/*
* Copyright 2006-2011 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.core.step.builder;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.partition.PartitionHandler;
import org.springframework.batch.core.partition.StepExecutionSplitter;
import org.springframework.batch.core.partition.support.PartitionStep;
import org.springframework.batch.core.partition.support.Partitioner;
import org.springframework.batch.core.partition.support.SimpleStepExecutionSplitter;
import org.springframework.batch.core.partition.support.StepExecutionAggregator;
import org.springframework.batch.core.partition.support.TaskExecutorPartitionHandler;
import org.springframework.core.task.SyncTaskExecutor;
import org.springframework.core.task.TaskExecutor;
/**
* Step builder for {@link PartitionStep} instances. A partition step executes the same step (possibly remotely)
* multiple times with different input parameters (in the form of execution context). Useful for parallelization.
*
* @author Dave Syer
*
* @since 2.2
*/
public class PartitionStepBuilder extends StepBuilderHelper<PartitionStepBuilder> {
private TaskExecutor taskExecutor;
private Partitioner partitioner;
private static final int DEFAULT_GRID_SIZE = 6;
private Step step;
private PartitionHandler partitionHandler;
private int gridSize = DEFAULT_GRID_SIZE;
private StepExecutionSplitter splitter;
private StepExecutionAggregator aggregator;
private String stepName;
/**
* Create a new builder initialized with any properties in the parent. The parent is copied, so it can be re-used.
*
* @param parent a parent helper containing common step properties
*/
public PartitionStepBuilder(StepBuilderHelper<?> parent) {
super(parent);
}
/**
* Add a partitioner which can be used to create a {@link StepExecutionSplitter}. Use either this or an explicit
* {@link #splitter(StepExecutionSplitter)} but not both.
*
* @param slaveStepName the name of the slave step (used to construct step execution names)
* @param partitioner a partitioner to use
* @return this for fluent chaining
*/
public PartitionStepBuilder partitioner(String slaveStepName, Partitioner partitioner) {
this.stepName = slaveStepName;
this.partitioner = partitioner;
return this;
}
/**
* Provide an actual step instance to execute in parallel. If an explicit
* {@link #partitionHandler(PartitionHandler)} is provided, the step is optional and is only used to extract
* configuration data (name and other basic properties of a step).
*
* @param step a step to execute in parallel
* @return this for fluent chaining
*/
public PartitionStepBuilder step(Step step) {
this.step = step;
return this;
}
/**
* Provide a task executor to use when constructing a {@link PartitionHandler} from the {@link #step(Step)}. Mainly
* used for running a step locally in parallel, but can be used to execute remotely if the step is remote. Not used
* if an explicit {@link #partitionHandler(PartitionHandler)} is provided.
*
* @param taskExecutor a task executor to use when executing steps in parallel
* @return this for fluent chaining
*/
public PartitionStepBuilder taskExecutor(TaskExecutor taskExecutor) {
this.taskExecutor = taskExecutor;
return this;
}
/**
* Provide an explicit partition handler that will carry out the work of the partition step. The partition handler
* is the main SPI for adapting a partition step to a specific distributed computation environment. Optional if you
* only need local or remote processing through the Step interface.
*
* @see #step(Step) for setting up a default handler that works with a local or remote Step
*
* @param partitionHandler a partition handler
* @return this for fluent chaining
*/
public PartitionStepBuilder partitionHandler(PartitionHandler partitionHandler) {
this.partitionHandler = partitionHandler;
return this;
}
/**
* A hint to the {@link #splitter(StepExecutionSplitter)} about how many step executions are required. If running
* locally or remotely through a {@link #taskExecutor(TaskExecutor)} determines precisely the number of step
* execution sin the first attempt at a partition step execution.
*
* @param gridSize the grid size
* @return this for fluent chaining
*/
public PartitionStepBuilder gridSize(int gridSize) {
this.gridSize = gridSize;
return this;
}
/**
* Provide an explicit {@link StepExecutionSplitter} instead of having one build from the
* {@link #partitioner(String, Partitioner)}. USeful if you need more control over the splitting.
*
* @param splitter a step execution splitter
* @return this for fluent chaining
*/
public PartitionStepBuilder splitter(StepExecutionSplitter splitter) {
this.splitter = splitter;
return this;
}
/**
* Provide a step execution aggregator for aggregating partitioned step executions into a single result for the
* {@link PartitionStep} itself. Default is a simple implementation that works in most cases.
*
* @param aggregator a step execution aggregator
* @return this for fluent chaining
*/
public PartitionStepBuilder aggregator(StepExecutionAggregator aggregator) {
this.aggregator = aggregator;
return this;
}
public Step build() {
PartitionStep step = new PartitionStep();
step.setName(getName());
super.enhance(step);
if (partitionHandler != null) {
step.setPartitionHandler(partitionHandler);
}
else {
TaskExecutorPartitionHandler partitionHandler = new TaskExecutorPartitionHandler();
partitionHandler.setStep(this.step);
if (taskExecutor == null) {
taskExecutor = new SyncTaskExecutor();
}
partitionHandler.setGridSize(gridSize);
partitionHandler.setTaskExecutor(taskExecutor);
step.setPartitionHandler(partitionHandler);
}
if (splitter != null) {
step.setStepExecutionSplitter(splitter);
}
else {
boolean allowStartIfComplete = isAllowStartIfComplete();
String name = stepName;
if (this.step != null) {
try {
allowStartIfComplete = this.step.isAllowStartIfComplete();
name = this.step.getName();
}
catch (Exception e) {
logger.info("Ignored exception from step asking for name and allowStartIfComplete flag. "
+ "Using default from enclosing PartitionStep (" + name + "," + allowStartIfComplete + ").");
}
}
SimpleStepExecutionSplitter splitter = new SimpleStepExecutionSplitter();
splitter.setPartitioner(partitioner);
splitter.setJobRepository(getJobRepository());
splitter.setAllowStartIfComplete(allowStartIfComplete);
splitter.setStepName(name);
this.splitter = splitter;
step.setStepExecutionSplitter(splitter);
}
if (aggregator != null) {
step.setStepExecutionAggregator(aggregator);
}
try {
step.afterPropertiesSet();
}
catch (Exception e) {
throw new StepBuilderException(e);
}
return step;
}
protected TaskExecutor getTaskExecutor() {
return taskExecutor;
}
protected Partitioner getPartitioner() {
return partitioner;
}
protected Step getStep() {
return step;
}
protected PartitionHandler getPartitionHandler() {
return partitionHandler;
}
protected int getGridSize() {
return gridSize;
}
protected StepExecutionSplitter getSplitter() {
return splitter;
}
protected StepExecutionAggregator getAggregator() {
return aggregator;
}
protected String getStepName() {
return stepName;
}
}