to resume an already resumed isolate. This may happen '
'when we lose a race with another tool (usually a debugger) that '
'is connected to the same isolate.'
} else {
// Failed to resume due to another reason. Fail hard.
throw e;
/// Waits for a signal from the VM service that the extension is registered.
/// Looks at the list of loaded extensions for the current [isolateRef], as
/// well as the stream of added extensions.
Future<void> waitForServiceExtension() async {
final Future<void> extensionAlreadyAdded = isolateRef
.then((VMIsolate isolate) async {
if (isolate.extensionRpcs.contains(_flutterExtensionMethodName)) {
// Never complete. Rely on the stream listener to find the service
// extension instead.
return Completer<void>().future;
final Completer<void> extensionAdded = Completer<void>();
StreamSubscription<String> isolateAddedSubscription;
isolateAddedSubscription = isolate.onExtensionAdded.listen(
(String extensionName) {
if (extensionName == _flutterExtensionMethodName) {
onError: extensionAdded.completeError,
cancelOnError: true);
await Future.any(<Future<void>>[
/// Tells the Dart VM Service to notify us about "Isolate" events.
/// This is a workaround for an issue in package:vm_service_client, which
/// subscribes to the "Isolate" stream lazily upon subscription, which
/// results in lost events.
/// Details:
Future<void> enableIsolateStreams() async {
await connection.peer.sendRequest('streamListen', <String, String>{
'streamId': 'Isolate',
// Attempt to resume isolate if it was paused
if (isolate.pauseEvent is VMPauseStartEvent) {
_log('Isolate is paused at start.');
await resumeLeniently();
} else if (isolate.pauseEvent is VMPauseExitEvent ||
isolate.pauseEvent is VMPauseBreakpointEvent ||
isolate.pauseEvent is VMPauseExceptionEvent ||
isolate.pauseEvent is VMPauseInterruptedEvent) {
// If the isolate is paused for any other reason, assume the extension is
// already there.
_log('Isolate is paused mid-flight.');
await resumeLeniently();
} else if (isolate.pauseEvent is VMResumeEvent) {
_log('Isolate is not paused. Assuming application is ready.');
} else {
'Unknown pause event type ${isolate.pauseEvent.runtimeType}. '
'Assuming application is ready.'
await enableIsolateStreams();
// We will never receive the extension event if the user does not register
// it. If that happens, show a message but continue waiting.
await _warnIfSlow<void>(
future: waitForServiceExtension(),
timeout: kUnusuallyLongTimeout,
message: 'Flutter Driver extension is taking a long time to become available. '
'Ensure your test app (often "lib/main.dart") imports '
'"package:flutter_driver/driver_extension.dart" and '
'calls enableFlutterDriverExtension() as the first call in main().',
final Health health = await driver.checkHealth();
if (health.status != HealthStatus.ok) {
await client.close();
throw DriverError('Flutter application health check failed.');
_log('Connected to Flutter application.');
return driver;
static int _nextDriverId = 0;
static const String _flutterExtensionMethodName = 'ext.flutter.driver';
static const String _setVMTimelineFlagsMethodName = 'setVMTimelineFlags';
static const String _getVMTimelineMethodName = 'getVMTimeline';
static const String _clearVMTimelineMethodName = 'clearVMTimeline';
static const String _collectAllGarbageMethodName = '_collectAllGarbage';
// The additional blank line in the beginning is for _log.
static const String _kDebugWarning = '''
│ │
│ Numbers obtained from a benchmark while asserts are │
│ enabled will not accurately reflect the performance │
│ that will be experienced by end users using release ╎
│ builds. Benchmarks should be run using this command ┆
│ line: flutter drive --profile test_perf.dart ┊
│ ┊
└─────────────────────────────────────────────────╌┄┈ 🐢
/// The unique ID of this driver instance.
final int _driverId;
/// Client connected to the Dart VM running the Flutter application.
