ShutdownCallbackRegistry

All Known Implementing Classes:

DefaultShutdownCallbackRegistry, Log4jContextFactory
```
public interface ShutdownCallbackRegistry
```
Registry used for Runnable shutdown callback instances. Due to differing requirements of how late in the JVM lifecycle Log4j should be shut down, this interface is provided for customizing how to register shutdown hook callbacks. Implementations may optionally implement LifeCycle.

Since:

2.1

Field Summary

Fields
Modifier and Type	Field	Description
`static java.lang.String`	`SHUTDOWN_CALLBACK_REGISTRY`	System property to set to choose the ShutdownCallbackRegistry.
`static java.lang.String`	`SHUTDOWN_HOOK_ENABLED`	System property to set to override the global ability to register shutdown hooks.
`static Marker`	`SHUTDOWN_HOOK_MARKER`	Shared Marker to indicate log messages corresponding to shutdown hooks.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Cancellable`	`addShutdownCallback(java.lang.Runnable callback)`	Adds a Runnable shutdown callback to this class.

- Field Detail
  - SHUTDOWN_CALLBACK_REGISTRY
```
static final java.lang.String SHUTDOWN_CALLBACK_REGISTRY
```
    System property to set to choose the ShutdownCallbackRegistry.
    
    See Also:
    
    Constant Field Values
  - SHUTDOWN_HOOK_ENABLED
```
static final java.lang.String SHUTDOWN_HOOK_ENABLED
```
    System property to set to override the global ability to register shutdown hooks.
    
    See Also:
    
    Constant Field Values
  - SHUTDOWN_HOOK_MARKER
```
static final Marker SHUTDOWN_HOOK_MARKER
```
    Shared Marker to indicate log messages corresponding to shutdown hooks.
- Method Detail
  - addShutdownCallback
```
Cancellable addShutdownCallback(java.lang.Runnable callback)
```
    Adds a Runnable shutdown callback to this class. Note: The returned Cancellable must be retained on heap by caller to avoid premature garbage-collection of the registered callback (and to ensure the callback runs on shutdown).
    
    Parameters:
    
    callback - the shutdown callback to be executed upon shutdown.
    
    Returns:
    
    a Cancellable wrapper of the provided callback or null if the shutdown hook is disabled and cannot be added.
    
    Since:
    
    2.1