Package org.apache.calcite.adapter.kafka

Class KafkaMessageEnumerator<K,V>

java.lang.Object
org.apache.calcite.adapter.kafka.KafkaMessageEnumerator<K,V>
Type Parameters:
K - Type for Kafka message key, refer to ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG;
V - Type for Kafka message value, refer to ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG;
All Implemented Interfaces:
AutoCloseable, Enumerator<@Nullable Object[]>
public class KafkaMessageEnumerator<K,V> extends Object implements Enumerator<@Nullable Object[]>
Enumerator to read data from Consumer, and converted into SQL rows with KafkaRowConverter.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    Closes this enumerable and releases resources.
    Object[]
    current()
    It returns an Array of Object, with each element represents a field of row.
    boolean
    moveNext()
    Advances the enumerator to the next element of the collection.
    void
    reset()
    Sets the enumerator to its initial position, which is before the first element in the collection.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • current

      public Object[] current()
      It returns an Array of Object, with each element represents a field of row.
      Specified by:
      current in interface Enumerator<K>
      Returns:
      Current element

    • moveNext

      public boolean moveNext()
      Description copied from interface: Enumerator
      Advances the enumerator to the next element of the collection.

      After an enumerator is created or after the reset method is called, an enumerator is positioned before the first element of the collection, and the first call to the moveNext method moves the enumerator over the first element of the collection.

      If moveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and moveNext returns false. When the enumerator is at this position, subsequent calls to moveNext also return false until #reset is called.

      An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated. The next call to moveNext or Enumerator.reset() may, at the discretion of the implementation, throw a ConcurrentModificationException.

      Specified by:
      moveNext in interface Enumerator<K>
      Returns:
      true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection

    • reset

      public void reset()
      Description copied from interface: Enumerator
      Sets the enumerator to its initial position, which is before the first element in the collection.

      An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated. The next call to Enumerator.moveNext() or reset may, at the discretion of the implementation, throw a ConcurrentModificationException.

      This method is optional; it may throw UnsupportedOperationException.

      Notes to Implementers

      All calls to Reset must result in the same state for the enumerator. The preferred implementation is to move the enumerator to the beginning of the collection, before the first element. This invalidates the enumerator if the collection has been modified since the enumerator was created, which is consistent with Enumerator.moveNext() and Enumerator.current().

      Specified by:
      reset in interface Enumerator<K>

    • close

      public void close()
      Description copied from interface: Enumerator
      Closes this enumerable and releases resources.

      This method is idempotent. Calling it multiple times has the same effect as calling it once.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Enumerator<K>