/* * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* @test * @bug 4094891 8157777 * @summary unable to retry call if cached connection to server is used * @library ../../../../java/rmi/testlibrary * @modules java.rmi/sun.rmi.registry * java.rmi/sun.rmi.server * java.rmi/sun.rmi.transport * java.rmi/sun.rmi.transport.tcp * @build TestLibrary REGISTRY RegistryRunner * @run main/othervm DeadCachedConnection */ /* Fault: Cached connections used for remote invocations exhibited * failure (sudden EOF or a TCP-related exception) immediately on * sending a new request. It was then impossible to tell whether the * connection had managed to transport the request before dying; even * deserialization of request arguments is non-idempotent in general. * * In fact, this problem cannot be solved generally without rewriting * the protocol. For now, the common case is the closing of an idle * connection by a loaded/bored/dead server host. * * The fix is/was to trivially attempt to execute a non-blocking read * on the connection before reusing it, to see if an exception/EOF is * waiting for delivery. This is a 99%/1% solution, but until the * great protocol rewrite, it's the best option. * * Reproducing is by establishing a connection to a registry and * killing/restarting that registry (this forces the TCP connection * to close). The next call to the registry will use the (stale) * cached connection, and will fail without the bugfix. */ import java.io.*; import java.rmi.*; import java.rmi.registry.*; import java.rmi.server.*; public class DeadCachedConnection { static public void main(String[] argv) throws Exception { try { Registry reg = null; int port = makeRegistry(0); // Get a handle to the registry System.err.println ("Locating just-started registry..."); try { reg = LocateRegistry.getRegistry(port); } catch (RemoteException e) { throw new InternalError ("Can't find registry after starting it."); } // Contact the registry by invoking something on it. System.err.println ("Connecting to registry..."); String[] junk = reg.list(); // Kill and restart the registry System.err.println("Killing registry..."); killRegistry(); System.err.println("Restarting registry..."); makeRegistry(port); // Try again (this is the test) System.err.println("Trying to use registry in spite of stale cache..."); junk = reg.list(); System.err.println("Test succeeded."); } catch (Exception e) { TestLibrary.bomb(e); } finally { // dont leave the registry around to affect other tests. killRegistry(); } } public static int makeRegistry(int port) { try { subreg = REGISTRY.createREGISTRY(System.out, System.err, "", port); subreg.start(); int regPort = subreg.getPort(); System.out.println("Starting registry on port " + regPort); return regPort; } catch (IOException e) { // one of these is summarily dropped, can't remember which one System.out.println ("Test setup failed - cannot run rmiregistry"); TestLibrary.bomb("Test setup failed - cannot run test", e); } return -1; } private static REGISTRY subreg = null; public static void killRegistry() throws InterruptedException { if (subreg != null) { subreg.shutdown(); subreg = null; } } }