使用Redis做任务队列(Golang)

        在 ​​上篇​​用纯go在本机模拟了下分布式队列的东西。这里补上Redis队列部份。
用Redis做队列有下面三个问题需解决：

 1. 队列构建
     使用Redis的RPUSH/LPOP来解决

 2. 参数传递/解析 
   客户端将JOSN参数存入Redis,Server端取出后解析还原。

 3. 连接池

      redigo支持Redis连接池

下面代码就是具体解决实现:

//Redis做后台任务队列
//author: Xiong Chuan Liang
//date: 2015-3-25

package main

import (
  "bytes"
  "encoding/json"
  "errors"
  "fmt"
  "time"

  "github.com/garyburd/redigo/redis"
)

func main() {

  r, err := newRedisPool("", "")
  if err != nil {
    fmt.Println(err)
    return
  }

  //将job放入队列
  r.Enqueue()

  //依次取出两个Job
  r.GetJob()
  r.GetJob()
}

type RedisPool struct {
  pool *redis.Pool
}

func newRedisPool(server, password string) (*RedisPool, error) {

  if server == "" {
    server = ":6379"
  }

  pool := &redis.Pool{
    MaxIdle:     3,
    IdleTimeout: 240 * time.Second,
    Dial: func() (redis.Conn, error) {
      c, err := redis.Dial("tcp", server)
      if err != nil {
        return nil, err
      }

      if password != "" {
        if _, err := c.Do("AUTH", password); err != nil {
          c.Close()
          return nil, err
        }
      }
      return c, err
    },
    TestOnBorrow: func(c redis.Conn, t time.Time) error {
      _, err := c.Do("PING")
      return err
    },
  }

  return &RedisPool{pool}, nil
}

type Job struct {
  Class string        `json:"Class"`
  Args  []interface{} `json:"Args"`
}

//模拟客户端
func (r *RedisPool) Enqueue() error {

  c := r.pool.Get()
  defer c.Close()

  j := &Job{}
  j.Class = "mail"
  j.Args = append(j.Args, "[e-mail]", "", "body", 2, true)

  j2 := &Job{}
  j2.Class = "Log"
  j2.Args = append(j2.Args, "ccc.log", "ddd.log", []int{222, 333})

  for _, v := range []*Job{j, j2} {
    b, err := json.Marshal(v)
    if err != nil {
      return err
    }

    _, err = c.Do("rpush", "queue", b)
    if err != nil {
      return err
    }
  }

  fmt.Println("[Enqueue()] succeed!")

  return nil
}

//模拟Job Server
func (r *RedisPool) GetJob() error {
  count, err := r.QueuedJobCount()
  if err != nil || count == 0 {
    return errors.New("暂无Job.")
  }
  fmt.Println("[GetJob()] Jobs count:", count)

  c := r.pool.Get()
  defer c.Close()

  for i := 0; i < int(count); i++ {
    reply, err := c.Do("LPOP", "queue")
    if err != nil {
      return err
    }

    var j Job
    decoder := json.NewDecoder(bytes.NewReader(reply.([]byte)))
    if err := decoder.Decode(&j); err != nil {
      return err
    }

    fmt.Println("[GetJob()] ", j.Class, " : ", j.Args)
  }
  return nil
}

func (r *RedisPool) QueuedJobCount() (int, error) {
  c := r.pool.Get()
  defer c.Close()

  lenqueue, err := c.Do("llen", "queue")
  if err != nil {
    return 0, err
  }

  count, ok := lenqueue.(int64)
  if !ok {
    return 0, errors.New("类型转换错误!")
  }
  return int(count), nil
}

/*
运行结果:

[Enqueue()] succeed!
[GetJob()] Jobs count: 2
[GetJob()]  mail  :  [[e-mail]  body 2 true]
[GetJob()]  Log  :  [ccc.log ddd.log [222 333]]
[root@xclos src]#

*/

    可以看到Go已能取得参数。都是些最基础的东西。