/**
 * 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.hadoop.yarn.server.resourcemanager.reservation;

import org.apache.hadoop.classification.InterfaceAudience.LimitedPrivate;
import org.apache.hadoop.classification.InterfaceStability.Unstable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.yarn.api.records.Resource;
import org.apache.hadoop.yarn.exceptions.YarnException;
import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
import org.apache.hadoop.yarn.server.resourcemanager.RMContext;
import org.apache.hadoop.yarn.server.resourcemanager.scheduler.QueueMetrics;
import org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceScheduler;
import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CSQueue;
import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler;
import org.apache.hadoop.yarn.util.resource.ResourceCalculator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This is the implementation of {@link ReservationSystem} based on the
 * {@link CapacityScheduler}
 */
@LimitedPrivate("yarn")
@Unstable
public class CapacityReservationSystem extends AbstractReservationSystem {

  private static final Logger LOG = LoggerFactory
      .getLogger(CapacityReservationSystem.class);

  private CapacityScheduler capScheduler;

  public CapacityReservationSystem() {
    super(CapacityReservationSystem.class.getName());
  }

  @Override
  public void reinitialize(Configuration conf, RMContext rmContext)
      throws YarnException {
    // Validate if the scheduler is capacity based
    ResourceScheduler scheduler = rmContext.getScheduler();
    if (!(scheduler instanceof CapacityScheduler)) {
      throw new YarnRuntimeException("Class "
          + scheduler.getClass().getCanonicalName() + " not instance of "
          + CapacityScheduler.class.getCanonicalName());
    }
    capScheduler = (CapacityScheduler) scheduler;
    this.conf = conf;
    super.reinitialize(conf, rmContext);
  }

  @Override
  protected Resource getMinAllocation() {
    return capScheduler.getMinimumResourceCapability();
  }

  @Override
  protected Resource getMaxAllocation() {
    return capScheduler.getMaximumResourceCapability();
  }

  @Override
  protected ResourceCalculator getResourceCalculator() {
    return capScheduler.getResourceCalculator();
  }

  @Override
  protected QueueMetrics getRootQueueMetrics() {
    return capScheduler.getRootQueueMetrics();
  }

  @Override
  protected String getPlanQueuePath(String planQueueName) {
    return capScheduler.getQueue(planQueueName).getQueuePath();
  }

  @Override
  protected Resource getPlanQueueCapacity(String planQueueName) {
    Resource minAllocation = getMinAllocation();
    ResourceCalculator rescCalc = getResourceCalculator();
    CSQueue planQueue = capScheduler.getQueue(planQueueName);
    return rescCalc.multiplyAndNormalizeDown(capScheduler.getClusterResource(),
        planQueue.getAbsoluteCapacity(), minAllocation);
  }

  @Override
  protected ReservationSchedulerConfiguration
      getReservationSchedulerConfiguration() {
    return capScheduler.getConfiguration();
  }

}