Class yii\mongodb\Cache

All Classes | Properties | Methods

Inheritance	yii\mongodb\Cache » yii\caching\Cache
Available since extension's version	2.0
Source Code	https://github.com/yiisoft/yii2-mongodb/blob/master/Cache.php

Cache implements a cache application component by storing cached data in a MongoDB.

By default, Cache stores session data in a MongoDB collection named 'cache' inside the default database. This collection is better to be pre-created with fields 'id' and 'expire' indexed. The collection name can be changed by setting $cacheCollection.

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

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

'cache' => [
    'class' => 'yii\mongodb\Cache',
    // 'db' => 'mymongodb',
    // 'cacheCollection' => 'my_cache',
]

Public Properties

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Property	Type	Description	Defined By
$cacheCollection	string\|array	The name of the MongoDB collection that stores the cache data.	yii\mongodb\Cache
$db	yii\mongodb\Connection\|array\|string	The MongoDB connection object or the application component ID of the MongoDB connection.	yii\mongodb\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\mongodb\Cache

Public Methods

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Method	Description	Defined By
gc()	Removes the expired data values.	yii\mongodb\Cache
init()	Initializes the Cache component.	yii\mongodb\Cache

Protected Methods

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Method	Description	Defined By
addValue()	Stores a value identified by a key into cache if the cache does not contain this key.	yii\mongodb\Cache
deleteValue()	Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage.	yii\mongodb\Cache
flushValues()	Deletes all values from cache.	yii\mongodb\Cache
getValue()	Retrieves a value from cache with a specified key.	yii\mongodb\Cache
setValue()	Stores a value identified by a key in cache.	yii\mongodb\Cache

Property Details

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$cacheCollection public property

The name of the MongoDB collection that stores the cache data. Please refer to yii\mongodb\Connection::getCollection() on how to specify this parameter. This collection is better to be pre-created with fields 'id' and 'expire' indexed.

public string|array $cacheCollection = 'cache'

$db public property

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

public yii\mongodb\Connection|array|string $db = 'mongodb'

$gcProbability public property

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

Method Details

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addValue() protected method

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

This method should be implemented by child classes to store the data in specific cache storage.

protected boolean addValue ( $key, $value, $expire )
$key	string	The key identifying the value to be cached
$value	string	The value to be cached
$expire	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

Source code

                protected function addValue($key, $value, $expire)
{
    $this->gc();
    if ($expire > 0) {
        $expire += time();
    } else {
        $expire = 0;
    }
    try {
        $this->db->getCollection($this->cacheCollection)
            ->insert([
                'id' => $key,
                'expire' => $expire,
                'data' => $value,
            ]);
        return true;
    } catch (\Exception $e) {
        return false;
    }
}

deleteValue() protected method

Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage.

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

Source code

                protected function deleteValue($key)
{
    $this->db->getCollection($this->cacheCollection)
        ->remove(['id' => $key]);
    return true;
}

flushValues() protected method

Deletes all values from cache.

Child classes may implement this method to realize the flush operation.

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

Source code

                protected function flushValues()
{
    $this->db->getCollection($this->cacheCollection)
        ->remove();
    return true;
}

gc() public method

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.

Source code

                public function gc($force = false)
{
    if ($force || mt_rand(0, 1000000) < $this->gcProbability) {
        $this->db->getCollection($this->cacheCollection)
            ->remove([
                'expire' => [
                    '$gt' => 0,
                    '$lt' => time(),
                ]
            ]);
    }
}

getValue() protected method

Retrieves a value from cache with a specified key.

This method should be implemented by child classes to retrieve the data from specific cache storage.

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

Source code

                protected function getValue($key)
{
    $query = new Query;
    $row = $query->select(['data'])
        ->from($this->cacheCollection)
        ->where([
            'id' => $key,
            '$or' => [
                [
                    'expire' => 0
                ],
                [
                    'expire' => ['$gt' => time()]
                ],
            ],
        ])
        ->one($this->db);
    if (empty($row)) {
        return false;
    } else {
        return $row['data'];
    }
}

init() public method

Initializes the Cache component.

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

public void init ( )
throws	\yii\base\InvalidConfigException	if $db is invalid.

Source code

                public function init()
{
    parent::init();
    $this->db = Instance::ensure($this->db, Connection::className());
}

setValue() protected method

Stores a value identified by a key in cache.

This method should be implemented by child classes to store the data in specific cache storage.

protected boolean setValue ( $key, $value, $expire )
$key	string	The key identifying the value to be cached
$value	string	The value to be cached
$expire	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

Source code

                protected function setValue($key, $value, $expire)
{
    $result = $this->db->getCollection($this->cacheCollection)
        ->update(['id' => $key], [
            'expire' => $expire > 0 ? $expire + time() : 0,
            'data' => $value,
        ]);
    if ($result) {
        $this->gc();
        return true;
    } else {
        return $this->addValue($key, $value, $expire);
    }
}