77 lines
1.8 KiB
C#
77 lines
1.8 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT License.
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// See the LICENSE file in the project root for more information.
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using System.Threading;
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namespace System.Reactive
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{
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internal sealed class CheckedObserver<T> : IObserver<T>
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{
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private readonly IObserver<T> _observer;
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private int _state;
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private const int Idle = 0;
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private const int Busy = 1;
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private const int Done = 2;
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public CheckedObserver(IObserver<T> observer)
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{
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_observer = observer;
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}
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public void OnNext(T value)
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{
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CheckAccess();
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try
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{
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_observer.OnNext(value);
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}
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finally
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{
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Interlocked.Exchange(ref _state, Idle);
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}
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}
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public void OnError(Exception error)
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{
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CheckAccess();
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try
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{
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_observer.OnError(error);
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}
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finally
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{
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Interlocked.Exchange(ref _state, Done);
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}
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}
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public void OnCompleted()
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{
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CheckAccess();
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try
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{
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_observer.OnCompleted();
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}
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finally
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{
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Interlocked.Exchange(ref _state, Done);
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}
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}
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private void CheckAccess()
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{
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switch (Interlocked.CompareExchange(ref _state, Busy, Idle))
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{
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case Busy:
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throw new InvalidOperationException(Strings_Core.REENTRANCY_DETECTED);
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case Done:
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throw new InvalidOperationException(Strings_Core.OBSERVER_TERMINATED);
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}
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}
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}
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}
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