# MemCache

> MemCache implements a cache application component based on [memcache](https://pecl.php.net/package/memcache) and [memcached](https://pecl.php.net/package/memcached).

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [caching](/docs/api/yii/caching/index.md) › MemCache

| class | `yii\caching\MemCache` |
| --- | --- |
| Extends | [`Cache`](/docs/api/yii/caching/cache/index.md) » [`yii\base\Component`](/docs/api/yii/base/component/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| Implements | [`CacheInterface`](/docs/api/yii/caching/cacheinterface/index.md), [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) |
| Since | 2.0 |
| Source | [`framework/caching/MemCache.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/caching/MemCache.php#L68) |

MemCache implements a cache application component based on [memcache](https://pecl.php.net/package/memcache)
and [memcached](https://pecl.php.net/package/memcached).

MemCache supports both [memcache](https://pecl.php.net/package/memcache) and
[memcached](https://pecl.php.net/package/memcached). By setting [`$useMemcached`](/docs/api/yii/caching/memcache/index.md#property-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`](/docs/api/yii/caching/memcache/index.md#property-servers) property.
By default, MemCache assumes there is a memcache server running on localhost at port 11211.

See [`Cache`](/docs/api/yii/caching/cache/index.md) 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 [`MemCacheServer`](/docs/api/yii/caching/memcacheserver/index.md) for available options.

For more details and usage information on Cache, see the [guide article on caching](/docs/guide/caching-overview/index.md).

## Properties

| Property | Type | Description | Defined by |
| --- | --- | --- | --- |
| <span id="property-behaviors"></span>[`$behaviors`](/docs/api/yii/base/component/index.md#property-behaviors) read-only | `array<`[`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md)`<static>>` | List of behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="property-defaultDuration"></span>[`$defaultDuration`](/docs/api/yii/caching/cache/index.md#property-defaultDuration) | `int` | Default duration in seconds before a cache entry will expire. Default: `0`. Available since 2.0.11. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="property-keyPrefix"></span>[`$keyPrefix`](/docs/api/yii/caching/cache/index.md#property-keyPrefix) | `string` | A string prefixed to every cache key so that it is unique globally in the whole cache storage. Default: `null`. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="property-memcache"></span>`$memcache` read-only | [`Memcache`](https://www.php.net/manual/en/class.memcache.php)`\|`[`Memcached`](https://www.php.net/manual/en/class.memcached.php) | The memcache (or memcached) object used by this cache component. | `MemCache` |
| [`$options`](#property-options) | `array` | Options for Memcached. Default: `null`. | `MemCache` |
| [`$password`](#property-password) | `string` | Memcached sasl password. Default: `null`. | `MemCache` |
| [`$persistentId`](#property-persistentId) | `string` | An ID that identifies a Memcached instance. Default: `null`. | `MemCache` |
| <span id="property-serializer"></span>[`$serializer`](/docs/api/yii/caching/cache/index.md#property-serializer) | `array\|null\|false` | The functions used to serialize and unserialize cached data. Default: `null`. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| [`$servers`](#property-servers) | `array` | List of memcache or memcached server configurations. | `MemCache` |
| [`$useMemcached`](#property-useMemcached) | `bool` | Whether to use memcached or memcache as the underlying caching extension. Default: `false`. | `MemCache` |
| [`$username`](#property-username) | `string` | Memcached sasl username. Default: `null`. | `MemCache` |

