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Revert "Remove CancelableEnumerator (#10099)" #10129

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Merged
merged 1 commit into from
May 10, 2019
Merged

Revert "Remove CancelableEnumerator (#10099)" #10129

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31 changes: 31 additions & 0 deletions src/SignalR/common/Shared/AsyncEnumerableAdapters.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,10 +51,37 @@ public IAsyncEnumerator<TResult> GetAsyncEnumerator(CancellationToken cancellati
{
((CancellationTokenSource)ctsState).Cancel();
}, _cts);

return new CancelableEnumerator<TResult>(_asyncEnumerable.GetAsyncEnumerator(), registration);
}

return enumerator;
}

private class CancelableEnumerator<T> : IAsyncEnumerator<T>
{
private IAsyncEnumerator<T> _asyncEnumerator;
private readonly CancellationTokenRegistration _cancellationTokenRegistration;

public T Current => (T)_asyncEnumerator.Current;

public CancelableEnumerator(IAsyncEnumerator<T> asyncEnumerator, CancellationTokenRegistration registration)
{
_asyncEnumerator = asyncEnumerator;
_cancellationTokenRegistration = registration;
}

public ValueTask<bool> MoveNextAsync()
{
return _asyncEnumerator.MoveNextAsync();
}

public ValueTask DisposeAsync()
{
_cancellationTokenRegistration.Dispose();
return _asyncEnumerator.DisposeAsync();
}
}
}

/// <summary>Converts an IAsyncEnumerable of T to an IAsyncEnumerable of object.</summary>
Expand All @@ -71,6 +98,10 @@ public CancelableAsyncEnumerable(IAsyncEnumerable<T> asyncEnumerable, Cancellati

public IAsyncEnumerator<object> GetAsyncEnumerator(CancellationToken cancellationToken = default)
{
// Assume that this will be iterated through with await foreach which always passes a default token.
// Instead use the token from the ctor.
Debug.Assert(cancellationToken == default);

var enumeratorOfT = _asyncEnumerable.GetAsyncEnumerator(_cancellationToken);
return enumeratorOfT as IAsyncEnumerator<object> ?? new BoxedAsyncEnumerator(enumeratorOfT);
}
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5 changes: 3 additions & 2 deletions src/SignalR/server/Core/src/Internal/DefaultHubDispatcher.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -403,12 +403,13 @@ private async Task StreamResultsAsync(string invocationId, HubConnectionContext
IHubActivator<THub> hubActivator, THub hub, CancellationTokenSource streamCts, HubMethodInvocationMessage hubMethodInvocationMessage)
{
string error = null;

try
{
await foreach(var item in enumerable.WithCancellation(streamCts.Token))
await foreach (var streamItem in enumerable)
{
// Send the stream item
await connection.WriteAsync(new StreamItemMessage(invocationId, item));
await connection.WriteAsync(new StreamItemMessage(invocationId, streamItem));
}
}
catch (ChannelClosedException ex)
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