hytrix.net 熔断降级

/// <summary>
    /// AOP 目标：use AspectCore ,在执行 HelloAsync 失败的时候自动执行 HelloFallBackAsync ，达到熔断降级
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            ProxyGeneratorBuilder proxyGeneratorBuilder = new ProxyGeneratorBuilder();
            using (IProxyGenerator proxyGenerator = proxyGeneratorBuilder.Build())
            {
                Person p = proxyGenerator.CreateClassProxy<Person>();
                Console.WriteLine(p.HelloAsync("Hello World").Result);
                Console.WriteLine(p.Add(1, 2));
            }
        }
    }

/// <summary>
    /// 目标：在执行 HelloAsync 失败的时候自动执行 HelloFallBackAsync ，达到熔断降级
    /// </summary>
    public class Person
    {
        [HystrixCommand(nameof(HelloFallBackAsync))]
        public virtual async Task<string> HelloAsync(string name)//需要是虚方法
        {
            Console.WriteLine("hello" + name);

            //抛错
            String s = null;
            s.ToString();

            return "ok";
        }

        public async Task<string> HelloFallBackAsync(string name)
        {
            Console.WriteLine("执行失败" + name);
            return "fail";
        }

        [HystrixCommand(nameof(AddFall))]
        public virtual int Add(int i, int j)
        {
            //抛错
            String s = null;
            //s.ToString();

            return i + j;
        }

        public int AddFall(int i, int j)
        {
            return 0;
        }
    }

    [AttributeUsage(AttributeTargets.Method)]
    public class HystrixCommandAttribute : AbstractInterceptorAttribute
    {
        public string FallBackMethod { get; set; }

        public HystrixCommandAttribute(string fallBackMethod)
        {
            this.FallBackMethod = fallBackMethod;
        }

        public override async Task Invoke(AspectContext context, AspectDelegate next)
        {
            try
            {
                await next(context);//执行被拦截的方法
            }
            catch (Exception ex)
            {
                /*
                 * context.ServiceMethod 被拦截的方法
                 * context.ServiceMethod.DeclaringType 被拦截的方法所在的类
                 * context.Implementation 实际执行的对象
                 * context.Parameters 方法参数值
                 * 如果执行失败，则执行FallBackMethod
                 */
                var fallBackMethod = context.ServiceMethod.DeclaringType.GetMethod(this.FallBackMethod);
                object fallBackResult = fallBackMethod.Invoke(context.Implementation, context.Parameters);
                context.ReturnValue = fallBackResult;
                await Task.FromResult(0);
            }
        }
    }