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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
#if !NO_PERF
using System;
using System.Collections.Generic;
using System.Reactive.Threading;
using System.Threading;
namespace System.Reactive.Linq.ObservableImpl
{
class Latest<TSource> : PushToPullAdapter<TSource, TSource>
{
public Latest(IObservable<TSource> source)
: base(source)
{
}
protected override PushToPullSink<TSource, TSource> Run(IDisposable subscription)
{
return new _(subscription);
}
class _ : PushToPullSink<TSource, TSource>
{
private readonly object _gate;
#if !NO_CDS
private readonly SemaphoreSlim _semaphore;
#else
private readonly Semaphore _semaphore;
#endif
public _(IDisposable subscription)
: base(subscription)
{
_gate = new object();
#if !NO_CDS
_semaphore = new SemaphoreSlim(0, 1);
#else
_semaphore = new Semaphore(0, 1);
#endif
}
private bool _notificationAvailable;
private NotificationKind _kind;
private TSource _value;
private Exception _error;
public override void OnNext(TSource value)
{
var lackedValue = false;
lock (_gate)
{
lackedValue = !_notificationAvailable;
_notificationAvailable = true;
_kind = NotificationKind.OnNext;
_value = value;
}
if (lackedValue)
_semaphore.Release();
}
public override void OnError(Exception error)
{
base.Dispose();
var lackedValue = false;
lock (_gate)
{
lackedValue = !_notificationAvailable;
_notificationAvailable = true;
_kind = NotificationKind.OnError;
_error = error;
}
if (lackedValue)
_semaphore.Release();
}
public override void OnCompleted()
{
base.Dispose();
var lackedValue = false;
lock (_gate)
{
lackedValue = !_notificationAvailable;
_notificationAvailable = true;
_kind = NotificationKind.OnCompleted;
}
if (lackedValue)
_semaphore.Release();
}
public override bool TryMoveNext(out TSource current)
{
var kind = default(NotificationKind);
var value = default(TSource);
var error = default(Exception);
#if !NO_CDS
_semaphore.Wait();
#else
_semaphore.WaitOne();
#endif
lock (_gate)
{
kind = _kind;
switch (kind)
{
case NotificationKind.OnNext:
value = _value;
break;
case NotificationKind.OnError:
error = _error;
break;
}
_notificationAvailable = false;
}
switch (kind)
{
case NotificationKind.OnNext:
current = _value;
return true;
case NotificationKind.OnError:
error.Throw();
break;
case NotificationKind.OnCompleted:
break;
}
current = default(TSource);
return false;
}
}
}
}
#endif
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