com.google.cloud.datastore.DatastoreHelper.java Source code

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Here is the source code for com.google.cloud.datastore.DatastoreHelper.java

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/*
 * Copyright 2015 Google LLC
 *
 * Licensed 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 com.google.cloud.datastore;

import com.google.common.collect.Iterators;
import com.google.common.collect.Maps;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * Provide functionality that should be added to the appropriate interfaces
 * via Java 8 default methods.
 */
class DatastoreHelper {

    private DatastoreHelper() {
    }

    static Key allocateId(Datastore service, IncompleteKey key) {
        return service.allocateId(new IncompleteKey[] { key }).get(0);
    }

    static Entity get(Transaction reader, Key key) {
        return Iterators.getNext(reader.get(new Key[] { key }), null);
    }

    static Entity get(Datastore reader, Key key, ReadOption... options) {
        return Iterators.getNext(reader.get(Collections.singletonList(key), options), null);
    }

    static Entity add(DatastoreWriter writer, FullEntity<?> entity) {
        return writer.add(new FullEntity<?>[] { entity }).get(0);
    }

    static Entity put(DatastoreWriter writer, FullEntity<?> entity) {
        return writer.put(new FullEntity<?>[] { entity }).get(0);
    }

    static KeyFactory newKeyFactory(DatastoreOptions options) {
        return new KeyFactory(options.getProjectId(), options.getNamespace());
    }

    /**
     * Returns a list with a value for each given key (ordered by input). {@code null} values are
     * returned for nonexistent keys.
     */
    static List<Entity> fetch(Transaction reader, Key... keys) {
        return compileEntities(keys, reader.get(keys));
    }

    /**
     * Returns a list with a value for each given key (ordered by input). {@code null} values are
     * returned for nonexistent keys.
     */
    static List<Entity> fetch(Datastore reader, Key[] keys, ReadOption... options) {
        return compileEntities(keys, reader.get(Arrays.asList(keys), options));
    }

    private static List<Entity> compileEntities(Key[] keys, Iterator<Entity> entities) {
        Map<Key, Entity> map = Maps.newHashMapWithExpectedSize(keys.length);
        while (entities.hasNext()) {
            Entity entity = entities.next();
            map.put(entity.getKey(), entity);
        }
        List<Entity> list = new ArrayList<>(keys.length);
        for (Key key : keys) {
            // this will include nulls for nonexistent keys
            list.add(map.get(key));
        }
        return list;
    }
}