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ExistenceChecker.java
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ExistenceChecker.java
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/*
* Copyright (c) 2022 Contributors to the Eclipse Foundation
*
* See the NOTICE file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0
*
* SPDX-License-Identifier: EPL-2.0
*/
package org.eclipse.ditto.policies.enforcement.pre_enforcement;
import static org.eclipse.ditto.base.model.common.ConditionChecker.checkNotNull;
import java.util.concurrent.CompletionStage;
import org.eclipse.ditto.base.model.signals.Signal;
import org.eclipse.ditto.base.service.DittoExtensionPoint;
import akka.actor.ActorSystem;
/**
* Checks existence of a signals' entity, in effort to validate f the entity already exists.
* @since 3.0.0
*/
public interface ExistenceChecker extends DittoExtensionPoint {
/**
* Checks the existence of the sings entity
* @param signal the signal from which to get the entity.
* @return whether the entity exists.
*/
CompletionStage<Boolean> checkExistence(final Signal<?> signal);
/**
* Loads the implementation of {@code ExistenceChecker} which is configured for the {@code ActorSystem}.
*
* @param actorSystem the actorSystem in which the {@code ExistenceChecker} should be loaded.
* @return the {@code ExistenceChecker} implementation.
* @throws NullPointerException if {@code actorSystem} is {@code null}.
*/
static ExistenceChecker get(final ActorSystem actorSystem) {
checkNotNull(actorSystem, "actorSystem");
return ExtensionId.INSTANCE.get(actorSystem);
}
final class ExtensionId extends DittoExtensionPoint.ExtensionId<ExistenceChecker> {
private static final String CONFIG_PATH = "ditto.existence-checker";
private static final ExistenceChecker.ExtensionId INSTANCE = new ExtensionId(ExistenceChecker.class);
private ExtensionId(final Class<ExistenceChecker> parentClass) {
super(parentClass);
}
@Override
protected String getConfigPath() {
return CONFIG_PATH;
}
}
}