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)

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	ReplicationStream.ReplicationMessageProcessor

Method Summary

Modifier and Type	Method and 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(long lsn) Sends a message to the server informing it about that latest position in the WAL that has successfully been processed.
Long	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
void	stopKeepAlive() Stops the background thread that is used to ensure the slot is kept alive.

Method Detail

read

void read(ReplicationStream.ReplicationMessageProcessor processor)
   throws SQLException,
          InterruptedException

Blocks and waits for a replication message to be sent over a replication connection. 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

Throws:

SQLException - if anything unexpected fails

InterruptedException

See Also:

PGReplicationStream.read()

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(long 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

Long 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

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()