flink-core/src/main/java/org/apache/flink/core/io/InputSplit.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.flink.core.io;

import org.apache.flink.annotation.Public;

import java.io.Serializable;

/**
 * This interface must be implemented by all kind of input splits that can be assigned to input formats.
 * 
 * <p>Input splits are transferred in serialized form via the messages, so they need to be serializable
 * as defined by {@link java.io.Serializable}.</p>
 *
 * <p>Notes: Input splits will be compared to filter out the ones already assigned when job master failover,
 * so the method equals(Object) must be implemented.</p>
 */
@Public
public interface InputSplit extends Serializable {
	
	/**
	 * Returns the number of this input split.
	 * 
	 * @return the number of this input split
	 */
	int getSplitNumber();
}