[hotfix][sqlserver] Fix backfill stream task hang (apache#2374)

* [sqlserver] Fix backfill stream task hang

* [sqlserver] Fix backfill stream task hang

Author: GOODBOY008

flink-connector-sqlserver-cdc/src/main/java/com/ververica/cdc/connectors/sqlserver/source/dialect/SqlServerChunkSplitter.java

@@ -274,7 +274,7 @@ private List<ChunkRange> splitUnevenlySizedChunks(
         while (chunkEnd != null && ObjectUtils.compare(chunkEnd, max) <= 0) {
             // we start from [null, min + chunk_size) and avoid [null, min)
             splits.add(ChunkRange.of(chunkStart, chunkEnd));
-            // may sleep a while to avoid DDOS on SqlServer server
+            // may sleep awhile to avoid DDOS on SqlServer server
             maySleep(count++, tableId);
             chunkStart = chunkEnd;
             chunkEnd = nextChunkEnd(jdbc, chunkEnd, tableId, splitColumnName, max, chunkSize);

flink-connector-sqlserver-cdc/src/main/java/com/ververica/cdc/connectors/sqlserver/source/offset/LsnOffset.java

@@ -47,12 +47,8 @@ public LsnOffset(Lsn scn, Lsn commitScn, Long eventSerialNo) {
         this.offset = offsetMap;
     }
 
-    public LsnOffset(Lsn lsn) {
-        this(lsn, null, null);
-    }
-
-    public Lsn getLcn() {
-        return Lsn.valueOf(offset.get(SourceInfo.COMMIT_LSN_KEY));
+    public LsnOffset(Lsn changeLsn) {
+        this(changeLsn, null, null);
     }
 
     @Override
@@ -69,8 +65,8 @@ public int compareTo(Offset offset) {
             return -1;
         }
 
-        Lsn lsn = this.getLcn();
-        Lsn targetLsn = that.getLcn();
+        Lsn lsn = Lsn.valueOf(this.offset.get(SourceInfo.COMMIT_LSN_KEY));
+        Lsn targetLsn = Lsn.valueOf(that.offset.get(SourceInfo.COMMIT_LSN_KEY));
         if (targetLsn.isAvailable()) {
             if (lsn.isAvailable()) {
                 return lsn.compareTo(targetLsn);

flink-connector-sqlserver-cdc/src/main/java/com/ververica/cdc/connectors/sqlserver/source/reader/fetch/SqlServerScanFetchTask.java

@@ -23,7 +23,7 @@
 import com.ververica.cdc.connectors.base.source.meta.wartermark.WatermarkKind;
 import com.ververica.cdc.connectors.base.source.reader.external.FetchTask;
 import com.ververica.cdc.connectors.sqlserver.source.offset.LsnOffset;
-import com.ververica.cdc.connectors.sqlserver.source.reader.fetch.SqlServerStreamFetchTask.LsnSplitReadTask;
+import com.ververica.cdc.connectors.sqlserver.source.reader.fetch.SqlServerStreamFetchTask.StreamSplitReadTask;
 import io.debezium.DebeziumException;
 import io.debezium.config.Configuration;
 import io.debezium.connector.sqlserver.SqlServerConnection;
@@ -118,7 +118,7 @@ public void execute(Context context) throws Exception {
             final SqlServerOffsetContext streamOffsetContext =
                     loader.load(backfillBinlogSplit.getStartingOffset().getOffset());
 
-            final LsnSplitReadTask backfillBinlogReadTask =
+            final StreamSplitReadTask backfillBinlogReadTask =
                     createBackFillLsnSplitReadTask(backfillBinlogSplit, sourceFetchContext);
             backfillBinlogReadTask.execute(
                     new SnapshotBinlogSplitChangeEventSourceContext(),
@@ -154,21 +154,27 @@ private void dispatchLsnEndEvent(
                 WatermarkKind.END);
     }
 
