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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
#nullable enable
using System;
using System.Threading;
using Microsoft.AspNetCore.Shared;
namespace Microsoft.Extensions.Internal;
// A convenience API for interacting with System.Threading.Timer in a way
// that doesn't capture the ExecutionContext. We should be using this (or equivalent)
// everywhere we use timers to avoid rooting any values stored in asynclocals.
internal static class NonCapturingTimer
{
public static Timer Create(TimerCallback callback, object? state, TimeSpan dueTime, TimeSpan period)
{
ArgumentNullThrowHelper.ThrowIfNull(callback);
// Don't capture the current ExecutionContext and its AsyncLocals onto the timer
bool restoreFlow = false;
try
{
if (!ExecutionContext.IsFlowSuppressed())
{
ExecutionContext.SuppressFlow();
restoreFlow = true;
}
return new Timer(callback, state, dueTime, period);
}
finally
{
// Restore the current ExecutionContext
if (restoreFlow)
{
ExecutionContext.RestoreFlow();
}
}
}
}
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