/** CASes the busy field from 0 to 1 to acquire lock. */
final boolean casBusy() {
return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
}
private boolean casSweepVotes(int cmp, int val) {
return UNSAFE.compareAndSwapInt(this, sweepVotesOffset, cmp, val);
}