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Java example source code file (PerfMemory.java)

This example Java source code file (PerfMemory.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

address, addressfield, cintegerfield, jintfield, object, observer, perfdataentry, perfdataentryvisitor, perfdataprologue, perfmemory, type, util

The PerfMemory.java Java example source code

/*
 * Copyright (c) 2004, 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.runtime;

import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.types.*;

public class PerfMemory {
    private static AddressField  startField;
    private static AddressField  endField;
    private static AddressField  topField;
    private static CIntegerField capacityField;
    private static AddressField  prologueField;
    private static JIntField     initializedField;

    static {
        VM.registerVMInitializedObserver(new Observer() {
                public void update(Observable o, Object data) {
                    initialize(VM.getVM().getTypeDataBase());
                }
            });
    }

    private static synchronized void initialize(TypeDataBase db) {
        Type type = db.lookupType("PerfMemory");
        startField = type.getAddressField("_start");
        endField = type.getAddressField("_end");
        topField = type.getAddressField("_top");
        capacityField = type.getCIntegerField("_capacity");
        prologueField = type.getAddressField("_prologue");
        initializedField = type.getJIntField("_initialized");
    }

    // Accessors
    public static Address start() {
        return startField.getValue();
    }

    public static Address end() {
        return endField.getValue();
    }

    public static Address top() {
        return topField.getValue();
    }

    public static long capacity() {
        return capacityField.getValue();
    }

    public static boolean initialized() {
        return ((int) initializedField.getValue()) != 0;
    }

    public static PerfDataPrologue prologue() {
        return (PerfDataPrologue) VMObjectFactory.newObject(
                   PerfDataPrologue.class, prologueField.getValue());
    }

    public static boolean contains(Address addr) {
        return start() != null &&
            addr.minus(start()) >= 0 &&
            end().minus(addr) > 0;
    }

    // an interface supplied to iterate PerfDataEntries
    public static interface PerfDataEntryVisitor {
        // returns false to stop the iteration
        public boolean visit(PerfDataEntry pde);
    }

    public static void iterate(PerfDataEntryVisitor visitor) {
        PerfDataPrologue header = prologue();
        int off = header.entryOffset();
        int num = header.numEntries();
        Address addr = header.getAddress();

        for (int i = 0; i < num; i++) {
            PerfDataEntry pde = (PerfDataEntry) VMObjectFactory.newObject(
                               PerfDataEntry.class, addr.addOffsetTo(off));
            off += pde.entryLength();
            if (visitor.visit(pde) == false) return;
        }
    }
}

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