Storage

Adapters

Storage adapters are wrappers for real storage resources such as memory or the filesystem, using the well known adapter pattern.

They come with tons of methods to read, write, and modify stored items, and to get information about stored items and the storage.

All adapters implement Zend\Cache\Storage\StorageInterface, and most extend Zend\Cache\Storage\Adapter\AbstractAdapter, which provides a foundation of common logic.

Configuration is handled by either Zend\Cache\Storage\Adapter\AdapterOptions, or an adapter-specific options class if it exists. You may pass the options instance to the class at instantiation, via the setOptions() method, or, alternately, pass an associative array of options in either place (internally, these are then passed to an options class instance). Alternately, you can pass either the options instance or associative array to the Zend\Cache\StorageFactory::factory method.

Many Methods throw Exceptions

Because many caching operations throw an exception on error, you need to catch them. You can do so manually, or you can use the plugin Zend\Cache\Storage\Plugin\ExceptionHandler with throw_exceptions set to false to automatically catch them. You can also define an exception_callback to log exceptions.

Quick Start

Caching adapters can either be created from the provided Zend\Cache\StorageFactory, or by instantiating one of the Zend\Cache\Storage\Adapter\* classes. To make life easier, the Zend\Cache\StorageFactory comes with a factory() method to create an adapter and all requested plugins at once.

use Zend\Cache\StorageFactory;

// Via factory:
$cache = StorageFactory::factory([
    'adapter' => [
        'name'    => 'apc',
        'options' => ['ttl' => 3600],
    ],
    'plugins' => [
        'exception_handler' => ['throw_exceptions' => false],
    ],
]);

// Alternately, create the adapter and plugin separately:
$cache  = StorageFactory::adapterFactory('apc', ['ttl' => 3600]);
$plugin = StorageFactory::pluginFactory('exception_handler', [
    'throw_exceptions' => false,
]);
$cache->addPlugin($plugin);

// Or do it completely manually:
$cache  = new Zend\Cache\Storage\Adapter\Apc();
$cache->getOptions()->setTtl(3600);

$plugin = new Zend\Cache\Storage\Plugin\ExceptionHandler();
$plugin->getOptions()->setThrowExceptions(false);
$cache->addPlugin($plugin);

Basic Configuration Options

The following configuration options are defined by Zend\Cache\Storage\Adapter\AdapterOptions and are available for every supported adapter. Adapter-specific configuration options are described on adapter level below.

The StorageInterface

Zend\Cache\Storage\StorageInterface is the basic interface implemented by all storage adapters.

namespace Zend\Cache\Storage;

use Traversable;

interface StorageInterface
{
    /**
     * Set options.
     *
     * @param array|Traversable|Adapter\AdapterOptions $options
     * @return StorageInterface Fluent interface
     */
    public function setOptions($options);

    /**
     * Get options
     *
     * @return Adapter\AdapterOptions
     */
    public function getOptions();

    /* reading */

    /**
     * Get an item.
     *
     * @param  string  $key
     * @param  bool $success
     * @param  mixed   $casToken
     * @return mixed Data on success, null on failure
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function getItem($key, & $success = null, & $casToken = null);

    /**
     * Get multiple items.
     *
     * @param  array $keys
     * @return array Associative array of keys and values
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function getItems(array $keys);

    /**
     * Test if an item exists.
     *
     * @param  string $key
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function hasItem($key);

    /**
     * Test multiple items.
     *
     * @param  array $keys
     * @return array Array of found keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function hasItems(array $keys);

    /**
     * Get metadata of an item.
     *
     * @param  string $key
     * @return array|bool Metadata on success, false on failure
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function getMetadata($key);

    /**
     * Get multiple metadata
     *
     * @param  array $keys
     * @return array Associative array of keys and metadata
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function getMetadatas(array $keys);

    /* writing */

    /**
     * Store an item.
     *
     * @param  string $key
     * @param  mixed  $value
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function setItem($key, $value);

    /**
     * Store multiple items.
     *
     * @param  array $keyValuePairs
     * @return array Array of not stored keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function setItems(array $keyValuePairs);

