Java example source code file (ExecutionManager.java)

This example Java source code file (ExecutionManager.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, breakpointspec, eventobject, eventrequestmanager, gui, jdi, linkedlist, list, map, nosessionexception, outputlistener, override, string, swing, threadinfo, util, virtualmachine, vmlaunchfailureexception

The ExecutionManager.java Java example source code

/*
 * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


package com.sun.tools.example.debug.bdi;

import com.sun.jdi.*;
import com.sun.jdi.request.*;
import com.sun.jdi.connect.*;
import com.sun.tools.example.debug.expr.ExpressionParser;
import com.sun.tools.example.debug.expr.ParseException;

import java.io.*;
import java.util.*;

import com.sun.tools.example.debug.event.*;

import javax.swing.SwingUtilities;

/**
 * Move this towards being only state and functionality
 * that spans across Sessions (and thus VMs).
 */
public class ExecutionManager {

    private Session session;

    /**
     * Get/set JDI trace mode.
     */
    int traceMode = VirtualMachine.TRACE_NONE;

  //////////////////    Listener registration    //////////////////

  // Session Listeners

    ArrayList<SessionListener> sessionListeners = new ArrayList();

    public void addSessionListener(SessionListener listener) {
        sessionListeners.add(listener);
    }

    public void removeSessionListener(SessionListener listener) {
        sessionListeners.remove(listener);
    }

  // Spec Listeners

  ArrayList<SpecListener> specListeners = new ArrayList();

    public void addSpecListener(SpecListener cl) {
        specListeners.add(cl);
    }

    public void removeSpecListener(SpecListener cl) {
        specListeners.remove(cl);
    }

    // JDI Listeners

    ArrayList<JDIListener> jdiListeners = new ArrayList();

    /**
     * Adds a JDIListener
     */
    public void addJDIListener(JDIListener jl) {
        jdiListeners.add(jl);
    }

    /**
     * Adds a JDIListener - at the specified position
     */
    public void addJDIListener(int index, JDIListener jl) {
        jdiListeners.add(index, jl);
    }

    /**
     * Removes a JDIListener
     */
    public void removeJDIListener(JDIListener jl) {
        jdiListeners.remove(jl);
    }

  // App Echo Listeners

    private ArrayList<OutputListener> appEchoListeners = new ArrayList();

    public void addApplicationEchoListener(OutputListener l) {
        appEchoListeners.add(l);
    }

    public void removeApplicationEchoListener(OutputListener l) {
        appEchoListeners.remove(l);
    }

  // App Output Listeners

    private ArrayList<OutputListener> appOutputListeners = new ArrayList();

    public void addApplicationOutputListener(OutputListener l) {
        appOutputListeners.add(l);
    }

    public void removeApplicationOutputListener(OutputListener l) {
        appOutputListeners.remove(l);
    }

  // App Error Listeners

    private ArrayList<OutputListener> appErrorListeners = new ArrayList();

    public void addApplicationErrorListener(OutputListener l) {
        appErrorListeners.add(l);
    }

    public void removeApplicationErrorListener(OutputListener l) {
        appErrorListeners.remove(l);
    }

  // Diagnostic Listeners

    private ArrayList<OutputListener> diagnosticsListeners = new ArrayList();

    public void addDiagnosticsListener(OutputListener l) {
        diagnosticsListeners.add(l);
    }

    public void removeDiagnosticsListener(OutputListener l) {
        diagnosticsListeners.remove(l);
    }

  ///////////    End Listener Registration    //////////////

    //### We probably don't want this public
    public VirtualMachine vm() {
        return session == null ? null : session.vm;
    }

    void ensureActiveSession() throws NoSessionException {
        if (session == null) {
         throw new NoSessionException();
      }
    }

    public EventRequestManager eventRequestManager() {
        return vm() == null ? null : vm().eventRequestManager();
    }

    /**
     * Get JDI trace mode.
     */
    public int getTraceMode(int mode) {
        return traceMode;
    }

    /**
     * Set JDI trace mode.
     */
    public void setTraceMode(int mode) {
        traceMode = mode;
        if (session != null) {
            session.setTraceMode(mode);
        }
    }

    /**
     * Determine if VM is interrupted, i.e, present and not running.
     */
    public boolean isInterrupted() /* should: throws NoSessionException */ {
//      ensureActiveSession();
        return session.interrupted;
    }

    /**
     * Return a list of ReferenceType objects for all
     * currently loaded classes and interfaces.
     * Array types are not returned.
     */
    public List<ReferenceType> allClasses() throws NoSessionException {
        ensureActiveSession();
        return vm().allClasses();
    }

