org.apache.pulsar.client.api.MessagePayloadProcessor Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.pulsar.client.api;
import java.util.function.Consumer;
/**
* The processor to process a message payload.
*
* It's responsible to convert the raw buffer to some messages, then trigger some callbacks so that consumer can consume
* these messages and handle the exception if it existed.
*
* The most important part is to decode the raw buffer. After that, we can call
* {@link MessagePayloadContext#getMessageAt} or {@link MessagePayloadContext#asSingleMessage} to construct
* {@link Message} for consumer to consume. Since we need to pass the {@link MessagePayload} object to these methods, we
* can use {@link MessagePayloadFactory#DEFAULT} to create it or just reuse the payload argument.
*/
public interface MessagePayloadProcessor {
/**
* Process the message payload.
*
* @param payload the payload whose underlying buffer is a Netty ByteBuf
* @param context the message context that contains the message format information and methods to create a message
* @param schema the message's schema
* @param messageConsumer the callback to consume each message
* @param
* @throws Exception
*/
void process(MessagePayload payload,
MessagePayloadContext context,
Schema schema,
Consumer> messageConsumer) throws Exception;
// The default processor for Pulsar format payload. It should be noted getNumMessages() and isBatch() methods of
// EntryContext only work for Pulsar format. For other formats, the message metadata might be stored in the payload.
MessagePayloadProcessor DEFAULT = new MessagePayloadProcessor() {
@Override
public void process(MessagePayload payload,
MessagePayloadContext context,
Schema schema,
Consumer> messageConsumer) {
if (context.isBatch()) {
final int numMessages = context.getNumMessages();
for (int i = 0; i < numMessages; i++) {
messageConsumer.accept(context.getMessageAt(i, numMessages, payload, true, schema));
}
} else {
messageConsumer.accept(context.asSingleMessage(payload, schema));
}
}
};
}