An implementation of the PSR-16 SimpleCache Interface for APCu with optional AEAD encryption

1.2.1 2018-03-22 07:17 UTC

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Last update: 2024-06-15 00:58:32 UTC



This is an implementation of PSR-16 for the APCu caching engine.

Two different classes are provided. The first just provides a PSR-16 compliant interface to APCu and the second provides encryption of the cached data via the libsodium extension.

Please refer to the files,, and for more information specific to SimpleCacheAPCu.

For instructions specific to the encryption option, see the file

Please refer to the file for the terms of the MIT License this software is released under.

About APCu Caching

APCu caches key => value pairs in the web server memory. The key must be a string but the value can be any type that can be serialized.

Effective use of APCu can greatly improve the performance of your web applications, reducing how often your web application needs to make database or filesystem queries or process data from those queries.

The information can usually be retrieved straight from system memory already in the form your web application needs it to be in, radically reducing server response times to client queries.

APCu cache only lives in the web server memory. If you restart the web server daemon, everything stored is gone. If the web server needs the memory for its own uses, it will dump some or all of the key => value pairs.

If you wish to have a more persistent cache than APCu provides, you should use SimpleCacheRedis instead.

When web applications need information that can be cached, a unique key for that information that should be used. The web application then attempts to fetch the needed information from the cache.

If it is there, the web application can then immediately use it resulting in fast response times. When the information is not there (what is called a ‘miss’) the web application then fetches the information by another means (e.g. database query with processing of the data) and then store it in the cache so it is highly likely to be there the next time it is queried from the cache.

If you need a networked cache, APCu is not the best choice for you, see the Redis link given earlier. However for local caching on the public facing server, it is incredibly lightweight and fast.

About PHP-FIG and PSR-16

PHP-FIG is the PHP Framework Interop Group. They exist largely to create standards that make it easier for different developers around the world to create different projects that will work well with each other. PHP-FIG was a driving force behind the PSR-0 and PSR-4 auto-load standards for example that make it much much easier to integrate PHP class libraries written by other people into your web applications.

The PHP-FIG previously released PSR-6 as a Caching Interface standard but the interface requirements of PSR-6 are beyond the needs of many web application developers. KISS - ‘Keep It Simple Silly’ applies for many of us who do not need some of the features PSR-6 requires.

To meet the needs of those of us who do not need what PSR-6 implements, PSR-16 was developed and is now an accepted standard.

When I read PSR-16, the defined interface it was not that different from my own APCu caching class that I have personally been using for years. So I decided to make my class meet the interface requirements, and this is the result.

Coding Standard

The coding standard used is primarily PSR-2 except with the closing ?> allowed, and the addition of some PHPDoc requirements largely but not completely borrowed from the PEAR standard.

The intent is switch PHPDoc standard to PSR-5 if it ever becomes an accepted standard.

The phpcs sniff rules being used: psr2.phpcs.xml

About AWonderPHP

I may become homeless before the end of 2018. I do not know how to survive, I try but what I try, it always seems to fail. This just is not a society people like me are meant to be a part of.

If I do become homeless, I fear my mental health will deteriorate at an accelerated rate and I do not want to witness that happening to myself.

AWonderPHP is my attempt to clean up and package a lot of the PHP classes I personally use so that something of me will be left behind.

If you wish to help, please see the file.

Thank you for your time.