## Methods

| Method | Description | Defined by |
| --- | --- | --- |
| <span id="method-__construct"></span>[`__construct()`](/docs/api/yii/base/baseobject/index.md#method-__construct) | Constructor. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__call"></span>[`__call()`](/docs/api/yii/base/component/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__clone"></span>[`__clone()`](/docs/api/yii/base/component/index.md#method-__clone) | This method is called after the object is created by cloning an existing one. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__get"></span>[`__get()`](/docs/api/yii/base/component/index.md#method-__get) | Returns the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__isset"></span>[`__isset()`](/docs/api/yii/base/component/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__set"></span>[`__set()`](/docs/api/yii/base/component/index.md#method-__set) | Sets the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__unset"></span>[`__unset()`](/docs/api/yii/base/component/index.md#method-__unset) | Sets a component property to be null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-add"></span>[`add()`](/docs/api/yii/caching/cache/index.md#method-add) | Stores a value identified by a key into cache if the cache does not contain this key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-attachBehavior"></span>[`attachBehavior()`](/docs/api/yii/base/component/index.md#method-attachBehavior) | Attaches a behavior to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehaviors"></span>[`attachBehaviors()`](/docs/api/yii/base/component/index.md#method-attachBehaviors) | Attaches a list of behaviors to the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-behaviors"></span>[`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) | Returns a list of behaviors that this component should behave as. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-buildKey"></span>[`buildKey()`](/docs/api/yii/caching/cache/index.md#method-buildKey) | Builds a normalized cache key from a given key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-canGetProperty"></span>[`canGetProperty()`](/docs/api/yii/base/component/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canSetProperty"></span>[`canSetProperty()`](/docs/api/yii/base/component/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-className"></span>[`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-delete"></span>[`delete()`](/docs/api/yii/caching/cache/index.md#method-delete) | Deletes a value with the specified key from cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-detachBehavior"></span>[`detachBehavior()`](/docs/api/yii/base/component/index.md#method-detachBehavior) | Detaches a behavior from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-detachBehaviors"></span>[`detachBehaviors()`](/docs/api/yii/base/component/index.md#method-detachBehaviors) | Detaches all behaviors from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-ensureBehaviors"></span>[`ensureBehaviors()`](/docs/api/yii/base/component/index.md#method-ensureBehaviors) | Makes sure that the behaviors declared in [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) are attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-exists"></span>[`exists()`](/docs/api/yii/caching/cache/index.md#method-exists) | Checks whether a specified key exists in the cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-flush"></span>[`flush()`](/docs/api/yii/caching/cache/index.md#method-flush) | Deletes all values from cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-get"></span>[`get()`](/docs/api/yii/caching/cache/index.md#method-get) | Retrieves a value from cache with a specified key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-getBehavior"></span>[`getBehavior()`](/docs/api/yii/base/component/index.md#method-getBehavior) | Returns the named behavior object. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehaviors"></span>[`getBehaviors()`](/docs/api/yii/base/component/index.md#method-getBehaviors) | Returns all behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`getMemcache()`](#method-getMemcache) | Returns the underlying memcache (or memcached) object. | `MemCache` |
| <span id="method-getOrSet"></span>[`getOrSet()`](/docs/api/yii/caching/cache/index.md#method-getOrSet) | Method combines both [`set()`](/docs/api/yii/caching/cache/index.md#method-set) and [`get()`](/docs/api/yii/caching/cache/index.md#method-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. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| [`getServers()`](#method-getServers) | Returns the memcache or memcached server configurations. | `MemCache` |
| <span id="method-hasEventHandlers"></span>[`hasEventHandlers()`](/docs/api/yii/base/component/index.md#method-hasEventHandlers) | Returns a value indicating whether there is any handler attached to the named event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasMethod"></span>[`hasMethod()`](/docs/api/yii/base/component/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasProperty"></span>[`hasProperty()`](/docs/api/yii/base/component/index.md#method-hasProperty) | Returns a value indicating whether a property is defined for this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`init()`](#method-init) | Initializes this application component. | `MemCache` |
| <span id="method-multiAdd"></span>[`multiAdd()`](/docs/api/yii/caching/cache/index.md#method-multiAdd) | Stores multiple items in cache. Each item contains a value identified by a key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-multiGet"></span>[`multiGet()`](/docs/api/yii/caching/cache/index.md#method-multiGet) | Retrieves multiple values from cache with the specified keys. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-multiSet"></span>[`multiSet()`](/docs/api/yii/caching/cache/index.md#method-multiSet) | Stores multiple items in cache. Each item contains a value identified by a key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-off"></span>[`off()`](/docs/api/yii/base/component/index.md#method-off) | Detaches an existing event handler from this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-offsetExists"></span>[`offsetExists()`](/docs/api/yii/caching/cache/index.md#method-offsetExists) | Returns whether there is a cache entry with a specified key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-offsetGet"></span>[`offsetGet()`](/docs/api/yii/caching/cache/index.md#method-offsetGet) | Retrieves the value from cache with a specified key. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-offsetSet"></span>[`offsetSet()`](/docs/api/yii/caching/cache/index.md#method-offsetSet) | Stores the value identified by a key into cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-offsetUnset"></span>[`offsetUnset()`](/docs/api/yii/caching/cache/index.md#method-offsetUnset) | Deletes the value with the specified key from cache This method is required by the interface [`ArrayAccess`](https://www.php.net/manual/en/class.arrayaccess.php). | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="method-on"></span>[`on()`](/docs/api/yii/base/component/index.md#method-on) | Attaches an event handler to an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-set"></span>[`set()`](/docs/api/yii/caching/cache/index.md#method-set) | Stores a value identified by a key into cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| [`setServers()`](#method-setServers) |  | `MemCache` |
| <span id="method-trigger"></span>[`trigger()`](/docs/api/yii/base/component/index.md#method-trigger) | Triggers an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`addMemcachedServers()`](#method-addMemcachedServers) protected | Add servers to the server pool of the cache specified Used for memcached PECL extension. | `MemCache` |
| [`addMemcacheServers()`](#method-addMemcacheServers) protected | Add servers to the server pool of the cache specified Used for memcache PECL extension. | `MemCache` |
| [`addServers()`](#method-addServers) protected | Add servers to the server pool of the cache specified. | `MemCache` |
| [`addValue()`](#method-addValue) protected | Stores a value identified by a key into cache if the cache does not contain this key. | `MemCache` |
| <span id="method-addValues"></span>[`addValues()`](/docs/api/yii/caching/cache/index.md#method-addValues) protected | Adds multiple key-value pairs to cache. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| [`deleteValue()`](#method-deleteValue) protected | Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class. | `MemCache` |
| [`flushValues()`](#method-flushValues) protected | Deletes all values from cache. | `MemCache` |
| [`getValue()`](#method-getValue) protected | Retrieves a value from cache with a specified key. | `MemCache` |
| [`getValues()`](#method-getValues) protected | Retrieves multiple values from cache with the specified keys. | `MemCache` |
| [`normalizeDuration()`](#method-normalizeDuration) protected | Normalizes duration value | `MemCache` |
| [`setValue()`](#method-setValue) protected | Stores a value identified by a key in cache. | `MemCache` |
| [`setValues()`](#method-setValues) protected | Stores multiple key-value pairs in cache. | `MemCache` |

