Package io.camunda.zeebe.engine

Class Engine

java.lang.Object

io.camunda.zeebe.engine.Engine

All Implemented Interfaces:

RecordProcessor

public class Engine
extends Object
implements RecordProcessor

Constructor Summary

Constructors

Constructor	Description
Engine(TypedRecordProcessorFactory typedRecordProcessorFactory, EngineConfiguration config)

Method Summary

Modifier and Type	Method	Description
boolean	accepts(ValueType valueType)	Returns true if the processor is responsible for processing a record with the given valueType.
void	init(RecordProcessorContext recordProcessorContext)	Called by platform to initialize the processor
ProcessingResult	onProcessingError(Throwable processingException, TypedRecord record, ProcessingResultBuilder processingResultBuilder)	Called by platform when a processing error occurred.
ProcessingResult	process(TypedRecord record, ProcessingResultBuilder processingResultBuilder)	Called by platform to process a single record.
void	replay(TypedRecord event)	Called by platform in order to replay a single record

Methods inherited from class java.lang.Object

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

Constructor Details

Engine

public Engine(TypedRecordProcessorFactory typedRecordProcessorFactory,
 EngineConfiguration config)

Method Details

init

public void init(RecordProcessorContext recordProcessorContext)

Description copied from interface: RecordProcessor

Called by platform to initialize the processor

Specified by:

init in interface RecordProcessor

Parameters:

recordProcessorContext - context object to initialize the processor

accepts

public boolean accepts(ValueType valueType)

Description copied from interface: RecordProcessor

Returns true if the processor is responsible for processing a record with the given valueType. If it returns true, then RecordProcessor.process(TypedRecord, ProcessingResultBuilder) and RecordProcessor.replay(TypedRecord) must successfully process or replay the record with the given valueType. The processor can also choose to skip the record depending on the intent of the record.

If it returns false, RecordProcessor.process(TypedRecord, ProcessingResultBuilder) * and RecordProcessor.replay(TypedRecord) with the given valueType will not be called.

Specified by:

accepts in interface RecordProcessor

Parameters:

valueType - valueType of a record

Returns:

true or false

replay

public void replay(TypedRecord event)

Description copied from interface: RecordProcessor

Called by platform in order to replay a single record

Contract

• Record will be an event
• Will be called before processing is called
• Implementors can write to the database. Transaction is provided by platform, which also takes care of lifecycle of the transaction
• Implementors must not write to the log stream
• Implementors must not schedule post commit tasks

Specified by:

replay in interface RecordProcessor

Parameters:

event - the record to replay

process

public ProcessingResult process(TypedRecord record,
 ProcessingResultBuilder processingResultBuilder)

Description copied from interface: RecordProcessor

Called by platform to process a single record.

Contract

• Record will be a command
• Will be called after replay is called
• Implementors can write to the database. Transaction is provided by platform, which also takes care of lifecycle of the transaction
• Implementors must ensure that if they generate follow up events, these are applied to the database while this method is called
• Implementors can produce follow up commands and events, client responses and on commit tasks via processingResultBuilder
• Implementors can indicate that the record should be skipped by returning EmptyProcessingResult.INSTANCE

Specified by:

process in interface RecordProcessor

Returns:

the result of the processing; must be generated via processingResultBuilder.build()

onProcessingError

public ProcessingResult onProcessingError(Throwable processingException,
 TypedRecord record,
 ProcessingResultBuilder processingResultBuilder)

Description copied from interface: RecordProcessor

Called by platform when a processing error occurred.

Contract

• Record will be a command
• Will be called if an uncaught exception is thrown in RecordProcessor.process(TypedRecord, ProcessingResultBuilder), or when an uncaught exception is thrown by the ProcessingStateMachine while committing the transaction
• Implementors can write to the database. Transaction is provided by platform, which also takes care of lifecycle of the transaction
• Implementors must ensure that if they generate follow up events, these are applied to the database while this method is called
• Implementors can produce follow up commands, events and rejections, client responses and on commit tasks via processingResultBuilder
• Implementors are responsible for error logging when needed

Specified by:

onProcessingError in interface RecordProcessor

Returns:

the result of the processing; must be generated via ProcessingResultBuilder processingResultBuilder