Java example source code file (Root.java)

This example Java source code file (Root.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

busy_monitor, class, invalid_type, java, java_local, javaheapobject, native_local, root, stacktrace, string, system_class, thread, thread_block, unknown

The Root.java Java example source code

/*
 * Copyright (c) 1997, 2008, 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.
 */


/*
 * The Original Code is HAT. The Initial Developer of the
 * Original Code is Bill Foote, with contributions from others
 * at JavaSoft/Sun.
 */

package com.sun.tools.hat.internal.model;

import com.sun.tools.hat.internal.util.Misc;

/**
 *
 * @author      Bill Foote
 */


/**
 * Represents a member of the rootset, that is, one of the objects that
 * the GC starts from when marking reachable objects.
 */

public class Root {

    private long id;            // ID of the JavaThing we refer to
    private long refererId;     // Thread or Class responsible for this, or 0
    private int index = -1;             // Index in Snapshot.roots
    private int type;
    private String description;
    private JavaHeapObject referer = null;
    private StackTrace stackTrace = null;

    // Values for type.  Higher values are more interesting -- see getType().
    // See also getTypeName()
    public final static int INVALID_TYPE = 0;
    public final static int UNKNOWN = 1;
    public final static int SYSTEM_CLASS = 2;

    public final static int NATIVE_LOCAL = 3;
    public final static int NATIVE_STATIC = 4;
    public final static int THREAD_BLOCK = 5;
    public final static int BUSY_MONITOR = 6;
    public final static int JAVA_LOCAL = 7;
    public final static int NATIVE_STACK = 8;
    public final static int JAVA_STATIC = 9;


    public Root(long id, long refererId, int type, String description) {
        this(id, refererId, type, description, null);
    }


    public Root(long id, long refererId, int type, String description,
                StackTrace stackTrace) {
        this.id = id;
        this.refererId = refererId;
        this.type = type;
        this.description = description;
        this.stackTrace = stackTrace;
    }

    public long getId() {
        return id;
    }

    public String getIdString() {
        return Misc.toHex(id);
    }

    public String getDescription() {
        if ("".equals(description)) {
            return getTypeName() + " Reference";
        } else {
            return description;
        }
    }

    /**
     * Return type.  We guarantee that more interesting roots will have
     * a type that is numerically higher.
     */
    public int getType() {
        return type;
    }

    public String getTypeName() {
        switch(type) {
            case INVALID_TYPE:          return "Invalid (?!?)";
            case UNKNOWN:               return "Unknown";
            case SYSTEM_CLASS:          return "System Class";
            case NATIVE_LOCAL:          return "JNI Local";
            case NATIVE_STATIC:         return "JNI Global";
            case THREAD_BLOCK:          return "Thread Block";
            case BUSY_MONITOR:          return "Busy Monitor";
            case JAVA_LOCAL:            return "Java Local";
            case NATIVE_STACK:          return "Native Stack (possibly Java local)";
            case JAVA_STATIC:           return "Java Static";
            default:                    return "??";
        }
    }

    /**
     * Given two Root instances, return the one that is most interesting.
     */
    public Root mostInteresting(Root other) {
        if (other.type > this.type) {
            return other;
        } else {
            return this;
        }
    }

    /**
     * Get the object that's responsible for this root, if there is one.
     * This will be null, a Thread object, or a Class object.
     */
    public JavaHeapObject getReferer() {
        return referer;
    }

    /**
     * @return the stack trace responsible for this root, or null if there
     * is none.
     */
    public StackTrace getStackTrace() {
        return stackTrace;
    }

    /**
     * @return The index of this root in Snapshot.roots
     */
    public int getIndex() {
        return index;
    }

    void resolve(Snapshot ss) {
        if (refererId != 0) {
            referer = ss.findThing(refererId);
        }
        if (stackTrace != null) {
            stackTrace.resolve(ss);
        }
    }

    void setIndex(int i) {
        index = i;
    }

}