CDbCache
| 包 | system.caching |
|---|---|
| 继承 | class CDbCache » CCache » CApplicationComponent » CComponent |
| 实现 | ArrayAccess, ICache, IApplicationComponent |
| 可用自 | 1.0 |
| 源码 | framework/caching/CDbCache.php |
CDbCache implements a cache application component by storing cached data in a database.
CDbCache stores cache data in a DB table named cacheTableName. If the table does not exist, it will be automatically created. By setting autoCreateCacheTable to false, you can also manually create the DB table.
CDbCache relies on PDO to access database. By default, it will use a SQLite3 database under the application runtime directory. You can also specify connectionID so that it makes use of a DB application component to access database.
See CCache manual for common cache operations that are supported by CDbCache.
CDbCache stores cache data in a DB table named cacheTableName. If the table does not exist, it will be automatically created. By setting autoCreateCacheTable to false, you can also manually create the DB table.
CDbCache relies on PDO to access database. By default, it will use a SQLite3 database under the application runtime directory. You can also specify connectionID so that it makes use of a DB application component to access database.
See CCache manual for common cache operations that are supported by CDbCache.
公共属性
| 属性 | 类型 | 描述 | 被定义在 |
|---|---|---|---|
| autoCreateCacheTable | boolean | whether the cache DB table should be created automatically if it does not exist. | CDbCache |
| behaviors | array | the behaviors that should be attached to this component. | CApplicationComponent |
| cacheTableName | string | name of the DB table to store cache content. | CDbCache |
| connectionID | string | the ID of the CDbConnection application component. | CDbCache |
| dbConnection | CDbConnection | the DB connection instance | CDbCache |
| gCProbability | integer | the probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. | CDbCache |
| hashKey | boolean | whether to md5-hash the cache key for normalization purposes. | CCache |
| isInitialized | boolean | Checks if this application component has been initialized. | CApplicationComponent |
| keyPrefix | string | a string prefixed to every cache key so that it is unique. | CCache |
| serializer | array|boolean | the functions used to serialize and unserialize cached data. | CCache |
公共方法
| 方法 | 描述 | 被定义在 |
|---|---|---|
| __call() | Calls the named method which is not a class method. | CComponent |
| __get() | Returns a property value, an event handler list or a behavior based on its name. | CComponent |
| __isset() | Checks if a property value is null. | CComponent |
| __set() | Sets value of a component property. | CComponent |
| __unset() | Sets a component property to be null. | CComponent |
| add() | Stores a value identified by a key into cache if the cache does not contain this key. | CCache |
| asa() | Returns the named behavior object. | CComponent |
| attachBehavior() | Attaches a behavior to this component. | CComponent |
| attachBehaviors() | Attaches a list of behaviors to the component. | CComponent |
| attachEventHandler() | Attaches an event handler to an event. | CComponent |
| canGetProperty() | Determines whether a property can be read. | CComponent |
| canSetProperty() | Determines whether a property can be set. | CComponent |
| delete() | Deletes a value with the specified key from cache | CCache |
| detachBehavior() | Detaches a behavior from the component. | CComponent |
| detachBehaviors() | Detaches all behaviors from the component. | CComponent |
| detachEventHandler() | Detaches an existing event handler. | CComponent |
| disableBehavior() | Disables an attached behavior. | CComponent |
| disableBehaviors() | Disables all behaviors attached to this component. | CComponent |
| enableBehavior() | Enables an attached behavior. | CComponent |
| enableBehaviors() | Enables all behaviors attached to this component. | CComponent |
| evaluateExpression() | Evaluates a PHP expression or callback under the context of this component. | CComponent |
| flush() | Deletes all values from cache. | CCache |
| get() | Retrieves a value from cache with a specified key. | CCache |
| getDbConnection() | Returns the DB connection instance | CDbCache |
| getEventHandlers() | Returns the list of attached event handlers for an event. | CComponent |
| getGCProbability() | Returns 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. | CDbCache |
| getIsInitialized() | Checks if this application component has been initialized. | CApplicationComponent |
| hasEvent() | Determines whether an event is defined. | CComponent |
| hasEventHandler() | Checks whether the named event has attached handlers. | CComponent |
| hasProperty() | Determines whether a property is defined. | CComponent |
| init() | Initializes this application component. | CDbCache |
