Caching Driver

CodeIgniter features wrappers around some of the most popular forms of fast and dynamic caching. All but file-based caching require specific server requirements, and a Fatal Exception will be thrown if server requirements are not met.

Example Usage
- Configuring the Cache
Class Reference
Drivers

Example Usage 

The following example shows a common usage pattern within your controllers.

<?php

if (! $foo = cache('foo')) {
    echo 'Saving to the cache!<br />';
    $foo = 'foobarbaz!';

    // Save into the cache for 5 minutes
    cache()->save('foo', $foo, 300);
}

echo $foo;

You can grab an instance of the cache engine directly through the Services class:

<?php

$cache = \Config\Services::cache();

$foo = $cache->get('foo');

Configuring the Cache 

All configuration for the cache engine is done in app/Config/Cache.php. In that file, the following items are available.

$handler

The is the name of the handler that should be used as the primary handler when starting up the engine. Available names are: dummy, file, memcached, redis, predis, wincache.

$backupHandler

In the case that the first choice $handler is not available, this is the next cache handler to load. This is commonly the file handler since the file system is always available, but may not fit more complex, multi-server setups.

$prefix

If you have more than one application using the same cache storage, you can add a custom prefix string here that is prepended to all key names.

$ttl

The default number of seconds to save items when none is specified. WARNING: This is not used by framework handlers where 60 seconds is hard-coded, but may be useful to projects and modules. This will replace the hard-coded value in a future release.

$file

This is an array of settings specific to the File handler to determine how it should save the cache files.

$memcached

This is an array of servers that will be used when using the Memcache(d) handler.

$redis

The settings for the Redis server that you wish to use when using the Redis and Predis handler.

Class Reference 

isSupported()

Returns: true if supported, false if not
Return type: bool

get($key): mixed

Parameters

$key (string) – Cache item name

Returns

Item value or null if not found

Return type

mixed

This method will attempt to fetch an item from the cache store. If the item does not exist, the method will return null.

Example:

<?php

$foo = $cache->get('my_cached_item');

remember(string $key, int $ttl, Closure $callback)

Parameters

$key (string) – Cache item name
$ttl (int) – Time to live in seconds
$callback (Closure) – Callback to invoke when the cache item returns null

Returns

The value of the cache item

Return type

mixed

Gets an item from the cache. If null was returned, this will invoke the callback and save the result. Either way, this will return the value.

save(string $key, $data[, int $ttl = 60[, $raw = false]])

Parameters

$key (string) – Cache item name
$data (mixed) – the data to save
$ttl (int) – Time To Live, in seconds (default 60)
$raw (bool) – Whether to store the raw value

Returns

true on success, false on failure

Return type

bool

This method will save an item to the cache store. If saving fails, the method will return false.

Example:

<?php

$cache->save('cache_item_id', 'data_to_cache');

Note

The $raw parameter is only utilized by Memcache, in order to allow usage of increment() and decrement().

delete($key): bool

Parameters

$key (string) – name of cached item

Returns

true on success, false on failure

Return type

bool

This method will delete a specific item from the cache store. If item deletion fails, the method will return false.

Example:

<?php

$cache->delete('cache_item_id');

deleteMatching($pattern): integer

Parameters

$pattern (string) – glob-style pattern to match cached items keys

Returns

number of deleted items

Return type

integer

This method will delete multiple items from the cache store at once by matching their keys against a glob-style pattern. It will return the total number of deleted items.

Important

This method is only implemented for File, Redis and Predis handlers. Due to limitations, it couldn’t be implemented for Memcached and Wincache handlers.

Example:

<?php

$cache->deleteMatching('prefix_*'); // deletes all items of which keys start with "prefix_"
$cache->deleteMatching('*_suffix'); // deletes all items of which keys end with "_suffix"

For more information on glob-style syntax, please see Glob (programming).

increment($key[, $offset = 1]): mixed

Parameters

$key (string) – Cache ID
$offset (int) – Step/value to add

Returns

New value on success, false on failure

Return type

mixed

Performs atomic incrementation of a raw stored value.

