fix EntityWhitelist causing huge performance drop

[MilonPL]

About the PR

optimizes EntityWhitelistSystem by caching component registrations

Why / Balance

EntityWhitelist would kill server performance the instant you had an entity with an invalid component name

from a trace:

• IsValid method: 98,960ms total time
• Dictionary FindValue: 25,376ms
• FrozenDictionary GetValueRefOrNullRefCore: 40,373ms

Technical details

1. component registration caching:

   • new _componentCache dict to store component availability and registration
   • cache initialized during system startup with all available registrations

2. improved registration handling:

   • added EnsureRegistrations method to convert strings to registrations once and cache results
   • removed redundant StringsToRegs method
   • registration lists are now built once and reused

3. optimized validation flow:

   • added fast path for empty lists
   • better structured RequireAll logic across all validation checks

You can test it yourself with this, just put it in Content.Shared:

using Content.Shared.Item;
using Content.Shared.Whitelist;
using Robust.Shared.Timing;

public sealed class WhitelistLagTestSystem : EntitySystem
{
    [Dependency] private readonly EntityWhitelistSystem _whitelist = default!;
    [Dependency] private readonly IGameTiming _timing = default!;

    private EntityWhitelist? _problematicWhitelist;
    private const int EntityCount = 25;
    private bool _initialized;
    private TimeSpan _startTime;

    public override void Initialize()
    {
        base.Initialize();
        _startTime = _timing.CurTime;

        // Create whitelist but don't spawn entities yet
        _problematicWhitelist = new EntityWhitelist
        {
            Components = new[] { "MisspelledComponent", "AnotherTypo" },
            RequireAll = true,
        };
    }

    private void InitializeTest()
    {
        Log.Info("Starting whitelist lag test...");

        // Spawn test entities
        for (var i = 0; i < EntityCount; i++)
        {
            var ent = Spawn("MobHuman");
            AddComp<ItemComponent>(ent);
        }

        _initialized = true;
        Log.Info($"Whitelist lag test initialized with {EntityCount} entities");
    }

    public override void Update(float frameTime)
    {
        base.Update(frameTime);

        if (!_initialized && (_timing.CurTime - _startTime).TotalSeconds >= 15)
        {
            InitializeTest();
            return;
        }

        if (!_initialized)
            return;

        var query = EntityQueryEnumerator<ItemComponent>();
        while (query.MoveNext(out var uid, out _))
        {
            if (_problematicWhitelist != null)
                _whitelist.IsValid(_problematicWhitelist, uid);
        }
    }
}

Media

holy shit

Requirements

• I have read and am following the Pull Request and Changelog Guidelines.
• I have added media to this PR or it does not require an ingame showcase.

Breaking changes

Changelog

no fun

[SaphireLattice]

Wait wait wait

It checked the registrations every single time something was trying to validate?

I’m guessing the huge performance hit is it causing shitton of errors and thus having to do terminal IO which is notoriously awful when spamming stuff…? Er, unless it doesn’t in fact spam? Not quite in position to check the behavior right now.

Oh and the constant lookups don’t help probably

[MilonPL]

It checked the registrations every single time something was trying to validate?

Yuuuup..

[metalgearsloth]

Isn't a frozendictionary going to be faster than this

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.