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Fix CancellationToken.Combine with 3+ cancelable tokens #1443

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Merged
AArnott merged 1 commit into from
Apr 1, 2025
Merged

Fix CancellationToken.Combine with 3+ cancelable tokens #1443

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5 changes: 5 additions & 0 deletions src/Microsoft.VisualStudio.Threading/CancellationTokenExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,11 @@ public static CombinedCancellationToken CombineWith(this CancellationToken origi
// Before this point we've checked every condition that would allow us to avoid it.
var cancelableTokens = new CancellationToken[cancelableTokensCount];
int i = 0;
if (original.CanBeCanceled)
{
cancelableTokens[i++] = original;
}

foreach (CancellationToken other in others)
{
if (other.CanBeCanceled)
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25 changes: 15 additions & 10 deletions test/Microsoft.VisualStudio.Threading.Tests/CancellationTokenExtensionsTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Linq;
using System.Threading;
using Microsoft.VisualStudio.Threading;
using Xunit;
Expand Down Expand Up @@ -226,19 +227,23 @@ public void CombineWith_Array_TwoCancelable_AmidMany(bool cancelFirst)
}
}

[Fact]
public void CombineWith_Array_ThreeCancelable_AmidMany()
[Theory, CombinatorialData]
public void CombineWith_Array_ThreeCancelable_AmidMany([CombinatorialRange(0, 3)] int canceledIndex)
{
var cts1 = new CancellationTokenSource();
var cts2 = new CancellationTokenSource();
var cts3 = new CancellationTokenSource();
using (CancellationTokenExtensions.CombinedCancellationToken combined = CancellationToken.None.CombineWith(cts1.Token, CancellationToken.None, cts2.Token, CancellationToken.None, cts3.Token))
CancellationTokenSource[] cts = new CancellationTokenSource[3];
for (int i = 0; i < 3; i++)
{
Assert.NotEqual(cts1.Token, combined.Token);
Assert.NotEqual(cts2.Token, combined.Token);
Assert.NotEqual(cts3.Token, combined.Token);
cts[i] = new();
}

cts2.Cancel();
using (CancellationTokenExtensions.CombinedCancellationToken combined = cts[0].Token.CombineWith(cts.Skip(1).Select(s => s.Token).ToArray()))
{
for (int i = 0; i < cts.Length; i++)
{
Assert.NotEqual(cts[i].Token, combined.Token);
}

cts[canceledIndex].Cancel();
Assert.True(combined.Token.IsCancellationRequested);
}
}
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