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.core.util;
018
019import java.nio.charset.Charset;
020import java.nio.charset.StandardCharsets;
021
022import org.apache.logging.log4j.util.PropertiesUtil;
023
024/**
025 * Log4j Constants.
026 */
027public final class Constants {
028
029    /**
030     * Name of the system property to use to identify the LogEvent factory.
031     */
032    public static final String LOG4J_LOG_EVENT_FACTORY = "Log4jLogEventFactory";
033
034    /**
035     * Name of the system property to use to identify the ContextSelector Class.
036     */
037    public static final String LOG4J_CONTEXT_SELECTOR = "Log4jContextSelector";
038
039    /**
040     * Property name for the default status (internal log4j logging) level to use if not specified in configuration.
041     */
042    public static final String LOG4J_DEFAULT_STATUS_LEVEL = "Log4jDefaultStatusLevel";
043
044    /**
045     * JNDI context name string literal.
046     */
047    public static final String JNDI_CONTEXT_NAME = "java:comp/env/log4j/context-name";
048
049    /**
050     * Line separator.
051     */
052    public static final String LINE_SEPARATOR = PropertiesUtil.getProperties().getStringProperty("line.separator",
053            "\n");
054
055    /**
056     * Number of milliseconds in a second.
057     */
058    public static final int MILLIS_IN_SECONDS = 1000;
059
060    /**
061     * Equivalent to StandardCharsets.UTF_8.
062     *
063     * @deprecated Use {@link StandardCharsets#UTF_8}. Will be removed in 2.5.
064     */
065    @Deprecated
066    public static final Charset UTF_8 = StandardCharsets.UTF_8;
067
068    /**
069     * Supports user request LOG4J2-898 to have the option to format a message in the background thread.
070     */
071    public static final boolean FORMAT_MESSAGES_IN_BACKGROUND = PropertiesUtil.getProperties().getBooleanProperty(
072            "log4j.format.msg.async", false);
073
074    /**
075     * {@code true} if we think we are running in a web container, based on the boolean value of system property
076     * "log4j2.is.webapp", or (if this system property is not set) whether the  {@code javax.servlet.Servlet} class
077     * is present in the classpath.
078     */
079    public static final boolean IS_WEB_APP = PropertiesUtil.getProperties().getBooleanProperty(
080            "log4j2.is.webapp", Loader.isClassAvailable("javax.servlet.Servlet"));
081
082    /**
083     * Kill switch for object pooling in ThreadLocals that enables much of the LOG4J2-1270 no-GC behaviour.
084     * <p>
085     * {@code True} for non-{@link #IS_WEB_APP web apps}, disable by setting system property
086     * "log4j2.enable.threadlocals" to "false".
087     *
088     * @since 2.6
089     */
090    public static final boolean ENABLE_THREADLOCALS = !IS_WEB_APP && PropertiesUtil.getProperties().getBooleanProperty(
091            "log4j2.enable.threadlocals", true);
092
093    /**
094     * Kill switch for garbage-free Layout behaviour that encodes LogEvents directly into
095     * {@link org.apache.logging.log4j.core.layout.ByteBufferDestination}s without creating intermediate temporary
096     * Objects.
097     * <p>
098     * {@code True} by default iff all loggers are asynchronous because system property
099     * {@code Log4jContextSelector} is set to {@code org.apache.logging.log4j.core.async.AsyncLoggerContextSelector}.
100     * Disable by setting system property "log4j2.enable.direct.encoders" to "false".
101     *
102     * @since 2.6
103     */
104    public static final boolean ENABLE_DIRECT_ENCODERS = PropertiesUtil.getProperties().getBooleanProperty(
105            "log4j2.enable.direct.encoders", true); // enable GC-free text encoding by default
106            // the alternative is to enable GC-free encoding only by default only when using all-async loggers:
107            //AsyncLoggerContextSelector.class.getName().equals(PropertiesUtil.getProperties().getStringProperty(LOG4J_CONTEXT_SELECTOR)));
108
109    /**
110     * Initial StringBuilder size used in RingBuffer LogEvents to store the contents of reusable Messages.
111     * <p>
112     * The default value is {@value}, users can override with system property "log4j.initialReusableMsgSize".
113     * </p>
114     * @since 2.6
115     */
116    public static final int INITIAL_REUSABLE_MESSAGE_SIZE = size("log4j.initialReusableMsgSize", 128);
117
118    /**
119     * Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages.
120     * After a large message has been delivered to the appenders, the StringBuilder is trimmed to this size.
121     * <p>
122     * The default value is {@value}, which allows the StringBuilder to resize three times from its initial size.
123     * Users can override with system property "log4j.maxReusableMsgSize".
124     * </p>
125     * @since 2.6
126     */
127    public static final int MAX_REUSABLE_MESSAGE_SIZE = size("log4j.maxReusableMsgSize", (128 * 2 + 2) * 2 + 2);
128
129    /**
130     * Size of CharBuffers used by text encoders.
131     * <p>
132     * The default value is {@value}, users can override with system property "log4j.encoder.charBufferSize".
133     * </p>
134     * @since 2.6
135     */
136    public static final int ENCODER_CHAR_BUFFER_SIZE = size("log4j.encoder.charBufferSize", 2048);
137
138    /**
139     * Default size of ByteBuffers used to encode LogEvents without allocating temporary objects.
140     * <p>
141     * The default value is {@value}, users can override with system property "log4j.encoder.byteBufferSize".
142     * </p>
143     * @see org.apache.logging.log4j.core.layout.ByteBufferDestination
144     * @since 2.6
145     */
146    public static final int ENCODER_BYTE_BUFFER_SIZE = size("log4j.encoder.byteBufferSize", 8 * 1024);
147
148
149    private static int size(final String property, final int defaultValue) {
150        return PropertiesUtil.getProperties().getIntegerProperty(property, defaultValue);
151    }
152
153    /**
154     * Prevent class instantiation.
155     */
156    private Constants() {
157    }
158}