英文:
How to pass WaitGroup to a sequential function call?
问题
我有一个函数，可以在单独的goroutine中按顺序或并发调用。
我想确保在主goroutine完成之前完全执行函数，所以我将*sync.WaitGroup参数传递给函数。现在，在某些地方，函数需要按顺序调用。
我可以像这样将nil waitGroup传递给函数：
func my_func(wg *sync.WaitGroup){
if wg != nil{
defer wg.Done()
}
// 执行任务
}
func main(){
my_func(nil) // 顺序调用
wg := sync.WaitGroup{}
wg.Add(1)
go my_func(&wg) // 并发调用
wg.Wait()
}
有没有更好的方法来实现这个？
英文:
I have a function which can be called sequentially or concurrently in separate goroutine.
I want to ensure that function is executed completely before main goroutine finishes, so I am passing *sync.WaitGroup argument to the function. Now, at some places the function is to be called sequentially.
I can pass nil waitGroup to the function like this:
func my_func(wg *sync.WaitGroup){
if wg != nil{
defer wg.Done()
}
// do the task
}
func main(){
my_func(nil) // sequential call
wg := sync.WaitGroup{}
wg.Add(1)
go my_func(&wg) // concurrent call
wg.Wait()
}
Is there any better way to achieve this ?
答案1
得分: 7
你的my_func()不应该知道/关心它是如何执行的（无论是在新的goroutine中还是其他方式）。因此，你不应该传递wg参数。不要强制要求并发或非并发使用你的API，让你的包的用户决定如何调用它。
如果有人希望并发地在新的goroutine中运行它，可以在my_func()之外处理wg，像这样：
wg.Add(1)
go func() {
defer wg.Done()
my_func()
}()
这样还可以在函数调用之前/之后执行其他代码，这些代码将在wg.Done()调用之前执行：
wg.Add(1)
go func() {
defer wg.Done()
// 其他代码
my_func()
// 其他代码
}()
另外请注意，如果你在多个地方都有这样的代码，你可以创建一个辅助函数来处理goroutine的启动和waitgroup的处理：
func launchMyFunc(wg *sync.WaitGroup) {
go func() {
defer wg.Done()
my_func()
}()
}
你还可以创建一个接受任意无参数无返回值函数的辅助函数：
func launchFunc(wg *sync.WaitGroup, f func()) {
go func() {
defer wg.Done()
f()
}()
}
使用上述辅助函数，你可以这样做：
wg.Add(1)
launchMyFunc(wg)
// 或者
wg.Add(1)
launchFunc(wg, my_func)
英文:
Your my_func() should not know / should not care how it is executed (whether in a new goroutine or not). So just for this you should not pass wg. Do not enforce concurrent or non-concurrent use of your API, let users of your package decide how they wish to call it.
If someone wishes to run it concurrently, in a new goroutine, wg can be handled outside of my_func() like this:
wg.Add(1)
go func() {
defer wg.Done()
my_func()
}()
This also gives possibility to put further code before / after the function call that will be executed before the wg.Done() call:
wg.Add(1)
go func() {
defer wg.Done()
// other code before
my_func()
// other code after
}()
Also note that if you have this in many places, you can create a helper function that takes care of the goroutine launching and waitgroup handling:
func launchMyFunc(wg *sync.WaitGroup) {
go func() {
defer wg.Done()
my_func()
}()
}
You can also create a helper that accepts an arbitrary no-arg no-return function:
func launchFunc(wg *sync.WaitGroup, f func()) {
go func() {
defer wg.Done()
f()
}()
}
Using the above helpers this is how you could do the same:
wg.Add(1)
launchMyFunc(wg)
// or
wg.Add(1)
launchFunc(wg, my_func)
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