了解如何在golang中设计可扩展的Select Channels Go并发式编程

type Task struct {
    ID    int
    Value int
}

type Dispatcher struct {
    workerCount  int
    taskQueue    chan Task
    workerDone   chan struct{}
    workerFinish chan struct{}
}

func NewDispatcher(workerCount int) *Dispatcher {
    return &Dispatcher{
        workerCount:  workerCount,
        taskQueue:    make(chan Task),
        workerDone:   make(chan struct{}, workerCount),
        workerFinish: make(chan struct{}),
    }
}

func (d *Dispatcher) Start() {
    for i := 0; i < d.workerCount; i++ {
        go d.worker()
    }

    go d.adjust()
}

func (d *Dispatcher) worker() {
    for task := range d.taskQueue {
        // 处理任务
        fmt.Printf("Worker[%d] processing task %d
", task.ID, task.Value)
        time.Sleep(1 * time.Second)
        d.workerDone <- struct{}{}
    }
}

func (d *Dispatcher) adjust() {
    for {
        select {
        case <-d.workerFinish:
            d.workerCount--
            if d.workerCount == 0 {
                return
            }
        case <-time.After(5 * time.Second):
            if len(d.taskQueue) > 10 && d.workerCount < 5 {
                d.workerCount++
                go d.worker()
            }
        }
    }
}

func (d *Dispatcher) Dispatch(task Task) {
    d.taskQueue <- task
}

func (d *Dispatcher) Wait() {
    for i := 0; i < d.workerCount; i++ {
        <-d.workerDone
    }
    close(d.taskQueue)
    close(d.workerFinish)
    close(d.workerDone)
}

func main() {
    dispatcher := NewDispatcher(3)
    dispatcher.Start()
    
    for i := 0; i < 20; i++ {
        task := Task{
            ID:    i,
            Value: i,
        }
        dispatcher.Dispatch(task)
    }
    
    dispatcher.Wait()
}