    /**
     * Return a ReferenceType object for the currently
     * loaded class or interface whose fully-qualified
     * class name is specified, else return null if there
     * is none.
     *
     * In general, we must return a list of types, because
     * multiple class loaders could have loaded a class
     * with the same fully-qualified name.
     */
    public List<ReferenceType> findClassesByName(String name) throws NoSessionException {
        ensureActiveSession();
        return vm().classesByName(name);
    }

    /**
     * Return a list of ReferenceType objects for all
     * currently loaded classes and interfaces whose name
     * matches the given pattern.  The pattern syntax is
     * open to some future revision, but currently consists
     * of a fully-qualified class name in which the first
     * component may optionally be a "*" character, designating
     * an arbitrary prefix.
     */
    public List<ReferenceType> findClassesMatchingPattern(String pattern)
                                                throws NoSessionException {
        ensureActiveSession();
        List<ReferenceType> result = new ArrayList();  //### Is default size OK?
        if (pattern.startsWith("*.")) {
            // Wildcard matches any leading package name.
            pattern = pattern.substring(1);
            for (ReferenceType type : vm().allClasses()) {
                if (type.name().endsWith(pattern)) {
                    result.add(type);
                }
            }
            return result;
        } else {
            // It's a class name.
            return vm().classesByName(pattern);
        }
    }

    /*
     * Return a list of ThreadReference objects corresponding
     * to the threads that are currently active in the VM.
     * A thread is removed from the list just before the
     * thread terminates.
     */

    public List<ThreadReference> allThreads() throws NoSessionException {
        ensureActiveSession();
        return vm().allThreads();
    }

    /*
     * Return a list of ThreadGroupReference objects corresponding
     * to the top-level threadgroups that are currently active in the VM.
     * Note that a thread group may be empty, or contain no threads as
     * descendents.
     */

    public List<ThreadGroupReference> topLevelThreadGroups() throws NoSessionException {
        ensureActiveSession();
        return vm().topLevelThreadGroups();
    }

    /*
     * Return the system threadgroup.
     */

    public ThreadGroupReference systemThreadGroup()
                                                throws NoSessionException {
        ensureActiveSession();
        return vm().topLevelThreadGroups().get(0);
    }

    /*
     * Evaluate an expression.
     */

    public Value evaluate(final StackFrame f, String expr)
        throws ParseException,
                                            InvocationException,
                                            InvalidTypeException,
                                            ClassNotLoadedException,
                                            NoSessionException,
                                            IncompatibleThreadStateException {
        ExpressionParser.GetFrame frameGetter = null;
        ensureActiveSession();
        if (f != null) {
            frameGetter = new ExpressionParser.GetFrame() {
                @Override
                public StackFrame get() /* throws IncompatibleThreadStateException */ {
                    return f;
                }
            };
        }
        return ExpressionParser.evaluate(expr, vm(), frameGetter);
    }


    /*
     * Start a new VM.
     */

    public void run(boolean suspended,
                    String vmArgs,
                    String className,
                    String args) throws VMLaunchFailureException {

        endSession();

        //### Set a breakpoint on 'main' method.
        //### Would be cleaner if we could just bring up VM already suspended.
        if (suspended) {
            //### Set breakpoint at 'main(java.lang.String[])'.
            List<String> argList = new ArrayList(1);
            argList.add("java.lang.String[]");
            createMethodBreakpoint(className, "main", argList);
        }

        String cmdLine = className + " " + args;

        startSession(new ChildSession(this, vmArgs, cmdLine,
                                      appInput, appOutput, appError,
                                      diagnostics));
    }

    /*
     * Attach to an existing VM.
     */
    public void attach(String portName) throws VMLaunchFailureException {
        endSession();

        //### Changes made here for connectors have broken the
        //### the 'Session' abstraction.  The 'Session.attach()'
        //### method is intended to encapsulate all of the various
        //### ways in which session start-up can fail. (maddox 12/18/98)

        /*
         * Now that attaches and launches both go through Connectors,
         * it may be worth creating a new subclass of Session for
         * attach sessions.
         */
        VirtualMachineManager mgr = Bootstrap.virtualMachineManager();
        AttachingConnector connector = mgr.attachingConnectors().get(0);
        Map<String, Connector.Argument> arguments = connector.defaultArguments();
        arguments.get("port").setValue(portName);

