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本文主要研究一下debezium的eventHandlers
handleInsert
debezium-v1.1.1.Final/debezium-connector-mysql/src/main/java/io/debezium/connector/mysql/BinlogReader.java
public class BinlogReader extends AbstractReader {
//......
protected void handleInsert(Event event) throws InterruptedException {
if (skipEvent) {
// We can skip this because we should already be at least this far ...
logger.debug("Skipping previously processed row event: {}", event);
return;
}
if (ignoreDmlEventByGtidSource) {
logger.debug("Skipping DML event because this GTID source is filtered: {}", event);
return;
}
WriteRowsEventData write = unwrapData(event);
long tableNumber = write.getTableId();
BitSet includedColumns = write.getIncludedColumns();
RecordsForTable recordMaker = recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord);
if (recordMaker != null) {
List rows = write.getRows();
final Instant ts = context.getClock().currentTimeAsInstant();
int count = 0;
int numRows = rows.size();
if (startingRowNumber < numRows) {
for (int row = startingRowNumber; row != numRows; ++row) {
count += recordMaker.create(rows.get(row), ts, row, numRows);
}
if (logger.isDebugEnabled()) {
if (startingRowNumber != 0) {
logger.debug("Recorded {} insert record(s) for last {} row(s) in event: {}",
count, numRows - startingRowNumber, event);
}
else {
logger.debug("Recorded {} insert record(s) for event: {}", count, event);
}
}
}
else {
// All rows were previously processed ...
logger.debug("Skipping previously processed insert event: {}", event);
}
}
else {
informAboutUnknownTableIfRequired(event, recordMakers.getTableIdFromTableNumber(tableNumber), "insert row");
}
startingRowNumber = 0;
}
//......
} - handleInsert方法将event解析为WriteRowsEventData，然后通过recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord)获取recordMaker，执行recordMaker.create(rows.get(row), ts, row, numRows)
handleUpdate
debezium-v1.1.1.Final/debezium-connector-mysql/src/main/java/io/debezium/connector/mysql/BinlogReader.java
public class BinlogReader extends AbstractReader {
//......
protected void handleUpdate(Event event) throws InterruptedException {
if (skipEvent) {
// We can skip this because we should already be at least this far ...
logger.debug("Skipping previously processed row event: {}", event);
return;
}
if (ignoreDmlEventByGtidSource) {
logger.debug("Skipping DML event because this GTID source is filtered: {}", event);
return;
}
UpdateRowsEventData update = unwrapData(event);
long tableNumber = update.getTableId();
BitSet includedColumns = update.getIncludedColumns();
// BitSet includedColumnsBefore = update.getIncludedColumnsBeforeUpdate();
RecordsForTable recordMaker = recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord);
if (recordMaker != null) {
List> rows = update.getRows();
final Instant ts = context.getClock().currentTimeAsInstant();
int count = 0;
int numRows = rows.size();
if (startingRowNumber < numRows) {
for (int row = startingRowNumber; row != numRows; ++row) {
Map.Entry changes = rows.get(row);
Serializable[] before = changes.getKey();
Serializable[] after = changes.getValue();
count += recordMaker.update(before, after, ts, row, numRows);
}
if (logger.isDebugEnabled()) {
if (startingRowNumber != 0) {
logger.debug("Recorded {} update record(s) for last {} row(s) in event: {}",
count, numRows - startingRowNumber, event);
}
else {
logger.debug("Recorded {} update record(s) for event: {}", count, event);
}
}
}
else {
// All rows were previously processed ...
logger.debug("Skipping previously processed update event: {}", event);
}
}
else {
informAboutUnknownTableIfRequired(event, recordMakers.getTableIdFromTableNumber(tableNumber), "update row");
}
startingRowNumber = 0;
}
//......
