System.nanoTime() can be negative

According to the javadoc, System.nanoTime() should only be used to measure elapsed time, but not compute a target time in the future, as nanoTime() might return a a time in the future.

Code like the one below might fail:

public boolean waitFor(long timeout) {
        long wait_time;
        final long target_time=System.nanoTime() + TimeUnit.NANOSECONDS.convert(timeout, TimeUnit.MILLISECONDS); // ns

        lock.lock();
        try {
            while(!done && (wait_time=target_time - System.nanoTime()) > 0) {
                try {
                    cond.await(wait_time,TimeUnit.NANOSECONDS);
                }
                catch(InterruptedException e) {
                }
            }
            return done;
        }
        finally {
            lock.unlock();
        }
    }

When computing target_time, System.nanoTime() could return a negative value (numeric overflow) or a value in the future. In the first case, target_time could be negative, so the method would not block at all. In the latter case, target_time could be huge, so the method would block for a long time.

Investigate all occurrences where we use nanoTime() to compute a time in the future, and see what impact a future value value could have. Possibly replace with System.currentTimeMillis() or the time service.