-    private LsnSplitReadTask createBackFillLsnSplitReadTask(
+    private StreamSplitReadTask createBackFillLsnSplitReadTask(
             StreamSplit backfillBinlogSplit, SqlServerSourceFetchTaskContext context) {
         // we should only capture events for the current table,
         // otherwise, we may can't find corresponding schema
         Configuration dezConf =
-                context.getSourceConfig()
-                        .getDbzConfiguration()
+                context.getDbzConnectorConfig()
+                        .getConfig()
                         .edit()
-                        .with("table.include.list", split.getTableId().toString())
+                        // table.include.list is schema.table format
+                        .with(
+                                "table.include.list",
+                                new TableId(
+                                        null,
+                                        split.getTableId().schema(),
+                                        split.getTableId().table()))
                         // Disable heartbeat event in snapshot split fetcher
                         .with(Heartbeat.HEARTBEAT_INTERVAL, 0)
                         .build();
         // task to read binlog and backfill for current split
-        return new LsnSplitReadTask(
-                context.getDbzConnectorConfig(),
+        return new StreamSplitReadTask(
+                new SqlServerConnectorConfig(dezConf),
                 context.getConnection(),
                 context.getMetaDataConnection(),
                 context.getDispatcher(),

flink-connector-sqlserver-cdc/src/main/java/com/ververica/cdc/connectors/sqlserver/source/reader/fetch/SqlServerSourceFetchTaskContext.java

@@ -77,8 +77,8 @@ public class SqlServerSourceFetchTaskContext extends JdbcSourceFetchTaskContext
      * A separate connection for retrieving details of the schema changes; without it, adaptive
      * buffering will not work.
      *
-     * @link
-     *     https://docs.microsoft.com/en-us/sql/connect/jdbc/using-adaptive-buffering?view=sql-server-2017#guidelines-for-using-adaptive-buffering
+     * <p>For more details, please refer to <a
+     * href="https://docs.microsoft.com/en-us/sql/connect/jdbc/using-adaptive-buffering?view=sql-server-2017#guidelines-for-using-adaptive-buffering">guidelines-for-using-adaptive-buffering</a>
      */
     private final SqlServerConnection metaDataConnection;
 

flink-connector-sqlserver-cdc/src/main/java/com/ververica/cdc/connectors/sqlserver/source/reader/fetch/SqlServerStreamFetchTask.java

@@ -17,12 +17,14 @@
 package com.ververica.cdc.connectors.sqlserver.source.reader.fetch;
 
 import com.ververica.cdc.connectors.base.relational.JdbcSourceEventDispatcher;
+import com.ververica.cdc.connectors.base.source.meta.offset.Offset;
 import com.ververica.cdc.connectors.base.source.meta.split.SourceSplitBase;
 import com.ververica.cdc.connectors.base.source.meta.split.StreamSplit;
 import com.ververica.cdc.connectors.base.source.meta.wartermark.WatermarkKind;
 import com.ververica.cdc.connectors.base.source.reader.external.FetchTask;
 import com.ververica.cdc.connectors.sqlserver.source.offset.LsnOffset;
 import io.debezium.DebeziumException;
+import io.debezium.connector.sqlserver.Lsn;
 import io.debezium.connector.sqlserver.SqlServerConnection;
 import io.debezium.connector.sqlserver.SqlServerConnectorConfig;
 import io.debezium.connector.sqlserver.SqlServerDatabaseSchema;
@@ -36,14 +38,13 @@
 import org.slf4j.LoggerFactory;
 
 import static com.ververica.cdc.connectors.sqlserver.source.offset.LsnOffset.NO_STOPPING_OFFSET;
-import static com.ververica.cdc.connectors.sqlserver.source.utils.SqlServerUtils.getLsnPosition;
 
 /** The task to work for fetching data of SqlServer table stream split . */
 public class SqlServerStreamFetchTask implements FetchTask<SourceSplitBase> {
 
     private final StreamSplit split;
     private volatile boolean taskRunning = false;
-    private LsnSplitReadTask redoLogSplitReadTask;
+    private StreamSplitReadTask redoLogSplitReadTask;
 
     public SqlServerStreamFetchTask(StreamSplit split) {
         this.split = split;
@@ -56,7 +57,7 @@ public void execute(Context context) throws Exception {
         sourceFetchContext.getOffsetContext().preSnapshotCompletion();
         taskRunning = true;
         redoLogSplitReadTask =
-                new LsnSplitReadTask(
+                new StreamSplitReadTask(
                         sourceFetchContext.getDbzConnectorConfig(),
                         sourceFetchContext.getConnection(),
                         sourceFetchContext.getMetaDataConnection(),
@@ -91,15 +92,15 @@ public void close() {
      * A wrapped task to read all binlog for table and also supports read bounded (from lowWatermark
      * to highWatermark) binlog.
      */
-    public static class LsnSplitReadTask extends SqlServerStreamingChangeEventSource {
+    public static class StreamSplitReadTask extends SqlServerStreamingChangeEventSource {
 
