RollbackOnFailure (nifi-processor-utils 1.9.1 API)

java.lang.Object
- org.apache.nifi.processor.util.pattern.RollbackOnFailure

```
public class RollbackOnFailure
extends Object
```
RollbackOnFailure can be used as a function context for process patterns such as Put to provide a configurable error handling.
RollbackOnFailure can add following characteristics to a processor:
When disabled, input FlowFiles caused an error will be routed to 'failure' or 'retry' relationship, based on the type of error.
When enabled, input FlowFiles are kept in the input queue. A ProcessException is thrown to rollback the process session.
It assumes anything happened during a processors onTrigger can rollback, if this is marked as transactional.
If transactional and enabled, even if some FlowFiles are already processed, it rollbacks the session when error occurs.
If not transactional and enabled, it only rollbacks the session when error occurs only if there was no progress.

There are two approaches to apply RollbackOnFailure. One is using ExceptionHandler.adjustError(BiFunction), and the other is implementing processor onTrigger using process patterns such as Put#adjustRoute(AdjustRoute).

It's also possible to use both approaches. ExceptionHandler can apply when an Exception is thrown immediately, while AdjustRoute respond later but requires less code.

Field Summary

Fields
Modifier and Type	Field and Description
`private boolean`	`discontinue`
`private int`	`processedCount`
`static PropertyDescriptor`	`ROLLBACK_ON_FAILURE`
`private boolean`	`rollbackOnFailure`
`private boolean`	`transactional`

Constructor Summary

Constructors
Constructor and Description

RollbackOnFailure(boolean rollbackOnFailure, boolean transactional)
Constructor.

Constructors
Constructor and Description
`RollbackOnFailure(boolean rollbackOnFailure, boolean transactional)` Constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`canRollback()`
`static <FCT extends RollbackOnFailure> BiFunction<FCT,ErrorTypes,ErrorTypes.Result>`	`createAdjustError(ComponentLog logger)` Create a function to use with `ExceptionHandler` that adjust error type based on functional context.
`static <FCT extends RollbackOnFailure> PartialFunctions.AdjustRoute<FCT>`	`createAdjustRoute(Relationship... failureRelationships)` Create an `PartialFunctions.AdjustRoute` function to use with process pattern such as `Put` that adjust routed FlowFiles based on context.
`static <FCT extends RollbackOnFailure,I> ExceptionHandler.OnError<FCT,I>`	`createOnError(ExceptionHandler.OnError<FCT,I> onError)`
`static PropertyDescriptor`	`createRollbackOnFailureProperty(String additionalDescription)`
`void`	`discontinue()`
`int`	`getProcessedCount()`
`boolean`	`isRollbackOnFailure()`
`boolean`	`isTransactional()`
`static <FCT extends RollbackOnFailure> void`	`onTrigger(ProcessContext context, ProcessSessionFactory sessionFactory, FCT functionContext, ComponentLog logger, PartialFunctions.OnTrigger onTrigger)`
`int`	`proceed()`
`boolean`	`shouldDiscontinue()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

rollbackOnFailure

private final boolean rollbackOnFailure

transactional
```
private final boolean transactional
```

discontinue
```
private boolean discontinue
```

processedCount
```
private int processedCount
```

ROLLBACK_ON_FAILURE

public static final PropertyDescriptor ROLLBACK_ON_FAILURE

Constructor Detail
- RollbackOnFailure
```
public RollbackOnFailure(boolean rollbackOnFailure,
                         boolean transactional)
```
  Constructor.
  
  Parameters:
  
  rollbackOnFailure - Should be set by user via processor configuration.
  
  transactional - Specify whether a processor is transactional. If not, it is important to call proceed() after successful execution of processors task, that indicates processor made an operation that can not be undone.

Method Detail

createRollbackOnFailureProperty

public static PropertyDescriptor createRollbackOnFailureProperty(String additionalDescription)

createAdjustError

public static <FCT extends RollbackOnFailure> BiFunction<FCT,ErrorTypes,ErrorTypes.Result> createAdjustError(ComponentLog logger)

Create a function to use with ExceptionHandler that adjust error type based on functional context.

createAdjustRoute
```
public static <FCT extends RollbackOnFailure> PartialFunctions.AdjustRoute<FCT> createAdjustRoute(Relationship... failureRelationships)
```
Create an PartialFunctions.AdjustRoute function to use with process pattern such as Put that adjust routed FlowFiles based on context. This function works as a safety net by covering cases that Processor implementation did not use ExceptionHandler and transfer FlowFiles without considering RollbackOnFailure context.

createOnError

public static <FCT extends RollbackOnFailure,I> ExceptionHandler.OnError<FCT,I> createOnError(ExceptionHandler.OnError<FCT,I> onError)

onTrigger

public static <FCT extends RollbackOnFailure> void onTrigger(ProcessContext context,
                                                             ProcessSessionFactory sessionFactory,
                                                             FCT functionContext,
                                                             ComponentLog logger,
                                                             PartialFunctions.OnTrigger onTrigger)
                                                      throws ProcessException

Throws:: ProcessException

proceed
```
public int proceed()
```

getProcessedCount
```
public int getProcessedCount()
```

isRollbackOnFailure
```
public boolean isRollbackOnFailure()
```

isTransactional
```
public boolean isTransactional()
```

canRollback
```
public boolean canRollback()
```

shouldDiscontinue
```
public boolean shouldDiscontinue()
```

discontinue
```
public void discontinue()
```

Class RollbackOnFailure

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

rollbackOnFailure

transactional

discontinue

processedCount

ROLLBACK_ON_FAILURE

Constructor Detail

RollbackOnFailure

Method Detail

createRollbackOnFailureProperty

createAdjustError

createAdjustRoute

createOnError

onTrigger

proceed

getProcessedCount

isRollbackOnFailure

isTransactional

canRollback

shouldDiscontinue

discontinue