com.ikanow.aleph2.management_db.mongodb.utils.MongoDbCollectionUtils.java Source code

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Here is the source code for com.ikanow.aleph2.management_db.mongodb.utils.MongoDbCollectionUtils.java

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/*******************************************************************************
 * Copyright 2015, The IKANOW Open Source Project.
 * 
 * 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.ikanow.aleph2.management_db.mongodb.utils;

import java.util.stream.IntStream;

import scala.Tuple3;

import com.ikanow.aleph2.data_model.utils.Tuples;
import com.mongodb.DB;
import com.mongodb.Mongo;

/** Utilities for handling naming bucket/library/analytics stores
 * @author Alex
 */
public class MongoDbCollectionUtils {

    private static final int MAX_COLLS_PER_DB = 201;

    /** Finds the right database - iterates through DBs until it either finds the collection or not, if not then it finds the first DB with < 200 collections in it
     * @param client
     * @param collection_name
     * @return
     */
    public static DB findDatabase(final Mongo client, String db_name_prefix, String collection_name) {

        // Does the collection exist? Keep looking until we find an empty DB
        final Tuple3<Boolean, Boolean, DB> intermediate = IntStream.iterate(1, i -> i + 1).boxed()
                .map(ii -> db_name_prefix + "_" + ii).map(dbn -> client.getDB(dbn)).map(db -> {
                    final boolean is_empty = db.getCollectionNames().isEmpty();
                    final boolean contains_names = !is_empty && db.collectionExists(collection_name);
                    return Tuples._3T(is_empty, contains_names, db);
                }).filter(t3 -> t3._1() || t3._2()).findFirst().get();
        //(guaranteed we'll either find an empty DB or one containing our collection)

        // If the collection doesn't exist, find the first available DB 
        return intermediate._2() ? intermediate._3()
                : IntStream.iterate(1, i -> i + 1).boxed().map(ii -> db_name_prefix + "_" + ii)
                        .map(dbn -> client.getDB(dbn))
                        .filter(db -> db.getCollectionNames().size() < MAX_COLLS_PER_DB).findFirst().get();
    }
}