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 package jdk.jshell.execution;

    26 

    27 import java.io.InputStream;

    28 import java.io.OutputStream;

    29 import java.io.PrintStream;

    30 import java.lang.reflect.Method;

    31 import java.net.Socket;

    32 

    33 import java.util.HashMap;

    34 import java.util.Map;

    35 import java.util.function.Consumer;

    36 import jdk.jshell.spi.ExecutionControl;

    37 import static jdk.jshell.execution.Util.forwardExecutionControlAndIO;

    38 

    39 /**

    40  * The remote agent runs in the execution process (separate from the main JShell

    41  * process). This agent loads code over a socket from the main JShell process,

    42  * executes the code, and other misc, Specialization of

    43  * {@link DirectExecutionControl} which adds stop support controlled by

    44  * an external process. Designed to work with {@link JdiDefaultExecutionControl}.

    45  *

    46  * @author Jan Lahoda

    47  * @author Robert Field

    48  * @since 9

    49  */

    50 public class RemoteExecutionControl extends DirectExecutionControl implements ExecutionControl {

    51 

    52     /**

    53      * Launch the agent, connecting to the JShell-core over the socket specified

    54      * in the command-line argument.

    55      *

    56      * @param args standard command-line arguments, expectation is the socket

    57      * number is the only argument

    58      * @throws Exception any unexpected exception

    59      */

    60     public static void main(String[] args) throws Exception {

    61         String loopBack = null;

    62         Socket socket = new Socket(loopBack, Integer.parseInt(args[0]));

    63         InputStream inStream = socket.getInputStream();

    64         OutputStream outStream = socket.getOutputStream();

    65         Map<String, Consumer<OutputStream>> outputs = new HashMap<>();

    66         outputs.put("out", st -> System.setOut(new PrintStream(st, true)));

    67         outputs.put("err", st -> System.setErr(new PrintStream(st, true)));

    68         Map<String, Consumer<InputStream>> input = new HashMap<>();

    69         input.put("in", System::setIn);

    70         forwardExecutionControlAndIO(new RemoteExecutionControl(), inStream, outStream, outputs, input);

    71     }

    72 

    73     // These three variables are used by the main JShell process in interrupting

    74     // the running process.  Access is via JDI, so the reference is not visible

    75     // to code inspection.

    76     private boolean inClientCode; // Queried by the main process (in superclass)

    77     private boolean expectingStop; // Set by the main process

    78 // Set by the main process

    79 

    80     // thrown by the main process via JDI:

    81     private final StopExecutionException stopException = new StopExecutionException();

    82 

    83     /**

    84      * Creates an instance, delegating loader operations to the specified

    85      * delegate.

    86      *

    87      * @param loaderDelegate the delegate to handle loading classes

    88      */

    89     public RemoteExecutionControl(LoaderDelegate loaderDelegate) {

    90         super(loaderDelegate);

    91     }

    92 

    93     /**

    94      * Create an instance using the default class loading.

    95      */

    96     public RemoteExecutionControl() {

    97     }

    98 

    99     /**

   100      * Redefine processing on the remote end is only to register the redefined classes

   101      */

   102     @Override

   103     public void redefine(ClassBytecodes[] cbcs)

   104             throws ClassInstallException, NotImplementedException, EngineTerminationException {

   105         classesRedefined(cbcs);

   106     }

   107 

   108     @Override

   109     public void stop() throws EngineTerminationException, InternalException {

   110         // handled by JDI

   111     }

   112 

   113     // Overridden only so this stack frame is seen

   114     @Override

   115     protected String invoke(Method doitMethod) throws Exception {

   116         return super.invoke(doitMethod);

   117     }

   118 

   119     // Overridden only so this stack frame is seen

   120     @Override

   121     public String varValue(String className, String varName) throws RunException, EngineTerminationException, InternalException {

   122         return super.varValue(className, varName);

   123     }

   124 

   125     @Override

   126     protected String throwConvertedInvocationException(Throwable cause) throws RunException, InternalException {

   127         if (cause instanceof StopExecutionException) {

   128             expectingStop = false;

   129             throw new StoppedException();

   130         } else {

   131             return super.throwConvertedInvocationException(cause);

   132         }

   133     }

   134 

   135     @Override

   136     protected String throwConvertedOtherException(Throwable ex) throws RunException, InternalException {

   137         if (ex instanceof StopExecutionException ||

   138                  ex.getCause() instanceof StopExecutionException) {

   139             expectingStop = false;

   140             throw new StoppedException();

   141         }

   142         return super.throwConvertedOtherException(ex);

   143     }

   144 

   145     @Override

   146     protected void clientCodeEnter() {

   147         expectingStop = false;

   148         inClientCode = true;

   149     }

   150 

   151     @Override

   152     protected void clientCodeLeave() throws InternalException {

   153         inClientCode = false;

   154         while (expectingStop) {

   155             try {

   156                 Thread.sleep(0);

   157             } catch (InterruptedException ex) {

   158                 throw new InternalException("*** Sleep interrupted while waiting for stop exception: " + ex);

   159             }

   160         }

   161     }

   162 

   163     @SuppressWarnings("serial")             // serialVersionUID intentionally omitted

   164     private class StopExecutionException extends ThreadDeath {

   165 

   166         @Override

   167         public synchronized Throwable fillInStackTrace() {

   168             return this;

   169         }

   170     }

   171 

   172 }