/*

 * Copyright (c) 2016, 2018, 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

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 */

package jdk.jfr.internal;

import java.lang.reflect.Modifier;

import jdk.jfr.Event;

import jdk.jfr.internal.handlers.EventHandler;

import jdk.jfr.internal.instrument.JDKEvents;

/**

 * All upcalls from the JVM should go through this class.

 *

 */

// Called by native

final class JVMUpcalls {

    /**

     * Called by the JVM when a retransform happens on a tagged class

     *

     * @param traceId

     *            Id of the class

     * @param dummy

     *            (not used but needed since invoke infrastructure in native

     *            uses same signature bytesForEagerInstrumentation)

     * @param clazz

     *            class being retransformed

     * @param oldBytes

     *            byte code

     * @return byte code to use

     * @throws Throwable

     */

    static byte[] onRetransform(long traceId, boolean dummy, Class<?> clazz, byte[] oldBytes) throws Throwable {

        try {

            if (Event.class.isAssignableFrom(clazz) && !Modifier.isAbstract(clazz.getModifiers())) {

                EventHandler handler = Utils.getHandler(clazz.asSubclass(Event.class));

                if (handler == null) {

                    Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "No event handler found for " + clazz.getName() + ". Ignoring instrumentation request.");

                    // Probably triggered by some other agent

                    return oldBytes;

                }

                Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Adding instrumentation to event class " + clazz.getName() + " using retransform");

                EventInstrumentation ei = new EventInstrumentation(clazz.getSuperclass(), oldBytes, traceId);

                byte[] bytes = ei.buildInstrumented();

                ASMToolkit.logASM(clazz.getName(), bytes);

                return bytes;

            }

            return JDKEvents.retransformCallback(clazz, oldBytes);

        } catch (Throwable t) {

            Logger.log(LogTag.JFR_SYSTEM, LogLevel.WARN, "Unexpected error when adding instrumentation to event class " + clazz.getName());

        }

        return oldBytes;

    }

    /**

     * Called by the JVM when requested to do an "eager" instrumentation. Would

     * normally happen when JVMTI retransform capabilities are not available.

     *

     * @param traceId

     *            Id of the class

     * @param forceInstrumentation

     *            add instrumentation regardless if event is enabled or not.

     * @param superClazz

     *            the super class of the class being processed

     * @param oldBytes

     *            byte code

     * @return byte code to use

     * @throws Throwable

     */

    static byte[] bytesForEagerInstrumentation(long traceId, boolean forceInstrumentation, Class<?> superClass, byte[] oldBytes) throws Throwable {

        if (JVMSupport.isNotAvailable()) {

            return oldBytes;

        }

        String eventName = "<Unknown>";

        try {

            EventInstrumentation ei = new EventInstrumentation(superClass, oldBytes, traceId);

            eventName = ei.getEventName();

            if (!forceInstrumentation) {

                // Assume we are recording

                MetadataRepository mr = MetadataRepository.getInstance();

                // No need to generate bytecode if:

                // 1) Event class is disabled, and there is not an external configuration that overrides.

                // 2) Event class has @Registered(false)

                if (!mr.isEnabled(ei.getEventName()) && !ei.isEnabled() || !ei.isRegistered()) {

                    Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Skipping instrumentation for event type " + eventName + " since event was disabled on class load");

                    return oldBytes;

                }

            }

            // Corner case when we are forced to generate bytecode. We can't reference the event

            // handler in #isEnabled() before event class has been registered, so we add a

            // guard against a null reference.

            ei.setGuardHandler(true);

            Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Adding " + (forceInstrumentation ? "forced " : "") + "instrumentation for event type " + eventName + " during initial class load");

            EventHandlerCreator eh = new EventHandlerCreator(traceId, ei.getSettingInfos(), ei.getFieldInfos());

            // Handler class must be loaded before instrumented event class can

            // be used

            eh.makeEventHandlerClass();

            byte[] bytes = ei.buildInstrumented();

            ASMToolkit.logASM(ei.getClassName() + "(" + traceId + ")", bytes);

            return bytes;

        } catch (Throwable t) {

            Logger.log(LogTag.JFR_SYSTEM, LogLevel.WARN, "Unexpected error when adding instrumentation for event type " + eventName);

            return oldBytes;

        }

    }

    /**

     * Called by the JVM to create the recorder thread.

     *

     * @param systemThreadGroup

     *            the system thread group

     *

     * @param contextClassLoader

     *            the context class loader.

     *

     * @return a new thread

     */

    static Thread createRecorderThread(ThreadGroup systemThreadGroup, ClassLoader contextClassLoader) {

        return SecuritySupport.createRecorderThread(systemThreadGroup, contextClassLoader);

    }

    /**

     * Called by the JVM to initialize the EventHandlerProxy class.

     *

     * @return the EventHandlerProxy class

     */

    static Class<? extends EventHandler> getEventHandlerProxyClass() {

        return EventHandlerProxyCreator.proxyClass;

    }

}