1 /*

     2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package jdk.jfr.internal;

    26 

    27 import java.lang.reflect.Modifier;

    28 

    29 import jdk.jfr.Event;

    30 import jdk.jfr.internal.handlers.EventHandler;

    31 import jdk.jfr.internal.instrument.JDKEvents;

    32 

    33 /**

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

    35  *

    36  */

    37 // Called by native

    38 final class JVMUpcalls {

    39     /**

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

    41      *

    42      * @param traceId

    43      *            Id of the class

    44      * @param dummy

    45      *            (not used but needed since invoke infrastructure in native

    46      *            uses same signature bytesForEagerInstrumentation)

    47      * @param clazz

    48      *            class being retransformed

    49      * @param oldBytes

    50      *            byte code

    51      * @return byte code to use

    52      * @throws Throwable

    53      */

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

    55         try {

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

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

    58                 if (handler == null) {

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

    60                     // Probably triggered by some other agent

    61                     return oldBytes;

    62                 }

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

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

    65                 byte[] bytes = ei.buildInstrumented();

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

    67                 return bytes;

    68             }

    69             return JDKEvents.retransformCallback(clazz, oldBytes);

    70         } catch (Throwable t) {

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

    72         }

    73         return oldBytes;

    74 

    75     }

    76 

    77     /**

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

    79      * normally happen when JVMTI retransform capabilities are not available.

    80      *

    81      * @param traceId

    82      *            Id of the class

    83      * @param forceInstrumentation

    84      *            add instrumentation regardless if event is enabled or not.

    85      * @param superClazz

    86      *            the super class of the class being processed

    87      * @param oldBytes

    88      *            byte code

    89      * @return byte code to use

    90      * @throws Throwable

    91      */

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

    93         if (JVMSupport.isNotAvailable()) {

    94             return oldBytes;

    95         }

    96         String eventName = "<Unknown>";

    97         try {

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

    99             eventName = ei.getEventName();

   100             if (!forceInstrumentation) {

   101                 // Assume we are recording

   102                 MetadataRepository mr = MetadataRepository.getInstance();

   103                 // No need to generate bytecode if:

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

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

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

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

   108                     return oldBytes;

   109                 }

   110             }

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

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

   113             // guard against a null reference.

   114             ei.setGuardHandler(true);

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

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

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

   118             // be used

   119             eh.makeEventHandlerClass();

   120             byte[] bytes = ei.buildInstrumented();

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

   122             return bytes;

   123         } catch (Throwable t) {

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

   125             return oldBytes;

   126         }

   127     }

   128 

   129     /**

   130      * Called by the JVM to create the recorder thread.

   131      *

   132      * @param systemThreadGroup

   133      *            the system thread group

   134      *

   135      * @param contextClassLoader

   136      *            the context class loader.

   137      *

   138      * @return a new thread

   139      */

   140     static Thread createRecorderThread(ThreadGroup systemThreadGroup, ClassLoader contextClassLoader) {

   141         return SecuritySupport.createRecorderThread(systemThreadGroup, contextClassLoader);

   142     }

   143 }