1 /*
2 * Copyright 2006-2007 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.batch.core.partition.support;
18
19 import java.util.Map;
20
21 import org.springframework.batch.item.ExecutionContext;
22
23 /**
24 * Central strategy interface for creating input parameters for a partitioned
25 * step in the form of {@link ExecutionContext} instances. The usual aim is to
26 * create a set of distinct input values, e.g. a set of non-overlapping primary
27 * key ranges, or a set of unique filenames.
28 *
29 * @author Dave Syer
30 * @since 2.0
31 */
32 public interface Partitioner {
33
34 /**
35 * Create a set of distinct {@link ExecutionContext} instances together with
36 * a unique identifier for each one. The identifiers should be short,
37 * mnemonic values, and only have to be unique within the return value (e.g.
38 * use an incrementer).
39 *
40 * @param gridSize the size of the map to return
41 * @return a map from identifier to input parameters
42 */
43 Map<String, ExecutionContext> partition(int gridSize);
44
45 }