Go语言读写锁如何设置超时

在Go语言中，没有内置的读写锁支持超时功能。但是，你可以使用time.After函数和select语句来实现一个带有超时的读写锁。下面是一个简单的示例：

package main

import (
	"fmt"
	"sync"
	"time"
)

type TimeoutReadWriteLock struct {
	mu        sync.RWMutex
	cond      *sync.Cond
	timeout   time.Duration
}

func NewTimeoutReadWriteLock(timeout time.Duration) *TimeoutReadWriteLock {
	return &TimeoutReadWriteLock{
		cond: sync.NewCond(&sync.Mutex{}),
		timeout: timeout,
	}
}

func (l *TimeoutReadWriteLock) ReadLock() {
	l.mu.RLock()
	defer l.mu.RUnlock()

	select {
	case <-time.After(l.timeout):
		return fmt.Errorf("read lock timeout")
	default:
		return nil
	}
}

func (l *TimeoutReadWriteLock) ReadUnlock() {
	l.mu.RUnlock()
}

func (l *TimeoutReadWriteLock) WriteLock() {
	l.mu.Lock()
	defer l.mu.Unlock()

	select {
	case <-time.After(l.timeout):
		return fmt.Errorf("write lock timeout")
	default:
		return nil
	}
}

func (l *TimeoutReadWriteLock) WriteUnlock() {
	l.mu.Unlock()
}

func main() {
	lock := NewTimeoutReadWriteLock(2 * time.Second)

	go func() {
		time.Sleep(1 * time.Second)
		lock.WriteLock()
		fmt.Println("Write lock acquired")
		time.Sleep(3 * time.Second)
		lock.WriteUnlock()
		fmt.Println("Write lock released")
	}()

	go func() {
		time.Sleep(500 * time.Millisecond)
		err := lock.ReadLock()
		if err != nil {
			fmt.Println("Read lock error:", err)
		} else {
			fmt.Println("Read lock acquired")
			time.Sleep(2 * time.Second)
			lock.ReadUnlock()
			fmt.Println("Read lock released")
		}
	}()

	time.Sleep(10 * time.Second)
}

在这个示例中，我们创建了一个TimeoutReadWriteLock结构体，它包含一个读写锁、一个条件变量和一个超时时间。ReadLock和WriteLock方法使用select语句来检查是否已经超过了超时时间。如果超过了超时时间，它们将返回一个错误；否则，它们将继续执行读写锁操作。