content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.client.block.policy;
  
  import alluxio.client.block.BlockWorkerInfo;
  import alluxio.client.block.policy.options.GetWorkerOptions;
  import alluxio.conf.AlluxioConfiguration;
  import alluxio.wire.WorkerNetAddress;
  
  import com.google.common.base.MoreObjects;
  
  import java.util.Optional;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * A policy that returns the worker with the most available bytes.
   */
  @ThreadSafe
  public final class MostAvailableFirstPolicy implements BlockLocationPolicy {
  
    /**
     * Constructs a new {@link MostAvailableFirstPolicy}
     * needed for instantiation in {@link BlockLocationPolicy.Factory}.
     *
     * @param ignoredConf is unused
     */
    public MostAvailableFirstPolicy(AlluxioConfiguration ignoredConf) {}
  
    /**
     * The policy returns null if no worker is qualified.
     */
    @Override
    public Optional<WorkerNetAddress> getWorker(GetWorkerOptions options) {
      long mostAvailableBytes = -1;
      WorkerNetAddress result = null;
      for (BlockWorkerInfo workerInfo : options.getBlockWorkerInfos()) {
        if (workerInfo.getCapacityBytes() - workerInfo.getUsedBytes() > mostAvailableBytes) {
          mostAvailableBytes = workerInfo.getCapacityBytes() - workerInfo.getUsedBytes();
          result = workerInfo.getNetAddress();
        }
      }
      return Optional.ofNullable(result);
    }
  
    @Override
    public boolean equals(Object o) {
      return o instanceof MostAvailableFirstPolicy;
    }
  
    @Override
    public int hashCode() {
      return 0;
    }
  
    @Override
    public String toString() {
      return MoreObjects.toStringHelper(this).toString();
    }
  }
  