bool stop(bool wait=true) {
if(!isrunning)return true;
keeprunning=false;
s_newdata.thaw();
if(!wait)
return (!isrunning);
struct timeval sleep;
while(isrunning) {
sleep.tv_sec=0;
sleep.tv_usec=10;
select(0,0,0,0,&sleep);
s_newdata.thaw();
}
return true;
}