Is it possible to use a single flag to control Mutex locking?

No, you cannot use a single flag to manage a Mutex lock in Go. sync.Mutex is a structure with internal state, and it cannot be replaced with a simple boolean flag, as this would not ensure proper synchronization between goroutines.

Using a single flag does not guarantee atomicity of lock and unlock operations, which can lead to race conditions and errors.

The correct way is to use the Lock() and Unlock() methods from the sync package:

var mu sync.Mutex

mu.Lock()
// critical section
mu.Unlock()