    /**
     * Add an item.
     *
     * @param  string $key
     * @param  mixed  $value
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function addItem($key, $value);

    /**
     * Add multiple items.
     *
     * @param  array $keyValuePairs
     * @return array Array of not stored keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function addItems(array $keyValuePairs);

    /**
     * Replace an existing item.
     *
     * @param  string $key
     * @param  mixed  $value
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function replaceItem($key, $value);

    /**
     * Replace multiple existing items.
     *
     * @param  array $keyValuePairs
     * @return array Array of not stored keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function replaceItems(array $keyValuePairs);

    /**
     * Set an item only if token matches
     *
     * It uses the token received from getItem() to check if the item has
     * changed before overwriting it.
     *
     * @param  mixed  $token
     * @param  string $key
     * @param  mixed  $value
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     * @see    getItem()
     * @see    setItem()
     */
    public function checkAndSetItem($token, $key, $value);

    /**
     * Reset lifetime of an item
     *
     * @param  string $key
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function touchItem($key);

    /**
     * Reset lifetime of multiple items.
     *
     * @param  array $keys
     * @return array Array of not updated keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function touchItems(array $keys);

    /**
     * Remove an item.
     *
     * @param  string $key
     * @return bool
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function removeItem($key);

    /**
     * Remove multiple items.
     *
     * @param  array $keys
     * @return array Array of not removed keys
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function removeItems(array $keys);

    /**
     * Increment an item.
     *
     * @param  string $key
     * @param  int    $value
     * @return int|bool The new value on success, false on failure
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function incrementItem($key, $value);

    /**
     * Increment multiple items.
     *
     * @param  array $keyValuePairs
     * @return array Associative array of keys and new values
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function incrementItems(array $keyValuePairs);

    /**
     * Decrement an item.
     *
     * @param  string $key
     * @param  int    $value
     * @return int|bool The new value on success, false on failure
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function decrementItem($key, $value);

    /**
     * Decrement multiple items.
     *
     * @param  array $keyValuePairs
     * @return array Associative array of keys and new values
     * @throws \Zend\Cache\Exception\ExceptionInterface
     */
    public function decrementItems(array $keyValuePairs);

    /* status */

    /**
     * Capabilities of this storage
     *
     * @return Capabilities
     */
    public function getCapabilities();
}

The AvailableSpaceCapableInterface

Zend\Cache\Storage\AvailableSpaceCapableInterface implements a method to allow retrieving the current available space remaining in storage.

namespace Zend\Cache\Storage;

interface AvailableSpaceCapableInterface
{
    /**
     * Get available space in bytes
     *
     * @return int|float
     */
    public function getAvailableSpace();
}

The TotalSpaceCapableInterface

Zend\Cache\Storage\TotalSpaceCapableInterface implements a method to allow retrieving the total storage space.

namespace Zend\Cache\Storage;

interface TotalSpaceCapableInterface
{
    /**
     * Get total space in bytes
     *
     * @return int|float
     */
    public function getTotalSpace();
}

The ClearByNamespaceInterface

Zend\Cache\Storage\ClearByNamespaceInterface implements a method to allow clearing all cached items within a given namespace.

namespace Zend\Cache\Storage;

interface ClearByNamespaceInterface
{
    /**
     * Remove items of given namespace
     *
     * @param string $namespace
     * @return bool
     */
    public function clearByNamespace($namespace);
}

The ClearByPrefixInterface

Zend\Cache\Storage\ClearByPrefixInterface implements a method to allow clearing all cached items that have a given prefix (within the currently configured namespace).

namespace Zend\Cache\Storage;

interface ClearByPrefixInterface
{
    /**
     * Remove items matching given prefix
     *
     * @param string $prefix
     * @return bool
     */
    public function clearByPrefix($prefix);
}

The ClearExpiredInterface

Zend\Cache\Storage\ClearExpiredInterface implements a method to allow clearing all expired items (within the current configured namespace).

