001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.util;
018
019import java.util.NoSuchElementException;
020import java.util.Stack;
021
022import org.apache.logging.log4j.status.StatusLogger;
023
024/**
025 * <em>Consider this class private.</em> Provides various methods to determine the caller class. <h3>Background</h3>
026 */
027public final class StackLocatorUtil {
028    private static StackLocator stackLocator = null;
029    private static volatile boolean errorLogged = false;
030
031    static {
032        stackLocator = StackLocator.getInstance();
033    }
034
035    private StackLocatorUtil() {
036    }
037
038    // TODO: return Object.class instead of null (though it will have a null ClassLoader)
039    // (MS) I believe this would work without any modifications elsewhere, but I could be wrong
040
041    // migrated from ReflectiveCallerClassUtility
042    @PerformanceSensitive
043    public static Class<?> getCallerClass(final int depth) {
044        return stackLocator.getCallerClass(depth + 1);
045    }
046
047    public static StackTraceElement getStackTraceElement(final int depth) {
048        return stackLocator.getStackTraceElement(depth + 1);
049    }
050    // migrated from ClassLoaderContextSelector
051    @PerformanceSensitive
052    public static Class<?> getCallerClass(final String fqcn) {
053        return getCallerClass(fqcn, Strings.EMPTY);
054    }
055
056    // migrated from Log4jLoggerFactory
057    @PerformanceSensitive
058    public static Class<?> getCallerClass(final String fqcn, final String pkg) {
059        return stackLocator.getCallerClass(fqcn, pkg);
060    }
061
062    // added for use in LoggerAdapter implementations mainly
063    @PerformanceSensitive
064    public static Class<?> getCallerClass(final Class<?> anchor) {
065        return stackLocator.getCallerClass(anchor);
066    }
067
068    // migrated from ThrowableProxy
069    @PerformanceSensitive
070    public static Stack<Class<?>> getCurrentStackTrace() {
071        return stackLocator.getCurrentStackTrace();
072    }
073
074    public static StackTraceElement calcLocation(final String fqcnOfLogger) {
075        try {
076            return stackLocator.calcLocation(fqcnOfLogger);
077        } catch (NoSuchElementException ex) {
078            if (!errorLogged) {
079                errorLogged = true;
080                StatusLogger.getLogger().warn("Unable to locate stack trace element for {}", fqcnOfLogger, ex);
081            }
082            return null;
083        }
084    }
085}