org.apache.kafka.streams.processor.RecordContext Maven / Gradle / Ivy
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* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.streams.processor;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.streams.kstream.ValueTransformerWithKeySupplier;
/**
* The context associated with the current record being processed by
* a {@link org.apache.kafka.streams.processor.Processor}
*/
public interface RecordContext {
/**
* Return the topic name of the current input record; could be {@code null} if it is not
* available.
*
* For example, if this method is invoked within a {@link Punctuator#punctuate(long)
* punctuation callback}, or while processing a record that was forwarded by a punctuation
* callback, the record won't have an associated topic.
* Another example is
* {@link org.apache.kafka.streams.kstream.KTable#transformValues(ValueTransformerWithKeySupplier, String...)}
* (and siblings), that do not always guarantee to provide a valid topic name, as they might be
* executed "out-of-band" due to some internal optimizations applied by the Kafka Streams DSL.
*
* @return the topic name
*/
String topic();
/**
* Return the partition id of the current input record; could be {@code -1} if it is not
* available.
*
*
For example, if this method is invoked within a {@link Punctuator#punctuate(long)
* punctuation callback}, or while processing a record that was forwarded by a punctuation
* callback, the record won't have an associated partition id.
* Another example is
* {@link org.apache.kafka.streams.kstream.KTable#transformValues(ValueTransformerWithKeySupplier, String...)}
* (and siblings), that do not always guarantee to provide a valid partition id, as they might be
* executed "out-of-band" due to some internal optimizations applied by the Kafka Streams DSL.
*
* @return the partition id
*/
int partition();
/**
* Return the offset of the current input record; could be {@code -1} if it is not
* available.
*
*
For example, if this method is invoked within a {@link Punctuator#punctuate(long)
* punctuation callback}, or while processing a record that was forwarded by a punctuation
* callback, the record won't have an associated offset.
* Another example is
* {@link org.apache.kafka.streams.kstream.KTable#transformValues(ValueTransformerWithKeySupplier, String...)}
* (and siblings), that do not always guarantee to provide a valid offset, as they might be
* executed "out-of-band" due to some internal optimizations applied by the Kafka Streams DSL.
*
* @return the offset
*/
long offset();
/**
* Return the current timestamp.
*
*
If it is triggered while processing a record streamed from the source processor,
* timestamp is defined as the timestamp of the current input record; the timestamp is extracted from
* {@link org.apache.kafka.clients.consumer.ConsumerRecord ConsumerRecord} by {@link TimestampExtractor}.
* Note, that an upstream {@link org.apache.kafka.streams.processor.api.Processor}
* might have set a new timestamp by calling
* {@link org.apache.kafka.streams.processor.api.ProcessorContext#forward(org.apache.kafka.streams.processor.api.Record)
* forward(..., To.all().withTimestamp(...))}.
* In particular, some Kafka Streams DSL operators set result record timestamps explicitly,
* to guarantee deterministic results.
*
*
If it is triggered while processing a record generated not from the source processor (for example,
* if this method is invoked from the punctuate call), timestamp is defined as the current
* task's stream time, which is defined as the largest timestamp of any record processed by the task.
*
* @return the timestamp
*/
long timestamp();
/**
* Return the headers of the current input record; could be an empty header if it is not
* available.
*
*
For example, if this method is invoked within a {@link Punctuator#punctuate(long)
* punctuation callback}, or while processing a record that was forwarded by a punctuation
* callback, the record might not have any associated headers.
* Another example is
* {@link org.apache.kafka.streams.kstream.KTable#transformValues(ValueTransformerWithKeySupplier, String...)}
* (and siblings), that do not always guarantee to provide a valid headers, as they might be
* executed "out-of-band" due to some internal optimizations applied by the Kafka Streams DSL.
*
* @return the headers
*/
Headers headers();
}