PSR-16 Simple Cache

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Caching, a common performance-boosting technique, is a staple feature in many frameworks and libraries. This interoperability allows libraries to utilize existing caching implementations rather than creating their own. PSR-6 has addressed this issue, but its formal and verbose nature complicates simple use cases. PSR-16 is a simpler approach seeks to create a streamlined standard interface for common situations, ensuring compatibility with PSR-6 in a straightforward manner.

Showcase

Simple Cache is utilized in Cache Master, a WordPress Cache Plugin, and it performs excellently. Check it out if you're running WordPress sites; it won't let you down.

Built-in drivers:

The required parameters are marked by an asterisk (*)

Driver name	($driver)	PHP modules	($config)
File	file	-	*storage
Redis	redis	redis	host, port, user, pass, unix_socket
MongoDB	mongo	mongodb	host, port, user, pass, dbname, collection, unix_socket
MySQL	mysql	pdo_mysql	host, port, *user, *pass, *dbname, table, charset
SQLite	sqlite	pdo_sqlite	*storage
APC	apc	apc	-
APCu	apcu	apcu	-
Memcache	memcache	memcache	host, port, unix_socket
LibMemcached	memcached	memcached	host, port, unix_socket
WinCache	wincache	wincache	-

Note:

• WinCache is excluded from unit testing since it's only used on Windows, and the testing processes are done on Linux environment.
• unix_socket is empty by default, accepting the absolute path of the unix domain socket file. If it is set, host and port will be ignored.

The following command displays a list of installed PHP modules.

php -m

Before using, make sure the required PHP modules are installed on your system.

---

Table of Contents

• Install
• Usage
  • Cache
    • Built-in drivers
    • __construct
    • $driver
    • $config
• API
  • set
  • get
  • has
  • delete
  • getMultiple
  • setMultiple
  • deleteMultiple
  • clear
  • clearExpiredItems (Non-PSR-16)
• Build Data Schema
  • MySQL
  • SQLite
• Garbage Collection
• Author
• License

---

Install

composer require shieldon/simple-cache

Usage

Cache

Class Cache is an adapter that not only allows the implemented instance of Psr\SimpleCache\CacheInterface, but also has built-in drivers already.

__construct($driver = '', $config = [])

Create a cache handler using the file driver.

Example:

$driver = new \Shieldon\SimpleCache\Cache('file', [
    'storage' => __DIR__ . '/../tmp'
]);

$driver

(string|CacheInterface)

The class name of a built-in driver, or a PSR-16 driver that implements Psr\SimpleCache\CacheInterface.

$config

(array)

An array of parameters will be passed to a built-in driver.

Example:

Redis

$config = [
    'host' => '127.0.0.1',
    'port' => 6379,
    'user' => null,
    'pass' => null,
];

File

$config = [
    'storage' => '/tmp/simple-cache',
];

Mysql

$config = [
    'host'    => '127.0.0.1',
    'port'    => 3306,
    'user'    => null,
    'pass'    => null,
    'dbname'  => null,
    'table'   => 'cache_data',
    'charset' => 'utf8'
];

Sqlite

$config = [
    'storage' => '/tmp/simple-cache',
];

Mongo

$config = [
    'host'       => '127.0.0.1',
    'port'       => 27017,
    'user'       => null,
    'pass'       => null,
    'database'   => 'test',
    'collection' => 'cache_data',
];

Memcache, Memcached

$config = [
    'host' => '127.0.0.1',
    'port' => 11211,
];

---

API

Those API methods are defined on Psr\SimpleCache\CacheInterface. Please check out the PSR-16 document to get the detailed explanation.

• set
• get
• has
• delete
• setMultiple
• getMultiple
• deleteMultiple
• clear
• clearExpiredItems (Non-PSR-16)

set

public function set(string $key, mixed value, $ttl = null);

Note that $ttl accepts null,int,DateInterval. The null means that the key never expires until deleted.

Example:

$cache->set('foo', 'bar', 300);
$cache->set('foo2', 'bar2');

$array = [
    'hello' => 'world',
    'yes' => 'Taiwan',
];

$cache->set('foo3', $array);
$cache->set('foo4', $array, 300);

get

public function get(string $key, mixed $default = null): mixed

Example:

echo $cache->get('foo', 'placeholder');
// bar

sleep(301);

echo $cache->get('foo', 'placeholder');
// placeholder

echo $cache->get('foo');
// null

echo $cache->get('foo2', 'placeholder');
// bar2

$example = $cache->get('foo3', 'placeholder');
var_dump($example);
// string(11) "placeholder"

$example = $cache->get('foo4', 'placeholder');
var_dump($example);
/* 
    array(2) {
    ["hello"]=>
    string(5) "world"
    ["yes"]=>
    string(6) "Taiwan"
    }
*/

has

public function has(string $key): bool

Example:

if ($cache->has('foo3')) {
    echo 'foo3 exists.';
} else {
    echo 'foo3 does not exist.';
}
// foo3 exists.

delete

public function delete(string $key): bool

Example:

if ($cache->delete('foo3')) {
    echo 'foo3 has been deleted successfully.';
} else {
    echo 'Failed to delete key foo3.';
}
// foo3 has been deleted successfully.

if ($cache->has('foo3')) {
    echo 'foo3 exists.';
} else {
    echo 'foo3 does not exist.';
}
// foo3 does not exist.

setMultiple

public function setMultiple(iterable $values, $ttl = null): bool

Note that $ttl accepts null,int,DateInterval. The null means that the key never expires until deleted.

