View Javadoc

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  
17  package org.springframework.batch.core.partition.support;
18  
19  import java.util.ArrayList;
20  import java.util.Collection;
21  
22  import org.springframework.batch.core.StepExecution;
23  import org.springframework.batch.core.explore.JobExplorer;
24  import org.springframework.beans.factory.InitializingBean;
25  import org.springframework.util.Assert;
26  
27  /**
28   * Convenience class for aggregating a set of {@link StepExecution} instances
29   * when the input comes from remote steps, so the data need to be refreshed from
30   * the repository.
31   *
32   * @author Dave Syer
33   * @since 2.1
34   */
35  public class RemoteStepExecutionAggregator implements StepExecutionAggregator, InitializingBean {
36  
37  	private StepExecutionAggregator delegate = new DefaultStepExecutionAggregator();
38  
39  	private JobExplorer jobExplorer;
40  
41  	/**
42  	 * Create a new instance (useful for configuration purposes).
43  	 */
44  	public RemoteStepExecutionAggregator() {
45  	}
46  
47  	/**
48  	 * Create a new instance with a job explorer that can be used to refresh the
49  	 * data when aggregating.
50  	 *
51  	 * @param jobExplorer the {@link JobExplorer} to use
52  	 */
53  	public RemoteStepExecutionAggregator(JobExplorer jobExplorer) {
54  		super();
55  		this.jobExplorer = jobExplorer;
56  	}
57  
58  	/**
59  	 * @param jobExplorer the jobExplorer to set
60  	 */
61  	public void setJobExplorer(JobExplorer jobExplorer) {
62  		this.jobExplorer = jobExplorer;
63  	}
64  
65  	/**
66  	 * @param delegate the delegate to set
67  	 */
68  	public void setDelegate(StepExecutionAggregator delegate) {
69  		this.delegate = delegate;
70  	}
71  
72  	/**
73  	 * @throws Exception if the job explorer is not provided
74  	 */
75  	@Override
76  	public void afterPropertiesSet() throws Exception {
77  		Assert.state(jobExplorer != null, "A JobExplorer must be provided");
78  	}
79  
80  	/**
81  	 * Aggregates the input executions into the result {@link StepExecution}
82  	 * delegating to the delegate aggregator once the input has been refreshed
83  	 * from the {@link JobExplorer}.
84  	 *
85  	 * @see StepExecutionAggregator #aggregate(StepExecution, Collection)
86  	 */
87  	@Override
88  	public void aggregate(StepExecution result, Collection<StepExecution> executions) {
89  		Assert.notNull(result, "To aggregate into a result it must be non-null.");
90  		if (executions == null) {
91  			return;
92  		}
93  		Collection<StepExecution> updates = new ArrayList<StepExecution>();
94  		for (StepExecution stepExecution : executions) {
95  			Long id = stepExecution.getId();
96  			Assert.state(id != null, "StepExecution has null id. It must be saved first: " + stepExecution);
97  			StepExecution update = jobExplorer.getStepExecution(stepExecution.getJobExecutionId(), id);
98  			Assert.state(update != null, "Could not reload StepExecution from JobRepository: " + stepExecution);
99  			updates.add(update);
100 		}
101 		delegate.aggregate(result, updates);
102 	}
103 
104 }