.netcore grpc截止时间和取消详解

一、截止时间概述

截止时间功能让 gRPC 客户端可以指定等待调用完成的时间。
超过截止时间时，将取消调用。
设定一个截止时间非常重要，因为它将提供调用可运行的最长时间。
它能阻止异常运行的服务持续运行并耗尽服务器资源。
截止时间对于构建可靠应用非常有效，应该进行配置。

二、取消概述

客户端主动取消不再需要长期运行的调用
线程故障自动取消
超出截止时间触发取消操作

三、实战案例

首先准备一个grpc后端服务
其次准备一个webapi服务作为客户端，方便HttpContext传递
客户端工厂配置EnableCallContextPropagation 用于上下文传递截止时间
传递CancellationTokenSource
话不多说，通过代码可以更好的看出程序的运行轨迹

// 引入proto文件
// 公共messages.proto

syntax = "proto3";

option csharp_namespace = "GrpcProject";

package grpc.serviceing;

// 请求体
message ServerRequest{
	string name = 1;
	double height = 2;
	int32 age = 3;
	bool flag = 4;
	float x = 5;
	float y = 6;
	float z= 7;
	repeated string departments = 8;
}

message ServerFileRequest{
	bytes fileBytes = 1;
}

// 响应体
message ServerResponse{
	bool result = 1;
}


// 服务dollar.proto文件

syntax = "proto3";

import "google/protobuf/empty.proto";
import "Protos/messages.proto";

option csharp_namespace = "GrpcProject";

package grpc.serviceing;

service DollarRpc{
	rpc ServerOne (ServerRequest) returns (ServerResponse);
	rpc ServerTwo (ServerRequest) returns (google.protobuf.Empty);
}

服务端接口实现：

   public class DollarService : DollarRpc.DollarRpcBase
    {
        public override async Task<ServerResponse> ServerOne(ServerRequest request, ServerCallContext context)
        {
            await Console.Out.WriteLineAsync("-------------------------ServerOne------------------------------\r\n");

            await Task.Delay(TimeSpan.FromSeconds(8), context.CancellationToken);

            foreach (var prop in request.GetType().GetProperties())
            {
                await Console.Out.WriteLineAsync($"property  name：{prop.Name}；value：{prop.GetValue(request)}");
            }

            return GetResponse();
        }

        public override async Task<Empty> ServerTwo(ServerRequest request, ServerCallContext context)
        {
            await Console.Out.WriteLineAsync("-------------------------ServerTwo------------------------------\r\n");

            await Task.Delay(TimeSpan.FromSeconds(8), context.CancellationToken);
            foreach (var prop in request.GetType().GetProperties())
            {
                await Console.Out.WriteLineAsync($"property  name：{prop.Name}；value：{prop.GetValue(request)}");
            }

            return new();
        }

        private ServerResponse GetResponse() => new() { Result = true };
    }

客户端实现重点：

program注入客户端工厂并启用截止时间配置
增加拦截器统一设定超时时间
调用查看结果

// program.cs

builder.Services.AddGrpcClient<DollarRpc.DollarRpcClient>(options =>
{
    options.Address = new Uri("https://localhost:7188");
}).EnableCallContextPropagation();

//拦截器过滤截止时间

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
    public class GrpcFilterAttribute : Attribute, IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext context)
        {
        }

        public void OnActionExecuting(ActionExecutingContext context)
        {
            CancellationTokenSource tokenSource = new();
            GrpcServerCallContextFeature callContext = new(DateTime.UtcNow.AddSeconds(5), tokenSource.Token);
            context.HttpContext.Features.Set<IServerCallContextFeature>(callContext);
        }
    }

    public class GrpcServerCallContextFeature : ServerCallContext, IServerCallContextFeature
    {
        /// <summary>
        /// 构造
        /// </summary>
        /// <param name="deadline"></param>
        /// <param name="cancellationToken"></param>
        public GrpcServerCallContextFeature(DateTime deadline, CancellationToken cancellationToken)
        {
            DeadlineCore = deadline;
            CancellationTokenCore = cancellationToken;
            AuthContextCore = new AuthContext(null, new Dictionary<string, List<AuthProperty>>());
        }

        public ServerCallContext ServerCallContext => this;

        protected override string MethodCore { get; }

        protected override string HostCore { get; }

        protected override string PeerCore { get; }

        protected override DateTime DeadlineCore { get; }

        protected override Metadata RequestHeadersCore { get; }

        protected override CancellationToken CancellationTokenCore { get; }

        protected override Metadata ResponseTrailersCore { get; }

        protected override Status StatusCore { get; set; }

        protected override WriteOptions? WriteOptionsCore { get; set; }

        protected override AuthContext AuthContextCore { get; }

        protected override ContextPropagationToken CreatePropagationTokenCore(ContextPropagationOptions? options)
        {
            return base.CreatePropagationToken(options);
        }
        protected override Task WriteResponseHeadersAsyncCore(Metadata responseHeaders)
        {
            throw new NotImplementedException();
        }
    }

//调用
// 在相应的类上打上标记   [GrpcFilter]

    [Route("api/[controller]")]
    [ApiController]
    [GrpcFilter] // 设定截止时间过滤
    public class GrpcTestController : ControllerBase
    {
        private readonly DollarRpc.DollarRpcClient _dollarRpcClient;

        public GrpcTestController(DollarRpc.DollarRpcClient dollarRpcClient) => _dollarRpcClient = dollarRpcClient;

        [HttpGet("one")]
        public async Task<string> GetOneResult()
        {
            ServerRequest request = new ServerRequest()
            {
                Departments = {
                "one","two","three","four","five"
                },
                Age = 10,
                Flag = true,
                Height = 10,
                Name = "zhangsan",
                X = 10F,
                Y = 11F,
                Z = 12F
            };

            try
            {
                var response = await _dollarRpcClient.ServerOneAsync(request);
                if (response.Result)
                {
                    return "Success";
                }
                return "Fail";
            }
            catch (RpcException ex) when (ex.StatusCode == Grpc.Core.StatusCode.DeadlineExceeded)
            {
                return "dealine timeout.";
            }
            catch (RpcException ex)
            {
                return ($"NoResult：{ex.Message}");
            }
        }

        [HttpGet("two")]
        public async Task<string> GetTwoResult()
        {
            ServerRequest request = new ServerRequest()
            {
                Departments = {
                "one","two","three","four","five"
                },
                Age = 10,
                Flag = true,
                Height = 10,
                Name = "zhangsan",
                X = 10F,
                Y = 11F,
                Z = 12F
            };

            try
            {
                var response = await _dollarRpcClient.ServerTwoAsync(request);
                return "Success";
            }
            catch (RpcException ex) when (ex.StatusCode == Grpc.Core.StatusCode.DeadlineExceeded)
            {
                return "dealine timeout.";
            }
            catch (RpcException ex)
            {
                return ($"NoResult：{ex.Message}");
            }
        }
    }