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Java example source code file (CLHSDB.java)

This example Java source code file (CLHSDB.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

bufferedreader, clhsdb, commandprocessor, debuggerexception, hotspotagent, jvmdebugger, numberformatexception, string, stringbuffer, stringtokenizer, unable, util

The CLHSDB.java Java example source code

/*
 * Copyright (c) 2005, 2013, 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.
 *
 * 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.
 *
 */

package sun.jvm.hotspot;

import sun.jvm.hotspot.*;
import sun.jvm.hotspot.debugger.*;

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

public class CLHSDB {

    public CLHSDB(JVMDebugger d) {
        jvmDebugger = d;
    }

    public static void main(String[] args) {
        new CLHSDB(args).run();
    }

    public void run() {
        // If jvmDebugger is already set, we have been given a JVMDebugger.
        // Otherwise, if pidText != null we are supposed to attach to it.
        // Finally, if execPath != null, it is the path of a jdk/bin/java
        // and coreFilename is the pathname of a core file we are
        // supposed to attach to.

        agent = new HotSpotAgent();

        Runtime.getRuntime().addShutdownHook(new java.lang.Thread() {
                public void run() {
                    detachDebugger();
                }
            });

        if (jvmDebugger != null) {
            attachDebugger(jvmDebugger);
        } else if (pidText != null) {
            attachDebugger(pidText);
        } else if (execPath != null) {
            attachDebugger(execPath, coreFilename);
        }


        CommandProcessor.DebuggerInterface di = new CommandProcessor.DebuggerInterface() {
                public HotSpotAgent getAgent() {
                    return agent;
                }
                public boolean isAttached() {
                    return attached;
                }
                public void attach(String pid) {
                    attachDebugger(pid);
                }
                public void attach(String java, String core) {
                    attachDebugger(java, core);
                }
                public void detach() {
                    detachDebugger();
                }
                public void reattach() {
                    if (attached) {
                        detachDebugger();
                    }
                    if (pidText != null) {
                        attach(pidText);
                    } else {
                        attach(execPath, coreFilename);
                    }
                }
            };


        BufferedReader in =
            new BufferedReader(new InputStreamReader(System.in));
        CommandProcessor cp = new CommandProcessor(di, in, System.out, System.err);
        cp.run(true);

    }

    //--------------------------------------------------------------------------------
    // Internals only below this point
    //
    private HotSpotAgent agent;
    private JVMDebugger jvmDebugger;
    private boolean      attached;
    // These had to be made data members because they are referenced in inner classes.
    private String pidText;
    private int pid;
    private String execPath;
    private String coreFilename;

    private void doUsage() {
        System.out.println("Usage:  java CLHSDB [[pid] | [path-to-java-executable [path-to-corefile]] | help ]");
        System.out.println("           pid:                     attach to the process whose id is 'pid'");
        System.out.println("           path-to-java-executable: Debug a core file produced by this program");
        System.out.println("           path-to-corefile:        Debug this corefile.  The default is 'core'");
        System.out.println("        If no arguments are specified, you can select what to do from the GUI.\n");
        HotSpotAgent.showUsage();
    }

    private CLHSDB(String[] args) {
        switch (args.length) {
        case (0):
            break;

        case (1):
            if (args[0].equals("help") || args[0].equals("-help")) {
                doUsage();
                return;
            }
            // If all numbers, it is a PID to attach to
            // Else, it is a pathname to a .../bin/java for a core file.
            try {
                int unused = Integer.parseInt(args[0]);
                // If we get here, we have a PID and not a core file name
                pidText = args[0];
            } catch (NumberFormatException e) {
                execPath = args[0];
                coreFilename = "core";
            }
            break;

        case (2):
            execPath = args[0];
            coreFilename = args[1];
            break;

        default:
            System.out.println("HSDB Error: Too many options specified");
            doUsage();
            return;
        }
    }

    private void attachDebugger(JVMDebugger d) {
        agent.attach(d);
        attached = true;
     }

    /** NOTE we are in a different thread here than either the main
        thread or the Swing/AWT event handler thread, so we must be very
        careful when creating or removing widgets */
    private void attachDebugger(String pidText) {
        try {
            this.pidText = pidText;
            pid = Integer.parseInt(pidText);
        }
        catch (NumberFormatException e) {
            System.err.print("Unable to parse process ID \"" + pidText + "\".\nPlease enter a number.");
        }

        try {
            System.err.println("Attaching to process " + pid + ", please wait...");

            // FIXME: display exec'd debugger's output messages during this
            // lengthy call
            agent.attach(pid);
            attached = true;
        }
        catch (DebuggerException e) {
            final String errMsg = formatMessage(e.getMessage(), 80);
            System.err.println("Unable to connect to process ID " + pid + ":\n\n" + errMsg);
            agent.detach();
            e.printStackTrace();
            return;
        }
    }

    /** NOTE we are in a different thread here than either the main
        thread or the Swing/AWT event handler thread, so we must be very
        careful when creating or removing widgets */
    private void attachDebugger(final String executablePath, final String corePath) {
        // Try to open this core file
        try {
            System.err.println("Opening core file, please wait...");

            // FIXME: display exec'd debugger's output messages during this
            // lengthy call
            agent.attach(executablePath, corePath);
            attached = true;
        }
        catch (DebuggerException e) {
            final String errMsg = formatMessage(e.getMessage(), 80);
            System.err.println("Unable to open core file\n" + corePath + ":\n\n" + errMsg);
            agent.detach();
            e.printStackTrace();
            return;
        }
    }

    /** NOTE we are in a different thread here than either the main
        thread or the Swing/AWT event handler thread, so we must be very
        careful when creating or removing widgets */
    private void connect(final String remoteMachineName) {
        // Try to open this core file
        try {
            System.err.println("Connecting to debug server, please wait...");
            agent.attach(remoteMachineName);
            attached = true;
        }
        catch (DebuggerException e) {
            final String errMsg = formatMessage(e.getMessage(), 80);
            System.err.println("Unable to connect to machine \"" + remoteMachineName + "\":\n\n" + errMsg);
            agent.detach();
            e.printStackTrace();
            return;
        }
    }

    private void detachDebugger() {
        if (!attached) {
            return;
        }
        agent.detach();
        attached = false;
    }

    private void detach() {
        detachDebugger();
    }

    /** Punctuates the given string with \n's where necessary to not
        exceed the given number of characters per line. Strips
        extraneous whitespace. */
    private String formatMessage(String message, int charsPerLine) {
        StringBuffer buf = new StringBuffer(message.length());
        StringTokenizer tokenizer = new StringTokenizer(message);
        int curLineLength = 0;
        while (tokenizer.hasMoreTokens()) {
            String tok = tokenizer.nextToken();
            if (curLineLength + tok.length() > charsPerLine) {
                buf.append('\n');
                curLineLength = 0;
            } else {
                if (curLineLength != 0) {
                    buf.append(' ');
                    ++curLineLength;
                }
            }
            buf.append(tok);
            curLineLength += tok.length();
        }
        return buf.toString();
    }
}

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