CleanTemporaryComponentsSystem.cs

using System.Collections.Generic;
using System.Reflection;
using Unity.Entities;
using UnityEngine.Profiling;

namespace Improbable.Gdk.Core
{
    /// <summary>
    ///     Removes components with attribute RemoveAtEndOfTick from all entities
    /// </summary>
    [DisableAutoCreation]
    [UpdateInGroup(typeof(SpatialOSSendGroup.InternalSpatialOSCleanGroup))]
    public class CleanTemporaryComponentsSystem : ComponentSystem
    {
        private readonly List<(ComponentGroup, ComponentType)> componentGroupsToRemove =
            new List<(ComponentGroup, ComponentType)>();

        protected override void OnCreateManager()
        {
            base.OnCreateManager();

            // Find all components with the RemoveAtEndOfTick attribute
            foreach (var type in ReflectionUtility.GetNonAbstractTypes(typeof(IComponentData),
                typeof(RemoveAtEndOfTickAttribute)))
            {
                componentGroupsToRemove.Add((GetComponentGroup(ComponentType.ReadOnly(type)), type));
            }

            foreach (var type in ReflectionUtility.GetNonAbstractTypes(typeof(ISharedComponentData),
                typeof(RemoveAtEndOfTickAttribute)))
            {
                componentGroupsToRemove.Add((GetComponentGroup(ComponentType.ReadOnly(type)), type));
            }
        }

        protected override void OnUpdate()
        {
            Profiler.BeginSample("RemoveRemoveAtEndOfTick");
            foreach ((var componentGroup, var componentType) in componentGroupsToRemove)
            {
                if (componentGroup.IsEmptyIgnoreFilter)
                {
                    continue;
                }

                var entityArray = componentGroup.GetEntityArray();
                for (var i = 0; i < entityArray.Length; i++)
                {
                    PostUpdateCommands.RemoveComponent(entityArray[i], componentType);
                }
            }

            Profiler.EndSample();
        }
    }
}