(PECL event >= 1.2.6-beta)
EventBuffer::expand — Reserves space in buffer
$len
   
   )
   Alters the last chunk of memory in the buffer, or adds a new chunk, such
   that the buffer is now large enough to contain
   len
   bytes without any further allocations.
  
len
    The number of bytes to reserve for the buffer
   Returns TRUE on success. Otherwise FALSE.