package mutex

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

type container struct {
	mu      sync.Mutex
	counter map[string]int
}

func Mutex() {
	var wg sync.WaitGroup
	c := container{
		counter: map[string]int{
			"a": 0,
			"b": 0,
		},
	}

	increment := func(key string, times uint) {
		c.mu.Lock()
		defer c.mu.Unlock()

		time.Sleep(200 * time.Millisecond)

		for range times {
			c.counter[key]++
		}

		wg.Done()
	}

	wg.Add(3)
	go increment("a", 1000)
	go increment("b", 1000)
	go increment("a", 1000)

	wg.Wait()

	fmt.Printf("counter after all increment() calls: %v\n", c.counter)
}