org.apache.rya.indexing.mongodb.update.MongoDocumentUpdater Maven / Gradle / Ivy

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/*
 * 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  - The key to find the object.
 * @param  - The type of object to get updated.
 */
@DefaultAnnotation(NonNull.class)
public interface MongoDocumentUpdater {
    public default void update(final T key, final DocumentMutator 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
            final Optional old = getOld(key);
            final Optional 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 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 MongoDocumentUpdater#V} in unison with a {@link MongoDocumentUpdater}.
     * 
     * This table describes what the updater will do depending on if the object
     * exists and if an updated object is returned.
     * 
     * 
     *     
     *     
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *     
     *     
     *         
     *         
     *         
     *     
     * Object Provided Update Returned Effect
true true The old Object will be updated using the returned state.
true false No work is performed.
false true A new Object will be created using the returned state.
false false No work is performed.
     */
    public interface DocumentMutator extends Function, Optional> { }
}
Object Provided	Update Returned	Effect
true	true	The old Object will be updated using the returned state.
true	false	No work is performed.
false	true	A new Object will be created using the returned state.
false	false	No work is performed.