# Class yii\caching\MemCache

Inheritance | yii\caching\MemCache » yii\caching\Cache » yii\base\Component » yii\base\BaseObject
Implements | yii\base\Configurable, yii\caching\CacheInterface
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/caching/MemCache.php

MemCache implements a cache application component based on memcache and memcached.

MemCache supports both memcache and memcached. By setting $useMemcached to be true or false, one can let MemCache to use either memcached or memcache, respectively.

MemCache can be configured with a list of memcache servers by settings its $servers property. By default, MemCache assumes there is a memcache server running on localhost at port 11211.

See yii\caching\Cache for common cache operations that MemCache supports.

Note, there is no security measure to protected data in memcache. All data in memcache can be accessed by any process running in the system.

To use MemCache as the cache application component, configure the application as follows,

    [
        'components' => [
            'cache' => [
                'class' => 'yii\caching\MemCache',
                'servers' => [
                    [
                        'host' => 'server1',
                        'port' => 11211,
                        'weight' => 60,
                    ],
                    [
                        'host' => 'server2',
                        'port' => 11211,
                        'weight' => 40,
                    ],
                ],
            ],
        ],
    ]

In the above, two memcache servers are used: server1 and server2. You can configure more properties of each server, such as `persistent`, `weight`, `timeout`. Please see yii\caching\MemCacheServer for available options.

For more details and usage information on Cache, see the guide article on caching.

## Public Properties

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Property | Type | Description | Defined By
--- | --- | --- | ---
$behaviors | yii\base\Behavior[] | List of behaviors attached to this component. This property is read-only. | yii\base\Component
$defaultDuration | integer | Default duration in seconds before a cache entry will expire. | yii\caching\Cache
$keyPrefix | string | A string prefixed to every cache key so that it is unique globally in the whole cache storage. | yii\caching\Cache
$memcache | \Memcache|\Memcached | The memcache (or memcached) object used by this cache component. This property is read-only. | yii\caching\MemCache
$options | array | Options for Memcached. | yii\caching\MemCache
$password | string | Memcached sasl password. | yii\caching\MemCache
$persistentId | string | An ID that identifies a Memcached instance. | yii\caching\MemCache
$serializer | null|array|false | The functions used to serialize and unserialize cached data. | yii\caching\Cache
$servers | yii\caching\MemCacheServer[] | List of memcache server configurations. Note that the type of this property differs in getter and setter. See getServers() and setServers() for details. | yii\caching\MemCache
$useMemcached | boolean | Whether to use memcached or memcache as the underlying caching extension. | yii\caching\MemCache
$username | string | Memcached sasl username. | yii\caching\MemCache

