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 class LoggingAttribute : MoAttribute
- {
- public override void OnEntry(MethodContext context)
- {
- Console.WriteLine("执行方法 {0}() 开始,参数:{1}.", context.Method.Name,
- JsonConvert.SerializeObject(context.Arguments));
- }
- public override void OnException(MethodContext context)
- {
- Console.WriteLine("执行方法 {0}() 异常,{1}.", context.Method.Name, context.Exception.Message);
- }
- public override void OnExit(MethodContext context)
- {
- Console.WriteLine("执行方法 {0}() 结束.", context.Method.Name);
- }
- public override void OnSuccess(MethodContext context)
- {
- Console.WriteLine("执行方法 {0}() 成功.", context.Method.Name);
- }
- }
- internal class Program
- {
- 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;
- }
运行后会指定创建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 class Program
- {
- private static void Main(string[] args)
- {
- Add(1, 2);
- AddAsync(1, 2);
- Divide(1m, 2m);
- }
- [DebuggerStepThrough]
- private static int Add(int a, int b)
- {
- LoggingAttribute loggingAttribute = new LoggingAttribute();
- 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);
- return result;
- }
- 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)
- {
- goto IL_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;
- }
- goto IL_0160;
- }
- flag = true;
- goto end_IL_00fc;
- IL_0160:
- loggingAttribute.OnExit(methodContext);
- end_IL_00fc:;
- }
- }
- while (flag);
- return result;
- }
- [DebuggerStepThrough]
- private static Task<int> AddAsync(int a, int b)
- {
- LoggingAttribute loggingAttribute = new LoggingAttribute();
- 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);
- return result;
- }
- 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)
- {
- goto IL_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;
- }
- goto IL_015b;
- }
- flag = true;
- goto end_IL_00fc;
- IL_015b:
- loggingAttribute.OnExit(methodContext);
- end_IL_00fc:;
- }
- }
- while (flag);
- return result;
- }
- [DebuggerStepThrough]
- private static decimal Divide(decimal a, decimal b)
- {
- LoggingAttribute loggingAttribute = new LoggingAttribute();
- 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);
- return result;
- }
- 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)
- {
- goto IL_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;
- }
- goto IL_0160;
- }
- flag = true;
- goto end_IL_00fc;
- IL_0160:
- loggingAttribute.OnExit(methodContext);
- end_IL_00fc:;
- }
- }
- while (flag);
- return result;
- }
- [Logging]
- private static int $Rougamo_Add(int a, int b)
- {
- return a + b;
- }
- [Logging]
- private static Task<int> $Rougamo_AddAsync(int a, int b)
- {
- return Task.FromResult(a + b);
- }
- [Logging]
- private static decimal $Rougamo_Divide(decimal a, decimal b)
- {
- 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 class HWAttribute : 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
- using Fody;
- using Mono.Cecil;
- using Mono.Cecil.Cil;
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Reflection;
- namespace HelloWorld.Fody
- {
- public partial class ModuleWeaver : BaseModuleWeaver
- {
- public override void Execute()
- {
- foreach (var type in ModuleDefinition.Types)
- {
- foreach (var method in type.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 void ProcessMethod(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 in GetInstructions(method))
- {
- processor.InsertAfter(current, instruction);
- current = instruction;
- }
- }
- private IEnumerable<Instruction> GetInstructions(MethodDefinition method)
- {
- yield return Instruction.Create(OpCodes.Nop);
- yield return Instruction.Create(OpCodes.Ldstr, "Hello World.");
- yield return Instruction.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 class Program
- {
- static void Main(string[] args)
- {
- Echo();
- Console.ReadKey();
- }
- [HW]
- public static void Echo()
- {
- 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。