using System.Reactive.Concurrency; using System.Reactive.Disposables; namespace System.Reactive.Linq.ObservableImpl { internal sealed class Sample<TSource> : Producer<TSource, Sample<TSource>._> { internal sealed class _ : Sink<TSource>, IObserver<TSource> { private object _gate = new object(); private IDisposable _sourceSubscription; private bool _hasValue; private TSource _value; private bool _atEnd; public _(IObserver<TSource> observer, IDisposable cancel) : base(observer, cancel) { } public IDisposable Run(Sample<TSource> parent) { SingleAssignmentDisposable singleAssignmentDisposable = (SingleAssignmentDisposable)(_sourceSubscription = new SingleAssignmentDisposable()); singleAssignmentDisposable.Disposable = ObservableExtensions.SubscribeSafe<TSource>(parent._source, (IObserver<TSource>)this); return StableCompositeDisposable.Create(singleAssignmentDisposable, parent._scheduler.SchedulePeriodic(parent._interval, Tick)); } private void Tick() { lock (_gate) { if (_hasValue) { _hasValue = false; _observer.OnNext(_value); } if (_atEnd) { _observer.OnCompleted(); base.Dispose(); } } } public void OnNext(TSource value) { lock (_gate) { _hasValue = true; _value = value; } } public void OnError(Exception error) { lock (_gate) { _observer.OnError(error); base.Dispose(); } } public void OnCompleted() { lock (_gate) { _atEnd = true; _sourceSubscription.Dispose(); } } } private readonly IObservable<TSource> _source; private readonly TimeSpan _interval; private readonly IScheduler _scheduler; public Sample(IObservable<TSource> source, TimeSpan interval, IScheduler scheduler) { _source = source; _interval = interval; _scheduler = scheduler; } protected override _ CreateSink(IObserver<TSource> observer, IDisposable cancel) { return new _(observer, cancel); } protected override IDisposable Run(_ sink) { return sink.Run(this); } } }