com.newrelic.weave.utils.SynchronizedInnerClassNode Maven / Gradle / Ivy
Show all versions of newrelic-weaver Show documentation
/*
*
* * Copyright 2020 New Relic Corporation. All rights reserved.
* * SPDX-License-Identifier: Apache-2.0
*
*/
package com.newrelic.weave.utils;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.tree.InnerClassNode;
/**
* This class exists only to work around the fact that InnerClassNode instances are NOT thread safe. If multiple threads
* call {@link #accept(ClassVisitor)} at the same time there is a race condition that exists that has been shown to
* cause VerifyErrors and other serious bytecode-related exceptions.
*
* By synchronizing on the {@link #accept(ClassVisitor)} method we are ensuring that any usage of this InnerClassNode in
* the agent can be accessed by multiple threads. One important thing to note is that this ties us pretty strongly to an
* ASM version due to the fact that we had to override constructors in the original asm class. If these constructors
* change or other accept() methods are added we will need to update accordingly.
*
* NOTE: If you are upgrading from org.ow2.asm:asm / org.ow2.asm:asm-tree make sure to double-check that this class hasn't changed between versions.
*/
public class SynchronizedInnerClassNode extends InnerClassNode {
public SynchronizedInnerClassNode(String name, String outerName, String innerName, int access) {
super(name, outerName, innerName, access);
}
/**
* This method is synchronized in order to prevent issues with bytecode modification that
* occur when multiple threads call accept on the same InnerClassNode instance.
*/
@Override
public synchronized void accept(ClassVisitor cv) {
super.accept(cv);
}
}