go同步元语sync.cond

cond的使用方式不太好理解，我尝试用短跑运动解释一下，但最好用下面的代码跑跑会理解的更快。

package main

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

var sharedRsc = false

func main() {
	var wg sync.WaitGroup
	wg.Add(2)
	m := sync.Mutex{}
	c := sync.NewCond(&m)
    
    //运动员1
	go func() {
		// this go routine wait for changes to the sharedRsc
		c.L.Lock()
		fmt.Println("goroutine1 pass Lock")
		for sharedRsc == false {
			fmt.Println("goroutine1 wait")
			c.Wait()
		}
		fmt.Println("goroutine1", sharedRsc)
		c.L.Unlock()
		wg.Done()
	}()

    //运动员2
	go func() {
		// this go routine wait for changes to the sharedRsc
		c.L.Lock()
		fmt.Println("goroutine2 pass Lock")
		for sharedRsc == false {   
			fmt.Println("goroutine2 wait")
			c.Wait()
		}
		fmt.Println("goroutine2", sharedRsc)
		c.L.Unlock()
		wg.Done()
	}()


	time.Sleep(2 * time.Second)
	c.L.Lock()
	fmt.Println("main goroutine ready")
	sharedRsc = true    
	c.Broadcast()
	fmt.Println("main goroutine broadcast")
	c.L.Unlock()
	wg.Wait()
}