org.dataconservancy.pass.support.messaging.cri

Class DefaultConflictHandler

java.lang.Object

org.dataconservancy.pass.support.messaging.cri.DefaultConflictHandler

All Implemented Interfaces:

ConflictHandler

@Component
public class DefaultConflictHandler
extends Object
implements ConflictHandler

Resolves 412 Precondition Failed responses by re-retrieving the latest state of the resource from the repository, insuring the pre-condition for applying the update still holds, and then applying the update.

Author:

Elliot Metsger (emetsger@jhu.edu)

Constructor Summary

Constructors

Constructor and Description
DefaultConflictHandler(org.dataconservancy.pass.client.PassClient passClient)

Method Summary

Modifier and Type	Method and Description
<T extends org.dataconservancy.pass.model.PassEntity,R> R	handleConflict(T conflictedResource, Class<T> resourceClass, Predicate<T> preCondition, Function<T,R> criticalUpdate) Invoked when a 412 Precondition Failed is returned from a PATCH request to the repository.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultConflictHandler

public DefaultConflictHandler(org.dataconservancy.pass.client.PassClient passClient)

Method Detail

handleConflict

public <T extends org.dataconservancy.pass.model.PassEntity,R> R handleConflict(T conflictedResource,
                                                                                Class<T> resourceClass,
                                                                                Predicate<T> preCondition,
                                                                                Function<T,R> criticalUpdate)

Invoked when a 412 Precondition Failed is returned from a PATCH request to the repository.

Implementations are provided the the resource that includes the state to be updated, the function that performs the update, and the precondition that ought to be satisfied prior to invoking the update function.

Because this handler is being invoked in response to a 412, simply re-submitting the {PATCH} request with the supplied resource will always fail. Implementations will need to re-retrieve the the latest state of the resource, optionally apply the preCondition (insuring that the new state of the resource is still valid with respect to the criticalUpdate to be applied), and invoke the criticalUpdate.

Implementation notes Resolves 412 Precondition Failed responses by re-retrieving the latest state of the resource from the repository, insuring the pre-condition for applying the update still holds, and then applying the update.

Specified by:

handleConflict in interface ConflictHandler

Type Parameters:

T - the type of resource

R - the type of the response returned by the criticalUpdate

Parameters:

conflictedResource - the resource with the state to be updated

resourceClass - the runtime class of the resource

preCondition - the precondition that must be satisfied in order for the criticalUpdate to be applied

criticalUpdate - the update to be applied to the resource

Returns:

the return from the criticalUpdate