org.springframework.instrument.InstrumentationSavingAgent Maven / Gradle / Ivy
/*
* Copyright 2002-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.instrument;
import java.lang.instrument.Instrumentation;
/**
* Java agent that saves the {@link Instrumentation} interface from the JVM
* for later use.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @since 2.0
* @see org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver
*/
public final class InstrumentationSavingAgent {
private static volatile Instrumentation instrumentation;
private InstrumentationSavingAgent() {
}
/**
* Save the {@link Instrumentation} interface exposed by the JVM.
*/
public static void premain(String agentArgs, Instrumentation inst) {
instrumentation = inst;
}
/**
* Save the {@link Instrumentation} interface exposed by the JVM.
* This method is required to dynamically load this Agent with the Attach API.
*/
public static void agentmain(String agentArgs, Instrumentation inst) {
instrumentation = inst;
}
/**
* Return the {@link Instrumentation} interface exposed by the JVM.
* Note that this agent class will typically not be available in the classpath
* unless the agent is actually specified on JVM startup. If you intend to do
* conditional checking with respect to agent availability, consider using
* {@link org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver#getInstrumentation()}
* instead - which will work without the agent class in the classpath as well.
* @return the {@code Instrumentation} instance previously saved when
* the {@link #premain} or {@link #agentmain} methods was called by the JVM;
* will be {@code null} if this class was not used as Java agent when this
* JVM was started or it wasn't installed as agent using the Attach API.
* @see org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver#getInstrumentation()
*/
public static Instrumentation getInstrumentation() {
return instrumentation;
}
}