## Property details

### $options <span id="property-options"></span>

```php
public array $options = null
```

Options for Memcached.

This property is used only when [`$useMemcached`](/docs/api/yii/caching/memcache/index.md#property-useMemcached) is true.

### $password <span id="property-password"></span>

```php
public string $password = null
```

Memcached sasl password.

This property is used only when [`$useMemcached`](/docs/api/yii/caching/memcache/index.md#property-useMemcached) is true.

### $persistentId <span id="property-persistentId"></span>

```php
public string $persistentId = null
```

An ID that identifies a Memcached instance.

This property is used only when [`$useMemcached`](/docs/api/yii/caching/memcache/index.md#property-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.

### $servers <span id="property-servers"></span>

```php
public array $servers
```

List of memcache or memcached server configurations.

Each element must be an
array with the following keys: host, port, persistent, weight, timeout, retryInterval, status.

### $useMemcached <span id="property-useMemcached"></span>

```php
public bool $useMemcached = false
```

Whether to use memcached or memcache as the underlying caching extension.

If true, [memcached](https://pecl.php.net/package/memcached) will be used.
If false, [memcache](https://pecl.php.net/package/memcache) will be used.
Defaults to false.

### $username <span id="property-username"></span>

```php
public string $username = null
```

Memcached sasl username.

This property is used only when [`$useMemcached`](/docs/api/yii/caching/memcache/index.md#property-useMemcached) is true.

## Method details

### getMemcache() <span id="method-getMemcache"></span>

```php
public function getMemcache(): Memcache|Memcached
```

Returns the underlying memcache (or memcached) object.

**Returns**

[`Memcache`](https://www.php.net/manual/en/class.memcache.php)`|`[`Memcached`](https://www.php.net/manual/en/class.memcached.php): The memcache (or memcached) object used by this cache component.

**Throws**

- [`yii\base\InvalidConfigException`](/docs/api/yii/base/invalidconfigexception/index.md): if memcache or memcached extension is not loaded

### getServers() <span id="method-getServers"></span>

```php
public function getServers(): yii\caching\MemCacheServer[]
```

Returns the memcache or memcached server configurations.

**Returns**

[`MemCacheServer`](/docs/api/yii/caching/memcacheserver/index.md)`[]`: List of memcache server configurations.

### init() <span id="method-init"></span>

```php
public function init(): mixed
```

Initializes this application component.

It creates the memcache instance and adds memcache servers.

