go操作kafka

Kafka是一种高吞吐量的分布式发布订阅消息系统，它可以处理消费者规模的网站中的所有动作流数据，具有高性能、持久化、多副本备份、横向扩展等特点。本文介绍了如何使用Go语言发送和接收kafka消息。

sarama

Go语言中连接kafka使用第三方库:github.com/Shopify/sarama。

下载及安装

go get github.com/Shopify/sarama

注意事项

sarama v1.20之后的版本加入了zstd压缩算法，需要用到cgo，在Windows平台编译时会提示类似如下错误：

# github.com/DataDog/zstd
exec: "gcc":executable file not found in %PATH%

所以在Windows平台请使用v1.19版本的sarama。

连接kafka发送消息

package main

import (
    "fmt"

    "github.com/Shopify/sarama"
)

// 基于sarama第三方库开发的kafka client

func main() {
    config := sarama.NewConfig()
    config.Producer.RequiredAcks = sarama.WaitForAll          // 发送完数据需要leader和follow都确认
    config.Producer.Partitioner = sarama.NewRandomPartitioner // 新选出一个partition
    config.Producer.Return.Successes = true                   // 成功交付的消息将在success channel返回

    // 构造一个消息
    msg := &sarama.ProducerMessage{}
    msg.Topic = "web_log"
    msg.Value = sarama.StringEncoder("this is a test log")
    // 连接kafka
    client, err := sarama.NewSyncProducer([]string{"192.168.1.7:9092"}, config)
    if err != nil {
        fmt.Println("producer closed, err:", err)
        return
    }
    defer client.Close()
    // 发送消息
    pid, offset, err := client.SendMessage(msg)
    if err != nil {
        fmt.Println("send msg failed, err:", err)
        return
    }
    fmt.Printf("pid:%v offset:%v\n", pid, offset)
}

连接kafka消费消息

package main

import (
    "fmt"

    "github.com/Shopify/sarama"
)

// kafka consumer

func main() {
    consumer, err := sarama.NewConsumer([]string{"127.0.0.1:9092"}, nil)
    if err != nil {
        fmt.Printf("fail to start consumer, err:%v\n", err)
        return
    }
    partitionList, err := consumer.Partitions("web_log") // 根据topic取到所有的分区
    if err != nil {
        fmt.Printf("fail to get list of partition:err%v\n", err)
        return
    }
    fmt.Println(partitionList)
    for partition := range partitionList { // 遍历所有的分区
        // 针对每个分区创建一个对应的分区消费者
        pc, err := consumer.ConsumePartition("web_log", int32(partition), sarama.OffsetNewest)
        if err != nil {
            fmt.Printf("failed to start consumer for partition %d,err:%v\n", partition, err)
            return
        }
        defer pc.AsyncClose()
        // 异步从每个分区消费信息
        go func(sarama.PartitionConsumer) {
            for msg := range pc.Messages() {
                fmt.Printf("Partition:%d Offset:%d Key:%v Value:%v", msg.Partition, msg.Offset, msg.Key, msg.Value)
            }
        }(pc)
    }
select{}
}

//一个问题，上一条信息长，下一条信息端短，显示有问题

package main

import (
    "fmt"
    "os"
    "os/exec"
    "runtime"

    "github.com/Shopify/sarama"
)


//go清空终端操作
var clear map[string]func() //create a map for storing clear funcs

func init() {
    clear = make(map[string]func()) //Initialize it
    clear["linux"] = func() {
        cmd := exec.Command("clear") //Linux example, its tested
        cmd.Stdout = os.Stdout
        cmd.Run()
    }
    clear["windows"] = func() {
        cmd := exec.Command("cmd", "/c", "cls") //Windows example, its tested
        cmd.Stdout = os.Stdout
        cmd.Run()
    }
}

func CallClear() {
    value, ok := clear[runtime.GOOS] //runtime.GOOS -> linux, windows, darwin etc.
    if ok { //if we defined a clear func for that platform:
        value()  //we execute it
    } else { //unsupported platform
        panic("Your platform is unsupported! I can't clear terminal screen :(")
    }
}

// kafka consumer

func main() {
    consumer, err := sarama.NewConsumer([]string{"127.0.0.1:9092"}, nil)
    if err != nil {
        fmt.Printf("fail to start consumer, err:%v\n", err)
        return
    }
    partitionList, err := consumer.Partitions("web_log") // 根据topic取到所有的分区
    if err != nil {
        fmt.Printf("fail to get list of partition:err%v\n", err)
        return
    }
    fmt.Println("分区列表",partitionList)
    for partition := range partitionList { // 遍历所有的分区
        // 针对每个分区创建一个对应的分区消费者
        pc, err := consumer.ConsumePartition("web_log", int32(partition), sarama.OffsetNewest)
        if err != nil {
            fmt.Printf("failed to start consumer for partition %d,err:%v\n", partition, err)
            return
        }
        defer pc.AsyncClose()
        // 异步从每个分区消费信息
        go func(sarama.PartitionConsumer) {
            for msg := range pc.Messages() {
                CallClear()
                fmt.Printf("Partition:%d Offset:%d Key:%v Value:%v", msg.Partition, msg.Offset, msg.Key, string(msg.Value))
            }
        }(pc)
    }
    select {

    }
}

增加了清空终端的代码，不过，会有点延迟。