| mget() | Retrieves multiple values from cache with the specified keys. | CCache |
| offsetExists() | Returns whether there is a cache entry with a specified key. | CCache |
| offsetGet() | Retrieves the value from cache with a specified key. | CCache |
| offsetSet() | Stores the value identified by a key into cache. | CCache |
| offsetUnset() | Deletes the value with the specified key from cache | CCache |
| raiseEvent() | Raises an event. | CComponent |
| set() | Stores a value identified by a key into cache. | CCache |
| setDbConnection() | Sets the DB connection used by the cache component. | CDbCache |
| setGCProbability() | Sets 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. | CDbCache |
受保护的方法
| 方法 | 描述 | 被定义在 |
|---|---|---|
| addValue() | Stores a value identified by a key into cache if the cache does not contain this key. | CDbCache |
| createCacheTable() | Creates the cache DB table. | CDbCache |
| deleteValue() | Deletes a value with the specified key from cache | CDbCache |
| flushValues() | Deletes all values from cache. | CDbCache |
| gc() | Removes the expired data values. | CDbCache |
| generateUniqueKey() | CCache | |
| getValue() | Retrieves a value from cache with a specified key. | CDbCache |
| getValues() | Retrieves multiple values from cache with the specified keys. | CDbCache |
| setValue() | Stores a value identified by a key in cache. | CDbCache |
属性详情
autoCreateCacheTable
属性
public boolean $autoCreateCacheTable;
whether the cache DB table should be created automatically if it does not exist. Defaults to true. If you already have the table created, it is recommended you set this property to be false to improve performance.
cacheTableName
属性
public string $cacheTableName;
name of the DB table to store cache content. Defaults to 'YiiCache'. Note, if autoCreateCacheTable is false and you want to create the DB table manually by yourself, you need to make sure the DB table is of the following structure:
(id CHAR(128) PRIMARY KEY, expire INTEGER, value BLOB)Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.)
connectionID
属性
public string $connectionID;
the ID of the CDbConnection application component. If not set,
a SQLite3 database will be automatically created and used. The SQLite database file
is protected/runtime/cache-YiiVersion.db.
dbConnection
属性
the DB connection instance
gCProbability
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.
方法详情
addValue()
方法
|
protected boolean addValue(string $key, string $value, integer $expire)
| ||
| $key | string | the key identifying the value to be cached |
| $value | string | the value to be cached |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
源码： framework/caching/CDbCache.php#255 (显示)
protected function addValue($key,$value,$expire)
{
if(!$this->_gced && mt_rand(0,1000000)<$this->_gcProbability)
{
$this->gc();
$this->_gced=true;
}
if($expire>0)
$expire+=time();
else
$expire=0;
$sql="INSERT INTO {$this->cacheTableName} (id,expire,value) VALUES ('$key',$expire,:value)";
try
{
$command=$this->getDbConnection()->createCommand($sql);
$command->bindValue(':value',$value,PDO::PARAM_LOB);
$command->execute();
return true;
}
catch(Exception $e)
{
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.
createCacheTable()
方法
|
protected void createCacheTable(CDbConnection $db, string $tableName)
| ||
| $db | CDbConnection | the database connection |
| $tableName | string | the name of the table to be created |
源码： framework/caching/CDbCache.php#122 (显示)
protected function createCacheTable($db,$tableName)
{
$driver=$db->getDriverName();
if($driver==='mysql')
$blob='LONGBLOB';
elseif($driver==='pgsql')
$blob='BYTEA';
else
$blob='BLOB';
$sql=<<<EOD
CREATE TABLE $tableName
(
id CHAR(128) PRIMARY KEY,
expire INTEGER,
value $blob
)
EOD;
$db->createCommand($sql)->execute();
}
Creates the cache DB table.
deleteValue()
方法
|
protected boolean deleteValue(string $key)
| ||
| $key | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
源码： framework/caching/CDbCache.php#287 (显示)
protected function deleteValue($key)
{
$sql="DELETE FROM {$this->cacheTableName} WHERE id='$key'";
$this->getDbConnection()->createCommand($sql)->execute();
return true;
}
Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class.
flushValues()
方法
（自版本 v1.1.5 可用）
|
protected boolean flushValues()
| ||
| {return} | boolean | whether the flush operation was successful. |
源码： framework/caching/CDbCache.php#308 (显示)
protected function flushValues()
{
$this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName}")->execute();
return true;
}
Deletes all values from cache. This is the implementation of the method declared in the parent class.
gc()
方法
|
protected void gc()
|
源码： framework/caching/CDbCache.php#297 (显示)
protected function gc()
{
$this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time())->execute();
}
Removes the expired data values.