Example:

$array = [
    'bar' => 'foo',
    'bar2' => 'foo2',
];

$cache->setMultiple($array, 300);

getMultiple

public function getMultiple(array $keys, mixed $default = null): iterable

Example:

$example = $cache->getMultiple(['bar', 'bar2', 'bar3'], 'hello');
var_dump($example);
/* 
    array(3) {
    ["bar"]=>
    string(3) "foo"
    ["bar2"]=>
    string(4) "foo2"
    ["bar3"]=>
    string(5) "hello"
    }
*/

deleteMultiple

public function deleteMultiple(array $keys): bool

Example:

if ($cache->deleteMultiple(['bar', 'bar2'])) {
    echo 'bar and bar2 have been deleted successfully.';
} else {
    echo 'Failed to delete keys bar or bar2.';
}
// bar and bar2 have been deleted successfully.

$example = $cache->getMultiple(['bar', 'bar2', 'bar3'], 'hello');
var_dump($example);
/* 
    array(3) {
    ["bar"]=>
    string(5) "hello"
    ["bar2"]=>
    string(5) "hello"
    ["bar3"]=>
    string(5) "hello"
    }
*/

clear

public function clear(): bool

Example:

if ($cache->clear()) {
    echo 'All cached data has been deleted successfully.';
} else {
    echo 'Failed to delete the cached data.';
}
// All cached data has been deleted successfully.

clearExpiredItems Non-PSR-16

public function clearExpiredItems(): array

This method returns a list of deleted cache keys.

Note: Redis and Memcache, Memcached drivers will always return an empty array. See Garbage Collection section below.

Example:

$cache->set('foo', 'bar', 300);
$cache->set('foo2', 'bar2', 5);
$cache->set('foo3', 'bar3', 5);

sleep(6);

$expiredItems = $cache->clearExpiredItems();
var_dump($expiredItems);

/* 
    array(2) {
    [0]=>
    string(4) "foo2"
    [1]=>
    string(4) "foo3"
    }
*/

---

Build Data Schema

The data schema needs to be built for the initial use of MySQL and SQLite drivers.

This API can be utilized for this purpose.

$cache->rebuild();

Or build it manually.

MySQL

CREATE TABLE IF NOT EXISTS `cache_data` (
    `cache_key` varchar(40) NOT NULL,
    `cache_value` longtext,
    PRIMARY KEY (`cache_key`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

SQLite

CREATE TABLE IF NOT EXISTS cache_data (
    cache_key VARCHAR(40) PRIMARY KEY,
    cache_value LONGTEXT
);

---

Garbage Collection

For built-in drivers, enabling garbage collection will automatically clear expired cache from your system.

Use the following parameters:

$config = [
    'gc_enable'      => true,
    'gc_divisor'     => 100, // default
    'gc_probability' => 1, // default
];

This implies a 1% probability of executing garbage collection. Avoid setting it to 100% as it will unnecessarily fetch and check all keys one by one.

Example:

$driver = new \Shieldon\SimpleCache\Cache('file', [
    'storage'   => __DIR__ . '/../tmp',
    'gc_enable' => true,
]);

You can just use the gc_enable to enable garbage collection.

Note

For the Redis, Memcache, and Memcached drivers, this method isn't necessary as expired items are automatically cleared.

---

Contributing

Thank you for your interest in contributing to our project! We welcome contributions from everyone. Before getting started, please take a moment to review the guidelines below:

Guidelines

• Fork the repository and create your branch from master.
• Make sure your code follows our coding style and conventions.
• Keep your code concise, well-documented, and modular.
• Write clear commit messages that describe the purpose of your changes.
• Test your changes thoroughly to ensure they don't introduce any new issues.
• Make sure your code builds successfully without any errors or warnings.
• Update relevant documentation, including README files if necessary.
• Submit a pull request (PR) to the master branch of the original repository.

Code Testing

We utilize a Docker image that includes various dependencies for our code testing. The image is based on /tests/Fixture/docker/Dockerfile and is preconfigured with the following components:

• Redis
• MongoDB
• MySQL
• PHP
• Memcached
• APCu

Follow the steps below to run the tests:

• Make sure you have Docker installed on your machine. If not, you can download and install it from the official Docker website.
• Navigate to the project directory and build the Docker image by running the following command:

  composer test:docker:build
  

• Once the Docker image is built, you can run the tests by executing the following command:

  composer test:docker:run
  

• Observe the test results and make note of any failures or errors. The output will be displayed in the terminal.

---

Author

• Terry L. and contributers, such as Jimmy and others.

The Origin of this Library

This PHP library was created for the 12th Ironman Game competition, hosted by ITHelp, a Taiwanese IT community. My chosen topic was "Road to PHP Master - The Best Practice in Open Source Code", composed in traditional Chinese. You can read it here if you're interested.

License

MIT