1 /*

     2  * Copyright (c) 2014, 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.  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 public abstract class JDIExecutionControl extends StreamingExecutionControl implements ExecutionControl {

    43 

    44     /**

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

    46      */

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

    48 

    49     /**

    50      * Create an instance.

    51      * @param out the output from the remote agent

    52      * @param in the input to the remote agent

    53      */

    54     protected JDIExecutionControl(ObjectOutput out, ObjectInput in) {

    55         super(out, in);

    56     }

    57 

    58     /**

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

    60      *

    61      * @return the virtual machine

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

    63      */

    64     protected abstract VirtualMachine vm() throws EngineTerminationException;

    65 

    66     /**

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

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

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

    70      * This implementation uses JDI

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

    72      * It will be unsuccessful if

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

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

    75      */

    76     @Override

    77     public void redefine(ClassBytecodes[] cbcs)

    78             throws ClassInstallException, EngineTerminationException {

    79         try {

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

    81             // by JDI.

    82             VirtualMachine vm = vm();

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

    84                     .collect(toMap(

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

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

    87             // Attempt redefine.  Throws exceptions on failure.

    88             vm().redefineClasses(rmp);

    89         } catch (EngineTerminationException ex) {

    90             throw ex;

    91         } catch (Exception ex) {

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

    93         }

    94     }

    95 

    96     /**

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

    98      * class name.

    99      *

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

   101      * {@code vm()}

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

   103      * @return the corresponding {@link ReferenceType}

   104      */

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

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

   107     }

   108 

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

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

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

   112             return null;

   113         }

   114         return rtl.get(0);

   115     }

   116 

   117 }