JreCompat.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.apache.tomcat.util.compat;
- import java.lang.reflect.Field;
- import java.security.PrivilegedExceptionAction;
- import java.util.concurrent.Callable;
- import java.util.concurrent.CompletionException;
- import javax.security.auth.Subject;
- import org.apache.tomcat.util.res.StringManager;
- /**
- * This is the base implementation class for JRE compatibility and provides an implementation based on Java 17.
- * Sub-classes may extend this class and provide alternative implementations for later JRE versions
- */
- public class JreCompat {
- private static final JreCompat instance;
- private static final boolean graalAvailable;
- private static final boolean jre19Available;
- private static final boolean jre21Available;
- private static final boolean jre22Available;
- private static final StringManager sm = StringManager.getManager(JreCompat.class);
- static {
- boolean result = false;
- try {
- Class<?> nativeImageClazz = Class.forName("org.graalvm.nativeimage.ImageInfo");
- result = Boolean.TRUE.equals(nativeImageClazz.getMethod("inImageCode").invoke(null));
- } catch (ClassNotFoundException e) {
- // Must be Graal
- } catch (ReflectiveOperationException | IllegalArgumentException e) {
- // Should never happen
- }
- graalAvailable = result || System.getProperty("org.graalvm.nativeimage.imagecode") != null;
- // This is Tomcat 11.0.x with a minimum Java version of Java 17.
- // Look for the highest supported JVM first
- if (Jre22Compat.isSupported()) {
- instance = new Jre22Compat();
- jre22Available = true;
- jre21Available = true;
- jre19Available = true;
- } else if (Jre21Compat.isSupported()) {
- instance = new Jre21Compat();
- jre22Available = false;
- jre21Available = true;
- jre19Available = true;
- } else if (Jre19Compat.isSupported()) {
- instance = new Jre19Compat();
- jre22Available = false;
- jre21Available = false;
- jre19Available = true;
- } else {
- instance = new JreCompat();
- jre22Available = false;
- jre21Available = false;
- jre19Available = false;
- }
- }
- public static JreCompat getInstance() {
- return instance;
- }
- public static boolean isGraalAvailable() {
- return graalAvailable;
- }
- public static boolean isJre19Available() {
- return jre19Available;
- }
- public static boolean isJre21Available() {
- return jre21Available;
- }
- public static boolean isJre22Available() {
- return jre22Available;
- }
- // Java 17 implementations of Java 19 methods
- /**
- * Obtains the executor, if any, used to create the provided thread.
- *
- * @param thread The thread to examine
- *
- * @return The executor, if any, that created the provided thread
- *
- * @throws NoSuchFieldException If a field used via reflection to obtain the executor cannot be found
- * @throws SecurityException If a security exception occurs while trying to identify the executor
- * @throws IllegalArgumentException If the instance object does not match the class of the field when obtaining a
- * field value via reflection
- * @throws IllegalAccessException If a field is not accessible due to access restrictions
- */
- public Object getExecutor(Thread thread)
- throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
- Object result = null;
- // Runnable wrapped by Thread
- // "target" in Sun/Oracle JDK
- // "runnable" in IBM JDK
- // "action" in Apache Harmony
- Object target = null;
- for (String fieldName : new String[] { "target", "runnable", "action" }) {
- try {
- Field targetField = thread.getClass().getDeclaredField(fieldName);
- targetField.setAccessible(true);
- target = targetField.get(thread);
- break;
- } catch (NoSuchFieldException nfe) {
- continue;
- }
- }
- // "java.util.concurrent" code is in public domain,
- // so all implementations are similar including our
- // internal fork.
- if (target != null && target.getClass().getCanonicalName() != null && (target.getClass().getCanonicalName()
- .equals("org.apache.tomcat.util.threads.ThreadPoolExecutor.Worker") ||
- target.getClass().getCanonicalName().equals("java.util.concurrent.ThreadPoolExecutor.Worker"))) {
- Field executorField = target.getClass().getDeclaredField("this$0");
- executorField.setAccessible(true);
- result = executorField.get(target);
- }
- return result;
- }
- // Java 17 implementations of Java 21 methods
- /**
- * Create a thread builder for virtual threads using the given name to name the threads.
- *
- * @param name The base name for the threads
- *
- * @return The thread buidler for virtual threads
- */
- public Object createVirtualThreadBuilder(String name) {
- throw new UnsupportedOperationException(sm.getString("jreCompat.noVirtualThreads"));
- }
- /**
- * Create a thread with the given thread builder and use it to execute the given runnable.
- *
- * @param threadBuilder The thread builder to use to create a thread
- * @param command The command to run
- */
- public void threadBuilderStart(Object threadBuilder, Runnable command) {
- throw new UnsupportedOperationException(sm.getString("jreCompat.noVirtualThreads"));
- }
- /*
- * This is a slightly different usage of JreCompat.
- *
- * Subject.doAs() was deprecated in Java 18 and replaced with Subject.callAs(). As of Java 23, calling
- * Subject.doAs() will trigger an UnsupportedOperationException unless the java.security.manager system property is
- * set. To avoid Tomcat installations using Spnego authentication having to set this value, JreCompat is used to
- * call Subject.callAs() instead.
- *
- * Because Java versions 18 to 22 inclusive support both the old and the new method, the switch over can occur at
- * any Java version from 18 to 22 inclusive. Java 21 onwards was selected as it as an LTS version and that removes
- * the need to add a Jre18Compat class.
- *
- * So, the slightly longer description for this method is:
- *
- * Java 17 implementation of a method replaced between Java 18 and 22 with the replacement method being used by
- * Tomcat when running on Java 21 onwards.
- */
- @SuppressWarnings("removal")
- public <T> T callAs(Subject subject, Callable<T> action) throws CompletionException {
- try {
- return Subject.doAs(subject, new PrivilegedExceptionAction<T>() {
- @Override
- public T run() throws Exception {
- return action.call();
- }
- });
- } catch (Exception e) {
- throw new CompletionException(e);
- }
- }
- }