Rougamo、Fody 实现静态Aop

最近在看项目，看到别人使用Rougamo框架，好奇花了点时间仔细研究了，在这里记录一下。

0. 静态编织 Aop

首先，我们先了解什么是Aop? Aop
是指面向切面编程 (Aspect Oriented Programming)，而所谓的切面，可以认为是具体拦截的某个业务点。

我们常用的aop框架是 AspectCore，他是属于动态代理，也就是发生在运行时期间对代码进行“修改”。

Rougamo、Fody 是属于静态编织，是指
在编译阶段将代码修改或额外的功能直接嵌入到程序集中，这个过程发生在源代码被编译成可执行文件或库之前。这意味着，一旦编译完成，插入的代码就已经是程
序集的一部分，无需在运行时再进行额外的操作。

1. Rougamo 肉夹馍

Rougamo 是一个开源项目，github:
https://github.com/inversionhourglass/Rougamo
，他是通过Fody -> Mono.Cecil 的方式实现静态编织实现Aop功能。

创建控制台程序，Nuget安装 Rougamo.Fody

[AttributeUsage(AttributeTargets.Method)]public classLoggingAttribute : MoAttribute

{public override voidOnEntry(MethodContext context)

    {

        Console.WriteLine("执行方法 {0}() 开始，参数：{1}.", context.Method.Name, 

            JsonConvert.SerializeObject(context.Arguments));

    }public override voidOnException(MethodContext context)

    {

        Console.WriteLine("执行方法 {0}() 异常，{1}.", context.Method.Name, context.Exception.Message);

    }public override voidOnExit(MethodContext context)

    {

        Console.WriteLine("执行方法 {0}() 结束.", context.Method.Name);

    }public override voidOnSuccess(MethodContext context)

    {

        Console.WriteLine("执行方法 {0}() 成功.", context.Method.Name);

    }

}internal classProgram

{static void Main(string[] args)

    {

        Add(1, 2);

        AddAsync(1, 2);

        Divide(1, 2);

    }



    [Logging]static int Add(int a, int b) => a +b;



    [Logging]static Task<int> AddAsync(int a, int b) => Task.FromResult(a +b);



    [Logging]static decimal Divide(decimal a, decimal b) => a /b;

}

运行后会自动创建FodyWeavers.xsd 和 FodyWeavers.xml

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <!-- This file was generated by Fody. Manual changes to this file will be lost when your project is rebuilt. -->
  <xs:element name="Weavers">
    <xs:complexType>
      <xs:all>
        <xs:element name="Rougamo" minOccurs="0" maxOccurs="1" type="xs:anyType" />
      </xs:all>
      <xs:attribute name="VerifyAssembly" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>'true' to run assembly verification (PEVerify) on the target assembly after all weavers have been executed.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
      <xs:attribute name="VerifyIgnoreCodes" type="xs:string">
        <xs:annotation>
          <xs:documentation>A comma-separated list of error codes that can be safely ignored in assembly verification.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
      <xs:attribute name="GenerateXsd" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>'false' to turn off automatic generation of the XML Schema file.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
</xs:schema>

<Weavers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="FodyWeavers.xsd">
  <Rougamo />
</Weavers>

下面是运行结果

这时候我们可以看到增加了LoggingAttribute 特性的方法在运行前、运行成功、运行结束执行了 OnEntry(MethodContext context) 、OnSuccess(MethodContext context)、OnExit(MethodContext context) 方法，这时我们打开ILSpy工具，看看实际运行的代码

internal classProgram

{private static void Main(string[] args)

    {

        Add(1, 2);

        AddAsync(1, 2);

        Divide(1m, 2m);

    }



    [DebuggerStepThrough]private static int Add(int a, intb)

    {

        LoggingAttribute loggingAttribute= newLoggingAttribute();

        IMo[] mos= new IMo[1] { loggingAttribute };

        MethodContext methodContext= new MethodContext(null, typeof(Program), MethodBase.GetMethodFromHandle((RuntimeMethodHandle)/*OpCode not supported: LdMemberToken*/, typeof(Program).TypeHandle), isAsync: false, isIterator: false, mosNonEntryFIFO: false, mos, new object[2] { a, b });

        loggingAttribute.OnEntry(methodContext);int result = default(int);if(methodContext.ReturnValueReplaced)

        {

            result= (int)methodContext.ReturnValue;

            loggingAttribute.OnExit(methodContext);returnresult;

