135 lines
3.9 KiB
Dart
135 lines
3.9 KiB
Dart
import 'dart:async';
|
|
import 'dart:collection';
|
|
|
|
import 'package:flutter/foundation.dart';
|
|
import 'package:tuple/tuple.dart';
|
|
|
|
final ServicePolicy servicePolicy = ServicePolicy._private();
|
|
|
|
class ServicePolicy {
|
|
final StreamController<QueueState> _queueStreamController = StreamController<QueueState>.broadcast();
|
|
final Map<Object, Tuple2<int, _Task>> _paused = {};
|
|
final SplayTreeMap<int, LinkedHashMap<Object, _Task>> _queues = SplayTreeMap();
|
|
final LinkedHashMap<Object, _Task> _runningQueue = LinkedHashMap();
|
|
|
|
// magic number
|
|
static const concurrentTaskMax = 4;
|
|
|
|
Stream<QueueState> get queueStream => _queueStreamController.stream;
|
|
|
|
ServicePolicy._private();
|
|
|
|
Future<T> call<T>(
|
|
Future<T> Function() platformCall, {
|
|
int priority = ServiceCallPriority.normal,
|
|
Object key,
|
|
}) {
|
|
Completer<T> completer;
|
|
_Task task;
|
|
key ??= platformCall.hashCode;
|
|
final toResume = _paused.remove(key);
|
|
if (toResume != null) {
|
|
priority = toResume.item1;
|
|
task = toResume.item2;
|
|
completer = task.completer;
|
|
} else {
|
|
completer = Completer<T>();
|
|
task = _Task(
|
|
() async {
|
|
try {
|
|
completer.complete(await platformCall());
|
|
} catch (error, stack) {
|
|
completer.completeError(error, stack);
|
|
}
|
|
_runningQueue.remove(key);
|
|
_pickNext();
|
|
},
|
|
completer,
|
|
);
|
|
}
|
|
_getQueue(priority)[key] = task;
|
|
_pickNext();
|
|
return completer.future;
|
|
}
|
|
|
|
Future<T> resume<T>(Object key) {
|
|
final toResume = _paused.remove(key);
|
|
if (toResume != null) {
|
|
final priority = toResume.item1;
|
|
final task = toResume.item2;
|
|
_getQueue(priority)[key] = task;
|
|
_pickNext();
|
|
return task.completer.future;
|
|
} else {
|
|
return null;
|
|
}
|
|
}
|
|
|
|
LinkedHashMap<Object, _Task> _getQueue(int priority) => _queues.putIfAbsent(priority, () => LinkedHashMap());
|
|
|
|
void _pickNext() {
|
|
_notifyQueueState();
|
|
if (_runningQueue.length >= concurrentTaskMax) return;
|
|
final queue = _queues.entries.firstWhere((kv) => kv.value.isNotEmpty, orElse: () => null)?.value;
|
|
if (queue != null && queue.isNotEmpty) {
|
|
final key = queue.keys.first;
|
|
final task = queue.remove(key);
|
|
_runningQueue[key] = task;
|
|
task.callback();
|
|
}
|
|
}
|
|
|
|
bool _takeOut(Object key, Iterable<int> priorities, void Function(int priority, _Task task) action) {
|
|
var out = false;
|
|
priorities.forEach((priority) {
|
|
final task = _getQueue(priority).remove(key);
|
|
if (task != null) {
|
|
out = true;
|
|
action(priority, task);
|
|
}
|
|
});
|
|
return out;
|
|
}
|
|
|
|
bool cancel(Object key, Iterable<int> priorities) {
|
|
return _takeOut(key, priorities, (priority, task) => task.completer.completeError(CancelledException()));
|
|
}
|
|
|
|
bool pause(Object key, Iterable<int> priorities) {
|
|
return _takeOut(key, priorities, (priority, task) => _paused.putIfAbsent(key, () => Tuple2(priority, task)));
|
|
}
|
|
|
|
bool isPaused(Object key) => _paused.containsKey(key);
|
|
|
|
void _notifyQueueState() {
|
|
if (!_queueStreamController.hasListener) return;
|
|
|
|
final queueByPriority = Map.fromEntries(_queues.entries.map((kv) => MapEntry(kv.key, kv.value.length)));
|
|
_queueStreamController.add(QueueState(queueByPriority, _runningQueue.length, _paused.length));
|
|
}
|
|
}
|
|
|
|
class _Task {
|
|
final VoidCallback callback;
|
|
final Completer completer;
|
|
|
|
const _Task(this.callback, this.completer);
|
|
}
|
|
|
|
class CancelledException {}
|
|
|
|
class ServiceCallPriority {
|
|
static const int getFastThumbnail = 100;
|
|
static const int getRegion = 150;
|
|
static const int getSizedThumbnail = 200;
|
|
static const int normal = 500;
|
|
static const int getMetadata = 1000;
|
|
static const int getLocation = 1000;
|
|
}
|
|
|
|
class QueueState {
|
|
final Map<int, int> queueByPriority;
|
|
final int runningCount, pausedCount;
|
|
|
|
const QueueState(this.queueByPriority, this.runningCount, this.pausedCount);
|
|
}
|