Leetcode concurrency #1226 The Dining Philosophers (in golang)

p1226.go

type DiningPhilosophers struct {
    wg *sync.WaitGroup
    n int
    forks [5]sync.Mutex
    ate [5]int
}

func (obj *DiningPhilosophers) checkAll() bool {
    end := true
    for i := 0 ; i < len(obj.ate) ; i++ {
        if obj.ate[i] < obj.n {
            end = false
        }
    }
    return end
}

func (obj *DiningPhilosophers) wantsToEat(philosopher int) {
    defer obj.wg.Done()
    leftHand := philosopher
    var rightHand int
    if rightHand = philosopher - 1 ; rightHand < 0 {
        rightHand += 5
    }
    for {
        var end bool
        if leftHand > rightHand {
            obj.forks[rightHand].Lock()
            fmt.Printf("[%d,2,1]\n", philosopher)
        
            obj.forks[leftHand].Lock()
            fmt.Printf("[%d,1,1]\n", philosopher)
        
            obj.ate[philosopher]++
            fmt.Printf("[%d,0,3]\n", philosopher)
            end = obj.checkAll()
            
            obj.forks[leftHand].Unlock()
            fmt.Printf("[%d,1,2]\n", philosopher)
        
            obj.forks[rightHand].Unlock()
            fmt.Printf("[%d,2,2]\n", philosopher)
        } else {
            obj.forks[leftHand].Lock()
            fmt.Printf("[%d,1,1]\n", philosopher)
        
            obj.forks[rightHand].Lock()
            fmt.Printf("[%d,2,1]\n", philosopher)
        
            obj.ate[philosopher]++
            fmt.Printf("[%d,0,3]\n", philosopher)
            end = obj.checkAll()
        
            obj.forks[rightHand].Unlock()
            fmt.Printf("[%d,2,2]\n", philosopher)
        
            obj.forks[leftHand].Unlock()
            fmt.Printf("[%d,1,2]\n", philosopher)
        }
        
        if end {
            return
        }
    }
    
}

func run(n int) {
    wg := &sync.WaitGroup{}
    obj := DiningPhilosophers{wg: wg, n :n}
    
    wg.Add(5)
    for i := 0; i < 5; i++ {
        go obj.wantsToEat(i)
    }
    wg.Wait()
}

func main() {
    run(1)
}