Avoid getTargetConnection call on transaction-aware Connection close

Closes gh-34484

(cherry picked from commit c64dae3)

Author: jhoeller

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -439,7 +439,11 @@ private static boolean connectionEquals(ConnectionHolder conHolder, Connection p
 	public static Connection getTargetConnection(Connection con) {
 		Connection conToUse = con;
 		while (conToUse instanceof ConnectionProxy connectionProxy) {
-			conToUse = connectionProxy.getTargetConnection();
+			Connection targetCon = connectionProxy.getTargetConnection();
+			if (targetCon == conToUse) {
+				break;
+			}
+			conToUse = targetCon;
 		}
 		return conToUse;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/TransactionAwareDataSourceProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -210,13 +210,23 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
 						sb.append('[').append(this.target).append(']');
 					}
 					else {
-						sb.append(" from DataSource [").append(this.targetDataSource).append(']');
+						sb.append("from DataSource [").append(this.targetDataSource).append(']');
 					}
 					return sb.toString();
 				}
 				case "close" -> {
 					// Handle close method: only close if not within a transaction.
-					DataSourceUtils.doReleaseConnection(this.target, this.targetDataSource);
+					if (this.target != null) {
+						ConnectionHolder conHolder = (ConnectionHolder)
+								TransactionSynchronizationManager.getResource(this.targetDataSource);
+						if (conHolder != null && conHolder.hasConnection() && conHolder.getConnection() == this.target) {
+							// It's the transactional Connection: Don't close it.
+							conHolder.released();
+						}
+						else {
+							DataSourceUtils.doCloseConnection(this.target, this.targetDataSource);
+						}
+					}
 					this.closed = true;
 					return null;
 				}

spring-jdbc/src/test/java/org/springframework/jdbc/datasource/DataSourceTransactionManagerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,7 +72,7 @@ public class DataSourceTransactionManagerTests {
 
 	protected DataSource ds = mock();
 
-	protected Connection con = mock();
+	protected ConnectionProxy con = mock();
 
 	protected DataSourceTransactionManager tm;
 
@@ -81,6 +81,7 @@ public class DataSourceTransactionManagerTests {
 	void setup() throws Exception {
 		tm = createTransactionManager(ds);
 		given(ds.getConnection()).willReturn(con);
+		given(con.getTargetConnection()).willThrow(new UnsupportedOperationException());
 	}
 
 	protected DataSourceTransactionManager createTransactionManager(DataSource ds) {
@@ -1074,9 +1075,9 @@ protected void doInTransactionWithoutResult(TransactionStatus status) {
 					Connection tCon = dsProxy.getConnection();
 					tCon.getWarnings();
 					tCon.clearWarnings();
-					assertThat(((ConnectionProxy) dsProxy.getConnection()).getTargetConnection()).isEqualTo(con);
+					assertThat(((ConnectionProxy) tCon).getTargetConnection()).isEqualTo(con);
 					// should be ignored
-					dsProxy.getConnection().close();
+					tCon.close();
 				}
 				catch (SQLException ex) {
 					throw new UncategorizedSQLException("", "", ex);
@@ -1110,9 +1111,9 @@ protected void doInTransactionWithoutResult(TransactionStatus status) {
 					Connection tCon = dsProxy.getConnection();
 					assertThatExceptionOfType(SQLException.class).isThrownBy(tCon::getWarnings);
 					tCon.clearWarnings();
-					assertThat(((ConnectionProxy) dsProxy.getConnection()).getTargetConnection()).isEqualTo(con);
+					assertThat(((ConnectionProxy) tCon).getTargetConnection()).isEqualTo(con);
 					// should be ignored
-					dsProxy.getConnection().close();
+					tCon.close();
 				}
 				catch (SQLException ex) {
 					throw new UncategorizedSQLException("", "", ex);
@@ -1128,6 +1129,42 @@ protected void doInTransactionWithoutResult(TransactionStatus status) {
 		verify(con).close();
 	}
 
+	@Test
+	void testTransactionAwareDataSourceProxyWithEarlyConnection() throws Exception {
+		given(ds.getConnection()).willReturn(mock(Connection.class), con);
+		given(con.getAutoCommit()).willReturn(true);
+		given(con.getWarnings()).willThrow(new SQLException());
+
+		TransactionAwareDataSourceProxy dsProxy = new TransactionAwareDataSourceProxy(ds);
+		dsProxy.setLazyTransactionalConnections(false);
+		Connection tCon = dsProxy.getConnection();
+
+		TransactionTemplate tt = new TransactionTemplate(tm);
+		assertThat(TransactionSynchronizationManager.hasResource(ds)).isFalse();
+		tt.execute(new TransactionCallbackWithoutResult() {
+			@Override
+			protected void doInTransactionWithoutResult(TransactionStatus status) {
+				// something transactional
+				assertThat(DataSourceUtils.getConnection(ds)).isEqualTo(con);
+				try {
+					// should close the early Connection obtained before the transaction
+					tCon.close();
+				}
+				catch (SQLException ex) {
+					throw new UncategorizedSQLException("", "", ex);
+				}
+			}
+		});
+
+		assertThat(TransactionSynchronizationManager.hasResource(ds)).isFalse();
+
+		InOrder ordered = inOrder(con);
+		ordered.verify(con).setAutoCommit(false);
+		ordered.verify(con).commit();
+		ordered.verify(con).setAutoCommit(true);
+		verify(con).close();
+	}
+
 	@Test
 	void testTransactionAwareDataSourceProxyWithSuspension() throws Exception {
 		given(con.getAutoCommit()).willReturn(true);