// Copyright (C) 2021 Marius Schellenberger

package db

import "sync/atomic"

type countMutex struct {
	mu  uint64
	max uint64
	c   uint64
}

func (cm *countMutex) Lock() (uint64, uint64, bool) {
	if atomic.CompareAndSwapUint64(&cm.mu, 0, 1) {
		return 0, 0, true
	}
	return atomic.LoadUint64(&cm.max), atomic.LoadUint64(&cm.c), false
}

func (cm *countMutex) Set(max uint64) {
	atomic.StoreUint64(&cm.max, max)
}

func (cm *countMutex) Inc() {
	atomic.AddUint64(&cm.c, 1)
}

func (cm *countMutex) Unlock() {
	atomic.StoreUint64(&cm.max, 0)
	atomic.StoreUint64(&cm.c, 0)
	atomic.StoreUint64(&cm.mu, 0)
}