Use async ChangeToken.OnChange overload in FileConfigurationProvider

[svick]

Uses the new async (Func<Task>) overload of ChangeToken.OnChange (see #69099) in FileConfigurationProvider.

The reload callback previously blocked a thread for the whole reload delay via Thread.Sleep(Source.ReloadDelay). It now awaits Task.Delay(...) instead, so no thread is blocked while waiting out the debounce delay before reloading:

_changeTokenRegistration = ChangeToken.OnChange(
    () => Source.FileProvider.Watch(Source.Path!),
    async () =>
    {
        await Task.Delay(Source.ReloadDelay).ConfigureAwait(false);
        Load(reload: true);
    });

Why only this call site

The other in-repo callers of ChangeToken.OnChange (ConfigurationRoot, ConfigurationManager, OptionsMonitor) invoke short, synchronous, non-blocking consumers (RaiseChanged / InvokeChanged) and gain nothing from the async overload, so they are intentionally left unchanged.

A closely related change is at dotnet/aspnetcore#67732.

Note

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[Copilot]

Pull request overview

This PR updates FileConfigurationProvider’s file-change reload callback to use the async ChangeToken.OnChange overload and replace a blocking Thread.Sleep debounce with an awaited Task.Delay, aiming to avoid tying up a thread during the reload delay.

Changes:

• Replace Thread.Sleep(Source.ReloadDelay) with await Task.Delay(Source.ReloadDelay).ConfigureAwait(false) inside the reload callback.
• Switch the callback passed to ChangeToken.OnChange to an async lambda (binding to the Func<Task> overload).
• Update using directives accordingly (System.Threading → System.Threading.Tasks).

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[tarekgh]

LGTM, Thanks!

[svick]

/ba-g failure is #130678 and is unrelated