runtime/executor/src/main/java/org/apache/nemo/runtime/executor/data/partition/Partition.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.nemo.runtime.executor.data.partition;

import java.io.IOException;

/**
 * A collection of data elements.
 * This is a unit of read / write towards {@link org.apache.nemo.runtime.executor.data.block.Block}s.
 *
 * @param <T> the type of the data stored in this {@link Partition}.
 * @param <K> the type of key used for {@link Partition}.
 */
public interface Partition<T, K> {

  /**
   * Writes an element to non-committed partition.
   *
   * @param element element to write.
   * @throws IOException if the partition is already committed.
   */
  void write(Object element) throws IOException;

  /**
   * Commits a partition to prevent further data write.
   *
   * @throws IOException if fail to commit partition.
   */
  void commit() throws IOException;

  /**
   * @return the key value.
   */
  K getKey();

  /**
   * @return whether the data in this {@link Partition} is serialized or not.
   */
  boolean isSerialized();

  /**
   * @return the data in this {@link Partition}.
   * @throws IOException if the partition is not committed yet.
   */
  T getData() throws IOException;
}