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.stress.cli.client;
  
  import alluxio.client.block.BlockWorkerInfo;
  import alluxio.client.block.policy.BlockLocationPolicy;
  import alluxio.client.block.policy.options.GetWorkerOptions;
  import alluxio.conf.AlluxioConfiguration;
  import alluxio.wire.WorkerNetAddress;
  
  import com.google.common.base.MoreObjects;
  import com.google.common.base.Objects;
  import com.google.common.collect.Lists;
  
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.atomic.AtomicInteger;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * Write type for restricting the writes to a set number of workers. This should only be used for
   * testing and benchmarking.
   */
  @NotThreadSafe
  public final class ClientIOWritePolicy implements BlockLocationPolicy {
    private static final AtomicInteger MAX_WORKERS = new AtomicInteger(1);
  
    private List<BlockWorkerInfo> mWorkerInfoList;
    private int mIndex;
    private volatile boolean mInitialized = false;
  
    /**
     * Updates the global state to reflect the max number of workers to write to. This must be set
     * before writes are performed to take effect.
     *
     * @param maxWorkers the max number of workers to write to
     */
    public static void setMaxWorkers(int maxWorkers) {
      MAX_WORKERS.set(maxWorkers);
    }
  
    /**
     * Constructs a new {@link ClientIOWritePolicy}.
     * needed for instantiation in {@link BlockLocationPolicy.Factory}.
     *
     * @param ignoredConf is unused
     */
    public ClientIOWritePolicy(AlluxioConfiguration ignoredConf) {}
  
    /**
     *
     * @param options options
     * @return the address of the worker to write to
     */
    @Override
    public synchronized Optional<WorkerNetAddress> getWorker(GetWorkerOptions options) {
      Map<WorkerNetAddress, BlockWorkerInfo> eligibleWorkers = new HashMap<>();
      for (BlockWorkerInfo info : options.getBlockWorkerInfos()) {
        eligibleWorkers.put(info.getNetAddress(), info);
      }
  
      if (!mInitialized) {
        mWorkerInfoList = Lists.newArrayList(options.getBlockWorkerInfos());
        // sort by hashcode
        mWorkerInfoList.sort(Comparator.comparing(w -> w.getNetAddress().getHost()));
        // take the first subset
        mWorkerInfoList =
            mWorkerInfoList.subList(0, Math.min(MAX_WORKERS.get(), mWorkerInfoList.size()));
        if (mWorkerInfoList.size() < MAX_WORKERS.get()) {
          throw new IllegalStateException(String
              .format("Not enough eligible workers. expected: %d actual: %d", MAX_WORKERS.get(),
                  mWorkerInfoList.size()));
        }
        mIndex = 0;
        mInitialized = true;
      }
  
      for (int i = 0; i < mWorkerInfoList.size(); i++) {
        WorkerNetAddress candidate = mWorkerInfoList.get(mIndex).getNetAddress();
        mIndex = (mIndex + 1) % mWorkerInfoList.size();
  
        BlockWorkerInfo workerInfo = eligibleWorkers.get(candidate);
        if (workerInfo != null && workerInfo.getCapacityBytes() >= options.getBlockInfo()
            .getLength()) {
          return Optional.of(candidate);
        }
      }
  
      return Optional.empty();
    }
  
    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (!(o instanceof ClientIOWritePolicy)) {
        return false;
      }
      ClientIOWritePolicy that = (ClientIOWritePolicy) o;
      return Objects.equal(mWorkerInfoList, that.mWorkerInfoList)
          && Objects.equal(mIndex, that.mIndex)
          && Objects.equal(mInitialized, that.mInitialized);
    }
  
    @Override
    public int hashCode() {
      return Objects.hashCode(mWorkerInfoList, mIndex, mInitialized);
    }
  
    @Override
    public String toString() {
      return MoreObjects.toStringHelper(this)
          .add("workerInfoList", mWorkerInfoList)
          .add("index", mIndex)
          .add("initialized", mInitialized)
          .toString();
    }
  }
  