| /* |
| * 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.phoenix.util; |
| |
| import java.util.concurrent.Callable; |
| |
| import org.apache.phoenix.call.CallWrapper; |
| |
| /** |
| * Executes {@code Callable}s using a context classloader that is set up to load classes from |
| * Phoenix. |
| * <p/> |
| * Loading HBase configuration settings and endpoint coprocessor classes is done via the context |
| * classloader of the calling thread. When Phoenix is being run via a JDBC-enabled GUI, the |
| * driver is often loaded dynamically and executed via multiple threads, which makes it difficult |
| * or impossible to predict the state of the classloader hierarchy in the current thread. This |
| * class is intended to get around that, to ensure that the same classloader used to load Phoenix |
| * classes is set as the context classloader for specific calls. |
| */ |
| public class PhoenixContextExecutor { |
| |
| // We cache the class loader because calls to Class.getClassLoader are relatively expensive |
| private static final ClassLoader CACHED_CLASSLOADER = PhoenixContextExecutor.class.getClassLoader(); |
| |
| private static class CurrentContextWrapper implements CallWrapper { |
| private ClassLoader saveCcl; |
| |
| @Override |
| public void before() { |
| saveCcl = Thread.currentThread().getContextClassLoader(); |
| Thread.currentThread().setContextClassLoader(CACHED_CLASSLOADER); |
| } |
| |
| @Override |
| public void after() { |
| Thread.currentThread().setContextClassLoader(saveCcl); |
| |
| }; |
| } |
| |
| public static CallWrapper inContext() { |
| return new CurrentContextWrapper(); |
| } |
| |
| /** |
| * Execute an operation (synchronously) using the context classloader used to load this class, |
| * instead of the currently-set context classloader of the current thread. This allows loading |
| * dynamically-loaded classes and configuration files using the same classloader used to |
| * load the rest of the JDBC driver. |
| * <p/> |
| * The context classloader of the current thread is reset to its original value after the |
| * callable has been executed. |
| * |
| * @param target the callable to be executed |
| * @return the return value from the callable |
| */ |
| public static <T> T call(Callable<T> target) throws Exception { |
| ClassLoader saveCcl = Thread.currentThread().getContextClassLoader(); |
| try { |
| Thread.currentThread().setContextClassLoader(CACHED_CLASSLOADER); |
| return target.call(); |
| } finally { |
| Thread.currentThread().setContextClassLoader(saveCcl); |
| } |
| } |
| |
| /** |
| * Same as {@link #call(java.util.concurrent.Callable)}, but doesn't throw checked exceptions. |
| * |
| * @param target the callable to be executed |
| * @return the return value from the callable |
| * @throws Exception any exception thrown by the underlying callable |
| */ |
| public static <T> T callWithoutPropagation(Callable<T> target) { |
| try { |
| return call(target); |
| } catch (RuntimeException e) { |
| throw e; |
| } catch (Exception e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| } |