PHP APC

The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. Its goal is to provide a free, open, and robust framework for caching and optimizing PHP intermediate code.

Check for the installation using:php -r 'phpinfo();' |grep apc 
If its not installed already use(on ubuntu):
  
 sudo apt-get install php-apc
 sudo /etc/init.d/apache2 restart
 or
 apt-get install apache2-prefork-dev
 pecl install apc
 
Use dpkg -L php-apc to know where the files are installed

There are two primary decisions to be made configuring APC. First, how much memory is going to be allocated to APC; and second, whether APC will check if a file has been modified on every request. The two ini directives that control these settings are apc.shm_size and apc.stat, respectively. Read the sections on these two directive carefully below. 



APC Functions

Table of Contents

• apc_add — Cache a variable in the data store
• apc_cache_info — Retrieves cached information from APC's data store
• apc_clear_cache — Clears the APC cache
• apc_compile_file — Stores a file in the bytecode cache, bypassing all filters.
• apc_define_constants — Defines a set of constants for retrieval and mass-definition
• apc_delete — Removes a stored variable from the cache
• apc_fetch — Fetch a stored variable from the cache
• apc_load_constants — Loads a set of constants from the cache
• apc_sma_info — Retrieves APC's Shared Memory Allocation information
• apc_store — Cache a variable in the data store

Eg:

1)$bar = 'BAR';apc_store('foo', $bar);var_dump(apc_fetch('foo'));?>

 

outputs : BAR 


2)

$constants = array(
    'ONE'   => 1,
    'TWO'   => 2,
    'THREE' => 3,
);apc_define_constants('numbers', $constants);
echo ONE, TWO, THREE;?>

 

From :php.net/apc