**Returns**

`mixed`

### setServers() <span id="method-setServers"></span>

```php
public function setServers(array $config): mixed
```

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$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. |

**Returns**

`mixed`

**See also**

- <https://www.php.net/manual/en/memcache.addserver.php>
- <https://www.php.net/manual/en/memcached.addserver.php>

### addMemcachedServers() <span id="method-addMemcachedServers"></span>

```php
protected function addMemcachedServers(Memcached $cache, yii\caching\MemCacheServer[] $servers): mixed
```

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$cache` | [`Memcached`](https://www.php.net/manual/en/class.memcached.php) |  |
| `$servers` | [`MemCacheServer`](/docs/api/yii/caching/memcacheserver/index.md)`[]` |  |

**Returns**

`mixed`

### addMemcacheServers() <span id="method-addMemcacheServers"></span>

```php
protected function addMemcacheServers(Memcache $cache, yii\caching\MemCacheServer[] $servers): mixed
```

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$cache` | [`Memcache`](https://www.php.net/manual/en/class.memcache.php) |  |
| `$servers` | [`MemCacheServer`](/docs/api/yii/caching/memcacheserver/index.md)`[]` |  |

**Returns**

`mixed`

### addServers() <span id="method-addServers"></span>

```php
protected function addServers(Memcache|Memcached $cache, yii\caching\MemCacheServer[] $servers): mixed
```

Add servers to the server pool of the cache specified.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$cache` | [`Memcache`](https://www.php.net/manual/en/class.memcache.php)`\|`[`Memcached`](https://www.php.net/manual/en/class.memcached.php) |  |
| `$servers` | [`MemCacheServer`](/docs/api/yii/caching/memcacheserver/index.md)`[]` |  |

**Returns**

`mixed`

**Throws**

- [`yii\base\InvalidConfigException`](/docs/api/yii/base/invalidconfigexception/index.md)

### addValue() <span id="method-addValue"></span>

```php
protected function addValue(string $key, mixed $value, int $duration): bool
```

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.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | The key identifying the value to be cached |
| `$value` | `mixed` | The value to be cached |
| `$duration` | `int` | The number of seconds in which the cached value will expire. 0 means never expire. |

**Returns**

`bool`: True if the value is successfully stored into cache, false otherwise

**See also**

- [Memcache::set()](https://www.php.net/manual/en/memcache.set.php)

### deleteValue() <span id="method-deleteValue"></span>

```php
protected function deleteValue(string $key): bool
```

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | The key of the value to be deleted |

**Returns**

`bool`: If no error happens during deletion

### flushValues() <span id="method-flushValues"></span>

```php
protected function flushValues(): bool
```

Deletes all values from cache.

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

**Returns**

`bool`: Whether the flush operation was successful.

### getValue() <span id="method-getValue"></span>

```php
protected function getValue(string $key): mixed|false
```

Retrieves a value from cache with a specified key.

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | A unique key identifying the cached value |

**Returns**

`mixed|false`: The value stored in cache, false if the value is not in the cache or expired.

### getValues() <span id="method-getValues"></span>

```php
protected function getValues(array $keys): array
```

Retrieves multiple values from cache with the specified keys.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$keys` | `array` | A list of keys identifying the cached values |

**Returns**

`array`: A list of cached values indexed by the keys

### normalizeDuration() <span id="method-normalizeDuration"></span>

```php
protected function normalizeDuration(int $duration): int
```

Normalizes duration value

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$duration` | `int` |  |

**Returns**

`int`

**Since**

2.0.31

**See also**

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

### setValue() <span id="method-setValue"></span>

```php
protected function setValue(string $key, mixed $value, int $duration): bool
```

Stores a value identified by a key in cache.

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

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | The key identifying the value to be cached |
| `$value` | `mixed` | The value to be cached. |
| `$duration` | `int` | The number of seconds in which the cached value will expire. 0 means never expire. |

**Returns**

`bool`: True if the value is successfully stored into cache, false otherwise

**See also**

- [Memcache::set()](https://www.php.net/manual/en/memcache.set.php)

### setValues() <span id="method-setValues"></span>

```php
protected function setValues(array $data, int $duration): array
```

Stores multiple key-value pairs in cache.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$data` | `array` | Array where key corresponds to cache key while value is the value stored |
| `$duration` | `int` | The number of seconds in which the cached values will expire. 0 means never expire. |

**Returns**

`array`: Array of failed keys.