        }if(methodContext.RewriteArguments)

        {

            a= (int)methodContext.Arguments[0];

            b= (int)methodContext.Arguments[1];

        }bool flag = default(bool);do{try{while (true)

                {try{

                        flag= false;

                        result=$Rougamo_Add(a, b);

                    }catch(Exception exception)

                    {

                        methodContext.Exception=exception;

                        methodContext.Arguments[0] =a;

                        methodContext.Arguments[1] =b;

                        loggingAttribute.OnException(methodContext);if (methodContext.RetryCount > 0)

                        {continue;

                        }if(methodContext.ExceptionHandled)

                        {

                            result= (int)methodContext.ReturnValue;break;

                        }throw;

                    }break;

                }

            }finally{if (methodContext.HasException ||methodContext.ExceptionHandled)

                {gotoIL_0160;

                }

                methodContext.ReturnValue=result;

                methodContext.Arguments[0] =a;

                methodContext.Arguments[1] =b;

                loggingAttribute.OnSuccess(methodContext);if (methodContext.RetryCount <= 0)

                {if(methodContext.ReturnValueReplaced)

                    {

                        result= (int)methodContext.ReturnValue;

                    }gotoIL_0160;

                }

                flag= true;gotoend_IL_00fc;

                IL_0160:

                loggingAttribute.OnExit(methodContext);

                end_IL_00fc:;

            }

        }while(flag);returnresult;

    }



    [DebuggerStepThrough]private static Task<int> AddAsync(int a, intb)

    {

        LoggingAttribute loggingAttribute= newLoggingAttribute();

        IMo[] mos= new IMo[1] { loggingAttribute };

        MethodContext methodContext= new MethodContext(null, typeof(Program), MethodBase.GetMethodFromHandle((RuntimeMethodHandle)/*OpCode not supported: LdMemberToken*/, typeof(Program).TypeHandle), isAsync: false, isIterator: false, mosNonEntryFIFO: false, mos, new object[2] { a, b });

        loggingAttribute.OnEntry(methodContext);

        Task<int> result = default(Task<int>);if(methodContext.ReturnValueReplaced)

        {

            result= (Task<int>)methodContext.ReturnValue;

            loggingAttribute.OnExit(methodContext);returnresult;

        }if(methodContext.RewriteArguments)

        {

            a= (int)methodContext.Arguments[0];

            b= (int)methodContext.Arguments[1];

        }bool flag = default(bool);do{try{while (true)

                {try{

                        flag= false;

                        result=$Rougamo_AddAsync(a, b);

                    }catch(Exception exception)

                    {

                        methodContext.Exception=exception;

                        methodContext.Arguments[0] =a;

                        methodContext.Arguments[1] =b;

                        loggingAttribute.OnException(methodContext);if (methodContext.RetryCount > 0)

                        {continue;

                        }if(methodContext.ExceptionHandled)

                        {

                            result= (Task<int>)methodContext.ReturnValue;break;

                        }throw;

                    }break;

                }

            }finally{if (methodContext.HasException ||methodContext.ExceptionHandled)

                {gotoIL_015b;

                }

                methodContext.ReturnValue=result;

                methodContext.Arguments[0] =a;

                methodContext.Arguments[1] =b;

                loggingAttribute.OnSuccess(methodContext);if (methodContext.RetryCount <= 0)

                {if(methodContext.ReturnValueReplaced)

                    {

                        result= (Task<int>)methodContext.ReturnValue;

                    }gotoIL_015b;

                }

                flag= true;gotoend_IL_00fc;

                IL_015b:

                loggingAttribute.OnExit(methodContext);

                end_IL_00fc:;

            }

        }while(flag);returnresult;

    }



    [DebuggerStepThrough]private static decimal Divide(decimal a, decimalb)

    {

        LoggingAttribute loggingAttribute= newLoggingAttribute();

        IMo[] mos= new IMo[1] { loggingAttribute };

        MethodContext methodContext= new MethodContext(null, typeof(Program), MethodBase.GetMethodFromHandle((RuntimeMethodHandle)/*OpCode not supported: LdMemberToken*/, typeof(Program).TypeHandle), isAsync: false, isIterator: false, mosNonEntryFIFO: false, mos, new object[2] { a, b });

        loggingAttribute.OnEntry(methodContext);decimal result = default(decimal);if(methodContext.ReturnValueReplaced)

