framework/caching/DbCache.php
<?php
/**
* @link https://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license https://www.yiiframework.com/license/
*/
namespace yii\caching;
use Yii;
use yii\base\InvalidConfigException;
use yii\db\Connection;
use yii\db\PdoValue;
use yii\db\Query;
use yii\di\Instance;
/**
* 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 [[Cache]] for common cache operations that are supported by DbCache.
*
* The following example shows how you can configure the application to use DbCache:
*
* ```php
* 'cache' => [
* 'class' => 'yii\caching\DbCache',
* // 'db' => 'mydb',
* // 'cacheTable' => 'my_cache',
* ]
* ```
*
* For more details and usage information on Cache, see the [guide article on caching](guide:caching-overview).
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
class DbCache extends Cache
{
/**
* @var Connection|array|string 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.
*/
public $db = 'db';
/**
* @var string name of the DB table to store cache content.
* The table should be pre-created as follows:
*
* ```php
* CREATE TABLE cache (
* id char(128) NOT NULL PRIMARY KEY,
* expire int(11),
* data BLOB
* );
* ```
*
* For MSSQL:
* ```php
* CREATE TABLE cache (
* id VARCHAR(128) NOT NULL PRIMARY KEY,
* expire INT(11),
* data VARBINARY(MAX)
* );
* ```
*
* 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
*
* 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 $cacheTable = '{{%cache}}';
/**
* @var int 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 $gcProbability = 100;
protected $isVarbinaryDataField;
/**
* Initializes the DbCache component.
* This method will initialize the [[db]] property to make sure it refers to a valid DB connection.
* @throws InvalidConfigException if [[db]] is invalid.
*/
public function init()
{
parent::init();
$this->db = Instance::ensure($this->db, Connection::className());
}
/**
* 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.
* @param mixed $key a key identifying the cached value. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @return bool true if a value exists in cache, false if the value is not in the cache or expired.
*/
public function exists($key)
{
$key = $this->buildKey($key);
$query = new Query();
$query->select(['COUNT(*)'])
->from($this->cacheTable)
->where('[[id]] = :id AND ([[expire]] = 0 OR [[expire]] >' . time() . ')', [':id' => $key]);
if ($this->db->enableQueryCache) {
// temporarily disable and re-enable query caching
$this->db->enableQueryCache = false;
$result = $query->createCommand($this->db)->queryScalar();
$this->db->enableQueryCache = true;
} else {
$result = $query->createCommand($this->db)->queryScalar();
}
return $result > 0;
}
/**
* Retrieves a value from cache with a specified key.
* This is the implementation of the method declared in the parent class.
* @param string $key a unique key identifying the cached value
* @return string|false the value stored in cache, false if the value is not in the cache or expired.
*/
protected function getValue($key)
{
$query = new Query();
$query->select([$this->getDataFieldName()])
->from($this->cacheTable)
->where('[[id]] = :id AND ([[expire]] = 0 OR [[expire]] >' . time() . ')', [':id' => $key]);
if ($this->db->enableQueryCache) {
// temporarily disable and re-enable query caching
$this->db->enableQueryCache = false;
$result = $query->createCommand($this->db)->queryScalar();
$this->db->enableQueryCache = true;
return $result;
}
return $query->createCommand($this->db)->queryScalar();
}
/**
* Retrieves multiple values from cache with the specified keys.
* @param array $keys a list of keys identifying the cached values
* @return array a list of cached values indexed by the keys
*/
protected function getValues($keys)
{
if (empty($keys)) {
return [];
}
$query = new Query();
$query->select(['id', $this->getDataFieldName()])
->from($this->cacheTable)
->where(['id' => $keys])
->andWhere('([[expire]] = 0 OR [[expire]] > ' . time() . ')');
if ($this->db->enableQueryCache) {
$this->db->enableQueryCache = false;
$rows = $query->createCommand($this->db)->queryAll();
$this->db->enableQueryCache = true;
} else {
$rows = $query->createCommand($this->db)->queryAll();
}
$results = [];
foreach ($keys as $key) {
$results[$key] = false;
}
foreach ($rows as $row) {
if (is_resource($row['data']) && get_resource_type($row['data']) === 'stream') {
$results[$row['id']] = stream_get_contents($row['data']);
} else {
$results[$row['id']] = $row['data'];
}
}
return $results;
}
/**
* Stores a value identified by a key in cache.