namespace Zend\Cache\Storage;

interface ClearExpiredInterface
{
    /**
     * Remove expired items
     *
     * @return bool
     */
    public function clearExpired();
}

The FlushableInterface

Zend\Cache\Storage\FlushableInterface implements a method for flushing the entire cache storage.

namespace Zend\Cache\Storage;

interface FlushableInterface
{
    /**
     * Flush the whole storage
     *
     * @return bool
     */
    public function flush();
}

The IterableInterface

Zend\Cache\Storage\IterableInterface implements a method for retrieving an iterator of all items in storage. It extends IteratorAggregate, so it's possible to directly iterate over the storage implementations that implement this interface using foreach.

namespace Zend\Cache\Storage;

use IteratorAggregate;

/**
 *
 * @method IteratorInterface getIterator() Get the storage iterator
 */
interface IterableInterface extends IteratorAggregate
{
    /**
     * @return \Traversable
     */
    public function getIterator();
}

The OptimizableInterface

Zend\Cache\Storage\OptimizableInterface implements a method for running optimization processes on the storage adapter.

namespace Zend\Cache\Storage;

interface OptimizableInterface
{
    /**
     * Optimize the storage
     *
     * @return bool
     */
    public function optimize();
}

The TaggableInterface

Zend\Cache\Storage\TaggableInterface implements methods for tagging items, and cleaning (expiring) items matching tags.

namespace Zend\Cache\Storage;

interface TaggableInterface
{
    /**
     * Set tags to an item by given key.
     * An empty array will remove all tags.
     *
     * @param string   $key
     * @param string[] $tags
     * @return bool
     */
    public function setTags($key, array $tags);

    /**
     * Get tags of an item by given key
     *
     * @param string $key
     * @return string[]|FALSE
     */
    public function getTags($key);

    /**
     * Remove items matching given tags.
     *
     * If $disjunction only one of the given tags must match
     * else all given tags must match.
     *
     * @param string[] $tags
     * @param  bool  $disjunction
     * @return bool
     */
    public function clearByTags(array $tags, $disjunction = false);
}

The Apc Adapter

Zend\Cache\Storage\Adapter\Apc stores cache items in shared memory through the PHP extension APC (Alternative PHP Cache).

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\ClearByPrefixInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\IterableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

The Dba Adapter

Zend\Cache\Storage\Adapter\Dba stores cache items into dbm-like databases using the PHP extension dba.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\ClearByPrefixInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\IterableInterface
• Zend\Cache\Storage\OptimizableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

This adapter doesn't support automatic expiry

Because this adapter doesn't support automatic expiry, it's very important to clean outdated items periodically!

The Filesystem Adapter

Zend\Cache\Storage\Adapter\Filesystem stores cache items on the filesystem.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\ClearByPrefixInterface
• Zend\Cache\Storage\ClearExpiredInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\IterableInterface
• Zend\Cache\Storage\OptimizableInterface
• Zend\Cache\Storage\TaggableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

Note: the suffix and tag_suffix options will be escaped in order to be safe for glob operations.

The Memcached Adapter

Zend\Cache\Storage\Adapter\Memcached stores cache items over the memcached protocol, using the PHP extension memcached, based on Libmemcached.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

The Redis Adapter

Zend\Cache\Storage\Adapter\Redis stores cache items over the redis protocol using the PHP extension redis.

This adapter implements the following interfaces:

• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

server can be described as any of the following:

• URI: /path/to/sock.sock
• Associative array: ['host' => <host>[, 'port' => <port>[, 'timeout' => <timeout>]]]
• List: [<host>[, <port>, [, <timeout>]]]

The Memory Adapter

The Zend\Cache\Storage\Adapter\Memory stores items in-memory in the current process only.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByPrefixInterface
• Zend\Cache\Storage\ClearExpiredInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\IterableInterface
• Zend\Cache\Storage\TaggableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

Memory Limit

The adapter has the following behavior with regards to the memory limit:

• If the consumed memory exceeds the limit provided, an OutOfSpaceException is thrown.
• A number less the or equal to zero disables the memory limit.
• When a value is provided for the memory limit, the value is measured in bytes. Shorthand notation may also be provided.