        {

            result= (decimal)methodContext.ReturnValue;

            loggingAttribute.OnExit(methodContext);returnresult;

        }if(methodContext.RewriteArguments)

        {

            a= (decimal)methodContext.Arguments[0];

            b= (decimal)methodContext.Arguments[1];

        }bool flag = default(bool);do{try{while (true)

                {try{

                        flag= false;

                        result=$Rougamo_Divide(a, b);

                    }catch(Exception exception)

                    {

                        methodContext.Exception=exception;

                        methodContext.Arguments[0] =a;

                        methodContext.Arguments[1] =b;

                        loggingAttribute.OnException(methodContext);if (methodContext.RetryCount > 0)

                        {continue;

                        }if(methodContext.ExceptionHandled)

                        {

                            result= (decimal)methodContext.ReturnValue;break;

                        }throw;

                    }break;

                }

            }finally{if (methodContext.HasException ||methodContext.ExceptionHandled)

                {gotoIL_0160;

                }

                methodContext.ReturnValue=result;

                methodContext.Arguments[0] =a;

                methodContext.Arguments[1] =b;

                loggingAttribute.OnSuccess(methodContext);if (methodContext.RetryCount <= 0)

                {if(methodContext.ReturnValueReplaced)

                    {

                        result= (decimal)methodContext.ReturnValue;

                    }gotoIL_0160;

                }

                flag= true;gotoend_IL_00fc;

                IL_0160:

                loggingAttribute.OnExit(methodContext);

                end_IL_00fc:;

            }

        }while(flag);returnresult;

    }



    [Logging]private static int $Rougamo_Add(int a, intb)

    {return a +b;

    }



    [Logging]private static Task<int> $Rougamo_AddAsync(int a, intb)

    {return Task.FromResult(a +b);

    }



    [Logging]private static decimal $Rougamo_Divide(decimal a, decimalb)

    {return a /b;

    }

}

从实际运行的代码我们可以看到，原先Add(int a, int b)方法中的执行内容被移动到 $Rougamo_Add方法中，而Add(int a, int b)方法先是new LoggingAttribute() 和 new Rougamo.Context.MethodContext() -> 执行了 loggingAttribute.OnEntry(methodContext); -> 在do{}while(bool) 执行了$Rougamo_Add(a, b); -> 在 exception 中执行了loggingAttribute.OnException(methodContext); -> 在 finally中执行了 loggingAttribute.OnSuccess(methodContext); 和 loggingAttribute.OnExit(methodContext);

注：do{}while(bool) 执行了$Rougamo_Add(a, b); 是因为 Rougamo 可以实现方法执行失败重试功能

至此我们明白了 Rougamo 实现 Aop功能是通过编译时修改IL代码，往代码增加对应的生命周期代码。那他为什么可以做到呢？其实是借用了Fody -> Mono.Cecil 的方式。

代码如下：
https://gitee.com/Karl_Albright/csharp-demo/tree/master/FodyDemo/RougamoDemo

2. Fody -> Mono.Cecil

Fody 是一个开源项目，github:
https://github.com/Fody/Fody
，相关教程文档在
https://github.com/Fody/Home/tree/master/pages

创建类库，选择netstandard2.0，命名为HelloWorld，Nuget安装 Fody 和 FodyPackaging

注：必须创建 netstandard2.0，因为FodyPackaging的目标是netstandard2.0，

在HelloWorld项目中，我们只放 HWAttribute类，继承于 Attribute。代码如下

[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Module | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method |AttributeTargets.Property)]public classHWAttribute : Attribute

{



}

再次创建类库，选择netstandard2.0，命名为HelloWorld.Fody，Nuget安装 FodyHelpers，引用HelloWorld类库

在HelloWorld.Fody项目中，我们只放ModuleWeaver类（类名是固定的，详情见Fody文档），继承于 BaseModuleWeaver。代码如下

usingFody;usingMono.Cecil;usingMono.Cecil.Cil;usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Reflection;namespaceHelloWorld.Fody

{public partial classModuleWeaver : BaseModuleWeaver

    {public override voidExecute()

        {foreach (var type inModuleDefinition.Types)

            {foreach (var method intype.Methods)

                {var customerAttribute = method.CustomAttributes.FirstOrDefault(x => x.AttributeType.Name ==nameof(HWAttribute));if (customerAttribute != null)

                    {

                        ProcessMethod(method);

