Asking mutex for its state is useless: it may be unlocked now, but by the time you get around to lock it, it may be locked. So it does not have such method.
It does, however, have a method try_lock()
which locks it if it is not locked and returns true
if it acquired the lock and false
otherwise. And std::unique_lock
(the more advanced version of std::lock_guard
) has option to call it.
So you can do:
void someFunctionCalledRepeatedlyFromAnotherThread()
{
std::unique_lock<std::mutex> lock(initMutex, std::try_to_lock);
if(!lock.owns_lock())
{
doSomeAlternativeAction();
return;
}
// otherwise ... go ahead, you have the lock
}