rwmutex_priority.go

package main

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

func main() {
	var mut sync.RWMutex
	var wg sync.WaitGroup
	wg.Add(5)
	
	go func() {
		defer wg.Done()
		fmt.Println("reader #1 started")
		mut.RLock()
		fmt.Println("reader #1 locked")
		defer mut.RUnlock()
		defer fmt.Println("reader #1 unlocked")
		time.Sleep(1000 * time.Millisecond)		
	}()
	
	
	time.Sleep(50 * time.Millisecond)
	
	go func() {
		defer wg.Done()
		fmt.Println("writer started")
		mut.Lock()
		fmt.Println("writer locked")
		defer mut.Unlock()
		defer fmt.Println("writer unlocked")
		time.Sleep(500 * time.Millisecond)		
	}()
	
	time.Sleep(50 * time.Millisecond)
	
	go func() {
		defer wg.Done()
		fmt.Println("reader #3 started")
		mut.RLock()
		fmt.Println("reader #3 locked")
		defer mut.RUnlock()
		defer fmt.Println("reader #3 unlocked")
		time.Sleep(1000 * time.Millisecond)		
	}()
	
	time.Sleep(50 * time.Millisecond)
	
	go func() {
		defer wg.Done()
		fmt.Println("reader #4 started")
		mut.RLock()
		fmt.Println("reader #4 locked")
		defer mut.RUnlock()
		defer fmt.Println("reader #4 unlocked")
		time.Sleep(1000 * time.Millisecond)		
	}()
	
	time.Sleep(50 * time.Millisecond)
	
	go func() {
		defer wg.Done()
		fmt.Println("reader #2 started")
		mut.RLock()
		fmt.Println("reader #2 locked")
		defer mut.RUnlock()
		defer fmt.Println("reader #2 unlocked")
		time.Sleep(1000 * time.Millisecond)		
	}()
	
	wg.Wait()
}