1 /*

     2  * Copyright (c) 2014, 2017, 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.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.jshell.execution;

    27 

    28 import java.io.ObjectInput;

    29 import java.io.ObjectOutput;

    30 import java.util.HashMap;

    31 import java.util.List;

    32 import java.util.Map;

    33 import java.util.stream.Stream;

    34 import com.sun.jdi.ReferenceType;

    35 import com.sun.jdi.VirtualMachine;

    36 import jdk.jshell.spi.ExecutionControl;

    37 import static java.util.stream.Collectors.toMap;

    38 

    39 /**

    40  * Abstract JDI implementation of {@link jdk.jshell.spi.ExecutionControl}.

    41  *

    42  * @since 9

    43  */

    44 public abstract class JdiExecutionControl extends StreamingExecutionControl implements ExecutionControl {

    45 

    46     /**

    47      * Mapping from class names to JDI {@link ReferenceType}.

    48      */

    49     private final Map<String, ReferenceType> toReferenceType = new HashMap<>();

    50 

    51     /**

    52      * Create an instance.

    53      * @param out the output from the remote agent

    54      * @param in the input to the remote agent

    55      */

    56     protected JdiExecutionControl(ObjectOutput out, ObjectInput in) {

    57         super(out, in);

    58     }

    59 

    60     /**

    61      * Returns the JDI {@link VirtualMachine} instance.

    62      *

    63      * @return the virtual machine

    64      * @throws EngineTerminationException if the VM is dead/disconnected

    65      */

    66     protected abstract VirtualMachine vm() throws EngineTerminationException;

    67 

    68     /**

    69      * Redefine the specified classes. Where 'redefine' is, as in JDI and JVMTI,

    70      * an in-place replacement of the classes (preserving class identity) --

    71      * that is, existing references to the class do not need to be recompiled.

    72      * This implementation uses JDI

    73      * {@link com.sun.jdi.VirtualMachine#redefineClasses(java.util.Map) }.

    74      * It will be unsuccessful if

    75      * the signature of the class has changed (see the JDI spec). The

    76      * JShell-core is designed to adapt to unsuccessful redefine.

    77      */

    78     @Override

    79     public void redefine(ClassBytecodes[] cbcs)

    80             throws ClassInstallException, EngineTerminationException {

    81         try {

    82             // Convert to the JDI ReferenceType to class bytes map form needed

    83             // by JDI.

    84             VirtualMachine vm = vm();

    85             Map<ReferenceType, byte[]> rmp = Stream.of(cbcs)

    86                     .collect(toMap(

    87                             cbc -> referenceType(vm, cbc.name()),

    88                             cbc -> cbc.bytecodes()));

    89             // Attempt redefine.  Throws exceptions on failure.

    90             vm().redefineClasses(rmp);

    91         } catch (EngineTerminationException ex) {

    92             throw ex;

    93         } catch (Exception ex) {

    94             throw new ClassInstallException("redefine: " + ex.getMessage(), new boolean[cbcs.length]);

    95         }

    96         // forward the redefine to remote-end to register the redefined bytecode

    97         try {

    98             super.redefine(cbcs);

    99         } catch (NotImplementedException ex) {

   100             // this remote doesn't care about registering bytecode, so we don't either

   101         }

   102     }

   103 

   104     /**

   105      * Returns the JDI {@link ReferenceType} corresponding to the specified

   106      * class name.

   107      *

   108      * @param vm the current JDI {@link VirtualMachine} as returned by

   109      * {@code vm()}

   110      * @param name the class name to look-up

   111      * @return the corresponding {@link ReferenceType}

   112      */

   113     protected ReferenceType referenceType(VirtualMachine vm, String name) {

   114         return toReferenceType.computeIfAbsent(name, n -> nameToRef(vm, n));

   115     }

   116 

   117     private static ReferenceType nameToRef(VirtualMachine vm, String name) {

   118         List<ReferenceType> rtl = vm.classesByName(name);

   119         if (rtl.size() != 1) {

   120             return null;

   121         }

   122         return rtl.get(0);

   123     }

   124 

   125 }