package sharememory

import (
	"fmt"
	"os"

	"golang.org/x/sys/unix"
)

func main() {
	// 打开文件
	file, err := os.OpenFile("testfile.txt", os.O_RDWR|os.O_CREATE, 0o666)
	if err != nil {
		fmt.Println("Error opening file:", err)
		return
	}
	defer file.Close()

	// 加独占锁
	fmt.Println("Acquiring exclusive lock...")
	err = unix.Flock(int(file.Fd()), unix.LOCK_EX)
	if err != nil {
		fmt.Println("Error acquiring exclusive lock:", err)
		return
	}
	defer unix.Flock(int(file.Fd()), unix.LOCK_UN) // 释放锁

	fmt.Println("Exclusive lock acquired. Writing to file...")
	// 这里可以添加写文件的逻辑
	fmt.Println("Writing complete.")

	// 打开文件
	file, err = os.OpenFile("testfile.txt", os.O_RDONLY, 0o666)
	if err != nil {
		fmt.Println("Error opening file:", err)
		return
	}
	defer file.Close()

	// 加共享锁
	fmt.Println("Acquiring shared lock...")
	err = unix.Flock(int(file.Fd()), unix.LOCK_SH)
	if err != nil {
		fmt.Println("Error acquiring shared lock:", err)
		return
	}
	defer unix.Flock(int(file.Fd()), unix.LOCK_UN) // 释放锁

	fmt.Println("Shared lock acquired. Reading from file...")
	// 这里可以添加读文件的逻辑
	fmt.Println("Reading complete.")
}