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package jdk.jfr.internal;

import java.lang.reflect.Modifier;

import jdk.jfr.internal.handlers.EventHandler;
import jdk.jfr.internal.instrument.JDKEvents;

All upcalls from the JVM should go through this class.
/** * 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
Params:
  • traceId – Id of the class
  • dummy – (not used but needed since invoke infrastructure in native uses same signature bytesForEagerInstrumentation)
  • clazz – class being retransformed
  • oldBytes – byte code
Throws:
Returns:byte code to use
/** * 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 (jdk.internal.event.Event.class.isAssignableFrom(clazz) && !Modifier.isAbstract(clazz.getModifiers())) { EventHandler handler = Utils.getHandler(clazz.asSubclass(jdk.internal.event.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.
Params:
  • traceId – Id of the class
  • forceInstrumentation – add instrumentation regardless if event is enabled or not.
  • superClass – the super class of the class being processed
  • oldBytes – byte code
Throws:
Returns:byte code to use
/** * 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 superClass * 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.
Params:
  • systemThreadGroup – the system thread group
  • contextClassLoader – the context class loader.
Returns:a new thread
/** * 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); } }