        Session newSession = internalAttach(connector, arguments);
        if (newSession != null) {
            startSession(newSession);
        }
    }

    private Session internalAttach(AttachingConnector connector,
                                   Map<String, Connector.Argument> arguments) {
        try {
            VirtualMachine vm = connector.attach(arguments);
            return new Session(vm, this, diagnostics);
        } catch (IOException ioe) {
            diagnostics.putString("\n Unable to attach to target VM: " +
                                  ioe.getMessage());
        } catch (IllegalConnectorArgumentsException icae) {
            diagnostics.putString("\n Invalid connector arguments: " +
                                  icae.getMessage());
        }
        return null;
    }

    private Session internalListen(ListeningConnector connector,
                                   Map<String, Connector.Argument> arguments) {
        try {
            VirtualMachine vm = connector.accept(arguments);
            return new Session(vm, this, diagnostics);
        } catch (IOException ioe) {
            diagnostics.putString(
                  "\n Unable to accept connection to target VM: " +
                                  ioe.getMessage());
        } catch (IllegalConnectorArgumentsException icae) {
            diagnostics.putString("\n Invalid connector arguments: " +
                                  icae.getMessage());
        }
        return null;
    }

    /*
     * Connect via user specified arguments
     * @return true on success
     */
    public boolean explictStart(Connector connector, Map<String, Connector.Argument> arguments)
                                           throws VMLaunchFailureException {
        Session newSession = null;

        endSession();

        if (connector instanceof LaunchingConnector) {
            // we were launched, use ChildSession
            newSession = new ChildSession(this, (LaunchingConnector)connector,
                                          arguments,
                                          appInput, appOutput, appError,
                                          diagnostics);
        } else if (connector instanceof AttachingConnector) {
            newSession = internalAttach((AttachingConnector)connector,
                                        arguments);
        } else if (connector instanceof ListeningConnector) {
            newSession = internalListen((ListeningConnector)connector,
                                        arguments);
        } else {
            diagnostics.putString("\n Unknown connector: " + connector);
        }
        if (newSession != null) {
            startSession(newSession);
        }
        return newSession != null;
    }

    /*
     * Detach from VM.  If VM was started by debugger, terminate it.
     */
    public void detach() throws NoSessionException {
        ensureActiveSession();
        endSession();
    }

    private void startSession(Session s) throws VMLaunchFailureException {
        if (!s.attach()) {
            throw new VMLaunchFailureException();
        }
        session = s;
        EventRequestManager em = vm().eventRequestManager();
        ClassPrepareRequest classPrepareRequest = em.createClassPrepareRequest();
        //### We must allow the deferred breakpoints to be resolved before
        //### we continue executing the class.  We could optimize if there
        //### were no deferred breakpoints outstanding for a particular class.
        //### Can we do this with JDI?
        classPrepareRequest.setSuspendPolicy(EventRequest.SUSPEND_ALL);
        classPrepareRequest.enable();
        ClassUnloadRequest classUnloadRequest = em.createClassUnloadRequest();
        classUnloadRequest.setSuspendPolicy(EventRequest.SUSPEND_NONE);
        classUnloadRequest.enable();
        ThreadStartRequest threadStartRequest = em.createThreadStartRequest();
        threadStartRequest.setSuspendPolicy(EventRequest.SUSPEND_NONE);
        threadStartRequest.enable();
        ThreadDeathRequest threadDeathRequest = em.createThreadDeathRequest();
        threadDeathRequest.setSuspendPolicy(EventRequest.SUSPEND_NONE);
        threadDeathRequest.enable();
        ExceptionRequest exceptionRequest =
                                em.createExceptionRequest(null, false, true);
        exceptionRequest.setSuspendPolicy(EventRequest.SUSPEND_ALL);
        exceptionRequest.enable();
        validateThreadInfo();
        session.interrupted = true;
        notifySessionStart();
    }

    void endSession() {
        if (session != null) {
            session.detach();
            session = null;
            invalidateThreadInfo();
            notifySessionDeath();
        }
    }

    /*
     * Suspend all VM activity.
     */

    public void interrupt() throws NoSessionException {
        ensureActiveSession();
        vm().suspend();
        //### Is it guaranteed that the interrupt has happened?
        validateThreadInfo();
        session.interrupted = true;
        notifyInterrupted();
    }

    /*
     * Resume interrupted VM.
     */

    public void go() throws NoSessionException, VMNotInterruptedException {
        ensureActiveSession();
        invalidateThreadInfo();
        session.interrupted = false;
        notifyContinued();
        vm().resume();
    }