/// You can use [VMServiceClient] to check VM version, flags and get
/// notified when a new isolate has been instantiated. That could be
/// useful if your application spawns multiple isolates that you
/// would like to instrument.
final VMServiceClient _serviceClient;
/// JSON-RPC client useful for sending raw JSON requests.
rpc.Peer _peer;
String _dartVmReconnectUrl;
Future<void> _restorePeerConnectionIfNeeded() async {
if (!_peer.isClosed || _dartVmReconnectUrl == null) {
'Peer connection is closed! Trying to restore the connection...'
final String webSocketUrl = _getWebSocketUrl(_dartVmReconnectUrl);
final WebSocket ws = await WebSocket.connect(webSocketUrl);
ws.done.whenComplete(() => _checkCloseCode(ws));
_peer = rpc.Peer(
onUnhandledError: _unhandledJsonRpcError,
VMIsolate get appIsolate => _appIsolate;
VMServiceClient get serviceClient => _serviceClient;
async_io.WebDriver get webDriver => throw UnsupportedError('VMServiceFlutterDriver does not support webDriver');
/// The main isolate hosting the Flutter application.
/// If you used the [registerExtension] API to instrument your application,
/// you can use this [VMIsolate] to call these extension methods via
/// [invokeExtension].
final VMIsolate _appIsolate;
/// Whether to print communication between host and app to `stdout`.
final bool _printCommunication;
/// Whether to log communication between host and app to `flutter_driver_commands.log`.
final bool _logCommunicationToFile;
Future<void> enableAccessibility() async {
throw UnsupportedError('VMServiceFlutterDriver does not support enableAccessibility');
Future<Map<String, dynamic>> sendCommand(Command command) async {
Map<String, dynamic> response;
try {
final Map<String, String> serialized = command.serialize();
_logCommunication('>>> $serialized');
final Future<Map<String, dynamic>> future = _appIsolate.invokeExtension(
).then<Map<String, dynamic>>((Object value) => value as Map<String, dynamic>);
response = await _warnIfSlow<Map<String, dynamic>>(
future: future,
timeout: command.timeout ?? kUnusuallyLongTimeout,
message: '${command.kind} message is taking a long time to complete...',
_logCommunication('<<< $response');
} catch (error, stackTrace) {
throw DriverError(
'Failed to fulfill ${command.runtimeType} due to remote error',
if (response['isError'] as bool)
throw DriverError('Error in Flutter application: ${response['response']}');
return response['response'] as Map<String, dynamic>;
void _logCommunication(String message) {
if (_printCommunication)
if (_logCommunicationToFile) {
final f.File file = fs.file(p.join(testOutputsDirectory, 'flutter_driver_commands_$_driverId.log'));
file.createSync(recursive: true); // no-op if file exists
file.writeAsStringSync('${} $message\n', mode: f.FileMode.append, flush: true);
Future<List<int>> screenshot() async {
await Future<void>.delayed(const Duration(seconds: 2));
final Map<String, dynamic> result = await _peer.sendRequest('_flutter.screenshot') as Map<String, dynamic>;
return base64.decode(result['screenshot'] as String);
Future<List<Map<String, dynamic>>> getVmFlags() async {
await _restorePeerConnectionIfNeeded();
final Map<String, dynamic> result = await _peer.sendRequest('getFlagList') as Map<String, dynamic>;
return result != null
? (result['flags'] as List<dynamic>).cast<Map<String,dynamic>>()
: const <Map<String, dynamic>>[];
Future<Map<String, Object>> _getVMTimelineMicros() async {
return await _peer.sendRequest('getVMTimelineMicros') as Map<String, dynamic>;
Future<void> startTracing({
List<TimelineStream> streams = const <TimelineStream>[TimelineStream.all],
Duration timeout = kUnusuallyLongTimeout,
}) async {
assert(streams != null && streams.isNotEmpty);
assert(timeout != null);
try {
await _warnIfSlow<void>(
future: _peer.sendRequest(_setVMTimelineFlagsMethodName, <String, String>{
'recordedStreams': _timelineStreamsToString(streams),
timeout: timeout,
message: 'VM is taking an unusually long time to respond to being told to start tracing...',
} catch (error, stackTrace) {
throw DriverError(
'Failed to start tracing due to remote error',
Future<Timeline> stopTracingAndDownloadTimeline({
Duration timeout = kUnusuallyLongTimeout,
int startTime,
int endTime,
}) async {
assert(timeout != null);
assert((startTime == null && endTime == null) ||
(startTime != null && endTime != null));
try {
await _warnIfSlow<void>(
future: _peer.sendRequest(_setVMTimelineFlagsMethodName, <String, String>{'recordedStreams': '[]'}),
timeout: timeout,
message: 'VM is taking an unusually long time to respond to being told to stop tracing...',
if (startTime == null) {
return Timeline.fromJson(await _peer.sendRequest(_getVMTimelineMethodName) as Map<String, dynamic>);
const int kSecondInMicros = 1000000;
int currentStart = startTime;
int currentEnd = startTime + kSecondInMicros; // 1 second of timeline
final List<Map<String, Object>> chunks = <Map<String, Object>>[];
do {
final Map<String, Object> chunk = await _peer.sendRequest(_getVMTimelineMethodName, <String, Object>{
'timeOriginMicros': currentStart,
// The range is inclusive, avoid double counting on the chance something
// aligns on the boundary.
