# ApcuCache

> ApcuCache provides APCu caching in terms of an application component.

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

| class | `yii\caching\ApcuCache` |
| --- | --- |
| 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 | [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md), [`CacheInterface`](/docs/api/yii/caching/cacheinterface/index.md) |
| Since | 22.0 |
| Source | [`framework/caching/ApcuCache.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/caching/ApcuCache.php#L38) |

ApcuCache provides APCu caching in terms of an application component.

To use this application component, the [APCu PHP extension](https://www.php.net/apcu) must be loaded.

In order to enable APCu for CLI you should add "apc.enable_cli = 1" to your `php.ini`.

See [`Cache`](/docs/api/yii/caching/cache/index.md) for common cache operations that ApcuCache supports.

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>[`$keyPrefix`](/docs/api/yii/caching/cache/index.md#property-keyPrefix) | `string` | A string prefixed to every cache key so that it is unique globally in the whole cache storage. Default: `null`. | [`Cache`](/docs/api/yii/caching/cache/index.md) |
| <span id="property-serializer"></span>[`$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) |

## 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) |
| [`exists()`](#method-exists) | Checks whether a specified key exists in the cache. | `ApcuCache` |
| <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) |
| <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) |
| <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. | `ApcuCache` |
| <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) |
| <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) |
| [`addValue()`](#method-addValue) protected | Stores a value identified by a key into cache if the cache does not contain this key. | `ApcuCache` |
| [`addValues()`](#method-addValues) protected | Adds multiple key-value pairs to cache. | `ApcuCache` |
| [`deleteValue()`](#method-deleteValue) protected | Deletes a value with the specified key from cache. | `ApcuCache` |
| [`flushValues()`](#method-flushValues) protected | Deletes all values from cache. | `ApcuCache` |
| [`getValue()`](#method-getValue) protected | Retrieves a value from cache with a specified key. | `ApcuCache` |
| [`getValues()`](#method-getValues) protected | Retrieves multiple values from cache with the specified keys. | `ApcuCache` |
| [`setValue()`](#method-setValue) protected | Stores a value identified by a key in cache. | `ApcuCache` |
| [`setValues()`](#method-setValues) protected | Stores multiple key-value pairs in cache. | `ApcuCache` |

## Method details

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

```php
public function exists(mixed $key): bool
```

Checks whether a specified key exists in the cache.

This can be faster than getting the value from the cache if the data is big.

Note that this method does not check whether the dependency associated with the cached data, if there is any, has
changed. So a call to [`get()`](/docs/api/yii/caching/cache/index.md#method-get) may return `false` while exists returns `true`.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `mixed` | A key identifying the cached value. This can be a simple string or a complex data structure consisting of factors representing the key. |

**Returns**

`bool`: `true` if a value exists in cache, `false` if the value is not in the cache or expired.

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

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

Initializes this application component.

It checks if the APCu extension is loaded.

**Returns**

`mixed`

### 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.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | The key identifying the value to be cached. |
| `$value` | `mixed` | The value to be cached. Most often it's a string. If you have disabled [`$serializer`](/docs/api/yii/caching/cache/index.md#property-serializer), it could be something else. |
| `$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.

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

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

Adds multiple key-value pairs to 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.

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

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

Deletes a value with the specified key from cache.

**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.

**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.

**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.

### 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.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$key` | `string` | The key identifying the value to be cached. |
| `$value` | `mixed` | The value to be cached. Most often it's a string. If you have disabled [`$serializer`](/docs/api/yii/caching/cache/index.md#property-serializer), it could be something else. |
| `$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.

### 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.