    /*
     * Stepping.
     */
    void clearPreviousStep(ThreadReference thread) {
        /*
         * A previous step may not have completed on this thread;
         * if so, it gets removed here.
         */
         EventRequestManager mgr = vm().eventRequestManager();
         for (StepRequest request : mgr.stepRequests()) {
             if (request.thread().equals(thread)) {
                 mgr.deleteEventRequest(request);
                 break;
             }
         }
    }

    private void generalStep(ThreadReference thread, int size, int depth)
                        throws NoSessionException {
        ensureActiveSession();
        invalidateThreadInfo();
        session.interrupted = false;
        notifyContinued();

        clearPreviousStep(thread);
        EventRequestManager reqMgr = vm().eventRequestManager();
        StepRequest request = reqMgr.createStepRequest(thread,
                                                       size, depth);
        // We want just the next step event and no others
        request.addCountFilter(1);
        request.enable();
        vm().resume();
    }

    public void stepIntoInstruction(ThreadReference thread)
                        throws NoSessionException {
        generalStep(thread, StepRequest.STEP_MIN, StepRequest.STEP_INTO);
    }

    public void stepOverInstruction(ThreadReference thread)
                        throws NoSessionException {
        generalStep(thread, StepRequest.STEP_MIN, StepRequest.STEP_OVER);
    }

    public void stepIntoLine(ThreadReference thread)
                        throws NoSessionException,
                        AbsentInformationException {
        generalStep(thread, StepRequest.STEP_LINE, StepRequest.STEP_INTO);
    }

    public void stepOverLine(ThreadReference thread)
                        throws NoSessionException,
                        AbsentInformationException {
        generalStep(thread, StepRequest.STEP_LINE, StepRequest.STEP_OVER);
    }

    public void stepOut(ThreadReference thread)
                        throws NoSessionException {
        generalStep(thread, StepRequest.STEP_MIN, StepRequest.STEP_OUT);
    }

    /*
     * Thread control.
     */

    public void suspendThread(ThreadReference thread) throws NoSessionException {
        ensureActiveSession();
        thread.suspend();
    }

    public void resumeThread(ThreadReference thread) throws NoSessionException {
        ensureActiveSession();
        thread.resume();
    }

    public void stopThread(ThreadReference thread) throws NoSessionException {
        ensureActiveSession();
        //### Need an exception now.  Which one to use?
        //thread.stop();
    }

    /*
     * ThreadInfo objects -- Allow query of thread status and stack.
     */

    private List<ThreadInfo> threadInfoList = new LinkedList();
    //### Should be weak! (in the value, not the key)
    private HashMap<ThreadReference, ThreadInfo> threadInfoMap = new HashMap();

    public ThreadInfo threadInfo(ThreadReference thread) {
        if (session == null || thread == null) {
            return null;
        }
        ThreadInfo info = threadInfoMap.get(thread);
        if (info == null) {
            //### Should not hardcode initial frame count and prefetch here!
            //info = new ThreadInfo(thread, 10, 10);
            info = new ThreadInfo(thread);
            if (session.interrupted) {
                info.validate();
            }
            threadInfoList.add(info);
            threadInfoMap.put(thread, info);
        }
        return info;
    }

     void validateThreadInfo() {
        session.interrupted = true;
        for (ThreadInfo threadInfo : threadInfoList) {
            threadInfo.validate();
            }
    }

    private void invalidateThreadInfo() {
        if (session != null) {
            session.interrupted = false;
            for (ThreadInfo threadInfo : threadInfoList) {
                threadInfo.invalidate();
            }
        }
    }

    void removeThreadInfo(ThreadReference thread) {
        ThreadInfo info = threadInfoMap.get(thread);
        if (info != null) {
            info.invalidate();
            threadInfoMap.remove(thread);
            threadInfoList.remove(info);
        }
    }

    /*
     * Listen for Session control events.
     */

    private void notifyInterrupted() {
      ArrayList<SessionListener> l = new ArrayList(sessionListeners);
        EventObject evt = new EventObject(this);
        for (int i = 0; i < l.size(); i++) {
            l.get(i).sessionInterrupt(evt);
        }
    }

    private void notifyContinued() {
        ArrayList<SessionListener> l = new ArrayList(sessionListeners);
        EventObject evt = new EventObject(this);
        for (int i = 0; i < l.size(); i++) {
            l.get(i).sessionContinue(evt);
        }
    }

    private void notifySessionStart() {
        ArrayList<SessionListener> l = new ArrayList(sessionListeners);
        EventObject evt = new EventObject(this);
        for (int i = 0; i < l.size(); i++) {
            l.get(i).sessionStart(evt);
        }
    }

    private void notifySessionDeath() {
/*** noop for now
        ArrayList<SessionListener> l = new ArrayList(sessionListeners);
        EventObject evt = new EventObject(this);
        for (int i = 0; i < l.size(); i++) {
            ((SessionListener)l.get(i)).sessionDeath(evt);
        }
****/
    }

