using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq.Expressions;
using System.Reflection;
using System.Threading.Tasks;

public class TestService
{
    private static Dictionary ExpressionCache = new Dictionary();

    public IEnumerable Execute(IEnumerable enums)
    {
        var expressionCache = (enums);
        var props = typeof(T).GetProperties();
        foreach (var e in enums)
        {
            foreach (var p in props)
            {
                var func = GetOrAddExpressionCache(p);
                var value = string.Empty;
                if (func == null)
                {
                    Debug.WriteLine("Use Reflection");
                    value = p.GetValue(e).ToString();
                }
                else
                {
                    Debug.WriteLine("Use Expression");
                    value = func(e);
                }
                yield return value;
            }
        }
    }

    private Func GetOrAddExpressionCache(PropertyInfo prop)
    {
        var key = prop.GetHashCode();
        if (ExpressionCache.ContainsKey(key))
        {
            var func = ExpressionCache[key] as Func;
            return func;
        }else{
            Task.Run(()=>AddExpressionCacheAsync(prop));
            return null;
        }
    }

    //Asynchronous nonblocking, which does not block a thread when adding a Cache
    private async Task AddExpressionCacheAsync(PropertyInfo propertyInfo)
    {
        var key = propertyInfo.GetHashCode();
        if (!ExpressionCache.ContainsKey(key))
        {
            var func = GetValueGetter(propertyInfo);
            ExpressionCache.Add(key, func);
        }
        await Task.Yield();
    }

    private static Func GetValueGetter(PropertyInfo propertyInfo)
    {
        var instance = Expression.Parameter(propertyInfo.DeclaringType);
        var property = Expression.Property(instance, propertyInfo);
        var toString = Expression.Call(property, "ToString", Type.EmptyTypes);
        return Expression.Lambda>(toString, instance).Compile();
    }
}

class Program{
    public static void Main(string[] args){
        var data = new[] { new { Name = "Henry", Age = 25 } };
        for (int i = 0; i < 2; i++)
        {
            var service = new TestService();
            var result = service.Execute(data).ToArray();
        }
    }
}

/* Console :
        Use Reflection
        Use Reflection
        Use Expression
        Use Expression
*/