class StringFifo: public BiVector<String>{
	ConditionVariable cv;
	Mutex mtx;
	
public:
	StringFifo(){
		
	}
	
	void Put(const String &s){
		mtx.Enter();
		AddTail(s);
		cv.Signal();
		mtx.Leave();
	}
	
	String Get(int timeout_ms=-1){
		mtx.Enter();
		if(GetCount() || (cv.Wait(mtx,timeout_ms) && GetCount())){
			String r=PopHead();
			mtx.Leave();
			return r;
		}
		else{
			mtx.Leave();
			return String::GetVoid();
		}
	}
};