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version 2.0.1 84b42ab
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╃巡洋艦㊣
271
framework/caching/DbCache.php
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271
framework/caching/DbCache.php
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<?php
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/**
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* @link http://www.yiiframework.com/
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* @copyright Copyright (c) 2008 Yii Software LLC
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* @license http://www.yiiframework.com/license/
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*/
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namespace yii\caching;
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use Yii;
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use yii\base\InvalidConfigException;
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use yii\db\Connection;
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use yii\db\Query;
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use yii\di\Instance;
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/**
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* DbCache implements a cache application component by storing cached data in a database.
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*
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* By default, DbCache stores session data in a DB table named 'cache'. This table
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* must be pre-created. The table name can be changed by setting [[cacheTable]].
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*
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* Please refer to [[Cache]] for common cache operations that are supported by DbCache.
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*
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* The following example shows how you can configure the application to use DbCache:
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*
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* ```php
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* 'cache' => [
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* 'class' => 'yii\caching\DbCache',
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* // 'db' => 'mydb',
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* // 'cacheTable' => 'my_cache',
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* ]
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* ```
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @since 2.0
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*/
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class DbCache extends Cache
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{
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/**
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* @var Connection|string the DB connection object or the application component ID of the DB connection.
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* After the DbCache object is created, if you want to change this property, you should only assign it
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* with a DB connection object.
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*/
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public $db = 'db';
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/**
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* @var string name of the DB table to store cache content.
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* The table should be pre-created as follows:
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*
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* ~~~
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* CREATE TABLE cache (
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* id char(128) NOT NULL PRIMARY KEY,
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* expire int(11),
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* data BLOB
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* );
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* ~~~
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*
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* where 'BLOB' refers to the BLOB-type of your preferred DBMS. Below are the BLOB type
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* that can be used for some popular DBMS:
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*
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* - MySQL: LONGBLOB
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* - PostgreSQL: BYTEA
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* - MSSQL: BLOB
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*
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* When using DbCache in a production server, we recommend you create a DB index for the 'expire'
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* column in the cache table to improve the performance.
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*/
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public $cacheTable = '{{%cache}}';
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/**
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* @var integer the probability (parts per million) that garbage collection (GC) should be performed
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* when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
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* This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all.
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*/
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public $gcProbability = 100;
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/**
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* Initializes the DbCache component.
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* This method will initialize the [[db]] property to make sure it refers to a valid DB connection.
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* @throws InvalidConfigException if [[db]] is invalid.
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*/
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public function init()
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{
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parent::init();
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$this->db = Instance::ensure($this->db, Connection::className());
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}
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/**
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* Checks whether a specified key exists in the cache.
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* This can be faster than getting the value from the cache if the data is big.
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* Note that this method does not check whether the dependency associated
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* with the cached data, if there is any, has changed. So a call to [[get]]
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* may return false while exists returns true.
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* @param mixed $key a key identifying the cached value. This can be a simple string or
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* a complex data structure consisting of factors representing the key.
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* @return boolean true if a value exists in cache, false if the value is not in the cache or expired.
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*/
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public function exists($key)
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{
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$key = $this->buildKey($key);
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$query = new Query;
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$query->select(['COUNT(*)'])
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->from($this->cacheTable)
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->where('[[id]] = :id AND ([[expire]] = 0 OR [[expire]] >' . time() . ')', [':id' => $key]);
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if ($this->db->enableQueryCache) {
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// temporarily disable and re-enable query caching
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$this->db->enableQueryCache = false;
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$result = $query->createCommand($this->db)->queryScalar();
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$this->db->enableQueryCache = true;
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} else {
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$result = $query->createCommand($this->db)->queryScalar();
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}
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return $result > 0;
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}
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/**
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* Retrieves a value from cache with a specified key.
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* This is the implementation of the method declared in the parent class.
