Fix infinite loop in Diagnostics CounterGroup OnTimer method.

[lateralusX]

If a counter event source is disabled while in System.Diagnostics.Tracing.CounterGroup.OnTimer, thread could end up in infinite loop. This happens since _pollingIntervalInMilliseconds is set to 0 when disabled, meaning that we could fail to advance _nextPollingTimeStamp past now:

lock (s_counterGroupLock)
{
    _timeStampSinceCollectionStarted = now;
    do
    {
        _nextPollingTimeStamp += new TimeSpan(0, 0, 0, 0, _pollingIntervalInMilliseconds);
    } while (_nextPollingTimeStamp <= now);
}

Fix use the local copy of pollingIntervalInMilliseconds and also adds an additional safe quard to make sure it always gets advance event if disabled check on _eventSource.IsEnabled() and lock (s_counterGroupLock), since that case will set _pollingIntervalInMilliseconds to 0 as well even before loaded into local variable.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[lateralusX]

//CC @josalem

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Issue Details

---

If a counter event source is disabled while in System.Diagnostics.Tracing.CounterGroup.OnTimer, thread could end up in infinite loop. This happens since _pollingIntervalInMilliseconds is set to 0 when disabled, meaning that we could fail to advance _nextPollingTimeStamp past now:

lock (s_counterGroupLock)
{
    _timeStampSinceCollectionStarted = now;
    do
    {
        _nextPollingTimeStamp += new TimeSpan(0, 0, 0, 0, _pollingIntervalInMilliseconds);
    } while (_nextPollingTimeStamp <= now);
}

Fix use the local copy of pollingIntervalInMilliseconds and also adds an additional safe quard to make sure it always gets advance event if disabled check on _eventSource.IsEnabled() and lock (s_counterGroupLock), since that case will set _pollingIntervalInMilliseconds to 0 as well even before loaded into local variable.

Author:	lateralusX
Assignees:	-
Labels:	area-System.Diagnostics.Tracing
Milestone:	-

[lateralusX]

Looks like this fix was investigated and done in parallel with #53836, it offers solution to same issue, so this could either be closed in favour of that implementation or we could use this implementation instead of for loop as proposed in #53836.

[lateralusX]

Fixed and merged in #53836.