基于 Docker 的 pubsub 包实现的 gRPC 的发布与订阅
1. 创建对应的文件和目录
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| mkdir pubsub
cd pubsub
go mod init pubsub
mkdir proto publisher subscribe
touch server.go
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2. 创建 proto 文件
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| cd proto
touch pubsub.proto
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pubsub.proto 内容如下
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| syntax = "proto3";
option go_package = "./;pb";
message Result {
string value = 1;
}
service PubSubService {
rpc Publish (Result) returns (Result);
rpc Subscribe (Result) returns (stream Result);
}
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如未安装 proto 扩展请先安装
执行 proto 命令
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| protoc --go_out=plugins=grpc:. pubsub.proto
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3. 进入 pubsub 编辑 server.go 文件；内容如下
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| package main
import (
"context"
"fmt"
"github.com/docker/docker/pkg/pubsub"
grpc "google.golang.org/grpc"
"log"
"net"
"strings"
pb "pubsub/proto"
"time"
)
type PubSubService struct {
pub *pubsub.Publisher
}
func main() {
grpcServer := grpc.NewServer()
pb.RegisterPubSubServiceServer(grpcServer, NewPubSubService())
listener, err := net.Listen("tcp", ":1234")
if err != nil {
log.Fatal("listen err: ", err)
} else {
fmt.Println("Service Start.")
}
grpcServer.Serve(listener)
}
func NewPubSubService() *PubSubService {
return &PubSubService{pub: pubsub.NewPublisher(100*time.Millisecond, 10)}
}
func (pub *PubSubService) Publish(ctx context.Context, arg *pb.Result) (*pb.Result, error) {
value := arg.GetValue()
pub.pub.Publish(value)
return &pb.Result{Value: value}, nil
}
func (pub *PubSubService) Subscribe(arg *pb.Result, stream pb.PubSubService_SubscribeServer) error {
ch := pub.pub.SubscribeTopic(func(v interface{}) bool {
if key, ok := v.(string); ok {
if strings.HasPrefix(key, arg.GetValue()) {
return true
}
}
return false
})
for v := range ch {
if err := stream.Send(&pb.Result{Value: v.(string)}); err != nil {
return err
}
}
return nil
}
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4. 进入 subscribe 目录，编写 subscribe.go 内容如下
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| package main
import (
"context"
"fmt"
"google.golang.org/grpc"
"io"
"log"
pb "pubsub/proto"
)
func main() {
conn, err := grpc.Dial("127.0.0.1:1234", grpc.WithInsecure())
if err != nil {
log.Fatal(err)
}
defer conn.Close()
client := pb.NewPubSubServiceClient(conn)
stream, err := client.Subscribe(
context.Background(),
&pb.Result{Value: "docker:"},
)
if err != nil {
log.Fatal(err)
}
for {
reply, err := stream.Recv()
if err != nil {
if err == io.EOF {
break
}
log.Fatal(err)
}
fmt.Println(reply.GetValue())
}
stream, err = client.Subscribe(
context.Background(),
&pb.Result{Value: "docker:"},
)
if err != nil {
log.Fatal(err)
}
for {
reply, err := stream.Recv()
if err != nil {
if err == io.EOF {
break
}
log.Fatal(err)
}
fmt.Println(reply.GetValue())
}
}
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5. 进入 publisher 目录，编写 publisher.go 内容如下
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| package main
import (
"context"
"fmt"
"log"
pb "pubsub/proto"
grpc "google.golang.org/grpc"
)
func main() {
conn, err := grpc.Dial("127.0.0.1:1234", grpc.WithInsecure())
if err != nil {
log.Fatal(err)
}
defer conn.Close()
client := pb.NewPubSubServiceClient(conn)
str, err := client.Publish(
context.Background(),
&pb.Result{Value: "docker: hello Docker"},
)
if err != nil {
log.Fatal(err)
} else {
fmt.Println("Publish: ", str.GetValue())
}
}
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6. 启动服务命令
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| 进入根目录执行
go run server.go // 启动服务
进入 subscribe 目录执行
go run subscribe.go // 订阅服务
进入 publisher 目录执行
go run publisher.go // 发布
执行 发布之后，就能通过订阅窗口
有内容输出 docker: hello Docker
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