Hudi 原理 | Apache Hudi 中自定義序列化和數(shù)據(jù)寫入邏輯

/** * Base class for all AVRO record based payloads, that can be ordered based on a field. */public abstract class BaseAvroPayload implements Serializable {  /**   * Avro data extracted from the source converted to bytes.   */  public final byte[] recordBytes;  /**   * For purposes of preCombining.   */  public final Comparable orderingVal;  /**   * Instantiate {@link BaseAvroPayload}.   *   * @param record      Generic record for the payload.   * @param orderingVal {@link Comparable} to be used in pre combine.   */  public BaseAvroPayload(GenericRecord record, Comparable orderingVal) {    this.recordBytes = record != null ? HoodieAvroUtils.avroToBytes(record) : new byte[0];    this.orderingVal = orderingVal;    if (orderingVal == null) {      throw new HoodieException("Ordering value is null for record: " + record);    }  }}

/** * Every Hoodie table has an implementation of the HoodieRecordPayloadcode> This abstracts out callbacks which depend on record specific logic. */@PublicAPIClass(maturity = ApiMaturityLevel.STABLE)public interface HoodieRecordPayload<T extends HoodieRecordPayload> extends Serializable {  /**   * This method is deprecated. Please use this {@link #preCombine(HoodieRecordPayload, Properties)} method.   */  @Deprecated  @PublicAPIMethod(maturity = ApiMaturityLevel.DEPRECATED)  T preCombine(T oldValue);  /**   * When more than one HoodieRecord have the same HoodieKey, this function combines them before attempting to insert/upsert by taking in a property map.   * Implementation can leverage the property to decide their business logic to do preCombine.   *   * @param oldValue   instance of the old {@link HoodieRecordPayload} to be combined with.   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage.   *   * @return the combined value   */  @PublicAPIMethod(maturity = ApiMaturityLevel.STABLE)  default T preCombine(T oldValue, Properties properties) {    return preCombine(oldValue);  }  /**   * This methods is deprecated. Please refer to {@link #combineAndGetUpdateValue(IndexedRecord, Schema, Properties)} for java docs.   */  @Deprecated  @PublicAPIMethod(maturity = ApiMaturityLevel.DEPRECATED)  Option<IndexedRecord> combineAndGetUpdateValue(IndexedRecord currentValue, Schema schema) throws IOException;  /**   * This methods lets you write custom merging/combining logic to produce new values as a function of current value on storage and whats contained   * in this object. Implementations can leverage properties if required.   * 
   * eg:   * 1) You are updating counters, you may want to add counts to currentValue and write back updated counts   * 2) You may be reading DB redo logs, and merge them with current image for a database row on storage   * p>   *   * @param currentValue Current value in storage, to merge/combine this payload with   * @param schema Schema used for record   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage.   * @return new combined/merged value to be written back to storage. EMPTY to skip writing this record.   */  default Option<IndexedRecord> combineAndGetUpdateValue(IndexedRecord currentValue, Schema schema, Properties properties) throws IOException {    return combineAndGetUpdateValue(currentValue, schema);  }  /**   * This method is deprecated. Refer to {@link #getInsertValue(Schema, Properties)} for java docs.   * @param schema Schema used for record   * @return the {@link IndexedRecord} to be inserted.   */  @Deprecated  @PublicAPIMethod(maturity = ApiMaturityLevel.DEPRECATED)  Option<IndexedRecord> getInsertValue(Schema schema) throws IOException;  /**   * Generates an avro record out of the given HoodieRecordPayload, to be written out to storage. Called when writing a new value for the given   * HoodieKey, wherein there is no existing record in storage to be combined against. (i.e insert) Return EMPTY to skip writing this record.   * Implementations can leverage properties if required.   * @param schema Schema used for record   * @param properties Payload related properties. For example pass the ordering field(s) name to extract from value in storage.   * @return the {@link IndexedRecord} to be inserted.   */  @PublicAPIMethod(maturity = ApiMaturityLevel.STABLE)  default Option<IndexedRecord> getInsertValue(Schema schema, Properties properties) throws IOException {    return getInsertValue(schema);  }  /**   * This method can be used to extract some metadata from HoodieRecordPayload. The metadata is passed to {@code WriteStatus.markSuccess()} and   * {@code WriteStatus.markFailure()} in order to compute some aggregate metrics using the metadata in the context of a write success or failure.   * @return the metadata in the form of Map<String, String> if any.   */  @PublicAPIMethod(maturity = ApiMaturityLevel.STABLE)  default Option<Map<String, String>> getMetadata() {    return Option.empty();  }}

public HoodieRecordPayload preCombine(HoodieRecordPayload oldValue, Properties properties) {    if (schema == null) {        this.schema = new Schema.Parser().parse(properties.get(HoodieWriteConfig.AVRO_SCHEMA_STRING.key()));    }    initialSchema(properties);    GenericRecord thisRecord = getInsertValue(schema).get();    GenericRecord otherRecord = oldValue.getInsertValue(schema).get();    List<Schema.Field> fields = schema.getFields();    for (Schema.Field field : fields) {        // logic for each column    }    return new HoodieRecordPayload(thisRecord, orderingVal);}