FIX #87983 - Enable events for LogAlways

[nickyMcDonald]

Repro of Issue #87983 demonstrates that when an EventListener enables events for NativeRuntimeEventSource with EventLevel.LogAlways then OnEventWritten receives no events.

With a change in src/native/eventpipe/ep-provider.c most events should fire.
With a change in src/coreclr/vm/eventtrace.cpp the rest should fire.
With a change in System.Private.CoreLib/src/System/Diagnostics/Tracing/EventPipeEventDispatcher.cs LogAlways will be treated as the highest level.

The issue was that the provider's level being LogAlways was not accounted for when enabling events and when firing them.

Test app that is helpful reproing the issue and providing useful information:

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Tracing;
using System.Linq;
using System.Threading;

Listener listener = Listener.Create(/*
    EventLevel.Informational//*/
    );
Stopwatch stopwatch = Stopwatch.StartNew();

while (stopwatch.Elapsed.TotalSeconds < 5d)
{
    Thread.Sleep(Random.Shared.Next().ToString().GetHashCode() & sbyte.MaxValue);
}
listener.DumpEvents();

internal sealed class Listener : EventListener
{
    public static EventLevel NextLevel = EventLevel.LogAlways;
    private readonly ConcurrentDictionary<string, int> Distinct = new();
    private EventLevel Level = EventLevel.LogAlways;
    private Listener? listener = null;

    public static Listener Create(params EventLevel[] levels)
    {
        NextLevel = levels.FirstOrDefault(EventLevel.LogAlways);
        return new()
        {
            listener = (levels.Length > 1) ? Create(levels[1..]) : null,
        };
    }

    public void DumpEvents()
    {
        Dispose();
        Console.WriteLine($"\n{nameof(Level)}\t\t{Level}");
        Console.WriteLine($"{nameof(Distinct)}\t{Distinct.Count}");
        Console.WriteLine($"Total\t\t{Distinct.Values.Sum()}");

        foreach (KeyValuePair<string, int> e in Distinct.OrderByDescending(e => e.Value))
        {
            Console.WriteLine($"#{e.Value}\t{e.Key}");
        }
        listener?.DumpEvents();
    }

    protected override void OnEventSourceCreated(EventSource source)
    {
        if (source.Name is "Microsoft-Windows-DotNETRuntime")
        {
            Level = NextLevel;
            EnableEvents(source, Level, EventKeywords.All);
        }
    }

    protected override void OnEventWritten(EventWrittenEventArgs e)
    {
        string str = $"{e.EventId}\t{e.EventSource.Name}\t{e.EventName}";
        Distinct[str] = Distinct.GetValueOrDefault(str, 0) + 1;
    }
}

[lateralusX]

LGTM!

[davmason]

Thanks!

[lateralusX]

Maybe we should add a CLI unit test (under src/tests/tracing) to better cover the different log levels and masks to make sure this doesn't regress? @n77y, something you would be interested in doing?

[nickyMcDonald]

@lateralusX, I can take a look.

[nickyMcDonald]

@lateralusX, #89816