Java example source code file (Tracker.java)

This example Java source code file (Tracker.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.

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Java - Java tags/keywords

callsite, illegalargumentexception, negative, newarray, null, object, objectinit, returnsite, tracker

The Tracker.java Java example source code

/*
 * Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.sun.demo.jvmti.hprof;

/* This class and it's methods are used by hprof when injecting bytecodes
 *   into class file images.
 *   See the directory src/share/demo/jvmti/hprof and the file README.txt
 *   for more details.
 */

public class Tracker {

    /* Master switch that activates calls to native functions. */

    private static int engaged = 0;

    /* To track memory allocated, we need to catch object init's and arrays. */

    /* At the beginning of java.jang.Object.<init>(), a call to
     *   Tracker.ObjectInit() is injected.
     */

    private static native void nativeObjectInit(Object thr, Object obj);

    public static void ObjectInit(Object obj)
    {
        if ( engaged != 0) {
            if (obj == null) {
                throw new IllegalArgumentException("Null object.");
            }
            nativeObjectInit(Thread.currentThread(), obj);
        }
    }

    /* Immediately following any of the newarray bytecodes, a call to
     *   Tracker.NewArray() is injected.
     */

    private static native void nativeNewArray(Object thr, Object obj);

    public static void NewArray(Object obj)
    {
        if ( engaged != 0) {
            if (obj == null) {
                throw new IllegalArgumentException("Null object.");
            }
            nativeNewArray(Thread.currentThread(), obj);
        }
    }

    /* For cpu time spent in methods, we need to inject for every method. */

    /* At the very beginning of every method, a call to
     *   Tracker.CallSite() is injected.
     */

    private static native void nativeCallSite(Object thr, int cnum, int mnum);

    public static void CallSite(int cnum, int mnum)
    {
        if ( engaged != 0 ) {
            if (cnum < 0) {
                throw new IllegalArgumentException("Negative class index");
            }

            if (mnum < 0) {
                throw new IllegalArgumentException("Negative method index");
            }

            nativeCallSite(Thread.currentThread(), cnum, mnum);
        }
    }

    /* Before any of the return bytecodes, a call to
     *   Tracker.ReturnSite() is injected.
     */

    private static native void nativeReturnSite(Object thr, int cnum, int mnum);

    public static void ReturnSite(int cnum, int mnum)
    {
        if ( engaged != 0 ) {
            if (cnum < 0) {
                throw new IllegalArgumentException("Negative class index");
            }

            if (mnum < 0) {
                throw new IllegalArgumentException("Negative method index");
            }

            nativeReturnSite(Thread.currentThread(), cnum, mnum);
        }
    }

}