eskabetxe commented on code in PR #2:
URL:
https://github.com/apache/flink-connector-jdbc/pull/2#discussion_r1441516846
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flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/datasource/transactions/xa/XaTransaction.java:
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@@ -0,0 +1,295 @@
+package org.apache.flink.connector.jdbc.datasource.transactions.xa;
+
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.connector.jdbc.JdbcExactlyOnceOptions;
+import
org.apache.flink.connector.jdbc.datasource.connections.xa.XaConnectionProvider;
+import
org.apache.flink.connector.jdbc.datasource.transactions.xa.domain.TransactionId;
+import
org.apache.flink.connector.jdbc.datasource.transactions.xa.exceptions.EmptyTransactionXaException;
+import
org.apache.flink.connector.jdbc.datasource.transactions.xa.exceptions.TransientXaException;
+import org.apache.flink.connector.jdbc.sink.writer.JdbcWriterState;
+import org.apache.flink.util.ExceptionUtils;
+import org.apache.flink.util.Preconditions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.transaction.xa.Xid;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+/** */
+public class XaTransaction implements Serializable, AutoCloseable {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(XaTransaction.class);
+
+ private final XaConnectionProvider xaConnectionProvider;
+ private final JdbcExactlyOnceOptions exactlyOnceOptions;
+
+ // checkpoints and the corresponding transactions waiting for completion
notification from JM
+ private transient List<TransactionId> preparedXids = new ArrayList<>();
+ // hanging XIDs - used for cleanup
+ // it's a list to support retries and scaling down
+ // possible transaction states: active, idle, prepared
+ // last element is the current xid
+ private transient Deque<TransactionId> hangingXids = new LinkedList<>();
+ private transient TransactionId currentTid;
+
+ private final TransactionId baseTransaction;
+
+ public XaTransaction(
+ JdbcExactlyOnceOptions exactlyOnceOptions,
+ TransactionId transactionId,
+ XaConnectionProvider xaFacade) {
+ this.xaConnectionProvider = xaFacade;
+ this.exactlyOnceOptions = exactlyOnceOptions;
+ this.baseTransaction = transactionId;
+ }
+
+ public Xid getCurrentXid() {
+ return currentTid;
+ }
+
+ public XaConnectionProvider getConnectionProvider() {
+ return xaConnectionProvider;
+ }
+
+ public JdbcWriterState getState() {
+ return JdbcWriterState.of(preparedXids, hangingXids);
+ }
+
+ public void open(JdbcWriterState state) throws IOException {
+ try {
+ xaConnectionProvider.open();
+ recoverState(state);
+ hangingXids = new
LinkedList<>(failOrRollback(hangingXids).getForRetry());
+ commitTx();
+ if (exactlyOnceOptions.isDiscoverAndRollbackOnRecovery()) {
+ // Pending transactions which are not included into the
checkpoint might hold locks
+ // and
+ // should be rolled back. However, rolling back ALL
transactions can cause data
+ // loss. So
+ // each subtask first commits transactions from its state and
then rolls back
+ // discovered
+ // transactions if they belong to it.
+ recoverAndRollback();
+ }
+ } catch (Exception e) {
+ ExceptionUtils.rethrowIOException(e);
+ }
+ }
+
+ @Override
+ public void close() throws Exception {
+ if (currentTid != null && xaConnectionProvider.isOpen()) {
+ try {
+ LOG.debug(
+ "remove current transaction before closing, xid={}",
+ currentTid.getXidValue());
+ xaConnectionProvider.failAndRollback(currentTid);
+ } catch (Exception e) {
+ LOG.warn(
+ "unable to fail/rollback current transaction, xid={}",
+ currentTid.getXidValue(),
+ e);
+ }
+ }
+ xaConnectionProvider.close();
+ currentTid = null;
+ hangingXids = null;
+ preparedXids = null;
+ }
+
+ public void recoverState(JdbcWriterState state) {
+ hangingXids = new LinkedList<>(state.getHanging());
+ preparedXids = new ArrayList<>(state.getPrepared());
+ LOG.info(
+ "initialized state: prepared xids: {}, hanging xids: {}",
+ preparedXids.size(),
+ hangingXids.size());
+ }
+
+ public void checkState() {
+ Preconditions.checkState(currentTid != null, "current xid must not be
null");
+ Preconditions.checkState(
+ !hangingXids.isEmpty() &&
hangingXids.peekLast().equals(currentTid),
+ "inconsistent internal state");
+ }
+
+ /** @param checkpointId to associate with the new transaction. */
+ public void createTx(long checkpointId) throws IOException {
+ try {
+ Preconditions.checkState(currentTid == null, "currentXid not
null");
+ currentTid = baseTransaction.withBranch(checkpointId);
+ hangingXids.offerLast(currentTid);
+ xaConnectionProvider.start(currentTid);
+ } catch (Exception e) {
+ ExceptionUtils.rethrowIOException(e);
+ }
+ }
+
+ public void prepareTx() throws IOException {
+ checkState();
