.netcore grpc截止时间和取消详解

一、截止时间概述

1. 截止时间功能让 gRPC 客户端可以指定等待调用完成的时间。
2.  超过截止时间时，将取消调用。
3.  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。
4. 它能阻止异常运行的服务持续运行并耗尽服务器资源。
5. 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

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

三、实战案例

1. 首先准备一个grpc后端服务
2. 其次准备一个webapi服务作为客户端，方便HttpContext传递
3. 客户端工厂配置EnableCallContextPropagation 用于上下文传递截止时间
4. 传递CancellationTokenSource
5. 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 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 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：

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

// program.cs

builder.Services.AddGrpcClient(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(callContext);
        }
    }

    public class GrpcServerCallContextFeature : ServerCallContext, IServerCallContextFeature
    {
        /// 

        /// 构造
        /// 
        /// 
        /// 
        public GrpcServerCallContextFeature(DateTime deadline, CancellationToken cancellationToken)
        {
            DeadlineCore = deadline;
            CancellationTokenCore = cancellationToken;
            AuthContextCore = new AuthContext(null, new Dictionary>());
        }

        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 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 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}");
            }
        }
    }

四、查看执行结果

服务端One：

客户端One：

 

 swagger:

 另一个Two效果类似。同时服务端任务取消错误，也在截图上有显示。

五、源码地址

链接：https://pan.baidu.com/s/1vleChFc3F6ILs-5ad8xQCA 
提取码：mud0