#include <iostream.h>
#include <rlocks.h>
void fetch_line(istream& istr, char* line, int& linecount)
{
    stream_locker sl(istr, stream_locker::lock_defer);

    sl.lock(); // lock the stream istr
    istr >> line;
    linecount = istr.gcount();
    sl.unlock(); // unlock istr
    ...
}