package org.javaee7.batch.sample.chunk.partition;
import org.javaee7.util.BatchTestHelper;
import org.jboss.arquillian.container.test.api.Deployment;
import org.jboss.arquillian.junit.Arquillian;
import org.jboss.shrinkwrap.api.ArchivePaths;
import org.jboss.shrinkwrap.api.ShrinkWrap;
import org.jboss.shrinkwrap.api.asset.EmptyAsset;
import org.jboss.shrinkwrap.api.spec.WebArchive;
import org.junit.Test;
import org.junit.runner.RunWith;
import javax.batch.operations.JobOperator;
import javax.batch.runtime.*;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import static org.junit.Assert.assertEquals;
/**
* The Batch specification provides a Chunk Oriented processing style. This style is defined by enclosing into a
* transaction a set of reads, process and write operations via +javax.batch.api.chunk.ItemReader+,
* +javax.batch.api.chunk.ItemProcessor+ and +javax.batch.api.chunk.ItemWriter+. Items are read one at a time, processed
* and aggregated. The transaction is then committed when the defined +checkpoint-policy+ is triggered.
*
* Many batch processing problems can be solved with single threaded, single process jobs, but the Batch specification
* allows for steps to be executed as a partitioned step, meaning that the step can be parallelized across multiple
* threads. This is useful if you have some kind of bottleneck or if you can considerable boost your batch processing
* performance by splitting the work to be done.
*
* You can define the number of partitions and the number of threads by using the element +partition+ in the +step+
* definition. Each partition is required to receive a set of unique parameters that instruct it into which data it
* should operate.
*
* Since each thread runs a separate copy of the step, chunking and checkpointing occur independently on each thread for
* chunk type steps.
*
* include::myJob.xml[]
*
* A job is defined in the +myJob.xml+ file. Just a single step with a reader, a processor and a writer. This step also
* defines that the step should be executed in two separate partitions: "1" and "2". Properties for each partition
* define the data that is going to be read. For partition "1" we start on 1 and end on 10. For partition "2" we start
* on 11 and end on 20. The +MyItemReader+ will generate the data based on these properties.
*
* include::MyItemReader[]
*
* @author Roberto Cortez
*/
@RunWith(Arquillian.class)
public class BatchChunkPartitionTest {
/**
* We're just going to deploy the application as a +web archive+. Note the inclusion of the following files:
*
* [source,file]
* ----
* /META-INF/batch-jobs/myJob.xml
* ----
*
* The +myJob.xml+ file is needed for running the batch definition.
*/
@Deployment
public static WebArchive createDeployment() {
WebArchive war = ShrinkWrap.create(WebArchive.class)
.addClass(BatchTestHelper.class)
.addPackage("org.javaee7.batch.sample.chunk.partition")
.addAsWebInfResource(EmptyAsset.INSTANCE, ArchivePaths.create("beans.xml"))
.addAsResource("META-INF/batch-jobs/myJob.xml");
System.out.println(war.toString(true));
return war;
}
/**
* In the test, we're just going to invoke the batch execution and wait for completion. To validate the test
* expected behaviour we need to query the +javax.batch.runtime.Metric+ object available in the step execution.
*
* The batch process itself will read and process 20 elements from numbers 1 to 20, but only write the odd
* elements. Elements from 1 to 10 will be processed in one partition and elements from 11 to 20 in another
* partition. Commits are executed after 3 elements are read by partition.
*
* @throws Exception an exception if the batch could not complete successfully.
*/
@Test
public void testBatchChunkPartition() throws Exception {
JobOperator jobOperator = BatchRuntime.getJobOperator();
Long executionId = jobOperator.start("myJob", new Properties());
JobExecution jobExecution = jobOperator.getJobExecution(executionId);
BatchTestHelper.keepTestAlive(jobExecution);
List<StepExecution> stepExecutions = jobOperator.getStepExecutions(executionId);
for (StepExecution stepExecution : stepExecutions) {
if (stepExecution.getStepName().equals("myStep")) {
Map<Metric.MetricType, Long> metricsMap = BatchTestHelper.getMetricsMap(stepExecution.getMetrics());
// <1> The read count should be 20 elements. Check +MyItemReader+.
assertEquals(20L, metricsMap.get(Metric.MetricType.READ_COUNT).longValue());
// <2> The write count should be 10. Only half of the elements read are processed to be written.
assertEquals(10L, metricsMap.get(Metric.MetricType.WRITE_COUNT).longValue());
// Number of elements by the item count value on myJob.xml, plus an additional transaction for the
// remaining elements by each partition.
long commitCount = (10L / 3 + (10 % 3 > 0 ? 1 : 0)) * 2;
// <3> The commit count should be 8. Checkpoint is on every 3rd read, 4 commits for read elements and 2 partitions.
assertEquals(commitCount, metricsMap.get(Metric.MetricType.COMMIT_COUNT).longValue());
}
}
// <4> Job should be completed.
assertEquals(BatchStatus.COMPLETED, jobExecution.getBatchStatus());
}
}