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; 018 019/** 020 * Log4j API Constants. 021 * 022 * @since 2.6.2 023 */ 024public final class Constants { 025 /** 026 * {@code true} if we think we are running in a web container, based on the boolean value of system property 027 * "log4j2.is.webapp", or (if this system property is not set) whether the {@code javax.servlet.Servlet} class 028 * is present in the classpath. 029 */ 030 public static final boolean IS_WEB_APP = PropertiesUtil.getProperties().getBooleanProperty( 031 "log4j2.is.webapp", isClassAvailable("javax.servlet.Servlet")); 032 033 /** 034 * Kill switch for object pooling in ThreadLocals that enables much of the LOG4J2-1270 no-GC behaviour. 035 * <p> 036 * {@code True} for non-{@link #IS_WEB_APP web apps}, disable by setting system property 037 * "log4j2.enable.threadlocals" to "false". 038 * </p> 039 */ 040 public static final boolean ENABLE_THREADLOCALS = !IS_WEB_APP && PropertiesUtil.getProperties().getBooleanProperty( 041 "log4j2.enable.threadlocals", true); 042 043 public static final int JAVA_MAJOR_VERSION = getMajorVersion(); 044 045 /** 046 * Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages. 047 * After a large message has been delivered to the appenders, the StringBuilder is trimmed to this size. 048 * <p> 049 * The default value is {@value}, which allows the StringBuilder to resize three times from its initial size. 050 * Users can override with system property "log4j.maxReusableMsgSize". 051 * </p> 052 * @since 2.9 053 */ 054 public static final int MAX_REUSABLE_MESSAGE_SIZE = size("log4j.maxReusableMsgSize", (128 * 2 + 2) * 2 + 2); 055 056 /** 057 * Name of the system property that will turn on TRACE level internal log4j2 status logging. 058 * <p> 059 * If system property {@value} is defined, regardless of the property value, all internal log4j2 logging will be 060 * printed to the console. The presence of this system property overrides any value set in the configuration's 061 * {@code <Configuration status="<level>" ...>} status attribute, as well as any value set for 062 * system property {@code org.apache.logging.log4j.simplelog.StatusLogger.level}. 063 * </p> 064 */ 065 public static final String LOG4J2_DEBUG = "log4j2.debug"; 066 067 private static int size(final String property, final int defaultValue) { 068 return PropertiesUtil.getProperties().getIntegerProperty(property, defaultValue); 069 } 070 071 /** 072 * Determines if a named Class can be loaded or not. 073 * 074 * @param className The class name. 075 * @return {@code true} if the class could be found or {@code false} otherwise. 076 */ 077 private static boolean isClassAvailable(final String className) { 078 try { 079 return LoaderUtil.loadClass(className) != null; 080 } catch (final Throwable e) { 081 return false; 082 } 083 } 084 085 /** 086 * Prevent class instantiation. 087 */ 088 private Constants() { 089 } 090 091 private static int getMajorVersion() { 092 return getMajorVersion(System.getProperty("java.version")); 093 } 094 095 static int getMajorVersion(final String version) { 096 final String[] parts = version.split("-|\\."); 097 boolean isJEP223; 098 try { 099 final int token = Integer.parseInt(parts[0]); 100 isJEP223 = token != 1; 101 if (isJEP223) { 102 return token; 103 } 104 return Integer.parseInt(parts[1]); 105 } catch (final Exception ex) { 106 return 0; 107 } 108 } 109}