Cache Design

Cache Data Copying

Shallow Copying

Deep Copying

Copying Source Or Destination

	Pointer Mem Cache	Offset Mem Cache	Disk Cache	PHP Scripting Engine
use pointer	yes	no	no	yes
use offset	no	yes	yes	no
block or object	block	block	block	object

As we copy data between php and cache, either src (source) or dest (destination) can be block or object.

object storage

allocate for each elements that to be stored

block storage

calc the total size of elements of data, allocate whole block 1 in go. but each elements is stored as if it allocate storage from the block.