1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17 package org.apache.logging.log4j.util;
18
19 /**
20 * Log4j API Constants.
21 *
22 * @since 2.6.2
23 */
24 public final class Constants {
25 /**
26 * {@code true} if we think we are running in a web container, based on the boolean value of system property
27 * "log4j2.is.webapp", or (if this system property is not set) whether the {@code javax.servlet.Servlet} class
28 * is present in the classpath.
29 */
30 public static final boolean IS_WEB_APP = PropertiesUtil.getProperties().getBooleanProperty(
31 "log4j2.is.webapp", isClassAvailable("javax.servlet.Servlet"));
32
33 /**
34 * Kill switch for object pooling in ThreadLocals that enables much of the LOG4J2-1270 no-GC behaviour.
35 * <p>
36 * {@code True} for non-{@link #IS_WEB_APP web apps}, disable by setting system property
37 * "log4j2.enable.threadlocals" to "false".
38 * </p>
39 */
40 public static final boolean ENABLE_THREADLOCALS = !IS_WEB_APP && PropertiesUtil.getProperties().getBooleanProperty(
41 "log4j2.enable.threadlocals", true);
42
43 public static final int JAVA_MAJOR_VERSION = getMajorVersion();
44
45 /**
46 * Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages.
47 * After a large message has been delivered to the appenders, the StringBuilder is trimmed to this size.
48 * <p>
49 * The default value is {@value}, which allows the StringBuilder to resize three times from its initial size.
50 * Users can override with system property "log4j.maxReusableMsgSize".
51 * </p>
52 * @since 2.9
53 */
54 public static final int MAX_REUSABLE_MESSAGE_SIZE = size("log4j.maxReusableMsgSize", (128 * 2 + 2) * 2 + 2);
55
56 /**
57 * Name of the system property that will turn on TRACE level internal log4j2 status logging.
58 * <p>
59 * If system property {@value} is defined, regardless of the property value, all internal log4j2 logging will be
60 * printed to the console. The presence of this system property overrides any value set in the configuration's
61 * {@code <Configuration status="<level>" ...>} status attribute, as well as any value set for
62 * system property {@code org.apache.logging.log4j.simplelog.StatusLogger.level}.
63 * </p>
64 */
65 public static final String LOG4J2_DEBUG = "log4j2.debug";
66
67 private static int size(final String property, final int defaultValue) {
68 return PropertiesUtil.getProperties().getIntegerProperty(property, defaultValue);
69 }
70
71 /**
72 * Determines if a named Class can be loaded or not.
73 *
74 * @param className The class name.
75 * @return {@code true} if the class could be found or {@code false} otherwise.
76 */
77 private static boolean isClassAvailable(final String className) {
78 try {
79 return LoaderUtil.loadClass(className) != null;
80 } catch (final Throwable e) {
81 return false;
82 }
83 }
84
85 /**
86 * Prevent class instantiation.
87 */
88 private Constants() {
89 }
90
91 private static int getMajorVersion() {
92 return getMajorVersion(System.getProperty("java.version"));
93 }
94
95 static int getMajorVersion(final String version) {
96 final String[] parts = version.split("-|\\.");
97 boolean isJEP223;
98 try {
99 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 }