Current process only!

All stored items will be lost on termination of the script. For web-facing requests, this typically means the cache is volatile.

The MongoDB Adapter

Zend\Cache\Storage\Adapter\MongoDB stores cache items using MongoDB, via either the PHP extension mongo, or a MongoDB polyfill library, such as Mongofill.

ext-mongodb

If you are using the mongodb extension (vs the mongo extension), you will need to use the ExtMongoDb adapter instead.

This adapter implements the following interfaces:

• Zend\Cache\Storage\FlushableInterface

Capabilities

Adapter specific Options

Available keys for lib_option include:

The ExtMongoDB Adapter

Available since version 2.8.0

Zend\Cache\Storage\Adapter\ExtMongoDB stores cache items using the mongodb extension, and requires that the MongoDB PHP Client library is also installed. You can install the client library using the following:

$ composer require mongodb/mongodb

ext-mongo

If you are using the mongo extension (vs the mongodb extension), you will need to use the MongoDb adapter instead.

This adapter implements the following interfaces:

• Zend\Cache\Storage\FlushableInterface

Capabilities

Adapter specific Options

Available keys for lib_option include:

The WinCache Adapter

Zend\Cache\Storage\Adapter\WinCache stores cache items into shared memory through the PHP extension WinCache.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

The XCache Adapter

Zend\Cache\Storage\Adapter\XCache stores cache items into shared memory through the PHP extension XCache.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\ClearByPrefixInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\IterableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Adapter specific Options

The ZendServerDisk Adapter

Zend\Cache\Storage\Adapter\ZendServerDisk stores cache items on the filesystem using the Zend Server Data Caching API.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\AvailableSpaceCapableInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

The ZendServerShm Adapter

Zend\Cache\Storage\Adapter\ZendServerShm stores cache items in shared memory through the Zend Server Data Caching API.

This adapter implements the following interfaces:

• Zend\Cache\Storage\StorageInterface
• Zend\Cache\Storage\ClearByNamespaceInterface
• Zend\Cache\Storage\FlushableInterface
• Zend\Cache\Storage\TotalSpaceCapableInterface

Capabilities

Examples

Basic Usage

use Zend\Cache\StorageFactory;

$cache = StorageFactory::factory([
    'adapter' => [
        'name' => 'filesystem'
    ],
    'plugins' => [
        // Don't throw exceptions on cache errors
        'exception_handler' => [
            'throw_exceptions' => false
        ],
    ],
]);

$key    = 'unique-cache-key';
$result = $cache->getItem($key, $success);
if (! $success) {
    $result = doExpensiveStuff();
    $cache->setItem($key, $result);
}

Get multiple Rows from a Database

use Zend\Cache\StorageFactory;

// Instantiate the cache instance using a namespace for the same type of items
$cache = StorageFactory::factory([
    'adapter' => [
        'name' => 'filesystem',
        // With a namespace, we can indicate the same type of items,
        // so we can simply use the database id as the cache key
        'options' => [
            'namespace' => 'dbtable',
        ],
    ],
    'plugins' => [
        // Don't throw exceptions on cache errors
        'exception_handler' => [
            'throw_exceptions' => false,
        ],
        // We store database rows on filesystem so we need to serialize them
        'Serializer',
    ],
]);

// Load two rows from cache if possible
$ids     = [1, 2];
$results = $cache->getItems($ids);
if (count($results) < count($ids)) {
    // Load rows from db if loading from cache failed
    $missingIds     = array_diff($ids, array_keys($results));
    $missingResults = [];
    $query          = 'SELECT * FROM dbtable WHERE id IN (' . implode(',', $missingIds) . ')';
    foreach ($pdo->query($query, PDO::FETCH_ASSOC) as $row) {
        $missingResults[ $row['id'] ] = $row;
    }

    // Update cache items of the loaded rows from db
    $cache->setItems($missingResults);

    // merge results from cache and db
    $results = array_merge($results, $missingResults);
}