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* @param string $key a unique key identifying the cached value
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* @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
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*/
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protected function getValue($key)
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{
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$query = new Query;
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$query->select(['data'])
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->from($this->cacheTable)
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->where('[[id]] = :id AND ([[expire]] = 0 OR [[expire]] >' . time() . ')', [':id' => $key]);
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if ($this->db->enableQueryCache) {
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// temporarily disable and re-enable query caching
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$this->db->enableQueryCache = false;
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$result = $query->createCommand($this->db)->queryScalar();
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$this->db->enableQueryCache = true;
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return $result;
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} else {
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return $query->createCommand($this->db)->queryScalar();
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}
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}
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/**
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* Retrieves multiple values from cache with the specified keys.
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* @param array $keys a list of keys identifying the cached values
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* @return array a list of cached values indexed by the keys
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*/
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protected function getValues($keys)
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{
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if (empty($keys)) {
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return [];
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}
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$query = new Query;
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$query->select(['id', 'data'])
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->from($this->cacheTable)
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->where(['id' => $keys])
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->andWhere('([[expire]] = 0 OR [[expire]] > ' . time() . ')');
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if ($this->db->enableQueryCache) {
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$this->db->enableQueryCache = false;
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$rows = $query->createCommand($this->db)->queryAll();
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$this->db->enableQueryCache = true;
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} else {
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$rows = $query->createCommand($this->db)->queryAll();
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}
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$results = [];
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foreach ($keys as $key) {
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$results[$key] = false;
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}
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foreach ($rows as $row) {
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$results[$row['id']] = $row['data'];
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}
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return $results;
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}
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/**
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* Stores a value identified by a key in cache.
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* This is the implementation of the method declared in the parent class.
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*
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* @param string $key the key identifying the value to be cached
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* @param string $value the value to be cached
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* @param integer $duration the number of seconds in which the cached value will expire. 0 means never expire.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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*/
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protected function setValue($key, $value, $duration)
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{
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$command = $this->db->createCommand()
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->update($this->cacheTable, [
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'expire' => $duration > 0 ? $duration + time() : 0,
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'data' => [$value, \PDO::PARAM_LOB],
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], ['id' => $key]);
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if ($command->execute()) {
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$this->gc();
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return true;
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} else {
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return $this->addValue($key, $value, $duration);
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}
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}
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/**
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* Stores a value identified by a key into cache if the cache does not contain this key.
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* This is the implementation of the method declared in the parent class.
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*
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* @param string $key the key identifying the value to be cached
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* @param string $value the value to be cached
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* @param integer $duration the number of seconds in which the cached value will expire. 0 means never expire.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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*/
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protected function addValue($key, $value, $duration)
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{
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$this->gc();
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try {
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$this->db->createCommand()
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->insert($this->cacheTable, [
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'id' => $key,
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'expire' => $duration > 0 ? $duration + time() : 0,
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'data' => [$value, \PDO::PARAM_LOB],
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])->execute();
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return true;
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} catch (\Exception $e) {
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return false;
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}
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}
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/**
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* Deletes a value with the specified key from cache
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* This is the implementation of the method declared in the parent class.
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* @param string $key the key of the value to be deleted
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* @return boolean if no error happens during deletion
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*/
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protected function deleteValue($key)
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{
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$this->db->createCommand()
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->delete($this->cacheTable, ['id' => $key])
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->execute();
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return true;
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}
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/**
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* Removes the expired data values.
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* @param boolean $force whether to enforce the garbage collection regardless of [[gcProbability]].
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* Defaults to false, meaning the actual deletion happens with the probability as specified by [[gcProbability]].
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*/
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public function gc($force = false)
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{
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if ($force || mt_rand(0, 1000000) < $this->gcProbability) {
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$this->db->createCommand()
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->delete($this->cacheTable, '[[expire]] > 0 AND [[expire]] < ' . time())
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->execute();
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}
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}
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/**
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* Deletes all values from cache.
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* This is the implementation of the method declared in the parent class.
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* @return boolean whether the flush operation was successful.
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*/
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protected function flushValues()
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{
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$this->db->createCommand()
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->delete($this->cacheTable)
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->execute();
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return true;
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}
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}
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