Method enter

src/common/classes/semaphore.cpp:160–167

	}

	void SignalSafeSemaphore::enter()
	{
		do {
			if (sem_wait(sem) != -1)
				return;
		} while (errno == EINTR);
		system_call_failed::raise("semaphore.h: enter: sem_wait()");
	}

#ifdef HAVE_SEM_TIMEDWAIT
	bool SignalSafeSemaphore::tryEnter(const int seconds, int milliseconds)