#928 Fix infinite loop in FBPooledConnection.fireConnectionError

(backport of #927)

Author: mrotteveel

src/docs/asciidoc/release_notes.adoc

@@ -54,6 +54,7 @@ This results in two minor breaking changes:
 * Fixed: JDBC escapes should not be parsed inside dialect 3 delimited identifiers or dialect 1 string literals (https://github.com/FirebirdSQL/jaybird/issues/922[#922])
 * Fixed: `IndexOutOfBoundsException` in `FBCachedBlob.getBytes(long, int)` for position or length beyond end of data (https://github.com/FirebirdSQL/jaybird/issues/924[#924])
 * Fixed: Using native client, password is limited to 255 bytes (https://github.com/FirebirdSQL/jaybird/issues/926[#926])
+* Fixed: Infinite loop in `FBPooledConnection#fireConnectionError(SQLException)` if the exception has a chained exception and neither is fatal (https://github.com/FirebirdSQL/jaybird/issues/928[#928])
 
 [#jaybird-5-0-11-changelog]
 === Jaybird 5.0.11

src/main/org/firebirdsql/ds/FBPooledConnection.java

@@ -161,7 +161,7 @@ protected void fireConnectionError(SQLException ex) {
                 fireFatalConnectionError(ex);
                 return;
             }
-            currentException = ex.getNextException();
+            currentException = currentException.getNextException();
         }
     }
 

src/test/org/firebirdsql/ds/FBPooledConnectionMockTest.java

@@ -20,13 +20,15 @@
 
 import java.sql.Connection;
 import java.sql.SQLException;
+import java.util.concurrent.TimeUnit;
 
 import javax.sql.ConnectionEvent;
 import javax.sql.ConnectionEventListener;
 
 import org.firebirdsql.jdbc.FBSQLException;
 import org.firebirdsql.jdbc.SQLStateConstants;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
@@ -190,4 +192,24 @@ void testGetConnectionRestoresAutoCommit() throws SQLException {
 
         verify(physical).setAutoCommit(true);
     }
+
+    /**
+     * See also <a href="https://github.com/FirebirdSQL/jaybird/issues/927">#927</a>.
+     */
+    @Test
+    @Timeout(value = 200, unit = TimeUnit.MILLISECONDS, threadMode = Timeout.ThreadMode.SEPARATE_THREAD)
+    void noInfiniteLoopWithNonFatalChainedExceptions(@Mock ConnectionEventListener cel) throws Exception {
+        pooled.addConnectionEventListener(cel);
+        Connection connection = pooled.getConnection();
+
+        SQLException nonFatalChainedException = new SQLException("Not fatal");
+        nonFatalChainedException.setNextException(new SQLException("Not fatal either"));
+        doThrow(nonFatalChainedException).when(physical).setAutoCommit(false);
+
+        SQLException exception = assertThrows(SQLException.class, () -> connection.setAutoCommit(false));
+        assertSame(nonFatalChainedException, exception);
+
+        verify(cel, never()).connectionErrorOccurred(any(ConnectionEvent.class));
+    }
+
 }