Go 使用 sync.Cond 交替打印奇偶数

package main

import (
	"sync"
	"sync/atomic"
	"time"
)

type GetNumFn func() int

type ConditionFn func() bool

type IncrementalNumGetter struct {
	num atomic.Int32
}

func (g *IncrementalNumGetter) GetAndIncrease() int {
	return int(g.num.Add(1))
}

func (g *IncrementalNumGetter) IsOdd() bool {
	return g.num.Load()%2 == 1
}

func (g *IncrementalNumGetter) IsEven() bool {
	return g.num.Load()%2 == 0
}

type StopFn func() bool

var neverStop StopFn = func() bool {
	return false
}

func main() {
	var (
		wg    sync.WaitGroup
		mu    sync.Mutex
		condA = sync.NewCond(&mu)
		condB = sync.NewCond(&mu)
	)

	wg.Add(2)

	var numGetter IncrementalNumGetter

	go PrintNum(&wg, condA, condB, numGetter.GetAndIncrease, numGetter.IsOdd, neverStop)
	go PrintNum(&wg, condB, condA, numGetter.GetAndIncrease, numGetter.IsEven, neverStop)

	condA.Signal()

	wg.Wait()
}

func PrintNum(wg *sync.WaitGroup, cond *sync.Cond, anotherCond *sync.Cond, getNum GetNumFn, conditionFn ConditionFn, stopFn StopFn) {
	defer wg.Done()

	for !stopFn() {
		cond.L.Lock()
		for !conditionFn() {
			cond.Wait()
		}

		num := getNum()
		println(num)
		time.Sleep(200 * time.Millisecond)

		cond.L.Unlock()

		anotherCond.Signal()
	}
}