cz.o2.proxima.direct.kafka.ElementConsumer Maven / Gradle / Ivy
/**
* Copyright 2017-2020 O2 Czech Republic, a.s.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cz.o2.proxima.direct.kafka;
import cz.o2.proxima.storage.StreamElement;
import cz.o2.proxima.time.WatermarkSupplier;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.function.Consumer;
import javax.annotation.Nullable;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.consumer.OffsetAndMetadata;
import org.apache.kafka.common.TopicPartition;
/**
* Consumer of stream elements. The callback may or might not be called depending on the consuming
* mode (bulk or online).
*/
interface ElementConsumer {
/**
* Process the ingest element and return result of {@code onNext} call to the observer.
*
* @param element element to process
* @param tp partition
* @param offset offset
* @param errorHandler function to call on error
* @return result of {@code onNext} call
*/
boolean consumeWithConfirm(
@Nullable StreamElement element,
TopicPartition tp,
long offset,
WatermarkSupplier watermarkSupplier,
Consumer errorHandler);
/**
* Retrieve map of offsets that should be committed right away. The offset map has to be
* atomically cloned and swapped with empty map
*
* @return map of actually committed offsets
*/
Map prepareOffsetsForCommit();
/** @return list of current offsets */
List getCurrentOffsets();
/** @return list of committed offsets */
List getCommittedOffsets();
/** Called when processing finishes. */
void onCompleted();
/** Called when processing is canceled. */
void onCancelled();
/**
* Called when processing throws error.
*
* @param err the error thrown
* @return result of {@link LogObserverBase#onError}
*/
boolean onError(Throwable err);
/**
* Called by reassign listener when partitions are assigned.
*
* @param consumer the consumer that actually reads data
* @param offsets the assigned partitions
*/
void onAssign(KafkaConsumer consumer, Collection offsets);
/** Called before the processing actually starts. */
void onStart();
/** Called when consumer is idle. */
void onIdle(WatermarkSupplier watermarkSupplier);
}