Class yii\caching\DbCache

继承yii\caching\DbCache » yii\caching\Cache » yii\base\Component » yii\base\BaseObject
实现yii\base\Configurable, yii\caching\CacheInterface
可用自版本2.0
源代码 https://github.com/yiisoft/yii2/blob/master/framework/caching/DbCache.php

DbCache implements a cache application component by storing cached data in a database.

By default, DbCache stores session data in a DB table named 'cache'. This table must be pre-created. The table name can be changed by setting $cacheTable.

Please refer to yii\caching\Cache for common cache operations that are supported by DbCache.

The following example shows how you can configure the application to use DbCache:

'cache' => [
    'class' => 'yii\caching\DbCache',
    // 'db' => 'mydb',
    // 'cacheTable' => 'my_cache',
]

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

公共属性

隐藏继承的属性

属性类型描述定义在
$behaviors yii\base\Behavior[] 附加到此组件的行为列表. 该属性是只读的. yii\base\Component
$cacheTable string Name of the DB table to store cache content. yii\caching\DbCache
$db yii\db\Connection|array|string The DB connection object or the application component ID of the DB connection. yii\caching\DbCache
$defaultDuration integer Default duration in seconds before a cache entry will expire. yii\caching\Cache
$gcProbability integer The probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. yii\caching\DbCache
$keyPrefix string A string prefixed to every cache key so that it is unique globally in the whole cache storage. yii\caching\Cache
$serializer null|array|false The functions used to serialize and unserialize cached data. yii\caching\Cache

公共方法

隐藏继承的方法

方法描述定义在
__call() 调用不是类方法的指定的方法. yii\base\Component
__clone() 在通过克隆现有对象创建对象之后调用此方法. yii\base\Component
__construct() 构造函数. yii\base\BaseObject
__get() 返回组件属性的值. yii\base\Component
__isset() 检查属性是否已设置, 即已定义且不为null. yii\base\Component
__set() 设置组件属性的值. yii\base\Component
__unset() 将组件属性设置为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() 将行为附加到此组件. yii\base\Component
attachBehaviors() 将行为列表附加到组件. yii\base\Component
behaviors() 返回此组件应该具有的行为列表. yii\base\Component
buildKey() Builds a normalized cache key from a given key. yii\caching\Cache
canGetProperty() 返回一个值, 指示属性是否可读取. yii\base\Component
canSetProperty() 返回一个值, 指示属性是否可设置. yii\base\Component
className() 返回此类的完全限定名称. yii\base\BaseObject
delete() Deletes a value with the specified key from cache. yii\caching\Cache
detachBehavior() 从组件中分离一个行为. yii\base\Component
detachBehaviors() 分离组件中的所有行为. yii\base\Component
ensureBehaviors() 确保在 behaviors() 中声明的行为已附加到此组件. yii\base\Component
exists() Checks whether a specified key exists in the cache. yii\caching\DbCache
flush() Deletes all values from cache. yii\caching\Cache
gc() Removes the expired data values. yii\caching\DbCache
get() Retrieves a value from cache with a specified key. yii\caching\Cache
getBehavior() 返回指定的行为对象. yii\base\Component
getBehaviors() 返回附加到此组件的所有行为. yii\base\Component
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
hasEventHandlers() 返回一个值, 指示是否有任何处理程序附加到指定的事件. yii\base\Component
hasMethod() 返回一个值, 指示方法是否已定义. yii\base\Component
hasProperty() 返回一个值, 指示属性是否已定义. yii\base\Component
init() Initializes the DbCache component. yii\caching\DbCache
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() 从该组件分离现有的事件处理程序. 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() 将事件处理程序附加到事件. yii\base\Component
set() Stores a value identified by a key into cache. yii\caching\Cache
trigger() 触发事件. yii\base\Component

受保护的方法

隐藏继承的方法

方法描述定义在
addValue() Stores a value identified by a key into cache if the cache does not contain this key. yii\caching\DbCache
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\DbCache
flushValues() Deletes all values from cache. yii\caching\DbCache
getValue() Retrieves a value from cache with a specified key. yii\caching\DbCache
getValues() Retrieves multiple values from cache with the specified keys. yii\caching\DbCache
setValue() Stores a value identified by a key in cache. yii\caching\DbCache
setValues() Stores multiple key-value pairs in cache. yii\caching\Cache

属性详情

$cacheTable public 属性

Name of the DB table to store cache content. The table should be pre-created as follows:

CREATE TABLE cache (
    id char(128) NOT NULL PRIMARY KEY,
    expire int(11),
    data BLOB
);

where 'BLOB' refers to the BLOB-type of your preferred DBMS. Below are the BLOB type that can be used for some popular DBMS:

  • MySQL: LONGBLOB
  • PostgreSQL: BYTEA
  • MSSQL: BLOB

When using DbCache in a production server, we recommend you create a DB index for the 'expire' column in the cache table to improve the performance.

public string $cacheTable '{{%cache}}'
$db public 属性

The DB connection object or the application component ID of the DB connection. After the DbCache object is created, if you want to change this property, you should only assign it with a DB connection object. Starting from version 2.0.2, this can also be a configuration array for creating the object.

$gcProbability public 属性

The probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all.

public integer $gcProbability 100

方法详情

addValue() protected 方法

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.

protected boolean addValue ( $key, $value, $duration )
$key string

The key identifying the value to be cached

$value string

The value to be cached. Other types (if you have disabled $serializer) cannot be saved.

$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 方法

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

exists() public 方法

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() may return false while exists returns true.

public boolean exists ( $key )
$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.

return boolean

True if a value exists in cache, false if the value is not in the cache or expired.

flushValues() protected 方法

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.

gc() public 方法

Removes the expired data values.

public void gc ( $force false )
$force boolean

Whether to enforce the garbage collection regardless of $gcProbability. Defaults to false, meaning the actual deletion happens with the probability as specified by $gcProbability.

getValue() protected 方法

Retrieves a value from cache with a specified key.

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

protected string|false getValue ( $key )
$key string

A unique key identifying the cached value

return string|false

The value stored in cache, false if the value is not in the cache or expired.

getValues() protected 方法

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 方法

Initializes the DbCache component.

This method will initialize the $db property to make sure it refers to a valid DB connection.

public void init ( )
throws yii\base\InvalidConfigException

if $db is invalid.

setValue() protected 方法

Stores a value identified by a key in cache.

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

protected boolean setValue ( $key, $value, $duration )
$key string

The key identifying the value to be cached

$value string

The value to be cached. Other types (if you have disabled $serializer) cannot be saved.

$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