class ThreadSafe::Util::Striped64

def retry_update(x, hash_code, was_uncontended) # :yields: current_value

:yields: current_value
false if CAS failed before call
[+x+]
hash code used
[+hash_code+]
the value
[+x+]
Arguments:

reads.
problems of optimistic retry code, relying on rechecked sets of
explanation. This method suffers the usual non-modularity
creating new Cells, and/or contention. See above for
Handles cases of updates involving initialization, resizing, 
def retry_update(x, hash_code, was_uncontended) # :yields: current_value
  hash     = hash_code
  collided = false # True if last slot nonempty
  while true
    if current_cells = cells
      if !(cell = current_cells.volatile_get_by_hash(hash))
        if busy?
          collided = false
        else # Try to attach new Cell
          if try_to_install_new_cell(Cell.new(x), hash) # Optimistically create and try to insert new cell
            break
          else
            redo # Slot is now non-empty
          end
        end
      elsif !was_uncontended # CAS already known to fail
        was_uncontended = true # Continue after rehash
      elsif cell.cas_computed {|current_value| yield current_value}
        break
      elsif current_cells.size >= CPU_COUNT || cells != current_cells # At max size or stale
        collided = false
      elsif collided && expand_table_unless_stale(current_cells)
        collided = false
        redo # Retry with expanded table
      else
        collided = true
      end
      hash = XorShiftRandom.xorshift(hash)
    elsif try_initialize_cells(x, hash) || cas_base_computed {|current_base| yield current_base}
      break
    end
  end
  self.hash_code = hash
end