Go微服务实战｜第8章：gRPC Cancelling RPCs

原创

Madman

8212 次阅读

Synopsis: 本文演示了客户端和服务端建立了双向流之后，双方都可以不断地向对方发送或接收数据，如果客户端不想再连接了，它主动调用 cancel() 方法，将会取消 context 上下文，即关闭双向流，那么服务端会立即收到 codes.Canceled 错误状态码。同时，如果之后客户端再次想从双向流中发送或读取数据，都会收到 codes.Canceled 错误状态码

代码已上传到 https://github.com/wangy8961/grpc-go-tutorial/tree/v0.8 ，欢迎 star

1. 双向流 RPC

创建 grpc-go-tutorial/features/cancel/server/main.go 文件：

// Package main implements a server for Echo service.
package main

import (
    "context"
    "flag"
    "fmt"
    "io"
    "log"
    "net"

    pb "github.com/wangy8961/grpc-go-tutorial/features/echopb"
    "google.golang.org/grpc"
    "google.golang.org/grpc/codes"
    "google.golang.org/grpc/status"
)

// server is used to implement echopb.EchoServer.
type server struct{}

func (s *server) UnaryEcho(ctx context.Context, req *pb.EchoRequest) (*pb.EchoResponse, error) {
    return nil, status.Errorf(codes.Unimplemented, "method UnaryEcho not implemented")
}

func (s *server) ServerStreamingEcho(req *pb.EchoRequest, stream pb.Echo_ServerStreamingEchoServer) error {
    return status.Errorf(codes.Unimplemented, "method ServerStreamingEcho not implemented")
}

func (s *server) ClientStreamingEcho(stream pb.Echo_ClientStreamingEchoServer) error {
    return status.Errorf(codes.Unimplemented, "method ClientStreamingEcho not implemented")
}

func (s *server) BidirectionalStreamingEcho(stream pb.Echo_BidirectionalStreamingEchoServer) error {
    for {
        in, err := stream.Recv()
        if err != nil {
            fmt.Printf("server: error receiving from stream: %v\n", err)
            if err == io.EOF {
                return nil
            }
            return err
        }
        fmt.Printf("echoing message %q\n", in.Message)
        stream.Send(&pb.EchoResponse{Message: in.Message})
    }
}

func main() {
    port := flag.Int("port", 50051, "the port to serve on")
    flag.Parse()

    lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *