Demonstrates some safe code with the use of locks.

safe_after_mutex.go

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
)

const totalEnemies = 2

var gameStats *globalGameStats = &globalGameStats{}

type globalGameStats struct {
	sync.RWMutex
	missed int
}

func (s *globalGameStats) incrementMissed() {
	s.Lock()
	s.missed += 1
	s.Unlock()
}

func (s *globalGameStats) dumpStats() {
	s.RLock()
	fmt.Printf("Total missed: %d\n", s.missed)
	s.RUnlock()
}

func main() {
	for i := 0; i < totalEnemies; i++ {
		go enemy()
	}

	time.Sleep(time.Second * 1)

	gameStats.dumpStats()
}

func enemy() {
	fmt.Println("Enemy created...")

	for {
		// Attempt attack.
		if rand.Intn(100) >= 90 {
			// Attack failed, record the miss.
			gameStats.incrementMissed()
		} else {
			// Attack succeeded, do some logic to hurt the player.
		}
	}
}