What synchronization primitives for goroutines exist in Go?

In Go, the following primitives are used for goroutine synchronization:

• Mutex (sync.Mutex) — provides mutual exclusion, blocking access to shared resources.
• RWMutex (sync.RWMutex) — an extension of Mutex that allows multiple goroutines to read simultaneously but blocks writing.
• WaitGroup (sync.WaitGroup) — allows waiting for a set of goroutines to finish.
• Channel (chan) — a data transfer medium between goroutines, providing synchronization through message passing.
• Once (sync.Once) — guarantees that a specific function is executed only once.
• Cond (sync.Cond) — a condition variable for more complex synchronization, such as waiting for a certain state.

Example of using WaitGroup and Mutex:

var mu sync.Mutex
var wg sync.WaitGroup
var counter int

func increment() {
    defer wg.Done()
    mu.Lock()
    counter++
    mu.Unlock()
}

func main() {
    wg.Add(3)
    go increment()
    go increment()
    go increment()
    wg.Wait()
    fmt.Println("Counter:", counter)
}