| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.rya.indexing.mongodb.update; |
| |
| import static java.util.Objects.requireNonNull; |
| |
| import java.util.Optional; |
| import java.util.function.Function; |
| |
| import org.apache.rya.indexing.mongodb.IndexingException; |
| |
| import edu.umd.cs.findbugs.annotations.DefaultAnnotation; |
| import edu.umd.cs.findbugs.annotations.NonNull; |
| |
| /** |
| * Performs an update operation on a Document in mongodb. |
| * @param <T> - The key to find the object. |
| * @param <V> - The type of object to get updated. |
| */ |
| @DefaultAnnotation(NonNull.class) |
| public interface DocumentUpdater<T, V> { |
| public default void update(final T key, final DocumentMutator<V> mutator) throws IndexingException { |
| requireNonNull(mutator); |
| |
| // Fetch the current state of the Entity. |
| boolean completed = false; |
| while(!completed) { |
| //this cast is safe since the mutator interface is defined below to use Optional<V> |
| final Optional<V> old = getOld(key); |
| final Optional<V> updated = mutator.apply(old); |
| |
| final boolean doWork = updated.isPresent(); |
| if(doWork) { |
| if(!old.isPresent()) { |
| create(updated.get()); |
| } else { |
| update(old.get(), updated.get()); |
| } |
| } |
| completed = true; |
| } |
| } |
| |
| Optional<V> getOld(T key) throws IndexingException; |
| |
| void create(final V newObj) throws IndexingException; |
| |
| void update(final V old, final V updated) throws IndexingException; |
| |
| /** |
| * Implementations of this interface are used to update the state of a |
| * {@link DocumentUpdater#V} in unison with a {@link DocumentUpdater}. |
| * </p> |
| * This table describes what the updater will do depending on if the object |
| * exists and if an updated object is returned. |
| * </p> |
| * <table border="1px"> |
| * <tr><th>Object Provided</th><th>Update Returned</th><th>Effect</th></tr> |
| * <tr> |
| * <td>true</td> |
| * <td>true</td> |
| * <td>The old Object will be updated using the returned state.</td> |
| * </tr> |
| * <tr> |
| * <td>true</td> |
| * <td>false</td> |
| * <td>No work is performed.</td> |
| * </tr> |
| * <tr> |
| * <td>false</td> |
| * <td>true</td> |
| * <td>A new Object will be created using the returned state.</td> |
| * </tr> |
| * <tr> |
| * <td>false</td> |
| * <td>false</td> |
| * <td>No work is performed.</td> |
| * </tr> |
| * </table> |
| */ |
| public interface DocumentMutator<V> extends Function<Optional<V>, Optional<V>> { } |
| } |