    /*
     * Listen for input and output requests from the application
     * being debugged.  These are generated only when the debuggee
     * is spawned as a child of the debugger.
     */

    private Object inputLock = new Object();
    private LinkedList<String> inputBuffer = new LinkedList();

    private void resetInputBuffer() {
        synchronized (inputLock) {
            inputBuffer = new LinkedList<String>();
        }
    }

    public void sendLineToApplication(String line) {
        synchronized (inputLock) {
            inputBuffer.addFirst(line);
            inputLock.notifyAll();
        }
    }

    private InputListener appInput = new InputListener() {
        @Override
        public String getLine() {
            // Don't allow reader to be interrupted -- catch and retry.
            String line = null;
            while (line == null) {
                synchronized (inputLock) {
                    try {
                        while (inputBuffer.size() < 1) {
                            inputLock.wait();
                        }
                        line = inputBuffer.removeLast();
                    } catch (InterruptedException e) {}
                }
            }
            // We must not be holding inputLock here, as the listener
            // that we call to echo a line might call us re-entrantly
            // to provide another line of input.
            // Run in Swing event dispatcher thread.
            final String input = line;
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    echoInputLine(input);
                }
            });
            return line;
        }
    };

    private static String newline = System.getProperty("line.separator");

    private void echoInputLine(String line) {
        ArrayList<OutputListener> l = new ArrayList(appEchoListeners);
        for (int i = 0; i < l.size(); i++) {
            OutputListener ol = l.get(i);
            ol.putString(line);
            ol.putString(newline);
        }
    }

    private OutputListener appOutput = new OutputListener() {
      @Override
        public void putString(String string) {
            ArrayList<OutputListener> l = new ArrayList(appEchoListeners);
            for (int i = 0; i < l.size(); i++) {
                l.get(i).putString(string);
            }
        }
    };

    private OutputListener appError = new OutputListener() {
      @Override
        public void putString(String string) {
            ArrayList<OutputListener> l = new ArrayList(appEchoListeners);
            for (int i = 0; i < l.size(); i++) {
                l.get(i).putString(string);
            }
        }
    };

   private OutputListener diagnostics = new OutputListener() {
      @Override
        public void putString(String string) {
            ArrayList<OutputListener> l = new ArrayList(diagnosticsListeners);
            for (int i = 0; i < l.size(); i++) {
                l.get(i).putString(string);
            }
        }
   };

  /////////////    Spec Request Creation/Deletion/Query   ///////////

    private EventRequestSpecList specList = new EventRequestSpecList(this);

    public BreakpointSpec
    createSourceLineBreakpoint(String sourceName, int line) {
        return specList.createSourceLineBreakpoint(sourceName, line);
    }

    public BreakpointSpec
    createClassLineBreakpoint(String classPattern, int line) {
        return specList.createClassLineBreakpoint(classPattern, line);
    }

    public BreakpointSpec
    createMethodBreakpoint(String classPattern,
                           String methodId, List<String> methodArgs) {
        return specList.createMethodBreakpoint(classPattern,
                                                 methodId, methodArgs);
    }

    public ExceptionSpec
    createExceptionIntercept(String classPattern,
                             boolean notifyCaught,
                             boolean notifyUncaught) {
        return specList.createExceptionIntercept(classPattern,
                                                   notifyCaught,
                                                   notifyUncaught);
    }

    public AccessWatchpointSpec
    createAccessWatchpoint(String classPattern, String fieldId) {
        return specList.createAccessWatchpoint(classPattern, fieldId);
    }

    public ModificationWatchpointSpec
    createModificationWatchpoint(String classPattern, String fieldId) {
        return specList.createModificationWatchpoint(classPattern,
                                                       fieldId);
    }

    public void delete(EventRequestSpec spec) {
        specList.delete(spec);
    }

    void resolve(ReferenceType refType) {
        specList.resolve(refType);
    }

    public void install(EventRequestSpec spec) {
        specList.install(spec, vm());
    }

    public List<EventRequestSpec> eventRequestSpecs() {
        return specList.eventRequestSpecs();
    }
}