io.zeebe.logstreams.processor

Interface EventProcessor

public interface EventProcessor

Process an event from a log stream. An implementation may be specified for one type of event.

Method Summary

Modifier and Type	Method and Description
default boolean	executeSideEffects() (Optional) Execute the side effects which are caused by the processed event.
default void	processEvent() Process the event.
default void	updateState() (Optional) Update the internal state of the processor based on the processed event.
default long	writeEvent(LogStreamRecordWriter writer) (Optional) Write an event to the log stream that is caused by the processed event.

Method Detail

processEvent

default void processEvent()

Process the event. Do no execute any side effect, or write an event, or update the internal state.

executeSideEffects

default boolean executeSideEffects()

(Optional) Execute the side effects which are caused by the processed event. A side effect can be e.g., the reply of a client request. Note that the controller may invoke this method multiple times if the execution fails.

Returns:

true, if the execution completes successfully or no side effect was executed.

writeEvent

default long writeEvent(LogStreamRecordWriter writer)

(Optional) Write an event to the log stream that is caused by the processed event. Note that the controller may invoke this method multiple times if the write operation fails.

Parameters:

writer - the log stream writer to write the event to the target log stream.

Returns:

the position of the written event, or

zero, if no event was written, or

a negate value, if the write operation fails.

updateState

default void updateState()

(Optional) Update the internal state of the processor based on the processed event.