'timeExtentMicros': kSecondInMicros - 1,
}) as Map<String, dynamic>;
currentStart = currentEnd;
currentEnd += kSecondInMicros;
} while (currentStart < endTime);
return Timeline.fromJson(<String, Object>{
'traceEvents': <Object> [
for (Map<String, Object> chunk in chunks)
...chunk['traceEvents'] as List<Object>,
} catch (error, stackTrace) {
throw DriverError(
'Failed to stop tracing due to remote error',
Future<bool> _isPrecompiledMode() async {
final List<Map<String, dynamic>> flags = await getVmFlags();
for(final Map<String, dynamic> flag in flags) {
if (flag['name'] == 'precompiled_mode') {
return flag['valueAsString'] == 'true';
return false;
Future<Timeline> traceAction(
Future<dynamic> action(), {
List<TimelineStream> streams = const <TimelineStream>[TimelineStream.all],
bool retainPriorEvents = false,
}) async {
if (retainPriorEvents) {
await startTracing(streams: streams);
await action();
if (!(await _isPrecompiledMode())) {
return stopTracingAndDownloadTimeline();
await clearTimeline();
final Map<String, Object> startTimestamp = await _getVMTimelineMicros();
await startTracing(streams: streams);
await action();
final Map<String, Object> endTimestamp = await _getVMTimelineMicros();
if (!(await _isPrecompiledMode())) {
return stopTracingAndDownloadTimeline(
startTime: startTimestamp['timestamp'] as int,
endTime: endTimestamp['timestamp'] as int,
Future<void> clearTimeline({
Duration timeout = kUnusuallyLongTimeout,
}) async {
assert(timeout != null);
try {
await _warnIfSlow<void>(
future: _peer.sendRequest(_clearVMTimelineMethodName, <String, String>{}),
timeout: timeout,
message: 'VM is taking an unusually long time to respond to being told to clear its timeline buffer...',
} catch (error, stackTrace) {
throw DriverError(
'Failed to clear event timeline due to remote error',
Future<T> runUnsynchronized<T>(Future<T> action(), { Duration timeout }) async {
await sendCommand(SetFrameSync(false, timeout: timeout));
T result;
try {
result = await action();
} finally {
await sendCommand(SetFrameSync(true, timeout: timeout));
return result;
Future<void> forceGC() async {
try {
await _peer
.sendRequest(_collectAllGarbageMethodName, <String, String>{
'isolateId': 'isolates/${_appIsolate.numberAsString}',
} catch (error, stackTrace) {
throw DriverError(
'Failed to force a GC due to remote error',
Future<void> close() async {
// Don't leak vm_service_client-specific objects, if any
await _serviceClient.close();
await _peer.close();
/// The connection function used by [FlutterDriver.connect].
/// Overwrite this function if you require a custom method for connecting to
/// the VM service.
VMServiceConnectFunction vmServiceConnectFunction = _waitAndConnect;
/// Restores [vmServiceConnectFunction] to its default value.
void restoreVmServiceConnectFunction() {
vmServiceConnectFunction = _waitAndConnect;
/// The JSON RPC 2 spec says that a notification from a client must not respond
/// to the client. It's possible the client sent a notification as a "ping", but
/// the service isn't set up yet to respond.
/// For example, if the client sends a notification message to the server for
/// 'streamNotify', but the server has not finished loading, it will throw an
/// exception. Since the message is a notification, the server follows the
/// specification and does not send a response back, but is left with an
/// unhandled exception. That exception is safe for us to ignore - the client
/// is signaling that it will try again later if it doesn't get what it wants
/// here by sending a notification.
