1 /*
   2  * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /* @test
  25  * @bug 4094891 8157777
  26  * @summary unable to retry call if cached connection to server is used
  27  * @library ../../../../java/rmi/testlibrary
  28  * @modules java.rmi/sun.rmi.registry
  29  *          java.rmi/sun.rmi.server
  30  *          java.rmi/sun.rmi.transport
  31  *          java.rmi/sun.rmi.transport.tcp
  32  * @build TestLibrary REGISTRY RegistryRunner
  33  * @run main/othervm DeadCachedConnection
  34  */
  35 
  36 /* Fault: Cached connections used for remote invocations exhibited
  37  * failure (sudden EOF or a TCP-related exception) immediately on
  38  * sending a new request.  It was then impossible to tell whether the
  39  * connection had managed to transport the request before dying; even
  40  * deserialization of request arguments is non-idempotent in general.
  41  *
  42  * In fact, this problem cannot be solved generally without rewriting
  43  * the protocol.  For now, the common case is the closing of an idle
  44  * connection by a loaded/bored/dead server host.
  45  *
  46  * The fix is/was to trivially attempt to execute a non-blocking read
  47  * on the connection before reusing it, to see if an exception/EOF is
  48  * waiting for delivery.  This is a 99%/1% solution, but until the
  49  * great protocol rewrite, it's the best option.
  50  *
  51  * Reproducing is by establishing a connection to a registry and
  52  * killing/restarting that registry (this forces the TCP connection
  53  * to close).  The next call to the registry will use the (stale)
  54  * cached connection, and will fail without the bugfix.
  55  */
  56 
  57 import java.io.*;
  58 import java.rmi.*;
  59 import java.rmi.registry.*;
  60 import java.rmi.server.*;
  61 
  62 public class DeadCachedConnection {
  63 
  64     static public void main(String[] argv)
  65         throws Exception {
  66         try {
  67             Registry reg = null;
  68             int port = makeRegistry(0);
  69 
  70             // Get a handle to the registry
  71             System.err.println ("Locating just-started registry...");
  72             try {
  73                 reg = LocateRegistry.getRegistry(port);
  74             } catch (RemoteException e) {
  75                 throw new InternalError ("Can't find registry after starting it.");
  76             }
  77 
  78             // Contact the registry by invoking something on it.
  79             System.err.println ("Connecting to registry...");
  80             String[] junk = reg.list();
  81 
  82             // Kill and restart the registry
  83             System.err.println("Killing registry...");
  84             killRegistry();
  85             System.err.println("Restarting registry...");
  86             makeRegistry(port);
  87 
  88             // Try again (this is the test)
  89             System.err.println("Trying to use registry in spite of stale cache...");
  90             junk = reg.list();
  91 
  92             System.err.println("Test succeeded.");
  93         } catch (Exception e) {
  94             TestLibrary.bomb(e);
  95         } finally {
  96             // dont leave the registry around to affect other tests.
  97             killRegistry();
  98         }
  99     }
 100 
 101     public static int makeRegistry(int port) {
 102         try {
 103             subreg = REGISTRY.createREGISTRY(System.out, System.err, "", port);
 104             subreg.start();
 105             int regPort = subreg.getPort();
 106             System.out.println("Starting registry on port " + regPort);
 107             return regPort;
 108         } catch (IOException e) {
 109             // one of these is summarily dropped, can't remember which one
 110             System.out.println ("Test setup failed - cannot run rmiregistry");
 111             TestLibrary.bomb("Test setup failed - cannot run test", e);
 112         }
 113         return -1;
 114     }
 115 
 116     private static REGISTRY subreg = null;
 117 
 118     public static void killRegistry() throws InterruptedException {
 119         if (subreg != null) {
 120             subreg.shutdown();
 121             subreg = null;
 122         }
 123     }
 124 }