org.neo4j.graphdb.event
Interface KernelEventHandler

public interface KernelEventHandler

Event handler interface for Neo4j Kernel life cycle events.

Author:

Tobias Ivarsson

Nested Class Summary

static class

KernelEventHandler.ExecutionOrder Represents the order of execution between two event handlers, if one handler should be executed KernelEventHandler.ExecutionOrder.BEFORE, KernelEventHandler.ExecutionOrder.AFTER another handler, or if it KernelEventHandler.ExecutionOrder.DOESNT_MATTER.

Method Summary

void	beforeShutdown() This method is invoked during the shutdown process of a Neo4j Graph Database.
Object	getResource() Returns the resource associated with this event handler, or null if no specific resource is associated with this handler or if it isn't desirable to expose it.
void	kernelPanic(ErrorState error) This is invoked when the Neo4j Graph Database enters a state from which it cannot continue.
KernelEventHandler.ExecutionOrder	orderComparedTo(KernelEventHandler other) Gives a hint about when to execute this event handler, compared to other handlers.

Method Detail

beforeShutdown

void beforeShutdown()

This method is invoked during the shutdown process of a Neo4j Graph Database. It is invoked while the GraphDatabaseService is still in an operating state, after the processing of this event has terminated the Neo4j Graph Database will terminate. This event can be used to shut down other services that depend on the GraphDatabaseService.

kernelPanic

void kernelPanic(ErrorState error)

This is invoked when the Neo4j Graph Database enters a state from which it cannot continue.

Parameters:

error - an object describing the state that the GraphDatabaseService failed to recover from.

getResource

Object getResource()

Returns the resource associated with this event handler, or null if no specific resource is associated with this handler or if it isn't desirable to expose it. It can be used to aid in the decision process of in which order to execute the handlers, see orderComparedTo(KernelEventHandler).

Returns:

the resource associated to this event handler, or null.

orderComparedTo

KernelEventHandler.ExecutionOrder orderComparedTo(KernelEventHandler other)

Gives a hint about when to execute this event handler, compared to other handlers. If this handler must be executed before other then KernelEventHandler.ExecutionOrder.BEFORE should be returned. If this handler must be executed after other then KernelEventHandler.ExecutionOrder.AFTER should be returned. If it doesn't matter KernelEventHandler.ExecutionOrder.DOESNT_MATTER should be returned.

Parameters:

other - the other event handler to compare to.

Returns:

the execution order compared to other.