src/main/java/org/codehaus/groovy/reflection/GroovyClassValueFactory.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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
 *
 *    http://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.codehaus.groovy.reflection;

import org.codehaus.groovy.reflection.GroovyClassValue.ComputeValue;
import org.codehaus.groovy.reflection.v7.GroovyClassValueJava7;
import org.codehaus.groovy.vmplugin.VMPluginFactory;

class GroovyClassValueFactory {
	/**
	 * This flag is introduced as a (hopefully) temporary workaround for a JVM bug, that is to say that using
	 * ClassValue prevents the classes and classloaders from being unloaded.
	 * See https://bugs.openjdk.java.net/browse/JDK-8136353
	 * This issue does not exist on IBM Java (J9) so use ClassValue by default on that JVM.
	 */
	private static final boolean USE_CLASSVALUE;
	static {
        String useClassValueDefault =
				(VMPluginFactory.getPlugin().getVersion() >= 7 || "IBM J9 VM".equals(System.getProperty("java.vm.name")))
						? "true" : "false";

        USE_CLASSVALUE = Boolean.valueOf(System.getProperty("groovy.use.classvalue", useClassValueDefault));
    }

	public static <T> GroovyClassValue<T> createGroovyClassValue(ComputeValue<T> computeValue) {
		return (USE_CLASSVALUE)
                ? new GroovyClassValueJava7<>(computeValue)
                : new GroovyClassValuePreJava7<>(computeValue);
	}
}