* This is the implementation of the method declared in the parent class.
*
* @param string $key the key identifying the value to be cached
* @param string $value the value to be cached. Other types (if you have disabled [[serializer]]) cannot be saved.
* @param int $duration the number of seconds in which the cached value will expire. 0 means never expire.
* @return bool true if the value is successfully stored into cache, false otherwise
*/
protected function setValue($key, $value, $duration)
{
try {
$this->db->noCache(function (Connection $db) use ($key, $value, $duration) {
$db->createCommand()->upsert($this->cacheTable, [
'id' => $key,
'expire' => $duration > 0 ? $duration + time() : 0,
'data' => $this->getDataFieldValue($value),
])->execute();
});
$this->gc();
return true;
} catch (\Exception $e) {
Yii::warning("Unable to update or insert cache data: {$e->getMessage()}", __METHOD__);
return false;
}
}
/**
* 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.
*
* @param string $key the key identifying the value to be cached
* @param string $value the value to be cached. Other types (if you have disabled [[serializer]]) cannot be saved.
* @param int $duration the number of seconds in which the cached value will expire. 0 means never expire.
* @return bool true if the value is successfully stored into cache, false otherwise
*/
protected function addValue($key, $value, $duration)
{
$this->gc();
try {
$this->db->noCache(function (Connection $db) use ($key, $value, $duration) {
$db->createCommand()
->insert($this->cacheTable, [
'id' => $key,
'expire' => $duration > 0 ? $duration + time() : 0,
'data' => $this->getDataFieldValue($value),
])->execute();
});
return true;
} catch (\Exception $e) {
Yii::warning("Unable to insert cache data: {$e->getMessage()}", __METHOD__);
return false;
}
}
/**
* Deletes a value with the specified key from cache
* This is the implementation of the method declared in the parent class.
* @param string $key the key of the value to be deleted
* @return bool if no error happens during deletion
*/
protected function deleteValue($key)
{
$this->db->noCache(function (Connection $db) use ($key) {
$db->createCommand()
->delete($this->cacheTable, ['id' => $key])
->execute();
});
return true;
}
/**
* Removes the expired data values.
* @param bool $force whether to enforce the garbage collection regardless of [[gcProbability]].
* Defaults to false, meaning the actual deletion happens with the probability as specified by [[gcProbability]].
*/
public function gc($force = false)
{
if ($force || random_int(0, 1000000) < $this->gcProbability) {
$this->db->createCommand()
->delete($this->cacheTable, '[[expire]] > 0 AND [[expire]] < ' . time())
->execute();
}
}
/**
* Deletes all values from cache.
* This is the implementation of the method declared in the parent class.
* @return bool whether the flush operation was successful.
*/
protected function flushValues()
{
$this->db->createCommand()
->delete($this->cacheTable)
->execute();
return true;
}
/**
* @return bool whether field is MSSQL varbinary
* @since 2.0.42
*/
protected function isVarbinaryDataField()
{
if ($this->isVarbinaryDataField === null) {
$this->isVarbinaryDataField = in_array($this->db->getDriverName(), ['sqlsrv', 'dblib']) &&
$this->db->getTableSchema($this->cacheTable)->columns['data']->dbType === 'varbinary';
}
return $this->isVarbinaryDataField;
}
/**
* @return string `data` field name converted for usage in MSSQL (if needed)
* @since 2.0.42
*/
protected function getDataFieldName()
{
return $this->isVarbinaryDataField() ? 'CONVERT(VARCHAR(MAX), [[data]]) data' : 'data';
}
/**
* @return PdoValue PdoValue or direct $value for usage in MSSQL
* @since 2.0.42
*/
protected function getDataFieldValue($value)
{
return $this->isVarbinaryDataField() ? $value : new PdoValue($value, \PDO::PARAM_LOB);
}
}