# DbMutex

> DbMutex is the base class for classes, which relies on database while implementing mutex "lock" mechanism.

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [mutex](/docs/api/yii/mutex/index.md) › DbMutex

| abstract class | `yii\mutex\DbMutex` |
| --- | --- |
| Extends | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) » [`yii\base\Component`](/docs/api/yii/base/component/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| Implements | [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) |
| Since | 2.0 |
| Source | [`framework/mutex/DbMutex.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/mutex/DbMutex.php#L23) |

3 subclasses:

- [`MysqlMutex`](/docs/api/yii/mutex/mysqlmutex/index.md)
- [`OracleMutex`](/docs/api/yii/mutex/oraclemutex/index.md)
- [`PgsqlMutex`](/docs/api/yii/mutex/pgsqlmutex/index.md)

DbMutex is the base class for classes, which relies on database while implementing mutex "lock" mechanism.

See also: [`Mutex`](/docs/api/yii/mutex/mutex/index.md).

## Properties

| Property | Type | Description | Defined by |
| --- | --- | --- | --- |
| <span id="property-autoRelease"></span>[`$autoRelease`](/docs/api/yii/mutex/mutex/index.md#property-autoRelease) | `bool` | Whether all locks acquired in this process (i.e. local locks) must be released automatically before finishing script execution. Default: `true`. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |
| <span id="property-behaviors"></span>[`$behaviors`](/docs/api/yii/base/component/index.md#property-behaviors) read-only | `array<`[`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md)`<static>>` | List of behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`$db`](#property-db) | [`yii\db\Connection`](/docs/api/yii/db/connection/index.md)`\|array\|string` | The DB connection object or the application component ID of the DB connection. Default: `'db'`. | `DbMutex` |

## Methods

| Method | Description | Defined by |
| --- | --- | --- |
| <span id="method-__construct"></span>[`__construct()`](/docs/api/yii/base/baseobject/index.md#method-__construct) | Constructor. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__call"></span>[`__call()`](/docs/api/yii/base/component/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__clone"></span>[`__clone()`](/docs/api/yii/base/component/index.md#method-__clone) | This method is called after the object is created by cloning an existing one. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__get"></span>[`__get()`](/docs/api/yii/base/component/index.md#method-__get) | Returns the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__isset"></span>[`__isset()`](/docs/api/yii/base/component/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__set"></span>[`__set()`](/docs/api/yii/base/component/index.md#method-__set) | Sets the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__unset"></span>[`__unset()`](/docs/api/yii/base/component/index.md#method-__unset) | Sets a component property to be null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-acquire"></span>[`acquire()`](/docs/api/yii/mutex/mutex/index.md#method-acquire) | Acquires a lock by name. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |
| <span id="method-attachBehavior"></span>[`attachBehavior()`](/docs/api/yii/base/component/index.md#method-attachBehavior) | Attaches a behavior to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehaviors"></span>[`attachBehaviors()`](/docs/api/yii/base/component/index.md#method-attachBehaviors) | Attaches a list of behaviors to the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-behaviors"></span>[`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) | Returns a list of behaviors that this component should behave as. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canGetProperty"></span>[`canGetProperty()`](/docs/api/yii/base/component/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canSetProperty"></span>[`canSetProperty()`](/docs/api/yii/base/component/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-className"></span>[`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-detachBehavior"></span>[`detachBehavior()`](/docs/api/yii/base/component/index.md#method-detachBehavior) | Detaches a behavior from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-detachBehaviors"></span>[`detachBehaviors()`](/docs/api/yii/base/component/index.md#method-detachBehaviors) | Detaches all behaviors from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-ensureBehaviors"></span>[`ensureBehaviors()`](/docs/api/yii/base/component/index.md#method-ensureBehaviors) | Makes sure that the behaviors declared in [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) are attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehavior"></span>[`getBehavior()`](/docs/api/yii/base/component/index.md#method-getBehavior) | Returns the named behavior object. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehaviors"></span>[`getBehaviors()`](/docs/api/yii/base/component/index.md#method-getBehaviors) | Returns all behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasEventHandlers"></span>[`hasEventHandlers()`](/docs/api/yii/base/component/index.md#method-hasEventHandlers) | Returns a value indicating whether there is any handler attached to the named event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasMethod"></span>[`hasMethod()`](/docs/api/yii/base/component/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasProperty"></span>[`hasProperty()`](/docs/api/yii/base/component/index.md#method-hasProperty) | Returns a value indicating whether a property is defined for this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`init()`](#method-init) | Initializes generic database table based mutex implementation. | `DbMutex` |
| <span id="method-isAcquired"></span>[`isAcquired()`](/docs/api/yii/mutex/mutex/index.md#method-isAcquired) | Checks if a lock is acquired by the current process. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |
| <span id="method-off"></span>[`off()`](/docs/api/yii/base/component/index.md#method-off) | Detaches an existing event handler from this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-on"></span>[`on()`](/docs/api/yii/base/component/index.md#method-on) | Attaches an event handler to an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-release"></span>[`release()`](/docs/api/yii/mutex/mutex/index.md#method-release) | Releases acquired lock. This method will return false in case the lock was not found. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |
| <span id="method-trigger"></span>[`trigger()`](/docs/api/yii/base/component/index.md#method-trigger) | Triggers an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-acquireLock"></span>[`acquireLock()`](/docs/api/yii/mutex/mutex/index.md#method-acquireLock) protected abstract | This method should be extended by a concrete Mutex implementations. Acquires lock by name. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |
| <span id="method-releaseLock"></span>[`releaseLock()`](/docs/api/yii/mutex/mutex/index.md#method-releaseLock) protected abstract | This method should be extended by a concrete Mutex implementations. Releases lock by given name. | [`Mutex`](/docs/api/yii/mutex/mutex/index.md) |

## Property details

### $db <span id="property-db"></span>

```php
public yii\db\Connection|array|string $db = 'db'
```

The DB connection object or the application component ID of the DB connection.

After the Mutex 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.

## Method details

### init() <span id="method-init"></span>

```php
public function init(): mixed
```

Initializes generic database table based mutex implementation.

**Returns**

`mixed`

**Throws**

- [`yii\base\InvalidConfigException`](/docs/api/yii/base/invalidconfigexception/index.md): if [`$db`](/docs/api/yii/mutex/dbmutex/index.md#property-db) is invalid.