getDbConnection()
方法
|
public CDbConnection getDbConnection()
| ||
| {return} | CDbConnection | the DB connection instance |
源码： framework/caching/CDbCache.php#146 (显示)
public function getDbConnection()
{
if($this->_db!==null)
return $this->_db;
elseif(($id=$this->connectionID)!==null)
{
if(($this->_db=Yii::app()->getComponent($id)) instanceof CDbConnection)
return $this->_db;
else
throw new CException(Yii::t('yii','CDbCache.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
array('{id}'=>$id)));
}
else
{
$dbFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'cache-'.Yii::getVersion().'.db';
return $this->_db=new CDbConnection('sqlite:'.$dbFile);
}
}
getGCProbability()
方法
|
public integer getGCProbability()
| ||
| {return} | integer | 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. |
源码： framework/caching/CDbCache.php#97 (显示)
public function getGCProbability()
{
return $this->_gcProbability;
}
getValue()
方法
|
protected string|boolean getValue(string $key)
| ||
| $key | string | a unique key identifying the cached value |
| {return} | string|boolean | the value stored in cache, false if the value is not in the cache or expired. |
源码： framework/caching/CDbCache.php#181 (显示)
protected function getValue($key)
{
$time=time();
$sql="SELECT value FROM {$this->cacheTableName} WHERE id='$key' AND (expire=0 OR expire>$time)";
$db=$this->getDbConnection();
if($db->queryCachingDuration>0)
{
$duration=$db->queryCachingDuration;
$db->queryCachingDuration=0;
$result=$db->createCommand($sql)->queryScalar();
$db->queryCachingDuration=$duration;
return $result;
}
else
return $db->createCommand($sql)->queryScalar();
}
Retrieves a value from cache with a specified key. This is the implementation of the method declared in the parent class.
getValues()
方法
|
protected array getValues(array $keys)
| ||
| $keys | array | a list of keys identifying the cached values |
| {return} | array | a list of cached values indexed by the keys |
源码： framework/caching/CDbCache.php#203 (显示)
protected function getValues($keys)
{
if(empty($keys))
return array();
$ids=implode("','",$keys);
$time=time();
$sql="SELECT id, value FROM {$this->cacheTableName} WHERE id IN ('$ids') AND (expire=0 OR expire>$time)";
$db=$this->getDbConnection();
if($db->queryCachingDuration>0)
{
$duration=$db->queryCachingDuration;
$db->queryCachingDuration=0;
$rows=$db->createCommand($sql)->queryAll();
$db->queryCachingDuration=$duration;
}
else
$rows=$db->createCommand($sql)->queryAll();
$results=array();
foreach($keys as $key)
$results[$key]=false;
foreach($rows as $row)
$results[$row['id']]=$row['value'];
return $results;
}
Retrieves multiple values from cache with the specified keys.
init()
方法
|
public void init()
|
源码： framework/caching/CDbCache.php#73 (显示)
public function init()
{
parent::init();
$db=$this->getDbConnection();
$db->setActive(true);
if($this->autoCreateCacheTable)
{
$sql="DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time();
try
{
$db->createCommand($sql)->execute();
}
catch(Exception $e)
{
$this->createCacheTable($db,$this->cacheTableName);
}
}
}
Initializes this application component.
This method is required by the IApplicationComponent interface.
It ensures the existence of the cache DB table.
It also removes expired data items from the cache.
setDbConnection()
方法
（自版本 v1.1.5 可用）
|
public void setDbConnection(CDbConnection $value)
| ||
| $value | CDbConnection | the DB connection instance |
源码： framework/caching/CDbCache.php#170 (显示)
public function setDbConnection($value)
{
$this->_db=$value;
}
Sets the DB connection used by the cache component.
setGCProbability()
方法
|
public void setGCProbability(integer $value)
| ||
| $value | integer | the probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all. |
源码： framework/caching/CDbCache.php#107 (显示)
public function setGCProbability($value)
{
$value=(int)$value;
if($value<0)
$value=0;
if($value>1000000)
$value=1000000;
$this->_gcProbability=$value;
}
setValue()
方法
|
protected boolean setValue(string $key, string $value, integer $expire)
| ||
| $key | string | the key identifying the value to be cached |
| $value | string | the value to be cached |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
源码： framework/caching/CDbCache.php#240 (显示)
protected function setValue($key,$value,$expire)
{
$this->deleteValue($key);
return $this->addValue($key,$value,$expire);
}
Stores a value identified by a key in cache. This is the implementation of the method declared in the parent class.