rkhachatryan commented on a change in pull request #15636: URL: https://github.com/apache/flink/pull/15636#discussion_r615437813
########## File path: flink-connectors/flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/xa/XaFacadePoolingImpl.java ########## @@ -0,0 +1,183 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.connector.jdbc.xa; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.util.function.ThrowingConsumer; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; +import javax.transaction.xa.Xid; + +import java.io.Serializable; +import java.sql.Connection; +import java.sql.SQLException; +import java.util.Collection; +import java.util.Deque; +import java.util.HashMap; +import java.util.LinkedList; +import java.util.Map; +import java.util.function.Supplier; + +import static org.apache.flink.util.ExceptionUtils.rethrow; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * A "pooling" implementation of {@link XaFacade}. Some database implement XA such that one + * connection is limited to a single transaction. As a workaround, this implementation creates a new + * XA resource after each xa_prepare call is made (and associates the current one with the xid to + * commit later). + */ +@Internal +class XaFacadePoolingImpl implements XaFacade { + private static final long serialVersionUID = 1L; + + public interface FacadeSupplier extends Serializable, Supplier<XaFacade> {} + + private static final transient Logger LOG = LoggerFactory.getLogger(XaFacadePoolingImpl.class); + private final FacadeSupplier facadeSupplier; + private transient XaFacade active; + private transient Map<Xid, XaFacade> prepared; + private transient Deque<XaFacade> pooled; + + XaFacadePoolingImpl(FacadeSupplier facadeSupplier) { + this.facadeSupplier = facadeSupplier; + } + + @Override + public void open() throws Exception { + checkState(active == null); + active = facadeSupplier.get(); + active.open(); + pooled = new LinkedList<>(); + prepared = new HashMap<>(); + } + + @Override + public boolean isOpen() { + return active != null && active.isOpen(); + } + + @Override + public void start(Xid xid) throws TransientXaException { + active.start(xid); + } + + @Override + public void endAndPrepare(Xid xid) throws Exception { + checkState(!prepared.containsKey(xid)); + active.endAndPrepare(xid); + prepared.put(xid, active); + if (pooled.isEmpty()) { + active = facadeSupplier.get(); + active.open(); + } else { + active = pooled.poll(); + } + } + + @Override + public void commit(Xid xid, boolean ignoreUnknown) throws TransientXaException { + runForXid(xid, facade -> facade.commit(xid, ignoreUnknown)); + } + + @Override + public void rollback(Xid xid) throws TransientXaException { + runForXid(xid, facade -> facade.rollback(xid)); + } + + @Override + public void failOrRollback(Xid xid) throws TransientXaException { + runForXid(xid, facade -> facade.failOrRollback(xid)); + } + + @Override + public Collection<Xid> recover() throws TransientXaException { + return peekPooled().recover(); + } + + @Override + public void close() throws Exception { + active.close(); + for (XaFacade facade : prepared.values()) { + facade.close(); + } + for (XaFacade facade : pooled) { + facade.close(); + } + } + + @Nullable + @Override + public Connection getConnection() { + return active.getConnection(); + } + + @Override + public boolean isConnectionValid() throws SQLException { + return active.isConnectionValid(); + } + + @Override + public Connection getOrEstablishConnection() throws SQLException, ClassNotFoundException { + return active.getOrEstablishConnection(); + } + + @Override + public void closeConnection() { + active.closeConnection(); + } + + @Override + public Connection reestablishConnection() throws SQLException, ClassNotFoundException { + return active.reestablishConnection(); + } + + // WARN: action MUST leave the facade in IDLE state (i.e. not start/end/prepare any tx) + private void runForXid(Xid xid, ThrowingConsumer<XaFacade, TransientXaException> action) { + XaFacade mapped = prepared.remove(xid); + if (mapped == null) { + LOG.debug("No XA resource found associated with XID: {}", xid); + action.accept(peekPooled()); Review comment: Yes, this can happen on recovery, I'll add a comment. -- This is an automated message from the Apache Git Service. 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