Package io.debezium.connector.postgresql.connection

Interface ReplicationStream

  • All Superinterfaces:
    AutoCloseable
    public interface ReplicationStream
extends AutoCloseable
    A stream from which messages sent by a logical decoding plugin can be consumed over a replication connection.
    Author:
    Horia Chiorean (hchiorea@redhat.com)

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      void close()
      //TODO author=Horia Chiorean date=13/10/2016 description=Don't use this for now, because of the bug from the PG server This is stream is closed atm.
      void flushLsn​(Lsn lsn)
      Sends a message to the server informing it about that latest position in the WAL that has successfully been processed.
      Lsn lastReceivedLsn()
      Returns the value for the latest server received LSN during a read operation.
      void read​(ReplicationStream.ReplicationMessageProcessor processor)
      Blocks and waits for a replication message to be sent over a replication connection.
      boolean readPending​(ReplicationStream.ReplicationMessageProcessor processor)
      Attempts to read a replication message from a replication connection, processing that message if it's available or returning false if nothing is available.
      void startKeepAlive​(ExecutorService service)
      Starts a background thread to ensure the slot is kept alive, useful for when temporarily stopping reads from the stream such as querying metadata, etc
      Lsn startLsn()
      Returns the value for the LSN form which the streaming is executed.
      void stopKeepAlive()
      Stops the background thread that is used to ensure the slot is kept alive.

    • Method Detail

      • readPending

        boolean readPending​(ReplicationStream.ReplicationMessageProcessor processor)
             throws SQLException,
                    InterruptedException
        Attempts to read a replication message from a replication connection, processing that message if it's available or returning false if nothing is available. Once a message has been received, the value of the last received LSN will also be updated accordingly.
        Parameters:
        processor - - a callback to which the arrived message is passed
        Returns:
        true if a message was received and processed
        Throws:
        SQLException - if anything unexpected fails
        InterruptedException
        See Also:
        PGReplicationStream.readPending()

      • flushLsn

        void flushLsn​(Lsn lsn)
       throws SQLException
        Sends a message to the server informing it about that latest position in the WAL that has successfully been processed. Due to the internal buffering the messages sent to Kafka (and thus committed offsets) will usually lag behind the latest received LSN, which is why this method must only be called after the accompanying event has been sent to Kafka and the offset has been committed there.

        This essentially tells the server that this stream has successfully processed messages up to the current read cursor and so the server is free to discard older segments with earlier LSNs. It also affects the catch-up behavior once a slot is restarted and the server attempt to bring it up-to-date.

        Throws:
        SQLException - if anything goes wrong

      • lastReceivedLsn

        Lsn lastReceivedLsn()
        Returns the value for the latest server received LSN during a read operation. The value is always updated once messages are read via the ReplicationConnection#startStreaming() or ReplicationConnection#startStreaming(Long) methods.
        Returns:
        a Long value, possibly null if this is called before anything has been read

      • startLsn

        Lsn startLsn()
        Returns the value for the LSN form which the streaming is executed.
        Returns:
        a Long value, possibly null if starting LSN is undefined

      • startKeepAlive

        void startKeepAlive​(ExecutorService service)
        Starts a background thread to ensure the slot is kept alive, useful for when temporarily stopping reads from the stream such as querying metadata, etc

      • stopKeepAlive

        void stopKeepAlive()
        Stops the background thread that is used to ensure the slot is kept alive.

      • close

        void close()
    throws Exception
        //TODO author=Horia Chiorean date=13/10/2016 description=Don't use this for now, because of the bug from the PG server This is stream is closed atm. once the replication connection which created it is closed.
        Specified by:
        close in interface AutoCloseable
        Throws:
        Exception
        See Also:
        PGReplicationStream.close()