/**
  * Try to reserve more bytes.
  *
  * @param count The number of bytes to add. We will round this up to the page size.
  * @return The new number of usedBytes if we succeeded; -1 if we failed.
  */
 long reserve(long count) {
   count = rounder.round(count);
   while (true) {
     long cur = usedBytes.get();
     long next = cur + count;
     if (next > maxBytes) {
       return -1;
     }
     if (usedBytes.compareAndSet(cur, next)) {
       return next;
     }
   }
 }
 /**
  * Release some bytes that we're using.
  *
  * @param count The number of bytes to release. We will round this up to the page size.
  * @return The new number of usedBytes.
  */
 long release(long count) {
   count = rounder.round(count);
   return usedBytes.addAndGet(-count);
 }