                    }

                }

            }

        }public override IEnumerable<string>GetAssembliesForScanning()

        {yield return "mscorlib";yield return "System";

        }private MethodInfo _writeLineMethod => typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) });private voidProcessMethod(MethodDefinition method)

        {//获取当前方法体中的第一个IL指令
            var processor =method.Body.GetILProcessor();var current =method.Body.Instructions.First();//插入一个 Nop 指令，表示什么都不做
            var first =Instruction.Create(OpCodes.Nop);

            processor.InsertBefore(current, first);

            current=first;//构造 Console.WriteLine("Hello World")
            foreach (var instruction inGetInstructions(method))

            {

                processor.InsertAfter(current, instruction);

                current=instruction;

            }

        }private IEnumerable<Instruction>GetInstructions(MethodDefinition method)

        {yield returnInstruction.Create(OpCodes.Nop);yield return Instruction.Create(OpCodes.Ldstr, "Hello World.");yield returnInstruction.Create(OpCodes.Call, ModuleDefinition.ImportReference(_writeLineMethod));

        }

    }

}

在代码中，我们遍历了所有类型的所有方法，如果方法标注了 HWAttribute特性，则增加 Console.WriteLine("Hello World."); 代码。

创建控制台应用程序，命名为HelloWorldFodyDemo，添加 HelloWorld 和 HelloWorld.Fody 项目引用，并且手动增加 WeaverFiles标签，目标是HelloWorld.Fody.dll

在控制台中，我们需要一个方法，方法上有 HWAttribute 特性就可以了，代码如下

internal classProgram

{static void Main(string[] args)

    {

        Echo();

        Console.ReadKey();

    }



    [HW]public static voidEcho()

    {

        Console.WriteLine("Hello Fody.");

    }

}

在控制台项目中，我们还需要 FodyWeavers.xml 和 FodyWeavers.xsd 文件，（我也是从上面Rougamo项目中复制的），内容如下

<Weavers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="FodyWeavers.xsd">
    <HelloWorld />
</Weavers>

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="Weavers">
    <xs:complexType>
      <xs:all>
        <xs:element name="HelloWorld" minOccurs="0" maxOccurs="1" type="xs:anyType" />
      </xs:all>
      <xs:attribute name="VerifyAssembly" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>'true' to run assembly verification (PEVerify) on the target assembly after all weavers have been executed.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
      <xs:attribute name="VerifyIgnoreCodes" type="xs:string">
        <xs:annotation>
          <xs:documentation>A comma-separated list of error codes that can be safely ignored in assembly verification.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
      <xs:attribute name="GenerateXsd" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>'false' to turn off automatic generation of the XML Schema file.</xs:documentation>
        </xs:annotation>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
</xs:schema>

目前，文件结构如下

FodyDemo

|--- HelloWorld

     |--- HWAttribute.cs

     |--- HelloWorld.csproj

|--- HelloWorld.Fody

     |--- HelloWorld.Fody.csproj

     |--- ModuleWeaver.cs

|--- HelloWorldFodyDemo

     |--- FodyWeavers.xml

     |--- FodyWeavers.xsd

     |--- HelloWorldFodyDemo.csproj

     |--- Program.cs

代码如下：
https://gitee.com/Karl_Albright/csharp-demo/tree/master/FodyDemo

最后运行结果如下，很明显，HWAttribute生效了，我们成功的在Echo()方法前打印了Hello World。

我们再次打开ILSpy工具，得到的结果如图，代码增加了Console.WriteLine("Hello World.");行代码

4. Fody 有很多其他的“插件”，大家可以多试试

AutoProperties.Fody
: 这个外接程序为您提供了对自动属性的扩展控制，比如直接访问backing字段或拦截getter和setter。

PropertyChanged.Fody:
将属性通知添加到实现INotifyPropertyChanged的所有类。

InlineIL.Fody:
在编译时注入任意IL代码。

MethodDecorator.Fody：
通过IL重写编译时间装饰器模式。

NullGuard.Fody:
将空参数检查添加到程序集。

ToString.Fody:
给属性生成ToString()方法

Rougamo.Fody:
在编译时生效的AOP组件，类似于PostSharp。

Rougamo、Fody 实现静态Aop

0. 静态编织 Aop

1. Rougamo 肉夹馍

2. Fody -> Mono.Cecil

添加新评论

最新文章

最近回复

分类

归档

其它