stopTracingAndDownloadTimeline method
override
Stops recording performance traces and downloads the timeline.
The timeout
argument causes a warning to be displayed to the user if the
operation exceeds the specified timeout; it does not actually cancel the
operation.
For WebFlutterDriver, this is only supported for Chrome.
Implementation
@override
Future<Timeline> stopTracingAndDownloadTimeline({
Duration timeout = kUnusuallyLongTimeout,
int? startTime,
int? endTime,
}) async {
assert((startTime == null && endTime == null) ||
(startTime != null && endTime != null));
try {
await _warnIfSlow<vms.Success>(
future: _serviceClient.setVMTimelineFlags(const <String>[]),
timeout: timeout,
message: 'VM is taking an unusually long time to respond to being told to stop tracing...',
);
if (startTime == null) {
final vms.Timeline timeline = await _serviceClient.getVMTimeline();
return Timeline.fromJson(timeline.json!);
}
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 vms.Timeline chunk = await _serviceClient.getVMTimeline(
timeOriginMicros: currentStart,
// The range is inclusive, avoid double counting on the chance something
// aligns on the boundary.
timeExtentMicros: kSecondInMicros - 1,
);
chunks.add(chunk.json);
currentStart = currentEnd;
currentEnd += kSecondInMicros;
} while (currentStart < endTime!);
return Timeline.fromJson(<String, Object>{
'traceEvents': <Object?> [
for (final Map<String, Object?>? chunk in chunks)
...chunk!['traceEvents']! as List<Object?>,
],
});
} catch (error, stackTrace) {
throw DriverError(
'Failed to stop tracing due to remote error',
error,
stackTrace,
);
}
}