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// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// VMOptions=--old_gen_heap_size=64 --no-background-compilation
library slow_consumer_test;
import 'package:async_helper/async_helper.dart';
import "package:expect/expect.dart";
import 'dart:async';
const int KB = 1024;
const int MB = KB * KB;
const int GB = KB * KB * KB;
class SlowConsumer extends StreamConsumer {
var current = new Future.value(0);
final int bytesPerSecond;
late int finalCount;
SlowConsumer(int this.bytesPerSecond);
Future consume(Stream stream) {
return addStream(stream).then((_) => close());
}
Future addStream(Stream stream) {
bool done = false;
Completer completer = new Completer();
var subscription;
subscription = stream.listen((dynamic _data) {
List data = _data;
current = current.then((count) {
// Simulated amount of time it takes to handle the data.
int ms = data.length * 1000 ~/ bytesPerSecond;
Duration duration = new Duration(milliseconds: ms);
if (!done) subscription.pause();
return new Future.delayed(duration, () {
if (!done) subscription.resume();
// Make sure we use data here to keep tracking it.
return count + data.length;
});
});
}, onDone: () {
done = true;
current.then((count) {
finalCount = count;
completer.complete(count);
});
});
return completer.future;
}
Future close() {
return new Future.value(finalCount);
}
}
class DataProvider {
final int chunkSize;
final int bytesPerSecond;
int sentCount = 0;
int targetCount;
late StreamController controller;
Timer? pendingSend;
DataProvider(int this.bytesPerSecond, int this.targetCount, this.chunkSize) {
controller = new StreamController(
sync: true, onPause: onPauseStateChange, onResume: onPauseStateChange);
Timer.run(send);
}
Stream get stream => controller.stream;
send() {
if (pendingSend != null) {
pendingSend!.cancel();
pendingSend = null;
}
if (controller.isPaused) return;
if (sentCount == targetCount) {
controller.close();
return;
}
int listSize = chunkSize;
sentCount += listSize;
if (sentCount > targetCount) {
listSize -= sentCount - targetCount;
sentCount = targetCount;
}
controller.add(new List.filled(listSize, null));
int ms = listSize * 1000 ~/ bytesPerSecond;
Duration duration = new Duration(milliseconds: ms);
if (!controller.isPaused) {
pendingSend = new Timer(duration, send);
}
}
onPauseStateChange() {
// We don't care if we just unpaused or paused. In either case we just
// call send which will test it for us.
send();
}
}
main() {
asyncStart();
// The data provider can deliver 800MB/s of data. It sends 100MB of data to
// the slower consumer who can only read 200MB/s. The data is sent in 1MB
// chunks.
//
// This test is limited to 64MB of heap-space (see VMOptions on top of the
// file). If the consumer doesn't pause the data-provider it will run out of
// heap-space.
new DataProvider(800 * MB, 100 * MB, 1 * MB)
.stream
.pipe(new SlowConsumer(200 * MB))
.then((count) {
Expect.equals(100 * MB, count);
asyncEnd();
});
}