io.debezium.connector.oracle.logminer

Class TransactionalBuffer

java.lang.Object

io.debezium.connector.oracle.logminer.TransactionalBuffer

All Implemented Interfaces:

AutoCloseable

@NotThreadSafe
public final class TransactionalBuffer
extends Object
implements AutoCloseable

Buffer that stores transactions and related callbacks that will be executed when a transaction commits or discarded when a transaction has been rolled back.

Author:

Andrey Pustovetov

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	TransactionalBuffer.DmlEvent Represents a DML event for a given table row.
private static class	TransactionalBuffer.Transaction Represents a logical database transaction

Field Summary

Fields

Modifier and Type	Field and Description
private Set<String>	abandonedTransactionIds
private Clock	clock
private ErrorHandler	errorHandler
private Scn	lastCommittedScn
private static org.slf4j.Logger	LOGGER
private Set<String>	rolledBackTransactionIds
private OracleDatabaseSchema	schema
private OracleStreamingChangeEventSourceMetrics	streamingMetrics
private Map<String,TransactionalBuffer.Transaction>	transactions

Constructor Summary

Constructors

Constructor and Description
TransactionalBuffer(OracleDatabaseSchema schema, Clock clock, ErrorHandler errorHandler, OracleStreamingChangeEventSourceMetrics streamingMetrics) Constructor to create a new instance.

Method Summary

Modifier and Type	Method and Description
(package private) void	abandonLongTransactions(Scn thresholdScn, OracleOffsetContext offsetContext) If for some reason the connector got restarted, the offset will point to the beginning of the oldest captured transaction.
private Scn	calculateSmallestScn()
void	close()
private void	commit(ChangeEventSource.ChangeEventSourceContext context, OracleOffsetContext offsetContext, Instant start, TransactionalBuffer.Transaction transaction, Timestamp timestamp, Scn smallestScn, Scn scn, EventDispatcher<TableId> dispatcher)
(package private) boolean	commit(String transactionId, Scn scn, OracleOffsetContext offsetContext, Timestamp timestamp, ChangeEventSource.ChangeEventSourceContext context, String debugMessage, EventDispatcher<TableId> dispatcher) Commits a transaction by looking up the transaction in the buffer and if exists, all registered callbacks will be executed in chronological order, emitting events for each followed by a transaction commit event.
(package private) Set<String>	getRolledBackTransactionIds()
(package private) boolean	isEmpty() Returns true if buffer is empty, otherwise false.
(package private) boolean	isTransactionRegistered(String txId)
(package private) void	registerDmlOperation(int operation, String transactionId, Scn scn, TableId tableId, LogMinerDmlEntry parseEntry, Instant changeTime, String rowId) Register a DML operation with the transaction buffer.
(package private) boolean	rollback(String transactionId, String debugMessage) Clears registered callbacks for given transaction identifier.
String	toString()
(package private) void	undoDmlOperation(String transactionId, String undoRowId, TableId tableId) Undo a staged DML operation in the transaction buffer.

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

private static final org.slf4j.Logger LOGGER

transactions

private final Map<String,TransactionalBuffer.Transaction> transactions

schema

private final OracleDatabaseSchema schema

clock

private final Clock clock

errorHandler

private final ErrorHandler errorHandler

abandonedTransactionIds

private final Set<String> abandonedTransactionIds

rolledBackTransactionIds

private final Set<String> rolledBackTransactionIds

streamingMetrics

private final OracleStreamingChangeEventSourceMetrics streamingMetrics

lastCommittedScn

private Scn lastCommittedScn

Constructor Detail

TransactionalBuffer

TransactionalBuffer(OracleDatabaseSchema schema,
                    Clock clock,
                    ErrorHandler errorHandler,
                    OracleStreamingChangeEventSourceMetrics streamingMetrics)

Constructor to create a new instance.

Parameters:

errorHandler - the connector error handler

streamingMetrics - the streaming metrics

Method Detail

getRolledBackTransactionIds

Set<String> getRolledBackTransactionIds()

Returns:

rolled back transactions

registerDmlOperation

void registerDmlOperation(int operation,
                          String transactionId,
                          Scn scn,
                          TableId tableId,
                          LogMinerDmlEntry parseEntry,
                          Instant changeTime,
                          String rowId)

Register a DML operation with the transaction buffer.

Parameters:

operation - operation type

transactionId - unique transaction identifier

scn - system change number

tableId - table identifier

parseEntry - parser entry

changeTime - time the DML operation occurred

rowId - unique row identifier

undoDmlOperation

void undoDmlOperation(String transactionId,
                      String undoRowId,
                      TableId tableId)

Undo a staged DML operation in the transaction buffer.

Parameters:

transactionId - unique transaction identifier

undoRowId - unique row identifier to be undone

tableId - table identifier

commit

boolean commit(String transactionId,
               Scn scn,
               OracleOffsetContext offsetContext,
               Timestamp timestamp,
               ChangeEventSource.ChangeEventSourceContext context,
               String debugMessage,
               EventDispatcher<TableId> dispatcher)

Commits a transaction by looking up the transaction in the buffer and if exists, all registered callbacks will be executed in chronological order, emitting events for each followed by a transaction commit event.

Parameters:

transactionId - transaction identifier

scn - SCN of the commit.

offsetContext - Oracle offset

timestamp - commit timestamp

context - context to check that source is running

debugMessage - message

dispatcher - event dispatcher

Returns:

true if committed transaction is in the buffer, was not processed yet and processed now

commit

private void commit(ChangeEventSource.ChangeEventSourceContext context,
                    OracleOffsetContext offsetContext,
                    Instant start,
                    TransactionalBuffer.Transaction transaction,
                    Timestamp timestamp,
                    Scn smallestScn,
                    Scn scn,
                    EventDispatcher<TableId> dispatcher)

rollback

boolean rollback(String transactionId,
                 String debugMessage)

Clears registered callbacks for given transaction identifier.

Parameters:

transactionId - transaction id

debugMessage - message

Returns:

true if the rollback is for a transaction in the buffer

abandonLongTransactions

void abandonLongTransactions(Scn thresholdScn,
                             OracleOffsetContext offsetContext)

If for some reason the connector got restarted, the offset will point to the beginning of the oldest captured transaction. If that transaction was lasted for a long time, let say > 4 hours, the offset might be not accessible after restart, Hence we have to address these cases manually.

In case of an abandonment, all DMLs/Commits/Rollbacks for this transaction will be ignored

Parameters:

thresholdScn - the smallest SVN of any transaction to keep in the buffer. All others will be removed.

offsetContext - the offset context

isTransactionRegistered

boolean isTransactionRegistered(String txId)

calculateSmallestScn

private Scn calculateSmallestScn()

isEmpty

boolean isEmpty()

Returns true if buffer is empty, otherwise false.

Returns:

true if buffer is empty, otherwise false

toString

public String toString()

Overrides:

toString in class Object

close

public void close()

Specified by:

close in interface AutoCloseable