OpCache Adapter (PSR-16 )

A PSR-16 Simple Cache Implementation., _(*1)

, _(*2)

Out-of-the-Box Bytecode Cache

PHP is an interpreted language. The default PHP runtime compiles PHP sourcecode to an intermediate representation called PHP bytecode which is then executed. A bytecode cache stores this compiled representation of PHP sourcecode in shared memory. This eliminates the need to load and compile sourcecode on each request which leads to a significant increase in performance (up to 70% more requests per second)., _(*3)

The basic idea, when executing a PHP script is in two steps:, _(*4)

First: the PHP code, written in plain-text, is compiled to opcodes
Then: those opcodes are executed.

When you have one PHP script, as long as it is not modified, the opcodes will always be the same ; so, doing the compilation phase each time that script is to be executed is kind of a waste of CPU-time., _(*5)

To prevent that redundant-compilation, there are some opcode caching mechanism that you can use., _(*6)

Once the PHP script has been compiled to opcodes, those will be kept in RAM -- and directly used from memory the next time the script is to be executed ; preventing the compilation from being done again and again., _(*7)

Read more, _(*8)

Requirements

PHP 7.2+ or 8.0+

Installation

composer require odan/cache

Usage

$cachePath = sys_get_temp_dir() . '/cache';

$cache = new \Odan\Cache\Simple\OpCache($cachePath);

// set a opcache value
$cache->set('foo', 'bar');

// get a opcache value
echo $cache->get('foo'); // bar

Known issues

Fatal error: Call to undefined method stdClass::__set_state(), _(*9)

If there are objects in the value, they will be written as stdClass::__set_state(). This is fine for objects where __set_state() can be added, but it can't be added to stdClass., _(*10)

To fix this issue just serialize the value you are trying to cache:, _(*11)

$cache->set('key', serialize($object));

Then unserialize the string back to the original value:, _(*12)

$object = unserialize($cache->get('key'));

Race conditions

If you're in a high-concurrency environment you should avoid using a filesystem cache. Multiple operations on the file system are very hard to make atomic in PHP., _(*13)