giraph-core/src/main/java/org/apache/giraph/partition/PartitionOwner.java

/*
 * 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.giraph.partition;

import org.apache.giraph.worker.WorkerInfo;
import org.apache.hadoop.io.Writable;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Map;

/**
 * Metadata about ownership of a partition.
 */
public interface PartitionOwner extends Writable {
  /**
   * Get the partition id that maps to the relevant {@link Partition} object
   *
   * @return Partition id
   */
  int getPartitionId();

  /**
   * Get the worker information that is currently responsible for
   * the partition id.
   *
   * @return Owning worker information.
   */
  WorkerInfo getWorkerInfo();

  /**
   * Set the current worker info.
   *
   * @param workerInfo Worker info responsible for partition
   */
  void setWorkerInfo(WorkerInfo workerInfo);

  /**
   * Get the worker information that was previously responsible for the
   * partition id.
   *
   * @return Owning worker information or null if no previous worker info.
   */
  WorkerInfo getPreviousWorkerInfo();

  /**
   * Set the previous worker info.
   *
   * @param workerInfo Worker info that was previously responsible for the
   *        partition.
   */
  void setPreviousWorkerInfo(WorkerInfo workerInfo);

  /**
   * Write to the output, but don't serialize the whole WorkerInfo,
   * instead use just the task id
   *
   * @param output Output to write to
   * @throws IOException
   */
  void writeWithWorkerIds(DataOutput output) throws IOException;

  /**
   * A match for writeWithWorkerIds method - for WorkerInfos it will read
   * just task ids from input and then find the matching WorkerInfo in the
   * provided map and set it
   *
   * @param input Input to read from
   * @param workerInfoMap Map from task id to WorkerInfo
   * @throws IOException
   */
  void readFieldsWithWorkerIds(DataInput input,
      Map<Integer, WorkerInfo> workerInfoMap) throws IOException;
}