} - handleUpdate方法将event解析为UpdateRowsEventData，然后通过recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord)获取recordMaker，执行recordMaker.update(before, after, ts, row, numRows)
handleDelete
debezium-v1.1.1.Final/debezium-connector-mysql/src/main/java/io/debezium/connector/mysql/BinlogReader.java
public class BinlogReader extends AbstractReader {
//......
protected void handleDelete(Event event) throws InterruptedException {
if (skipEvent) {
// We can skip this because we should already be at least this far ...
logger.debug("Skipping previously processed row event: {}", event);
return;
}
if (ignoreDmlEventByGtidSource) {
logger.debug("Skipping DML event because this GTID source is filtered: {}", event);
return;
}
DeleteRowsEventData deleted = unwrapData(event);
long tableNumber = deleted.getTableId();
BitSet includedColumns = deleted.getIncludedColumns();
RecordsForTable recordMaker = recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord);
if (recordMaker != null) {
List rows = deleted.getRows();
final Instant ts = context.getClock().currentTimeAsInstant();
int count = 0;
int numRows = rows.size();
if (startingRowNumber < numRows) {
for (int row = startingRowNumber; row != numRows; ++row) {
count += recordMaker.delete(rows.get(row), ts, row, numRows);
}
if (logger.isDebugEnabled()) {
if (startingRowNumber != 0) {
logger.debug("Recorded {} delete record(s) for last {} row(s) in event: {}",
count, numRows - startingRowNumber, event);
}
else {
logger.debug("Recorded {} delete record(s) for event: {}", count, event);
}
}
}
else {
// All rows were previously processed ...
logger.debug("Skipping previously processed delete event: {}", event);
}
}
else {
informAboutUnknownTableIfRequired(event, recordMakers.getTableIdFromTableNumber(tableNumber), "delete row");
}
startingRowNumber = 0;
}
//......
} - handleDelete方法将event解析为DeleteRowsEventData，然后通过recordMakers.forTable(tableNumber, includedColumns, super::enqueueRecord)获取recordMaker，执行recordMaker.delete(rows.get(row), ts, row, numRows)
handleQueryEvent
debezium-v1.1.1.Final/debezium-connector-mysql/src/main/java/io/debezium/connector/mysql/BinlogReader.java
public class BinlogReader extends AbstractReader {
//......
protected void handleQueryEvent(Event event) throws InterruptedException {
QueryEventData command = unwrapData(event);
logger.debug("Received query command: {}", event);
String sql = command.getSql().trim();
if (sql.equalsIgnoreCase("BEGIN")) {
// We are starting a new transaction ...
source.startNextTransaction();
source.setBinlogThread(command.getThreadId());
if (initialEventsToSkip != 0) {
logger.debug("Restarting partially-processed transaction; change events will not be created for the first {} events plus {} more rows in the next event",
initialEventsToSkip, startingRowNumber);
// We are restarting, so we need to skip the events in this transaction that we processed previously...
skipEvent = true;
}
return;
}
if (sql.equalsIgnoreCase("COMMIT")) {
handleTransactionCompletion(event);
return;
}
String upperCasedStatementBegin = Strings.getBegin(sql, 7).toUpperCase();
if (upperCasedStatementBegin.startsWith("XA ")) {
// This is an XA transaction, and we currently ignore these and do nothing ...
return;
}
if (context.ddlFilter().test(sql)) {
logger.debug("DDL '{}' was filtered out of processing", sql);
return;
}
if (upperCasedStatementBegin.equals("INSERT ") || upperCasedStatementBegin.equals("UPDATE ") || upperCasedStatementBegin.equals("DELETE ")) {
throw new ConnectException(
"Received DML '" + sql + "' for processing, binlog probably contains events generated with statement or mixed based replication format");
}
if (sql.equalsIgnoreCase("ROLLBACK")) {
// We have hit a ROLLBACK which is not supported
logger.warn("Rollback statements cannot be handled without binlog buffering, the connector will fail. Please check '{}' to see how to enable buffering",
MySqlConnectorConfig.BUFFER_SIZE_FOR_BINLOG_READER.name());
}
context.dbSchema().applyDdl(context.source(), command.getDatabase(), command.getSql(), (dbName, tables, statements) -> {
if (recordSchemaChangesInSourceRecords && recordMakers.schemaChanges(dbName, tables, statements, super::enqueueRecord) > 0) {
logger.debug("Recorded DDL statements for database '{}': {}", dbName, statements);
}
});
}
//......
}- handleQueryEvent方法将event解析为QueryEventData，然后通过context.dbSchema().applyDdl来执行ddl
小结
BinlogReader注册了增删改查的eventHandlers，它们分别解析event对对应的data，对于增删改则执行recordMakers的对应方法，对于查询则作用对应的ddl语句