在go例程更新后未返回已更新的值。

Question

我遇到了一个问题，即使在go子例程中更新了该值之后，返回的整数值也与一个集合相同。我好像搞不清出了什么问题。

//HostUptimeReporter - struct
type HostUptimeReporter struct {
    updateInterval int
    uptime int
    shutdownSignal chan bool

}

//NewHostUpTimeReporter - create reporter instance
func NewHostUpTimeReporter(updateIntervalInSeconds int) HostUptimeReporter {
    instance := HostUptimeReporter{updateInterval: updateIntervalInSeconds, shutdownSignal: make(chan bool), uptime:59}
    ticker := time.NewTicker(time.Duration(updateIntervalInSeconds) * time.Second)
    go func() {
        for {
            select {
            case <-ticker.C:
                instance.uptime += updateIntervalInSeconds          
                fmt.Printf("updated uptime:%v\n", instance.uptime)
            case <-instance.shutdownSignal:
                ticker.Stop()
                return
            }
        }
    }()

    return instance
}

//Shutdown - shuts down the go routine
func (hupr *HostUptimeReporter) Shutdown(){
    hupr.shutdownSignal <- true
}

func main() {

    hurp := NewHostUpTimeReporter(2)
    defer hurp.Shutdown()
    fmt.Printf("current uptime:%v\n", hurp.uptime)
    time.Sleep(3*time.Second)
    fmt.Printf("new uptime:%v\n", hurp.uptime)

}

https://play.golang.org/p/ODjSBb0YugK

任何指点都会受到赞赏。

谢谢!

Answer 1

启动goroutine的函数返回一个HostUptimeReporter。

func NewHostUpTimeReporter(updateIntervalInSeconds int) HostUptimeReporter {

返回一个像这样的完整结构，返回一个结构的副本，因此goroutine和NewHostUpTimeReporter调用者正在查看不同的内容。您希望返回一个指针，以便它们共享数据：

// -----------------------------------------------------v
func NewHostUpTimeReporter(updateIntervalInSeconds int) *HostUptimeReporter {
    instance := &HostUptimeReporter{updateInterval: updateIntervalInSeconds, shutdownSignal: make(chan bool), uptime:59}
    // ---------^
    ...