-        private static final Logger LOG = LoggerFactory.getLogger(LsnSplitReadTask.class);
+        private static final Logger LOG = LoggerFactory.getLogger(StreamSplitReadTask.class);
         private final StreamSplit lsnSplit;
         private final JdbcSourceEventDispatcher<SqlServerPartition> dispatcher;
         private final ErrorHandler errorHandler;
         private ChangeEventSourceContext context;
 
-        public LsnSplitReadTask(
+        public StreamSplitReadTask(
                 SqlServerConnectorConfig connectorConfig,
                 SqlServerConnection connection,
                 SqlServerConnection metadataConnection,
@@ -121,26 +122,25 @@ public LsnSplitReadTask(
         }
 
         @Override
-        public void afterHandleLsn(
-                SqlServerPartition partition, SqlServerOffsetContext offsetContext) {
+        public void afterHandleLsn(SqlServerPartition partition, Lsn toLsn) {
             // check do we need to stop for fetch binlog for snapshot split.
             if (isBoundedRead()) {
-                final LsnOffset currentRedoLogOffset = getLsnPosition(offsetContext.getOffset());
-                // reach the high watermark, the binlog fetcher should be finished
-                if (currentRedoLogOffset.isAtOrAfter(lsnSplit.getEndingOffset())) {
-                    // send binlog end event
+                LsnOffset currentLsnOffset = new LsnOffset(null, toLsn, null);
+                Offset endingOffset = lsnSplit.getEndingOffset();
+                if (currentLsnOffset.isAtOrAfter(endingOffset)) {
+                    // send streaming end event
                     try {
                         dispatcher.dispatchWatermarkEvent(
                                 partition.getSourcePartition(),
                                 lsnSplit,
-                                currentRedoLogOffset,
+                                currentLsnOffset,
                                 WatermarkKind.END);
                     } catch (InterruptedException e) {
                         LOG.error("Send signal event error.", e);
                         errorHandler.setProducerThrowable(
                                 new DebeziumException("Error processing binlog signal event", e));
                     }
-                    // tell fetcher the binlog task finished
+                    // tell fetcher the streaming task finished
                     ((SqlServerScanFetchTask.SnapshotBinlogSplitChangeEventSourceContext) context)
                             .finished();
                 }

flink-connector-sqlserver-cdc/src/main/java/io/debezium/connector/sqlserver/SqlServerStreamingChangeEventSource.java

@@ -38,11 +38,11 @@
 
 /**
  * Copied from Debezium project(1.9.7.final) to add method {@link
- * SqlServerStreamingChangeEventSource#afterHandleLsn(SqlServerPartition, SqlServerOffsetContext)}.
- * Also implemented {@link SqlServerStreamingChangeEventSource#execute( ChangeEventSourceContext,
- * SqlServerPartition, SqlServerOffsetContext)}. A {@link StreamingChangeEventSource} based on SQL
- * Server change data capture functionality. A main loop polls database DDL change and change data
- * tables and turns them into change events.
+ * SqlServerStreamingChangeEventSource#afterHandleLsn(SqlServerPartition, Lsn)}. Also implemented
+ * {@link SqlServerStreamingChangeEventSource#execute( ChangeEventSourceContext, SqlServerPartition,
+ * SqlServerOffsetContext)}. A {@link StreamingChangeEventSource} based on SQL Server change data
+ * capture functionality. A main loop polls database DDL change and change data tables and turns
+ * them into change events.
  *
  * <p>The connector uses CDC functionality of SQL Server that is implemented as as a process that
  * monitors source table and write changes from the table into the change table.
@@ -198,7 +198,6 @@ public boolean executeIteration(
 
             if (context.isRunning()) {
                 commitTransaction();
-                afterHandleLsn(partition, offsetContext);
                 final Lsn toLsn =
                         getToLsn(
                                 dataConnection,
@@ -449,6 +448,8 @@ public boolean executeIteration(
                             TxLogPosition.valueOf(toLsn));
                     // Terminate the transaction otherwise CDC could not be disabled for tables
                     dataConnection.rollback();
+                    // Determine whether to continue streaming in sqlserver cdc snapshot phase
+                    afterHandleLsn(partition, toLsn);
                 } catch (SQLException e) {
                     tablesSlot.set(
                             processErrorFromChangeTableQuery(databaseName, e, tablesSlot.get()));
@@ -625,8 +626,7 @@ private Lsn getToLsn(
     }
 
     /** expose control to the user to stop the connector. */
-    protected void afterHandleLsn(
-            SqlServerPartition partition, SqlServerOffsetContext offsetContext) {
+    protected void afterHandleLsn(SqlServerPartition partition, Lsn toLsn) {
         // do nothing
     }
 }