+ hangingXids.pollLast();
+ try {
+ xaConnectionProvider.endAndPrepare(currentTid);
+ preparedXids.add(currentTid);
+ } catch (EmptyTransactionXaException e) {
+ LOG.info(
+ "empty XA transaction (skip), xid: {}, checkpoint {}",
+ currentTid.getXidValue(),
+ currentTid.getCheckpointId());
+ } catch (Exception e) {
+ ExceptionUtils.rethrowIOException(e);
+ }
+ currentTid = null;
+ }
+
+ public void commitTx() {
+ List<TransactionId> toCommit = preparedXids;
+ preparedXids = new ArrayList<>();
+ preparedXids.addAll(commitXids(toCommit));
+ }
+
+ public void commitTxUntil(long checkpointId) {
+ Tuple2<List<TransactionId>, List<TransactionId>> splittedXids =
+ split(preparedXids, checkpointId);
+
+ if (splittedXids.f0.isEmpty()) {
+ LOG.warn("nothing to commit up to checkpoint: {}", checkpointId);
+ } else {
+ preparedXids = splittedXids.f1;
+ preparedXids.addAll(commitXids(splittedXids.f0));
+ }
+ }
+
+ public List<TransactionId> commitXids(List<TransactionId> xids) {
+ return commit(
+ xids,
+ exactlyOnceOptions.isAllowOutOfOrderCommits(),
+ exactlyOnceOptions.getMaxCommitAttempts())
+ .getForRetry();
+ }
+
+ private Tuple2<List<TransactionId>, List<TransactionId>> split(
+ List<TransactionId> list, long checkpointId) {
+ return split(list, checkpointId, true);
+ }
+
+ private Tuple2<List<TransactionId>, List<TransactionId>> split(
+ List<TransactionId> list, long checkpointId, boolean
checkpointIntoLo) {
+
+ List<TransactionId> lo = new ArrayList<>(list.size() / 2);
+ List<TransactionId> hi = new ArrayList<>(list.size() / 2);
+ list.forEach(
+ i -> {
+ if (i.getCheckpointId() < checkpointId
+ || (i.getCheckpointId() == checkpointId &&
checkpointIntoLo)) {
+ lo.add(i);
+ } else {
+ hi.add(i);
+ }
+ });
+ return new Tuple2<>(lo, hi);
+ }
+
+ private XaTransactionResult<TransactionId> commit(
+ List<TransactionId> xids, boolean allowOutOfOrderCommits, int
maxCommitAttempts) {
+ XaTransactionResult<TransactionId> result = new
XaTransactionResult<>();
+ int origSize = xids.size();
+ LOG.debug("commit {} transactions", origSize);
+ for (Iterator<TransactionId> i = xids.iterator();
+ i.hasNext() && (result.hasNoFailures() ||
allowOutOfOrderCommits); ) {
+ TransactionId x = i.next();
+ i.remove();
+ try {
+ xaConnectionProvider.commit(x, x.getRestored());
+ result.succeeded(x);
+ } catch (TransientXaException e) {
+ result.failedTransiently(x.withAttemptsIncremented(), e);
+ } catch (Exception e) {
+ result.failed(x, e);
+ }
+ }
+ result.getForRetry().addAll(xids);
+ result.throwIfAnyFailed("commit");
+ throwIfAnyReachedMaxAttempts(result, maxCommitAttempts);
+ result.getTransientFailure()
+ .ifPresent(
+ f ->
+ LOG.warn(
+ "failed to commit {} transactions out
of {} (keep them to retry later)",
+ result.getForRetry().size(),
+ origSize,
+ f));
+ return result;
+ }
+
+ private XaTransactionResult<TransactionId>
failOrRollback(Collection<TransactionId> xids) {
+ XaTransactionResult<TransactionId> result = new
XaTransactionResult<>();
+ if (xids.isEmpty()) {
+ return result;
+ }
+ if (LOG.isDebugEnabled()) {
+ LOG.debug("rolling back {} transactions: {}", xids.size(), xids);
+ }
+ for (TransactionId x : xids) {
+ try {
+ xaConnectionProvider.failAndRollback(x);
+ result.succeeded(x);
+ } catch (TransientXaException e) {
+ LOG.info("unable to fail/rollback transaction, xid={}: {}", x,
e.getMessage());
+ result.failedTransiently(x, e);
+ } catch (Exception e) {
+ LOG.warn("unable to fail/rollback transaction, xid={}: {}", x,
e.getMessage());
+ result.failed(x, e);
+ }
+ }
+ if (!result.getForRetry().isEmpty()) {
+ LOG.info("failed to roll back {} transactions",
result.getForRetry().size());
+ }
+ return result;
+ }
+
+ private void recoverAndRollback() {
+ Collection<Xid> recovered = xaConnectionProvider.recover();
+ if (recovered.isEmpty()) {
+ return;
+ }
+ LOG.warn("rollback {} recovered transactions", recovered.size());
+ for (Xid xid : recovered) {
+ if (baseTransaction.belongsTo(xid)) {
+ try {
+ xaConnectionProvider.rollback(xid);
+ } catch (Exception e) {
+ LOG.info("unable to rollback recovered transaction,
xid={}", xid, e);
+ }
+ }
+ }
+ }
+
+ private void throwIfAnyReachedMaxAttempts(
+ XaTransactionResult<TransactionId> result, int maxAttempts) {
+ List<TransactionId> reached = null;
+ for (TransactionId x : result.getForRetry()) {
+ if (x.getAttempts() >= maxAttempts) {
+ if (reached == null) {
+ reached = new ArrayList<>();
+ }
+ reached.add(x);
+ }
+ }
+ if (reached != null) {
Review Comment:
I would need to change to checkArgument(reached == null, "error message")
and this will throw a IllegalArgumentException.
Its not really a bad argument, I would say that I prefer the way it is
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