Go 实现心跳

心跳最典型的应用场景是是探测服务是否存活，比如在 Zookeeper 中，会使用心跳探测服务是否存货，如果服务已经死亡，会将服务从注册表中删除，避免服务请求路由到一个已经宕机的服务中。

Go 中实现心跳机制可以通过 time.NewTimeTicker()，配合 channel 使用，就可以实现一个简单的心跳程序：

go 复制代码

import (
	"code.byted.org/gopkg/logs"
	"context"
	"fmt"
	"testing"
	"time"
)

func sendHeartbeat(heartbeatChan chan<- time.Time) {
	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()
	for {
		select {
		case t := <-ticker.C:
			heartbeatChan <- t
		}
	}
}

func TestHeartbeat(t *testing.T) {

	heartbeatChan := make(chan time.Time)
	go doWork([]int{1, 2, 3, 5, 5}, heartbeatChan)
	for t := range heartbeatChan {
		// 上报心跳包的逻辑，可以在这里实现
		fmt.Println("Received heartbeat at", t)
	}
    fmt.Println("heartbeat finished")
}

func doWork(nums []int, heartbeatChan chan time.Time) {
	go sendHeartbeat(heartbeatChan)
	defer func() {
		close(heartbeatChan)
	}()
	for num := range nums {
        time.Sleep(1 * time.Second)
		fmt.Println(num)
	}
}

执行结果如下：

go 复制代码

=== RUN   TestHeartbeat
0
Received heartbeat at 2024-01-31 11:30:46.3363 +0800 CST m=+1.002830252
Received heartbeat at 2024-01-31 11:30:47.335975 +0800 CST m=+2.002513164
1
Received heartbeat at 2024-01-31 11:30:48.336252 +0800 CST m=+3.002795914
2
Received heartbeat at 2024-01-31 11:30:49.33622 +0800 CST m=+4.002768883
3
Received heartbeat at 2024-01-31 11:30:50.336222 +0800 CST m=+5.002775378
4
heartbeat finished
--- PASS: TestHeartbeat (5.00s)
PASS

心跳程序

客户端发送心跳请求, 并通过重试机制。判断重试X次失败认为服务离线服务端响应心跳请求，通过超时机制。超时X秒未收到心跳则判断客户端离线

go 复制代码

package main

import (
	"fmt"
	"net"
	"time"
)

func main() {
	// 启动服务端
	go startServer()

	// 启动客户端
	go startClient()

	// 保持 main goroutine 活跃，避免程序退出
	select {}
}

func startServer() {
	ln, err := net.Listen("tcp", ":8080")
	if err != nil {
		fmt.Println(err)
		return
	}
	defer ln.Close()

	for {
		conn, err := ln.Accept()
		if err != nil {
			fmt.Println(err)
			continue
		}
		go handleConnection(conn)
	}
}

func handleConnection(conn net.Conn) {
	// 使用 bufio 包中的 ReadWriter 类型，方便读写字符串
	rw := bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn))

	// 启动一个 goroutine，定时发送心跳消息
	go func() {
		for {
			time.Sleep(time.Second)
			if _, err := rw.WriteString("heartbeat\n"); err != nil {
				fmt.Println(err)
				return
			}
			if err := rw.Flush(); err != nil {
				fmt.Println(err)
				return
			}
		}
	}()

	// 循环读取客户端发送的消息
	for {
		line, err := rw.ReadString('\n')
		if err != nil {
			fmt.Println(err)
			return
		}
		fmt.Println("received:", line)
	}
}

func startClient() {
	conn, err := net.Dial("tcp", "localhost:8080")
	if err != nil {
		fmt.Println(err)
		return
	}
	defer conn.Close()

	//
}

Go 实现心跳

Go 实现心跳

心跳程序

参考资料