Details
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Bug
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Status: Reopened
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Minor
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Resolution: Unresolved
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0.10.1.1
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None
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all
Description
Quick intro: A ByteBuffer.rewind() resets the position to zero. What if the ByteBuffer was created with an offset? new ByteBuffer(data, 3, 10)? The ByteBufferSerializer will send from pos=0 and not from pos=3 onwards.
Solution: No rewind() but flip() for reading a ByteBuffer. That's what the flip is meant for.
Story:
Imagine the incoming data comes from a byte[], e.g. a network stream containing topicname, partition, key, value, ... and you want to create a new ProducerRecord for that. As the constructor of ProducerRecord requires (topic, partition, key, value) you have to copy from above byte[] the key and value. That means there is a memcopy taking place. Since the payload can be potentially large, that introduces a lot of overhead. Twice the memory.
A nice solution to this problem is to simply wrap the network byte[] into new ByteBuffers:
ByteBuffer key = ByteBuffer.wrap(data, keystart, keylength);
ByteBuffer value = ByteBuffer.wrap(data, valuestart, valuelength);
and then use the ByteBufferSerializer instead of the ByteArraySerializer.
But that does not work as the ByteBufferSerializer does a rewind(), hence both, key and value, will start at position=0 of the data[].
public class ByteBufferSerializer implements Serializer<ByteBuffer> {
public byte[] serialize(String topic, ByteBuffer data) {
data.rewind();
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