Activator.CreateInstance-Leistungsalternative

Vergessen Sie nicht - DynamicMethod

Beispiel zum Erstellen einer neuen Instanz durch den Standardkonstruktor

public static ObjectActivator CreateCtor(Type type)
{
    if (type == null)
    {
        throw new NullReferenceException("type");
    }
    ConstructorInfo emptyConstructor = type.GetConstructor(Type.EmptyTypes);
    var dynamicMethod = new DynamicMethod("CreateInstance", type, Type.EmptyTypes, true);
    ILGenerator ilGenerator = dynamicMethod.GetILGenerator();
    ilGenerator.Emit(OpCodes.Nop);
    ilGenerator.Emit(OpCodes.Newobj, emptyConstructor);
    ilGenerator.Emit(OpCodes.Ret);
    return (ObjectActivator)dynamicMethod.CreateDelegate(typeof(ObjectActivator));
}

public delegate object ObjectActivator();

hier ist mehr über Leistungsvergleich

InvokeMember wird gemessen ... 1000000 Iterationen in 1.5643784 Sekunden.

Messen von MethodInfo.Invoke ... 1000000 Iterationen in 0,8150111 Sekunden.

Messen von DynamicMethod ... 1000000 Iterationen in 0,0330202 Sekunden.

Messen des direkten Anrufs ... 1000000 Iterationen in 0.0136752 Sekunden.

Ich habe eine Lösung erstellt, die als Ersatz für Activator.CreateInstance verwendet werden kann. Sie finden es auf meinem blog .

Beispiel:

var myInstance = InstanceFactory.CreateInstance(typeof(MyClass));
var myArray1 = InstanceFactory.CreateInstance(typeof(int[]), 1024);
var myArray2 = InstanceFactory.CreateInstance(typeof(int[]), new object[] { 1024 });

Code:

public static class InstanceFactory
{
  private delegate object CreateDelegate(Type type, object arg1, object arg2, object arg3);

  private static ConcurrentDictionary<Tuple<Type, Type, Type, Type>, CreateDelegate> cachedFuncs = new ConcurrentDictionary<Tuple<Type, Type, Type, Type>, CreateDelegate>();

  public static object CreateInstance(Type type)
  {
    return InstanceFactoryGeneric<TypeToIgnore, TypeToIgnore, TypeToIgnore>.CreateInstance(type, null, null, null);
  }

  public static object CreateInstance<TArg1>(Type type, TArg1 arg1)
  {
    return InstanceFactoryGeneric<TArg1, TypeToIgnore, TypeToIgnore>.CreateInstance(type, arg1, null, null);
  }

  public static object CreateInstance<TArg1, TArg2>(Type type, TArg1 arg1, TArg2 arg2)
  {
    return InstanceFactoryGeneric<TArg1, TArg2, TypeToIgnore>.CreateInstance(type, arg1, arg2, null);
  }

  public static object CreateInstance<TArg1, TArg2, TArg3>(Type type, TArg1 arg1, TArg2 arg2, TArg3 arg3)
  {
    return InstanceFactoryGeneric<TArg1, TArg2, TArg3>.CreateInstance(type, arg1, arg2, arg3);
  }

  public static object CreateInstance(Type type, params object[] args)
  {
    if (args == null)
      return CreateInstance(type);

    if (args.Length > 3 || 
      (args.Length > 0 && args[0] == null) ||
      (args.Length > 1 && args[1] == null) ||
      (args.Length > 2 && args[2] == null))
    {
        return Activator.CreateInstance(type, args);   
    }

    var arg0 = args.Length > 0 ? args[0] : null;
    var arg1 = args.Length > 1 ? args[1] : null;
    var arg2 = args.Length > 2 ? args[2] : null;

    var key = Tuple.Create(
      type,
      arg0?.GetType() ?? typeof(TypeToIgnore),
      arg1?.GetType() ?? typeof(TypeToIgnore),
      arg2?.GetType() ?? typeof(TypeToIgnore));

    if (cachedFuncs.TryGetValue(key, out CreateDelegate func))
      return func(type, arg0, arg1, arg2);
    else
      return CacheFunc(key)(type, arg0, arg1, arg2);
  }

  private static CreateDelegate CacheFunc(Tuple<Type, Type, Type, Type> key)
  {
    var types = new Type[] { key.Item1, key.Item2, key.Item3, key.Item4 };
    var method = typeof(InstanceFactory).GetMethods()
                                        .Where(m => m.Name == "CreateInstance")
                                        .Where(m => m.GetParameters().Count() == 4).Single();
    var generic = method.MakeGenericMethod(new Type[] { key.Item2, key.Item3, key.Item4 });

    var paramExpr = new List<ParameterExpression>();
    paramExpr.Add(Expression.Parameter(typeof(Type)));
    for (int i = 0; i < 3; i++)
      paramExpr.Add(Expression.Parameter(typeof(object)));

    var callParamExpr = new List<Expression>();
    callParamExpr.Add(paramExpr[0]);
    for (int i = 1; i < 4; i++)
      callParamExpr.Add(Expression.Convert(paramExpr[i], types[i]));

    var callExpr = Expression.Call(generic, callParamExpr);
    var lambdaExpr = Expression.Lambda<CreateDelegate>(callExpr, paramExpr);
    var func = lambdaExpr.Compile();
    cachedFuncs.TryAdd(key, func);
    return func;
  }
}

public static class InstanceFactoryGeneric<TArg1, TArg2, TArg3>
{
  private static ConcurrentDictionary<Type, Func<TArg1, TArg2, TArg3, object>> cachedFuncs = new ConcurrentDictionary<Type, Func<TArg1, TArg2, TArg3, object>>();

  public static object CreateInstance(Type type, TArg1 arg1, TArg2 arg2, TArg3 arg3)
  {
    if (cachedFuncs.TryGetValue(type, out Func<TArg1, TArg2, TArg3, object> func))
      return func(arg1, arg2, arg3);
    else
      return CacheFunc(type, arg1, arg2, arg3)(arg1, arg2, arg3);
  }

  private static Func<TArg1, TArg2, TArg3, object> CacheFunc(Type type, TArg1 arg1, TArg2 arg2, TArg3 arg3)
  {
    var constructorTypes = new List<Type>();
    if (typeof(TArg1) != typeof(TypeToIgnore))
      constructorTypes.Add(typeof(TArg1));
    if (typeof(TArg2) != typeof(TypeToIgnore))
      constructorTypes.Add(typeof(TArg2));
    if (typeof(TArg3) != typeof(TypeToIgnore))
      constructorTypes.Add(typeof(TArg3));

    var parameters = new List<ParameterExpression>()
    {
      Expression.Parameter(typeof(TArg1)),
      Expression.Parameter(typeof(TArg2)),
      Expression.Parameter(typeof(TArg3)),
    };

    var constructor = type.GetConstructor(constructorTypes.ToArray());
    var constructorParameters = parameters.Take(constructorTypes.Count).ToList();
    var newExpr = Expression.New(constructor, constructorParameters);
    var lambdaExpr = Expression.Lambda<Func<TArg1, TArg2, TArg3, object>>(newExpr, parameters);
    var func = lambdaExpr.Compile();
    cachedFuncs.TryAdd(type, func);
    return func;
  }
}

public class TypeToIgnore
{
}