/*
 * Copyright 2010-2014 Orient Technologies LTD (info(at)orientechnologies.com)
 *
 * 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.orientechnologies.orient.core.metadata.schema.clusterselection;

import com.orientechnologies.orient.core.metadata.schema.OClass;
import com.orientechnologies.orient.core.record.impl.ODocument;

import java.util.concurrent.atomic.AtomicLong;

/**
 * Returns the cluster selecting by round robin algorithm.
 * 
 * @author Luca Garulli (l.garulli--at--orientechnologies.com)
 */
public class ORoundRobinClusterSelectionStrategy implements OClusterSelectionStrategy {
  public static final String NAME    = "round-robin";
  private AtomicLong         pointer = new AtomicLong(0);

  public int getCluster(final OClass clazz, final ODocument doc) {
    final int[] clusters = clazz.getClusterIds();
    if (clusters.length == 1)
      // ONLY ONE: RETURN THE FIRST ONE
      return clusters[0];

    return clusters[(int) (pointer.getAndIncrement() % clusters.length)];
  }

  @Override
  public String getName() {
    return NAME;
  }
}