blob: 0c4b5c0ba1d57e612bd375d72fa5ac6c9e34c8d5 [file] [log] [blame]
// Copyright 2015 The Chromium 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 'base/file_system.dart';
import 'base/utils.dart';
import 'build_info.dart';
import 'globals.dart';
import 'vmservice.dart';
// Names of some of the Timeline events we care about.
const String _kFlutterEngineMainEnterEventName = 'FlutterEngineMainEnter';
const String _kFrameworkInitEventName = 'Framework initialization';
const String _kFirstUsefulFrameEventName = 'Widgets completed first useful frame';
class Tracing {
Tracing(this.vmService);
static Future<Tracing> connect(Uri uri) async {
final VMService observatory = await VMService.connect(uri);
return new Tracing(observatory);
}
final VMService vmService;
Future<Null> startTracing() async {
await vmService.vm.setVMTimelineFlags(<String>['Compiler', 'Dart', 'Embedder', 'GC']);
await vmService.vm.clearVMTimeline();
}
/// Stops tracing; optionally wait for first frame.
Future<Map<String, dynamic>> stopTracingAndDownloadTimeline({
bool waitForFirstFrame: false
}) async {
Map<String, dynamic> timeline;
if (!waitForFirstFrame) {
// Stop tracing immediately and get the timeline
await vmService.vm.setVMTimelineFlags(<String>[]);
timeline = await vmService.vm.getVMTimeline();
} else {
final Completer<Null> whenFirstFrameRendered = new Completer<Null>();
(await vmService.onTimelineEvent).listen((ServiceEvent timelineEvent) {
final List<Map<String, dynamic>> events = timelineEvent.timelineEvents;
for (Map<String, dynamic> event in events) {
if (event['name'] == _kFirstUsefulFrameEventName)
whenFirstFrameRendered.complete();
}
});
await whenFirstFrameRendered.future.timeout(
const Duration(seconds: 10),
onTimeout: () {
printError(
'Timed out waiting for the first frame event. Either the '
'application failed to start, or the event was missed because '
'"flutter run" took too long to subscribe to timeline events.'
);
return null;
}
);
timeline = await vmService.vm.getVMTimeline();
await vmService.vm.setVMTimelineFlags(<String>[]);
}
return timeline;
}
}
/// Download the startup trace information from the given observatory client and
/// store it to build/start_up_info.json.
Future<Null> downloadStartupTrace(VMService observatory) async {
final String traceInfoFilePath = fs.path.join(getBuildDirectory(), 'start_up_info.json');
final File traceInfoFile = fs.file(traceInfoFilePath);
// Delete old startup data, if any.
if (await traceInfoFile.exists())
await traceInfoFile.delete();
// Create "build" directory, if missing.
if (!(await traceInfoFile.parent.exists()))
await traceInfoFile.parent.create();
final Tracing tracing = new Tracing(observatory);
final Map<String, dynamic> timeline = await tracing.stopTracingAndDownloadTimeline(
waitForFirstFrame: true
);
int extractInstantEventTimestamp(String eventName) {
final List<Map<String, dynamic>> events = timeline['traceEvents'];
final Map<String, dynamic> event = events.firstWhere(
(Map<String, dynamic> event) => event['name'] == eventName, orElse: () => null
);
return event == null ? null : event['ts'];
}
final int engineEnterTimestampMicros = extractInstantEventTimestamp(_kFlutterEngineMainEnterEventName);
final int frameworkInitTimestampMicros = extractInstantEventTimestamp(_kFrameworkInitEventName);
final int firstFrameTimestampMicros = extractInstantEventTimestamp(_kFirstUsefulFrameEventName);
if (engineEnterTimestampMicros == null) {
printTrace('Engine start event is missing in the timeline: $timeline');
throw 'Engine start event is missing in the timeline. Cannot compute startup time.';
}
if (firstFrameTimestampMicros == null) {
printTrace('First frame event is missing in the timeline: $timeline');
throw 'First frame event is missing in the timeline. Cannot compute startup time.';
}
final int timeToFirstFrameMicros = firstFrameTimestampMicros - engineEnterTimestampMicros;
final Map<String, dynamic> traceInfo = <String, dynamic>{
'engineEnterTimestampMicros': engineEnterTimestampMicros,
'timeToFirstFrameMicros': timeToFirstFrameMicros,
};
if (frameworkInitTimestampMicros != null) {
traceInfo['timeToFrameworkInitMicros'] = frameworkInitTimestampMicros - engineEnterTimestampMicros;
traceInfo['timeAfterFrameworkInitMicros'] = firstFrameTimestampMicros - frameworkInitTimestampMicros;
}
traceInfoFile.writeAsStringSync(toPrettyJson(traceInfo));
printStatus('Time to first frame: ${timeToFirstFrameMicros ~/ 1000}ms.');
printStatus('Saved startup trace info in ${traceInfoFile.path}.');
}