## Public Methods

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Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\Component
__clone() | This method is called after the object is created by cloning an existing one. | yii\base\Component
__construct() | Constructor. | yii\base\BaseObject
__get() | Returns the value of a component property. | yii\base\Component
__isset() | Checks if a property is set, i.e. defined and not null. | yii\base\Component
__set() | Sets the value of a component property. | yii\base\Component
__unset() | Sets a component property to be null. | yii\base\Component
add() | Stores a value identified by a key into cache if the cache does not contain this key. | yii\caching\Cache
attachBehavior() | Attaches a behavior to this component. | yii\base\Component
attachBehaviors() | Attaches a list of behaviors to the component. | yii\base\Component
behaviors() | Returns a list of behaviors that this component should behave as. | yii\base\Component
buildKey() | Builds a normalized cache key from a given key. | yii\caching\Cache
canGetProperty() | Returns a value indicating whether a property can be read. | yii\base\Component
canSetProperty() | Returns a value indicating whether a property can be set. | yii\base\Component
className() | Returns the fully qualified name of this class. | yii\base\BaseObject
delete() | Deletes a value with the specified key from cache. | yii\caching\Cache
detachBehavior() | Detaches a behavior from the component. | yii\base\Component
detachBehaviors() | Detaches all behaviors from the component. | yii\base\Component
ensureBehaviors() | Makes sure that the behaviors declared in behaviors() are attached to this component. | yii\base\Component
exists() | Checks whether a specified key exists in the cache. | yii\caching\Cache
flush() | Deletes all values from cache. | yii\caching\Cache
get() | Retrieves a value from cache with a specified key. | yii\caching\Cache
getBehavior() | Returns the named behavior object. | yii\base\Component
getBehaviors() | Returns all behaviors attached to this component. | yii\base\Component
getMemcache() | Returns the underlying memcache (or memcached) object. | yii\caching\MemCache
getOrSet() | Method combines both set() and get() methods to retrieve value identified by a $key, or to store the result of $callable execution if there is no cache available for the $key. | yii\caching\Cache
getServers() | Returns the memcache or memcached server configurations. | yii\caching\MemCache
hasEventHandlers() | Returns a value indicating whether there is any handler attached to the named event. | yii\base\Component
hasMethod() | Returns a value indicating whether a method is defined. | yii\base\Component
hasProperty() | Returns a value indicating whether a property is defined for this component. | yii\base\Component
init() | Initializes this application component. | yii\caching\MemCache
madd() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
mget() | Retrieves multiple values from cache with the specified keys. | yii\caching\Cache
mset() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
multiAdd() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
multiGet() | Retrieves multiple values from cache with the specified keys. | yii\caching\Cache
multiSet() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
off() | Detaches an existing event handler from this component. | yii\base\Component
offsetExists() | Returns whether there is a cache entry with a specified key. | yii\caching\Cache
offsetGet() | Retrieves the value from cache with a specified key. | yii\caching\Cache
offsetSet() | Stores the value identified by a key into cache. | yii\caching\Cache
offsetUnset() | Deletes the value with the specified key from cache This method is required by the interface ArrayAccess. | yii\caching\Cache
on() | Attaches an event handler to an event. | yii\base\Component
set() | Stores a value identified by a key into cache. | yii\caching\Cache
setServers() |  | yii\caching\MemCache
trigger() | Triggers an event. | yii\base\Component

## Protected Methods

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Method | Description | Defined By
--- | --- | ---
addMemcacheServers() | Add servers to the server pool of the cache specified Used for memcache PECL extension. | yii\caching\MemCache
addMemcachedServers() | Add servers to the server pool of the cache specified Used for memcached PECL extension. | yii\caching\MemCache
addServers() | Add servers to the server pool of the cache specified. | yii\caching\MemCache
addValue() | Stores a value identified by a key into cache if the cache does not contain this key. | yii\caching\MemCache
addValues() | Adds multiple key-value pairs to cache. | yii\caching\Cache
deleteValue() | Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class. | yii\caching\MemCache
flushValues() | Deletes all values from cache. | yii\caching\MemCache
getValue() | Retrieves a value from cache with a specified key. | yii\caching\MemCache
getValues() | Retrieves multiple values from cache with the specified keys. | yii\caching\MemCache
normalizeDuration() | Normalizes duration value | yii\caching\MemCache
setValue() | Stores a value identified by a key in cache. | yii\caching\MemCache
setValues() | Stores multiple key-value pairs in cache. | yii\caching\MemCache

## Property Details

$memcache public property

The memcache (or memcached) object used by this cache component. This property is read-only.

public \Memcache|\Memcached $memcache = null
$options public property

Options for Memcached. This property is used only when $useMemcached is true.

See also https://secure.php.net/manual/en/memcached.setoptions.php.

public array $options = null
$password public property

Memcached sasl password. This property is used only when $useMemcached is true.

See also https://secure.php.net/manual/en/memcached.setsaslauthdata.php.

public string $password = null
$persistentId public property

An ID that identifies a Memcached instance. This property is used only when $useMemcached is true. By default the Memcached instances are destroyed at the end of the request. To create an instance that persists between requests, you may specify a unique ID for the instance. All instances created with the same ID will share the same connection.

See also https://secure.php.net/manual/en/memcached.construct.php.

public string $persistentId = null
$servers public property

List of memcache server configurations. Note that the type of this property differs in getter and setter. See getServers() and setServers() for details.

public yii\caching\MemCacheServer[] $servers = null
$useMemcached public property

Whether to use memcached or memcache as the underlying caching extension. If true, memcached will be used. If false, memcache will be used. Defaults to false.

public boolean $useMemcached = false
$username public property

Memcached sasl username. This property is used only when $useMemcached is true.