// This may be ignoring too many exceptions. It would be best to rewrite
// the client code to not use notifications so that it gets error replies back
// and can decide what to do from there.
// TODO(dnfield):
bool _ignoreRpcError(dynamic error) {
if (error is rpc.RpcException) {
final rpc.RpcException exception = error;
return == null ||['id'] == null;
} else if (error is String && error.startsWith('JSON-RPC error -32601')) {
return true;
return false;
void _unhandledJsonRpcError(dynamic error, dynamic stack) {
if (_ignoreRpcError(error)) {
_log('Unhandled RPC error:\n$error\n$stack');
// TODO(dnfield):
// assert(false);
String _getWebSocketUrl(String url) {
Uri uri = Uri.parse(url);
final List<String> pathSegments = <String>[
// If there's an authentication code (default), we need to add it to our path.
if (uri.pathSegments.isNotEmpty) uri.pathSegments.first,
if (uri.scheme == 'http')
uri = uri.replace(scheme: 'ws', pathSegments: pathSegments);
return uri.toString();
void _checkCloseCode(WebSocket ws) {
if (ws.closeCode != 1000 && ws.closeCode != null) {
_log('$ws is closed with an unexpected code ${ws.closeCode}');
/// Waits for a real Dart VM service to become available, then connects using
/// the [VMServiceClient].
Future<VMServiceClientConnection> _waitAndConnect(
String url, {Map<String, dynamic> headers}) async {
final String webSocketUrl = _getWebSocketUrl(url);
int attempts = 0;
while (true) {
WebSocket ws1;
WebSocket ws2;
try {
ws1 = await WebSocket.connect(webSocketUrl, headers: headers);
ws2 = await WebSocket.connect(webSocketUrl, headers: headers);
ws1.done.whenComplete(() => _checkCloseCode(ws1));
ws2.done.whenComplete(() => _checkCloseCode(ws2));
return VMServiceClientConnection(
onUnhandledError: _unhandledJsonRpcError,
} catch (e) {
await ws1?.close();
await ws2?.close();
if (attempts > 5)
_log('It is taking an unusually long time to connect to the VM...');
attempts += 1;
await Future<void>.delayed(_kPauseBetweenReconnectAttempts);
/// The amount of time we wait prior to making the next attempt to connect to
/// the VM service.
const Duration _kPauseBetweenReconnectAttempts = Duration(seconds: 1);
// See `timeline_streams` in
String _timelineStreamsToString(List<TimelineStream> streams) {
final String contents =<String>((TimelineStream stream) {
switch (stream) {
case TimelineStream.all: return 'all';
case TimelineStream.api: return 'API';
case TimelineStream.compiler: return 'Compiler';
case TimelineStream.compilerVerbose: return 'CompilerVerbose';
case TimelineStream.dart: return 'Dart';
case TimelineStream.debugger: return 'Debugger';
case TimelineStream.embedder: return 'Embedder';
case TimelineStream.gc: return 'GC';
case TimelineStream.isolate: return 'Isolate';
case TimelineStream.vm: return 'VM';
throw 'Unknown timeline stream $stream';
}).join(', ');
return '[$contents]';
void _log(String message) {
driverLog('VMServiceFlutterDriver', message);
Future<T> _warnIfSlow<T>({
@required Future<T> future,
@required Duration timeout,
@required String message,
}) {
assert(future != null);
assert(timeout != null);
assert(message != null);
.timeout(timeout, onTimeout: () {
return null;
// Don't duplicate errors if [future] completes with an error.
.catchError((dynamic e) => null);
return future;
/// Encapsulates connection information to an instance of a Flutter application.
class VMServiceClientConnection {
/// Creates an instance of this class given a [client] and a [peer].
VMServiceClientConnection(this.client, this.peer);
/// Use this for structured access to the VM service's public APIs.
final VMServiceClient client;
/// Use this to make arbitrary raw JSON-RPC calls.
/// This object allows reaching into private VM service APIs. Use with
/// caution.
final rpc.Peer peer;
/// A function that connects to a Dart VM service
/// with [headers] given the [url].
typedef VMServiceConnectFunction =
Future<VMServiceClientConnection> Function(
String url, {Map<String, dynamic> headers});