算法：golang使用channel实现非阻塞队列和超时阻塞队列

忘是亡心i 2023-02-26 10:29 13阅读 0赞

Channel是Golang中非常重要的数据结构, 默认它是阻塞的。那么如何实现一个非阻塞队列呢？

package main
    
    import (
        "errors"
        "fmt"
    )
    
    func push(q chan int, item int) error {
        
        select {
        
        case q <- item:
            return nil
        default:
            return errors.New("queue full")
        }
    
    }
    
    func get(q chan int) (int, error) {
        
        var item int
        select {
        
        case item = <-q:
            return item, nil
        default:
            return 0, errors.New("queue empty")
        }
    
    }
    
    func main() {
        
        q := make(chan int, 5)
        x := []int{
        1, 2, 3, 4, 5, 6}
        for _, value := range x {
        
            err := push(q, value)
            fmt.Printf("error:%v\n", err)
        }
    
        for _, value := range x {
        
            fmt.Println(value)
            v, err := get(q)
            fmt.Printf("v:%v, error:%v\n", v, err)
        }
    }

我们还可以把channel变成一个带超时的阻塞队列

package main
    
    import (
        "errors"
        "fmt"
        "time"
    )
    
    func push(q chan int, item int, timeoutSecs int) error {
        
    
        select {
        
        case q <- item:
            return nil
        case <-time.After(time.Duration(timeoutSecs) * time.Second):
            return errors.New("queue full, wait timeout")
        }
    }
    
    func get(q chan int, timeoutSecs int) (int, error) {
        
        var item int
        select {
        
        case item = <-q:
            return item, nil
        case <-time.After(time.Duration(timeoutSecs) * time.Second):
            return 0, errors.New("queue empty, wait timeout")
        }
    
    }
    
    func main() {
        
        q := make(chan int, 5)
        x := []int{
        1, 2, 3, 4, 5, 6}
        for _, value := range x {
        
            err := push(q, value, 3)
            fmt.Printf("error:%v\n", err)
        }
    
        for _, value := range x {
        
            fmt.Println(value)
            v, err := get(q, 3)
            fmt.Printf("v:%v, error:%v\n", v, err)
        }
    }