See also https://secure.php.net/manual/en/memcached.setsaslauthdata.php.

public string $username = null

## Method Details

addMemcacheServers() protected method

Add servers to the server pool of the cache specified Used for memcache PECL extension.

protected void addMemcacheServers ( $cache, $servers )
$cache | \Memcache |
$servers | yii\caching\MemCacheServer[] |

addMemcachedServers() protected method

Add servers to the server pool of the cache specified Used for memcached PECL extension.

protected void addMemcachedServers ( $cache, $servers )
$cache | \Memcached |
$servers | yii\caching\MemCacheServer[] |

addServers() protected method

Add servers to the server pool of the cache specified.

protected void addServers ( $cache, $servers )
$cache | \Memcache|\Memcached |
$servers | yii\caching\MemCacheServer[] |
throws | yii\base\InvalidConfigException |

addValue() protected method

Stores a value identified by a key into cache if the cache does not contain this key.

This is the implementation of the method declared in the parent class.

See also Memcache::set().

protected boolean addValue ( $key, $value, $duration )
$key | string | The key identifying the value to be cached
$value | mixed | The value to be cached
$duration | integer | The number of seconds in which the cached value will expire. 0 means never expire.
return | boolean | True if the value is successfully stored into cache, false otherwise

deleteValue() protected method

Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class.

protected boolean deleteValue ( $key )
$key | string | The key of the value to be deleted
return | boolean | If no error happens during deletion

flushValues() protected method

Deletes all values from cache.

This is the implementation of the method declared in the parent class.

protected boolean flushValues ( )
return | boolean | Whether the flush operation was successful.

getMemcache() public method

Returns the underlying memcache (or memcached) object.

public \Memcache|\Memcached getMemcache ( )
return | \Memcache|\Memcached | The memcache (or memcached) object used by this cache component.
throws | yii\base\InvalidConfigException | if memcache or memcached extension is not loaded

getServers() public method

Returns the memcache or memcached server configurations.

public yii\caching\MemCacheServer[] getServers ( )
return | yii\caching\MemCacheServer[] | List of memcache server configurations.

getValue() protected method

Retrieves a value from cache with a specified key.

This is the implementation of the method declared in the parent class.

protected mixed|false getValue ( $key )
$key | string | A unique key identifying the cached value
return | mixed|false | The value stored in cache, false if the value is not in the cache or expired.

getValues() protected method

Retrieves multiple values from cache with the specified keys.

protected array getValues ( $keys )
$keys | array | A list of keys identifying the cached values
return | array | A list of cached values indexed by the keys

init() public method

Initializes this application component.

It creates the memcache instance and adds memcache servers.

public void init ( )

normalizeDuration() protected method (available since version 2.0.31)

Normalizes duration value

See also:

- https://github.com/yiisoft/yii2/issues/17710
- https://secure.php.net/manual/en/memcache.set.php
- https://secure.php.net/manual/en/memcached.expiration.php

protected integer normalizeDuration ( $duration )
$duration | integer |

setServers() public method

See also:

- https://secure.php.net/manual/en/memcache.addserver.php
- https://secure.php.net/manual/en/memcached.addserver.php

public void setServers ( $config )
$config | array | List of memcache or memcached server configurations. Each element must be an array with the following keys: host, port, persistent, weight, timeout, retryInterval, status.

setValue() protected method

Stores a value identified by a key in cache.

This is the implementation of the method declared in the parent class.

See also Memcache::set().

protected boolean setValue ( $key, $value, $duration )
$key | string | The key identifying the value to be cached
$value | mixed | The value to be cached.
$duration | integer | The number of seconds in which the cached value will expire. 0 means never expire.
return | boolean | True if the value is successfully stored into cache, false otherwise

setValues() protected method

Stores multiple key-value pairs in cache.

protected array setValues ( $data, $duration )
$data | array | Array where key corresponds to cache key while value is the value stored
$duration | integer | The number of seconds in which the cached values will expire. 0 means never expire.
return | array | Array of failed keys.