Racontes-moi plus sur WaitGroup: kā tas darbojas, ko dara Add, Done, Wait?

In Go, WaitGroup is used to wait for a collection of goroutines to finish.

• Add(n int) — increases the counter by n, usually called before starting goroutines.
• Done() — decreases the counter by 1, called inside a goroutine after completing its work.
• Wait() — blocks execution until the counter reaches zero, i.e., until all goroutines have called Done.

Example:

var wg sync.WaitGroup
wg.Add(3) // wait for 3 goroutines

for i := 0; i < 3; i++ {
    go func(id int) {
        defer wg.Done()
        fmt.Println("Goroutine", id, "completed")
    }(i)
}

wg.Wait() // wait for all goroutines to finish
fmt.Println("All goroutines have finished")

This way, WaitGroup helps synchronize parallel tasks and wait for their completion.