/*
 * Copyright 2006-2022 the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.springframework.batch.core.partition.support;

import java.util.Map;

import org.springframework.batch.item.ExecutionContext;

/**
 * Central strategy interface for creating input parameters for a partitioned step in the
 * form of {@link ExecutionContext} instances. The usual aim is to create a set of
 * distinct input values, e.g. a set of non-overlapping primary key ranges, or a set of
 * unique filenames.
 *
 * @author Dave Syer
 * @author Taeik Lim
 * @since 2.0
 */
@FunctionalInterface
public interface Partitioner {

	/**
	 * Create a set of distinct {@link ExecutionContext} instances together with a unique
	 * identifier for each one. The identifiers should be short, mnemonic values, and only
	 * have to be unique within the return value (e.g. use an incrementer).
	 * @param gridSize the size of the map to return
	 * @return a map from identifier to input parameters
	 */
	Map<String, ExecutionContext> partition(int gridSize);

}
