Question

我有3个struct：Queue，Config，Tasker

type Queue struct {
  Name        string
  Concurrent  int
  Connections []*redis.Client
}

type Config struct {
  Queues    []Queue
  RedisAddr string
  RedisDB   int
}

type Tasker struct {
  Config Config
}

在这个方法中发生的问题，我在for循环中初始化queue.Connections，但是我得到零长度的队列。在for循环之外的连接

func (t *Tasker) StartListening() {
  for j := 0; j < len(t.Config.Queues); j++ {
    queue := t.Config.Queues[j]
    queue.Connections = make([]*redis.Client, queue.Concurrent)
    fmt.Println(len(queue.Connections)) //here print correct length, 1 for default queue, 2 for mail queue
  }
  fmt.Println(len(t.Config.Queues[0].Connections)) //but why here print 0?
}

这是我的测试代码

func main() {
  config := Config{
    RedisAddr: "10.1.1.59:6379",
    RedisDB:   8,
    Queues: []Queue{
      Queue{Name: "default", Concurrent: 1},
      Queue{Name: "mail", Concurrent: 2},
    },
  }
  daemon := Tasker{Config: config}
  daemon.StartListening()

}

为什么fmt.Println(len(t.Config.Queues[0].Connections))在for循环之外是0？

Answer 1

您正在创建新的Queue，而不是访问Config结构中的Queue，而这个新值会阻止修改Config.Queues中的// ... t.Config.Queues[j].Connections = make([]*redis.Client, queue.Concurrent) // ...。尝试直接分配：

Config.Queues

或者如果您想使用辅助变量，请将[]*Queue类型更改为type Config struct { Queues []*Queue RedisAddr string RedisDB int } // ... config := Config{ RedisAddr: "10.1.1.59:6379", RedisDB: 8, Queues: []*Queue{ &Queue{Name: "default", Concurrent: 1}, &Queue{Name: "mail", Concurrent: 2}, }, }：

var schedule = require('node-schedule'),
email_scheduler = {};

email_scheduler["H1e5nE2GW"] = schedule.scheduleJob(Date.now() + 10000, function(){
  console.log('its been a total of 10 seconds since initalization / reset.');
});

var second_attempt = schedule.scheduleJob(Date.now() + 5000, function(){
  console.log("5 seconds elapsed from start, time to reset original scheduled job");

  email_scheduler["H1e5nE2GW"].cancel();

  email_scheduler["H1e5nE2GW"] = schedule.scheduleJob(Date.now() + 10000, function(){
    console.log('its been a total of 10 since last one seconds.');
  });

  schedule.scheduleJob(Date.now() + 5000, function(){
    console.log("it's been another 5 seconds since reset");

  });
});

现在您的原始代码应该可以使用。

初始化后golang得到空切片

1 个答案: