1 /*

     2  * Copyright (c) 1998, 2014, 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.util.function.Consumer;

    29 import com.sun.jdi.*;

    30 import com.sun.jdi.event.*;

    31 

    32 /**

    33  * Handler of Java Debug Interface events.

    34  * Adapted from jdb EventHandler.

    35  * Only exit and disconnect events processed.

    36  */

    37 class JDIEventHandler implements Runnable {

    38 

    39     private final Thread thread;

    40     private volatile boolean connected = true;

    41     private boolean completed = false;

    42     private final VirtualMachine vm;

    43     private final Consumer<String> reportVMExit;

    44 

    45     /**

    46      * Creates an event handler. Start with {@code start()}.

    47      *

    48      * @param vm the virtual machine for which to handle events

    49      * @param reportVMExit callback to report exit/disconnect

    50      * (passed true if the VM has died)

    51      */

    52     JDIEventHandler(VirtualMachine vm, Consumer<String> reportVMExit) {

    53         this.vm = vm;

    54         this.reportVMExit = reportVMExit;

    55         this.thread = new Thread(this, "event-handler");

    56         this.thread.setDaemon(true);

    57     }

    58 

    59     /**

    60      * Starts the event handler.

    61      */

    62     void start() {

    63         thread.start();

    64     }

    65 

    66     synchronized void shutdown() {

    67         connected = false;  // force run() loop termination

    68         thread.interrupt();

    69         while (!completed) {

    70             try {wait();} catch (InterruptedException exc) {}

    71         }

    72     }

    73 

    74     @Override

    75     public void run() {

    76         EventQueue queue = vm.eventQueue();

    77         while (connected) {

    78             try {

    79                 EventSet eventSet = queue.remove();

    80                 boolean resumeStoppedApp = false;

    81                 EventIterator it = eventSet.eventIterator();

    82                 while (it.hasNext()) {

    83                     resumeStoppedApp |= handleEvent(it.nextEvent());

    84                 }

    85 

    86                 if (resumeStoppedApp) {

    87                     eventSet.resume();

    88                 }

    89             } catch (InterruptedException exc) {

    90                 // Do nothing. Any changes will be seen at top of loop.

    91             } catch (VMDisconnectedException discExc) {

    92                 handleDisconnectedException();

    93                 break;

    94             }

    95         }

    96         synchronized (this) {

    97             completed = true;

    98             notifyAll();

    99         }

   100     }

   101 

   102     private boolean handleEvent(Event event) {

   103         handleExitEvent(event);

   104         return true;

   105     }

   106 

   107     private void handleExitEvent(Event event) {

   108         if (event instanceof VMDeathEvent) {

   109             reportVMExit.accept("VM Died");

   110         } else if (event instanceof VMDisconnectEvent) {

   111             connected = false;

   112             reportVMExit.accept("VM Disconnected");

   113         } else {

   114             // ignore everything else

   115         }

   116     }

   117 

   118     private synchronized void handleDisconnectedException() {

   119         /*

   120          * A VMDisconnectedException has happened while dealing with

   121          * another event. We need to flush the event queue, dealing only

   122          * with exit events (VMDeath, VMDisconnect) so that we terminate

   123          * correctly.

   124          */

   125         EventQueue queue = vm.eventQueue();

   126         while (connected) {

   127             try {

   128                 EventSet eventSet = queue.remove();

   129                 EventIterator iter = eventSet.eventIterator();

   130                 while (iter.hasNext()) {

   131                     handleExitEvent(iter.next());

   132                 }

   133             } catch (InterruptedException exc) {

   134                 // ignore

   135             } catch (InternalError exc) {

   136                 // ignore

   137             }

   138         }

   139     }

   140 }