Package io.smallrye.reactive.messaging.kafka.commit

Interface CheckpointMetadata<T>

Type Parameters:
T - type of the processing state
All Known Implementing Classes:
DefaultCheckpointMetadata
public interface CheckpointMetadata<T>
Checkpoint metadata type for injecting state checkpointing interactions into received messages. This allows accessing the current processing state restored from the state store, and produce the next state. The next state can be saved locally or persisted into the external store.

A sample processing method with checkpointing would be: 

 @Incoming("in")
 public CompletionStage<Void> process(Message<String> msg) {
     CheckpointMetadata<Integer> checkpoint = CheckpointMetadata.fromMessage(msg);
     if (checkpoint != null) {
         checkpoint.transform(0, current -> current + msg.getPayload());
     }
     return CompletableFuture.completed(null);
 }

  • Method Details

    • fromMessage

      static <S> CheckpointMetadata<S> fromMessage(org.eclipse.microprofile.reactive.messaging.Message<?> message)

    • getTopicPartition

      org.apache.kafka.common.TopicPartition getTopicPartition()
      Returns:
      the topic-partition of this record

    • getRecordOffset

      long getRecordOffset()
      Returns:
      the offset of this record

    • isPersistOnAck

      boolean isPersistOnAck()
      Returns:
      true if the processing state will be persisted on message acknowledgement

    • getCurrent

      ProcessingState<T> getCurrent()
      Returns:
      the current processing state

    • getNext

      ProcessingState<T> getNext()
      Returns:
      the next processing state set during this processing

    • setNext

      T setNext(T state, boolean persistOnAck)
      Set the next processing state to the given state, associated with the current record offset + 1.
      Parameters:
      state - the next state
      persistOnAck - If true then the state will be persisted on message acknowledgement
      Returns:
      the previous state

    • setNext

      T setNext(T state)
      Set the next processing state to the given state, associated with the current record offset + 1. The state will not be persisted on message acknowledgement.
      Parameters:
      state - the next state
      Returns:
      the previous state

    • transform

      T transform(Supplier<T> initialStateSupplier, Function<T,T> transformation, boolean persistOnAck)
      Apply the transformation to the current state, if a previous state doesn't exist, start the transformation from the supplied initial state. The state will be associated with the current record offset + 1.
      Parameters:
      initialStateSupplier - if no previous state does exist, start the transformation from this state.
      transformation - the transformation function
      persistOnAck - If true then the state will be persisted on message acknowledgement
      Returns:
      the previous state

    • transform

      T transform(T initialState, Function<T,T> transformation, boolean persistOnAck)
      See transform(Supplier, Function, boolean)
      Parameters:
      initialState - if no previous state does exist, start the transformation from this state.
      transformation - the transformation function
      persistOnAck - If true then the state will be persisted on message acknowledgement
      Returns:
      the previous state

    • transform

      T transform(Supplier<T> initialStateSupplier, Function<T,T> transformation)
      See transform(Supplier, Function, boolean) The state will not be persisted on message acknowledgement.
      Parameters:
      initialStateSupplier - if no previous state does exist, start the transformation from this state.
      transformation - the transformation function
      Returns:
      the previous state

    • transform

      T transform(T initialState, Function<T,T> transformation)
      See transform(Supplier, Function, boolean) The state will not be persisted on message acknowledgement.
      Parameters:
      initialState - if no previous state does exist, start the transformation from this state.
      transformation - the transformation function
      Returns:
      the previous state