Follow-up: memory-based activation shedding

[DeagleGross]

Adding logs and refactoring configuration of #9532.
also testing whether the memory pressure works against CI agents here.

Microsoft Reviewers: Open in CodeFlow

[ReubenBond]

This looks like a find-and-replace error

[DeagleGross]

rollbacked

[ReubenBond]

Wont this always be false?

[DeagleGross]

I left this code intentionally in this way to let people know that we try with stats, and we fallback to realStatisticsProvider in case something is wrong with the stats.

At this point we should probably just remove all "fake" stat providers - because why do we need them if we are ending up using the real one?

[DeagleGross]

I mean next time this code is touched, all people will do is fake the stats somehow, and they will be valid, but faked. In case something went wrong stats are replaced

[ReubenBond]

The reason fake stats are used is for testing - i.e, to present some condition like high memory or CPU usage and verify that the behavior is expected.

But if a branch can never be taken, leaving it in the code is misleading. If I read some code and there is a branch, I expect that sometimes the branch will be taken, and sometimes it will not, depending on some condition. In this case, new EnvironmentStatistics().IsValid() is always false, so the branch will always be taken, and therefore the whole method may as well just return the real stats to begin with rather than misdirect the reader.

[ReubenBond]

It looks like we can remove the entire type because there is an IEnvironmentStatisticsProvider available by default in Orleans now. That wasn't true when this test was written but the test wasn't updated since.

[ReubenBond]

The test can be changed to:

/// <summary>
/// Ensures <see cref="LoadSheddingValidator"/> fails when LoadSheddingLimit greater than 100.
/// </summary>
[Fact]
public async Task SiloBuilder_LoadSheddingValidatorAbove100ShouldFail()
{
    await Assert.ThrowsAsync<OrleansConfigurationException>(async () =>
    {
        await new HostBuilder().UseOrleans((ctx, siloBuilder) =>
        {
            siloBuilder
                .UseLocalhostClustering()
                .Configure<ClusterOptions>(options => options.ClusterId = "someClusterId")
                .Configure<EndpointOptions>(options => options.AdvertisedIPAddress = IPAddress.Loopback)
                .ConfigureServices(services => services.AddSingleton<IMembershipTable, NoOpMembershipTable>())
                .Configure<LoadSheddingOptions>(options =>
                {
                    options.LoadSheddingEnabled = true;
                    options.CpuThreshold = 101;
                });
        }).RunConsoleAsync();
    });
}

[DeagleGross]

removed completely noop stats providers, now only meaningful set of stats or just taking the real ones.