src/java.base/share/classes/jdk/internal/event/FinalFieldMutationEvent.java - master - githubmirror/panama-vector

src/java.base/share/classes/jdk/internal/event/FinalFieldMutationEvent.java

59 строк2 KB

Markus Grönlund

8382332: Large regression (~50%) in SPECjbb2015 when using JFR after JEP 500

27 май 2026, 14:48

27 май 2026, 14:48eb7da8c

/*
 * Copyright (c) 2025, 2026, 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.
 */
package jdk.internal.event;

import java.lang.reflect.Field;

public class FinalFieldMutationEvent extends Event {

    public Class<?> declaringClass;
    public String fieldName;

    /**
     * We throttle FinalFieldMutation JFR events by generating only one event per field
     * during each JFR epoch.
     *
     * An event is emitted if enabled, the epoch encoded in the root instance differs
     * from the current epoch, and a thread exclusively updates to the current epoch.
     */
    public static void offer(Field root) {
        if (enabled() && tryUpdateEpoch(root)) {
            var event = new FinalFieldMutationEvent();
            event.declaringClass = root.getDeclaringClass();
            event.fieldName = root.getName();
            event.commit();
        }
    }

    private static boolean tryUpdateEpoch(Field root) {
        // Generated by JFR
        return false;
    }

    public static boolean enabled() {
        // Generated by JFR
        return false;
    }
}