tomcat-jdbc check if returned connection is closed

modules/jdbc-pool/src/main/java/org/apache/tomcat/jdbc/pool/ConnectionPool.java

@@ -911,6 +911,12 @@ protected boolean terminateTransaction(PooledConnection con) {
     protected boolean shouldClose(PooledConnection con, int action) {
         if (con.getConnectionVersion() < getPoolVersion()) return true;
         if (con.isDiscarded()) return true;
+        try {
+            if (con.isClosed()) return true;
+        } catch (SQLException e) {
+            log.warn("Unable to check if connection is closed", e);
+            return true;
+        }
         if (isClosed()) return true;
         if (!con.validate(action)) return true;
         if (!terminateTransaction(con)) return true;

modules/jdbc-pool/src/test/java/org/apache/tomcat/jdbc/test/TestValidation.java

@@ -19,6 +19,7 @@
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.DriverPropertyInfo;
+import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.SQLFeatureNotSupportedException;
 import java.sql.Savepoint;
@@ -141,6 +142,29 @@ public void testOnConnectValidationWithValidationSQLDoesNotOccurWhenDisabled() t
         Assert.assertFalse("No transaction must be running after connection is obtained", getMock(cxn).isRunningTransaction());
     }
 
+    @Test
+    public void returnClosedConnection() throws SQLException {
+        datasource.setDriverClassName("org.h2.Driver");
+        datasource.setUrl("jdbc:h2:~/.h2/test;QUERY_TIMEOUT=0;DB_CLOSE_ON_EXIT=FALSE");
+        Assert.assertFalse(datasource.getPoolProperties().isTestOnBorrow());
+        Assert.assertFalse(datasource.getPoolProperties().isTestOnReturn());
+        Assert.assertFalse(datasource.getPoolProperties().isTestWhileIdle());
+        try (Connection connection = datasource.getConnection()) {
+            // this gets the real connection and closes it to simulate close by driver because of I/O error
+            final Connection realConnection = connection.getMetaData().getConnection();
+            Assert.assertNotSame(connection, realConnection);
+            realConnection.close();
+        }
+        try (Connection connection = datasource.getConnection()) {
+            try (Statement statement = connection.createStatement()) {
+                try (ResultSet resultSet = statement.executeQuery("select 1")) {
+                    Assert.assertTrue(resultSet.next());
+                    Assert.assertEquals(1, resultSet.getInt(1));
+                }
+            }
+        }
+    }
+
     @Test
     public void testOnConnectValidationSuccessWithValidationQueryAndAutoCommitEnabled() throws SQLException {
         checkOnConnectValidationWithOutcome(ValidationOutcome.SUCCESS, WITHVALIDATIONQUERY, WITHAUTOCOMMIT);