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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.Reactive.Disposables;
namespace System.Reactive.Linq.ObservableImpl
{
class Amb<TSource> : Producer<TSource>
{
private readonly IObservable<TSource> _left;
private readonly IObservable<TSource> _right;
public Amb(IObservable<TSource> left, IObservable<TSource> right)
{
_left = left;
_right = right;
}
protected override IDisposable Run(IObserver<TSource> observer, IDisposable cancel, Action<IDisposable> setSink)
{
var sink = new _(this, observer, cancel);
setSink(sink);
return sink.Run();
}
class _ : Sink<TSource>
{
private readonly Amb<TSource> _parent;
public _(Amb<TSource> parent, IObserver<TSource> observer, IDisposable cancel)
: base(observer, cancel)
{
_parent = parent;
}
private AmbState _choice;
public IDisposable Run()
{
var ls = new SingleAssignmentDisposable();
var rs = new SingleAssignmentDisposable();
var d = new CompositeDisposable(ls, rs);
var gate = new object();
var lo = new AmbObserver();
lo._disposable = d;
lo._target = new DecisionObserver(this, gate, AmbState.Left, ls, rs, lo);
var ro = new AmbObserver();
ro._disposable = d;
ro._target = new DecisionObserver(this, gate, AmbState.Right, rs, ls, ro);
_choice = AmbState.Neither;
ls.Disposable = _parent._left.SubscribeSafe(lo);
rs.Disposable = _parent._right.SubscribeSafe(ro);
return d;
}
class DecisionObserver : IObserver<TSource>
{
private readonly _ _parent;
private readonly AmbState _me;
private readonly IDisposable _subscription;
private readonly IDisposable _otherSubscription;
private readonly object _gate;
private readonly AmbObserver _observer;
public DecisionObserver(_ parent, object gate, AmbState me, IDisposable subscription, IDisposable otherSubscription, AmbObserver observer)
{
_parent = parent;
_gate = gate;
_me = me;
_subscription = subscription;
_otherSubscription = otherSubscription;
_observer = observer;
}
public void OnNext(TSource value)
{
lock (_gate)
{
if (_parent._choice == AmbState.Neither)
{
_parent._choice = _me;
_otherSubscription.Dispose();
_observer._disposable = _subscription;
_observer._target = _parent._observer;
}
if (_parent._choice == _me)
_parent._observer.OnNext(value);
}
}
public void OnError(Exception error)
{
lock (_gate)
{
if (_parent._choice == AmbState.Neither)
{
_parent._choice = _me;
_otherSubscription.Dispose();
_observer._disposable = _subscription;
_observer._target = _parent._observer;
}
if (_parent._choice == _me)
{
_parent._observer.OnError(error);
_parent.Dispose();
}
}
}
public void OnCompleted()
{
lock (_gate)
{
if (_parent._choice == AmbState.Neither)
{
_parent._choice = _me;
_otherSubscription.Dispose();
_observer._disposable = _subscription;
_observer._target = _parent._observer;
}
if (_parent._choice == _me)
{
_parent._observer.OnCompleted();
_parent.Dispose();
}
}
}
}
class AmbObserver : IObserver<TSource>
{
public IObserver<TSource> _target;
public IDisposable _disposable;
public void OnNext(TSource value)
{
_target.OnNext(value);
}
public void OnError(Exception error)
{
_target.OnError(error);
_disposable.Dispose();
}
public void OnCompleted()
{
_target.OnCompleted();
_disposable.Dispose();
}
}
enum AmbState
{
Left,
Right,
Neither
}
}
}
}
#endif
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