pl.allegro.tech.hermes.common.message.wrapper.SchemaAwareSerDe Maven / Gradle / Ivy

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Fast and reliable message broker built on top of Kafka.

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package pl.allegro.tech.hermes.common.message.wrapper;

import pl.allegro.tech.hermes.schema.SchemaId;

import java.nio.ByteBuffer;

import static java.lang.String.format;

public class SchemaAwareSerDe {
    private static final byte MAGIC_BYTE_VALUE = 0;
    private static final byte MAGIC_BYTE_INDEX = 0;
    private static final int HEADER_SIZE = 5;

    private SchemaAwareSerDe() {
    }

    public static byte[] serialize(SchemaId schemaId, byte[] binaryAvro) {
        ByteBuffer buffer = ByteBuffer.allocate(HEADER_SIZE + binaryAvro.length);
        buffer.put(MAGIC_BYTE_VALUE);
        buffer.putInt(schemaId.value());
        buffer.put(binaryAvro);
        return buffer.array();
    }

    public static SchemaAwarePayload deserialize(byte[] payloadWithHeader) {
        ByteBuffer buffer = ByteBuffer.wrap(payloadWithHeader);
        assertMagicByte(buffer.get());
        int schemaId = buffer.getInt();
        byte[] payload = new byte[payloadWithHeader.length - HEADER_SIZE];
        buffer.get(payload);
        return new SchemaAwarePayload(payload, SchemaId.valueOf(schemaId));
    }

    public static boolean startsWithMagicByte(byte[] payload) {
        return payload[MAGIC_BYTE_INDEX] == MAGIC_BYTE_VALUE;
    }

    private static void assertMagicByte(byte magicByte) {
        if (magicByte != MAGIC_BYTE_VALUE) {
            throw new DeserializationException(format("Could not deserialize payload, unknown magic byte: \'%s\'.", magicByte));
        }
    }

    public  static byte[] trimMagicByteAndSchemaVersion(byte[] data) {
        int length = data.length - HEADER_SIZE;
        byte[] dataWithoutMagicByteAndSchemaVersion = new byte[length];
        System.arraycopy(data, HEADER_SIZE, dataWithoutMagicByteAndSchemaVersion, 0, length);
        return dataWithoutMagicByteAndSchemaVersion;
    }
}