Example:

<?php

// 'iterator' has a value of 2
$cache->increment('iterator'); // 'iterator' is now 3
$cache->increment('iterator', 3); // 'iterator' is now 6

decrement($key[, $offset = 1]): mixed

Parameters

$key (string) – Cache ID
$offset (int) – Step/value to reduce by

Returns

New value on success, false on failure

Return type

mixed

Performs atomic decrementation of a raw stored value.

Example:

<?php

// 'iterator' has a value of 6
$cache->decrement('iterator'); // 'iterator' is now 5
$cache->decrement('iterator', 2); // 'iterator' is now 3

clean()

Returns: true on success, false on failure
Return type: bool

This method will ‘clean’ the entire cache. If the deletion of the cache files fails, the method will return false.

Example:

<?php

$cache->clean();

getCacheInfo()

Returns: Information on the entire cache database
Return type: mixed

This method will return information on the entire cache.

Example:

<?php

var_dump($cache->getCacheInfo());

Note

The information returned and the structure of the data is dependent on which adapter is being used.

getMetadata(string $key)

Parameters

$key (string) – Cache item name

Returns

Metadata for the cached item. null for missing items, or an array with at least the “expire” key for absolute epoch expiry (null for never expires).

Return type

array|null

This method will return detailed information on a specific item in the cache.

Example:

<?php

var_dump($cache->getMetadata('my_cached_item'));

Note

The information returned and the structure of the data is dependent on which adapter is being used. Some adapters (File, Memcached, Wincache) still return false for missing items.

static validateKey(string $key, string $prefix)

Parameters

$key (string) – Potential cache key
$prefix (string) – Optional prefix

Returns

The verified and prefixed key. If the key exceeds the driver’s max key length it will be hashed.

Return type

string

This method is used by handler methods to check that keys are valid. It will throw an InvalidArgumentException for non-strings, invalid characters, and empty lengths.

Example:

<?php

$prefixedKey = BaseHandler::validateKey($key, $prefix);

Drivers 

File-based Caching 

Unlike caching from the Output Class, the driver file-based caching allows for pieces of view files to be cached. Use this with care, and make sure to benchmark your application, as a point can come where disk I/O will negate positive gains by caching. This requires a cache directory to be really writable by the application.

Memcached Caching 

Memcached servers can be specified in the cache configuration file. Available options are:

<?php

namespace Config;

use CodeIgniter\Config\BaseConfig;

class Cache extends BaseConfig
{
    // ...

    public $memcached = [
        'host'   => '127.0.0.1',
        'port'   => 11211,
        'weight' => 1,
        'raw'    => false,
    ];

    // ...
}

For more information on Memcached, please see https://www.php.net/memcached.

WinCache Caching 

Under Windows, you can also utilize the WinCache driver.

For more information on WinCache, please see https://www.php.net/wincache.

Redis Caching 

Redis is an in-memory key-value store which can operate in LRU cache mode. To use it, you need Redis server and phpredis PHP extension.

Config options to connect to redis server stored in the cache configuration file. Available options are:

<?php

namespace Config;

use CodeIgniter\Config\BaseConfig;

class Cache extends BaseConfig
{
    // ...

    public $redis = [
        'host'     => '127.0.0.1',
        'password' => null,
        'port'     => 6379,
        'timeout'  => 0,
        'database' => 0,
    ];

    // ...
}

For more information on Redis, please see https://redis.io.

Predis Caching 

Predis is a flexible and feature-complete PHP client library for the Redis key-value store. To use it, from the command line inside your project root:

> composer require predis/predis

For more information on Redis, please see https://github.com/nrk/predis.

Dummy Cache 

This is a caching backend that will always ‘miss.’ It stores no data, but lets you keep your caching code in place in environments that don’t support your chosen cache.