在.NET Core中批量注入Grpc服務

時間 2020-01-09

標籤 core 批量注入 grpc 服務简体版

原文原文鏈接

　　GRPC 是谷歌發佈的一個開源、高性能、通用RPC服務，儘管大部分 RPC 框架都使用 TCP 協議，但其實 UDP 也能夠，而 gRPC 乾脆就用了 HTTP2。還有就是它具備跨平臺、跨語言等特性，這裏就再也不說明RPC是啥。git

　　在寫項目當中，grp服務過多會很是頭疼，那麼咱們分析一下若是解決這個問題。咱們都知道在grpc注入到.NET Core 中使用的方法是 MapGrpcService 方法，是一個泛型方法。github

    [NullableAttribute(0)]
    [NullableContextAttribute(1)]
    public static class GrpcEndpointRouteBuilderExtensions
    {
        public static GrpcServiceEndpointConventionBuilder MapGrpcService<TService>(this IEndpointRouteBuilder builder) where TService : class;
    }

那咱們就能夠經過反射調用這個方法來進行服務批量註冊，看方法的樣子咱們只須要將咱們的服務對應 TService 以及將咱們的 endpointBuilder 傳入便可，咱們看下源碼是否是就像我所說的那樣？app

    public static class GrpcEndpointRouteBuilderExtensions
    {
        public static GrpcServiceEndpointConventionBuilder MapGrpcService<TService>(this IEndpointRouteBuilder builder) where TService : class
        {
            if (builder == null)
            {
                throw new ArgumentNullException(nameof(builder));
            }

            ValidateServicesRegistered(builder.ServiceProvider);

            var serviceRouteBuilder = builder.ServiceProvider.GetRequiredService<ServiceRouteBuilder<TService>>();
            var endpointConventionBuilders = serviceRouteBuilder.Build(builder);

            return new GrpcServiceEndpointConventionBuilder(endpointConventionBuilders);
        }

        private static void ValidateServicesRegistered(IServiceProvider serviceProvider)
        {
            var marker = serviceProvider.GetService(typeof(GrpcMarkerService));
            if (marker == null)
            {
                throw new InvalidOperationException("Unable to find the required services. Please add all the required services by calling " +
                    "'IServiceCollection.AddGrpc' inside the call to 'ConfigureServices(...)' in the application startup code.");
            }
        }
    }

　　ok，看樣子沒什麼問題就像我剛纔所說的那樣作。如今咱們準備一個proto以及一個Service.這個就在網上找個吧..首先定義一個proto，它是grpc中的協議，也就是每一個消費者遵循的。框架

syntax = "proto3";
option csharp_namespace = "Grpc.Server";
package Greet;
service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}
message HelloRequest {
  string name = 1;
  enum Laguage{
      en_us =0 ;
      zh_cn =1 ;
  }
  Laguage LaguageEnum = 2;
}
message HelloReply {
  string message = 1;
  int32 num = 2;
  int32 adsa =3;
}

隨後定義Service，固然很是簡單， Greeter.GreeterBase 是從新生成項目根據proto來生成的。dom

public class GreeterService : Greeter.GreeterBase
    {
        public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
        {
            var greeting = string.Empty;
            switch (request.LaguageEnum)
            {
                case HelloRequest.Types.Laguage.EnUs:
                    greeting = "Hello";
                    break;
                case HelloRequest.Types.Laguage.ZhCn:
                    greeting = "你好";
                    break;
            }
            return Task.FromResult(new HelloReply
            {
                Message = $"{greeting} {request.Name}",
                Num = new Random().Next()
            });
        }
    }

此時咱們須要自定義一箇中間件，來批量注入grpc服務，其中咱們獲取了類型爲 GrpcEndpointRouteBuilderExtensions ，並獲取了它的方法，隨後傳入了他的TService，最後經過Invoke轉入了咱們的終點對象。ide

public static class GrpcServiceExtension
    {
        public static void Add_Grpc_Services(IEndpointRouteBuilder builder)
        {
            Assembly assembly = Assembly.GetExecutingAssembly(); 
            foreach (var item in ServicesHelper.GetGrpcServices("Grpc.Server"))
            {
                Type mytype = assembly.GetType(item.Value + "."+item.Key);
                var method = typeof(GrpcEndpointRouteBuilderExtensions).GetMethod("MapGrpcService").MakeGenericMethod(mytype);
                method.Invoke(null, new[] { builder }); 
            };
        }
        public static void useMyGrpcServices(this IApplicationBuilder app)
        {
            app.UseEndpoints(endpoints =>
            {
                Add_Grpc_Services(endpoints);
            });
        }
    }

在 ServicesHelper 中經過反射找到程序集當中的全部文件而後判斷並返回。性能

 public static class ServicesHelper
    {
        public static Dictionary<string,string> GetGrpcServices(string assemblyName)
        {
            if (!string.IsNullOrEmpty(assemblyName))
            {
                Assembly assembly = Assembly.Load(assemblyName);
                List<Type> ts = assembly.GetTypes().ToList();

                var result = new Dictionary<string, string>();
                foreach (var item in ts.Where(u=>u.Namespace == "Grpc.Server.Services"))
                {
                    result.Add(item.Name,item.Namespace);
                }
                return result;
            }
            return new Dictionary<string, string>();
        }
}

這樣子咱們就注入了全部命名空間爲Grpc.Server.Services的服務，但這樣好像沒法達到某些控制，咱們應當如何處理呢，我建議攜程Attribute的形式，建立一個Flag.ui

public class GrpcServiceAttribute : Attribute
{
        public bool IsStart { get; set; }
}

將要在注入的服務商添加該標識，例如這樣。this

 [GrpcService]
    public class GreeterService : Greeter.GreeterBase
    {...}

隨後根據反射出來的值找到 AttributeType 的名稱進行判斷便可。spa

 public static Dictionary<string,string> GetGrpcServices(string assemblyName)
        {
            if (!string.IsNullOrEmpty(assemblyName))
            {
                Assembly assembly = Assembly.Load(assemblyName);
                List<Type> ts = assembly.GetTypes().ToList();

                var result = new Dictionary<string, string>();
                foreach (var item in ts.Where(u=>u.CustomAttributes.Any(a=>a.AttributeType.Name == "GrpcServiceAttribute")))
                {
                    result.Add(item.Name,item.Namespace);
                }
                return result;
            }
            return new Dictionary<string, string>();
        }