001/*
002 * Copyright 2006-2007 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.batch.core.partition.support;
018
019import java.util.Map;
020
021import org.springframework.batch.item.ExecutionContext;
022
023/**
024 * Central strategy interface for creating input parameters for a partitioned
025 * step in the form of {@link ExecutionContext} instances. The usual aim is to
026 * create a set of distinct input values, e.g. a set of non-overlapping primary
027 * key ranges, or a set of unique filenames.
028 * 
029 * @author Dave Syer
030 * @since 2.0
031 */
032public interface Partitioner {
033
034        /**
035         * Create a set of distinct {@link ExecutionContext} instances together with
036         * a unique identifier for each one. The identifiers should be short,
037         * mnemonic values, and only have to be unique within the return value (e.g.
038         * use an incrementer).
039         * 
040         * @param gridSize the size of the map to return
041         * @return a map from identifier to input parameters
042         */
043        Map<String, ExecutionContext> partition(int gridSize);
044
045}