org.springframework.batch.core.step.item
Class FaultTolerantChunkProcessor<I,O>

java.lang.Object
  org.springframework.batch.core.step.item.SimpleChunkProcessor<I,O>
      org.springframework.batch.core.step.item.FaultTolerantChunkProcessor<I,O>

All Implemented Interfaces:

ChunkProcessor<I>, InitializingBean

public class FaultTolerantChunkProcessor<I,O>
extends SimpleChunkProcessor<I,O>

FaultTolerant implementation of the ChunkProcessor interface, that allows for skipping or retry of items that cause exceptions during writing.

Constructor Summary

FaultTolerantChunkProcessor(ItemProcessor<? super I,? extends O> itemProcessor, ItemWriter<? super O> itemWriter, BatchRetryTemplate batchRetryTemplate)

Method Summary

protected Chunk<O>	getAdjustedOutputs(Chunk<I> inputs, Chunk<O> outputs) Extension point for subclasses that want to adjust the outputs based on additional saved data in the inputs.
protected int	getFilterCount(Chunk<I> inputs, Chunk<O> outputs) Extension point for subclasses to calculate the filter count.
protected void	initializeUserData(Chunk<I> inputs) Extension point for subclasses to allow them to memorise the contents of the inputs, in case they are needed for accounting purposes later.
protected boolean	isComplete(Chunk<I> inputs) Extension point for subclasses that want to store additional data in the inputs.
void	setBuffering(boolean buffering) A flag to indicate that items have been buffered and therefore will always come back as a chunk after a rollback.
void	setChunkMonitor(org.springframework.batch.core.step.item.ChunkMonitor chunkMonitor)
void	setKeyGenerator(KeyGenerator keyGenerator) The KeyGenerator to use to identify failed items across rollback.
void	setProcessorTransactional(boolean processorTransactional) Flag to say that the ItemProcessor is transactional (defaults to true).
void	setProcessSkipPolicy(SkipPolicy SkipPolicy)
void	setRollbackClassifier(Classifier<Throwable,Boolean> rollbackClassifier) A classifier that can distinguish between exceptions that cause rollback (return true) or not (return false).
void	setWriteSkipPolicy(SkipPolicy SkipPolicy)
protected Chunk<O>	transform(StepContribution contribution, Chunk<I> inputs)
protected void	write(StepContribution contribution, Chunk<I> inputs, Chunk<O> outputs) Simple implementation delegates to the SimpleChunkProcessor.doWrite(List) method and increments the write count in the contribution.

Methods inherited from class org.springframework.batch.core.step.item.SimpleChunkProcessor

afterPropertiesSet, doAfterWrite, doOnWriteError, doProcess, doWrite, getListener, process, registerListener, setItemProcessor, setItemWriter, setListeners, writeItems

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FaultTolerantChunkProcessor

public FaultTolerantChunkProcessor(ItemProcessor<? super I,? extends O> itemProcessor,
                                   ItemWriter<? super O> itemWriter,
                                   BatchRetryTemplate batchRetryTemplate)

Method Detail

setKeyGenerator

public void setKeyGenerator(KeyGenerator keyGenerator)

The KeyGenerator to use to identify failed items across rollback. Not used in the case of the buffering flag being true (the default).

Parameters:

keyGenerator - the KeyGenerator to set

setProcessSkipPolicy

public void setProcessSkipPolicy(SkipPolicy SkipPolicy)

Parameters:

SkipPolicy - the SkipPolicy for item processing

setWriteSkipPolicy

public void setWriteSkipPolicy(SkipPolicy SkipPolicy)

Parameters:

SkipPolicy - the SkipPolicy for item writing

setRollbackClassifier

public void setRollbackClassifier(Classifier<Throwable,Boolean> rollbackClassifier)

A classifier that can distinguish between exceptions that cause rollback (return true) or not (return false).

Parameters:

rollbackClassifier -

setChunkMonitor

public void setChunkMonitor(org.springframework.batch.core.step.item.ChunkMonitor chunkMonitor)

Parameters:

chunkMonitor -

setBuffering

public void setBuffering(boolean buffering)

A flag to indicate that items have been buffered and therefore will always come back as a chunk after a rollback. Otherwise things are more complicated because after a rollback the new chunk might or might not contain items from the previous failed chunk.

Parameters:

buffering -

setProcessorTransactional

public void setProcessorTransactional(boolean processorTransactional)

Flag to say that the ItemProcessor is transactional (defaults to true). If false then the processor is only called once per item per chunk, even if there are rollbacks with retries and skips.

Parameters:

processorTransactional - the flag value to set

initializeUserData

protected void initializeUserData(Chunk<I> inputs)

Description copied from class: SimpleChunkProcessor

Extension point for subclasses to allow them to memorise the contents of the inputs, in case they are needed for accounting purposes later. The default implementation sets up some user data to remember the original size of the inputs. If this method is overridden then some or all of SimpleChunkProcessor.isComplete(Chunk), SimpleChunkProcessor.getFilterCount(Chunk, Chunk) and SimpleChunkProcessor.getAdjustedOutputs(Chunk, Chunk) might also need to be, to ensure that the user data is handled consistently.

Overrides:

initializeUserData in class SimpleChunkProcessor<I,O>

Parameters:

inputs - the inputs for the process

getFilterCount

protected int getFilterCount(Chunk<I> inputs,
                             Chunk<O> outputs)

Description copied from class: SimpleChunkProcessor

Extension point for subclasses to calculate the filter count. Defaults to the difference between input size and output size.

Overrides:

getFilterCount in class SimpleChunkProcessor<I,O>

Parameters:

inputs - the inputs after transformation

outputs - the outputs after transformation

Returns:

the difference in sizes

See Also:

SimpleChunkProcessor.initializeUserData(Chunk)

isComplete

protected boolean isComplete(Chunk<I> inputs)

Description copied from class: SimpleChunkProcessor

Extension point for subclasses that want to store additional data in the inputs. Default just checks if inputs are empty.

Overrides:

isComplete in class SimpleChunkProcessor<I,O>

Parameters:

inputs - the input chunk

Returns:

true if it is empty

See Also:

SimpleChunkProcessor.initializeUserData(Chunk)

getAdjustedOutputs

protected Chunk<O> getAdjustedOutputs(Chunk<I> inputs,
                                      Chunk<O> outputs)

Description copied from class: SimpleChunkProcessor

Extension point for subclasses that want to adjust the outputs based on additional saved data in the inputs. Default implementation just returns the outputs unchanged.

Overrides:

getAdjustedOutputs in class SimpleChunkProcessor<I,O>

Parameters:

inputs - the inputs for the transformation

outputs - the result of the transformation

Returns:

the outputs unchanged

See Also:

SimpleChunkProcessor.initializeUserData(Chunk)

transform

protected Chunk<O> transform(StepContribution contribution,
                             Chunk<I> inputs)
                      throws Exception

Overrides:

transform in class SimpleChunkProcessor<I,O>

Throws:

Exception

write

protected void write(StepContribution contribution,
                     Chunk<I> inputs,
                     Chunk<O> outputs)
              throws Exception

Description copied from class: SimpleChunkProcessor

Simple implementation delegates to the SimpleChunkProcessor.doWrite(List) method and increments the write count in the contribution. Subclasses can handle more complicated scenarios, e.g.with fault tolerance. If output items are skipped they should be removed from the inputs as well.

Overrides:

write in class SimpleChunkProcessor<I,O>

Parameters:

contribution - the current step contribution

inputs - the inputs that gave rise to the ouputs

outputs - the outputs to write

Throws:

Exception - if there is a problem