1 /*
2 * Copyright 2006-2013 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 package org.springframework.batch.core.partition.support;
17
18 import java.util.Collection;
19 import java.util.Set;
20
21 import org.springframework.batch.core.StepExecution;
22 import org.springframework.batch.core.partition.PartitionHandler;
23 import org.springframework.batch.core.partition.StepExecutionSplitter;
24
25 /**
26 * Base {@link PartitionHandler} implementation providing common base
27 * features. Subclasses are expected to implement only the
28 * {@link #doHandle(org.springframework.batch.core.StepExecution, java.util.Set)}
29 * method which returns with the result of the execution(s) or an exception if
30 * the step failed to process.
31 *
32 * @author Sebastien Gerard
33 * @author Dave Syer
34 */
35 public abstract class AbstractPartitionHandler implements PartitionHandler {
36
37 private int gridSize = 1;
38
39 /**
40 * Executes the specified {@link StepExecution} instances and returns an updated
41 * view of them. Throws an {@link Exception} if anything goes wrong.
42 *
43 * @param masterStepExecution the whole partition execution
44 * @param partitionStepExecutions the {@link StepExecution} instances to execute
45 * @return an updated view of these completed {@link StepExecution} instances
46 * @throws Exception if anything goes wrong. This allows implementations to
47 * be liberal and rely on the caller to translate an exception into a step
48 * failure as necessary.
49 */
50 protected abstract Set<StepExecution> doHandle(StepExecution masterStepExecution,
51 Set<StepExecution> partitionStepExecutions) throws Exception;
52
53 /**
54 * @see PartitionHandler#handle(StepExecutionSplitter, StepExecution)
55 */
56 @Override
57 public Collection<StepExecution> handle(final StepExecutionSplitter stepSplitter,
58 final StepExecution masterStepExecution) throws Exception {
59 final Set<StepExecution> stepExecutions = stepSplitter.split(masterStepExecution, gridSize);
60
61 return doHandle(masterStepExecution, stepExecutions);
62 }
63
64 /**
65 * Returns the number of step executions.
66 *
67 * @return the number of step executions
68 */
69 public int getGridSize() {
70 return gridSize;
71 }
72
73 /**
74 * Passed to the {@link StepExecutionSplitter} in the
75 * {@link #handle(StepExecutionSplitter, StepExecution)} method, instructing
76 * it how many {@link StepExecution} instances are required, ideally. The
77 * {@link StepExecutionSplitter} is allowed to ignore the grid size in the
78 * case of a restart, since the input data partitions must be preserved.
79 *
80 * @param gridSize the number of step executions that will be created
81 */
82 public void setGridSize(int gridSize) {
83 this.gridSize = gridSize;
84 }
85
86 }
87