ILGenerated 方法中的 System.ObjectDisposedException

Question

我添加到 ILGenerator 字符串

ilGen.Emit(OpCodes.Ldarg_0);
ilGen.Emit(OpCodes.Ldfld, readField);

和

ilGen.Emit(OpCodes.Call, _read.GetMethodInfo());

进入基础代码

private ReadItemDelegate _read;

    /// <summary>
    /// Init Get method of instance
    /// </summary>
    private void InitGetMethod()
    {
        var ti = typeof (int);
        Type[] methodArgs2 = { _globalType, ti, ti, ti, ti, ti, ti, ti, ti, ti, ti };// 10 elements

        #region this.Get = double(int, .., int) { return _shift0[i0] + .. + _shiftn[in] }
        var dynamicMethod = new DynamicMethod("", ChildrenType, methodArgs2, _globalType);// create dynmic method

        var ilGen = dynamicMethod.GetILGenerator();
        var fiShift = new FieldInfo[_dims.Length];

        for (var i = 0; i < _dims.Length; i++) // get links to all shift arrays
        {
            fiShift[i] = _globalType.GetField("_shift" + i, BindingFlags.NonPublic | BindingFlags.Instance);
        }

        var ldargs = new[] {OpCodes.Ldarg_1, OpCodes.Ldarg_2, OpCodes.Ldarg_3};

        var readField = _globalType.GetField("_read", BindingFlags.NonPublic | BindingFlags.Instance);
        if (readField == null) throw new ArgumentNullException("_read");

        ilGen.Emit(OpCodes.Ldarg_0);
        ilGen.Emit(OpCodes.Ldfld, readField);

        for (var i = 0; i < _dims.Length; i++)
        {

            ilGen.Emit(OpCodes.Ldarg_0); //push link to class member 
            ilGen.Emit(OpCodes.Ldfld, fiShift[i]); //push link to shift array
            if (i < 3) // push next param
                ilGen.Emit(ldargs[i]);
            else
                ilGen.Emit(OpCodes.Ldarg_S, i+1);

            ilGen.Emit(OpCodes.Ldelem_I8); // pop 3 vars and push value from our array by param as index. Result as I8

            if (i>0) ilGen.Emit(OpCodes.Add); // pop 2 vars, summ and push back

        }

        ilGen.Emit(OpCodes.Call, _read.GetMethodInfo());

        ilGen.Emit(OpCodes.Ret);

        Get = (GetItemDelegate) dynamicMethod.CreateDelegate( typeof(GetItemDelegate), this); // save method as Get variable
        #endregion
    }

当我尝试使用时

this.Get(1,2,3)

我收到了这个错误，但是当我使用时

this._read(2568)

我得到了正确的结果。

代码中的哪些地方可能存在错误？

任何愿意提供帮助的人提前致谢。

这里是一个简短的例子来解释错误：

using System;
using System.Collections.Generic;
using System.IO.MemoryMappedFiles;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{

    public class test
    {

        public delegate double GetItemDelegate(int i0 = 0, int i1 = 0, int i2 = 0);
        public delegate double ReadItemDelegate(Int64 offset);


        Type _globalType = typeof(test);
        Type ChildrenType = typeof(double);

        public GetItemDelegate Get;
        private ReadItemDelegate _read;

        public test()
        {
            var file = MemoryMappedFile.CreateOrOpen("file", 123);
            var readMethod = typeof(MemoryMappedViewAccessor).GetMethod("ReadDouble");
            var viewAccessor = file.CreateViewAccessor(0, 123);
            _read = (ReadItemDelegate)Delegate.CreateDelegate(typeof(ReadItemDelegate), viewAccessor, readMethod);


            var ti = typeof(int);
            Type[] methodArgs2 = { _globalType, ti, ti, ti };// 10 elements

            var dynamicMethod = new DynamicMethod("", ChildrenType, methodArgs2, _globalType);// create dynmic method
            var ilGen = dynamicMethod.GetILGenerator();


            var readField = _globalType.GetField("_read", BindingFlags.NonPublic | BindingFlags.Instance);

            ilGen.Emit(OpCodes.Ldarg_0);
            ilGen.Emit(OpCodes.Ldfld, readField);

            ilGen.Emit(OpCodes.Ldc_I4, 3214);
            ilGen.Emit(OpCodes.Conv_I8);

            ilGen.Emit(OpCodes.Call, _read.GetMethodInfo());

            ilGen.Emit(OpCodes.Ret);

            Get = (GetItemDelegate)dynamicMethod.CreateDelegate(typeof(GetItemDelegate), this); // save method as Get variable
        }
    }
    class Program
    {

        static void Main(string[] args)
        {
            var tmp = new test();

            Console.WriteLine(tmp.Get());

            Console.ReadLine();
        }

    }
}

Answer 1

对于编辑中的示例：问题很简单，就像不正确的字段访问和方法调用一样；看这里：

ilGen.Emit(OpCodes.Ldarg_0);
ilGen.Emit(OpCodes.Ldfld, readField);

ilGen.Emit(OpCodes.Ldc_I4, 3214);
ilGen.Emit(OpCodes.Conv_I8);

ilGen.Emit(OpCodes.Call, _read.GetMethodInfo());
ilGen.Emit(OpCodes.Ret);

这里，_read 是 viewAccessor.ReadDouble 的委托 - 即 ReadDouble 是实例方法，viewAccessor 是目标实例。我们有两种选择：

• 针对我们之前存储在viewAccessor 中的实例调用ReadDouble
• 在委托上调用 Invoke

其中的第二个我们可以通过以下方式完成：

// removed: ilGen.Emit(OpCodes.Call, _read.GetMethodInfo());
ilGen.Emit(OpCodes.Callvirt, _read.GetType().GetMethod("Invoke"));
ilGen.Emit(OpCodes.Ret);

请注意，您必须使用3214 以外的值，或将文件/视图访问器的容量/大小更改为大于123 的值。

但是，忘记_read 并存储viewAccessor 并调用virt readMethod 可能会更有效。例如：

private MemoryMappedViewAccessor _acc;

// ...

var viewAccessor = file.CreateViewAccessor(0, 123 * 1000);
_acc = viewAccessor; 
var accField = _globalType.GetField("_acc",
    BindingFlags.NonPublic | BindingFlags.Instance);

// ...

ilGen.Emit(OpCodes.Ldarg_0);
ilGen.Emit(OpCodes.Ldfld, accField);

ilGen.Emit(OpCodes.Ldc_I4, 3214);
ilGen.Emit(OpCodes.Conv_I8);

ilGen.Emit(OpCodes.Callvirt, readMethod);
ilGen.Emit(OpCodes.Ret);