net.openhft.chronicle.core.shutdown

Class PriorityHook

java.lang.Object

net.openhft.chronicle.core.shutdown.PriorityHook

public class PriorityHook
extends Object

Manager for orderly shutdown.

Hooklets are stored in a priority ordered map and executed by a single dedicated thread when the JVM terminates. All modifications are synchronised to make the class thread-safe.

Use unique priorities between 0-100 so that unrelated components do not interfere with each other's shutdown ordering.

Method Summary

Modifier and Type	Method and Description
static boolean	add(int priority, Runnable hook) Add a shutdown hook with a specified priority.
static <H extends Hooklet> H	addAndGet(H hooklet) Add a custom shutdown hook.
static void	clear() Remove the registered JVM shutdown hook and discard all hooklets.
static PriorityHook	getRegisteredHook() Obtain the singleton managing the shutdown hook, if present.
void	onShutdown() Execute registered hooklets in priority order.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

add

public static boolean add(int priority,
                          Runnable hook)

Add a shutdown hook with a specified priority.

Will prevent adding the same hook (by parameter's class) more than once, return false in that case.

Parameters:

priority - value passed to Hooklet.priority()

hook - action to run on shutdown

Returns:

true if the hook was newly registered

Throws:

NullPointerException - if hook is null

addAndGet

public static <H extends Hooklet> H addAndGet(H hooklet)

Add a custom shutdown hook.

Will prevent adding the same hook (by parameter's class) more than once, return the existing one in that case. See Hooklet.identity().

Type Parameters:

H - hooklet subtype

Parameters:

hooklet - instance to register

Returns:

the hooklet that will be executed

Throws:

NullPointerException - if hooklet is null

clear

public static void clear()

Remove the registered JVM shutdown hook and discard all hooklets.

onShutdown

public void onShutdown()

Execute registered hooklets in priority order.

getRegisteredHook

public static PriorityHook getRegisteredHook()

Obtain the singleton managing the shutdown hook, if present.

Returns:

current PriorityHook instance or null