/*
* 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.logging.log4j.core.pattern;
import org.apache.logging.log4j.util.PerformanceSensitive;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.util.Constants;
import org.apache.logging.log4j.util.TriConsumer;
import org.apache.logging.log4j.util.StringBuilders;
/**
* Able to handle the contents of the LogEvent's MDC and either
* output the entire contents of the properties in a similar format to the
* java.util.Hashtable.toString(), or to output the value of a specific key
* within the property bundle
* when this pattern converter has the option set.
*/
@Plugin(name = "MdcPatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys({ "X", "mdc", "MDC" })
@PerformanceSensitive("allocation")
public final class MdcPatternConverter extends LogEventPatternConverter {
private static final ThreadLocal<StringBuilder> threadLocal = new ThreadLocal<>();
private static final int DEFAULT_STRING_BUILDER_SIZE = 64;
/**
* Name of property to output.
*/
private final String key;
private final String[] keys;
private final boolean full;
/**
* Private constructor.
*
* @param options options, may be null.
*/
private MdcPatternConverter(final String[] options) {
super(options != null && options.length > 0 ? "MDC{" + options[0] + '}' : "MDC", "mdc");
if (options != null && options.length > 0) {
full = false;
if (options[0].indexOf(',') > 0) {
keys = options[0].split(",");
for (int i = 0; i < keys.length; i++) {
keys[i] = keys[i].trim();
}
key = null;
} else {
keys = null;
key = options[0];
}
} else {
full = true;
key = null;
keys = null;
}
}
/**
* Obtains an instance of PropertiesPatternConverter.
*
* @param options options, may be null or first element contains name of property to format.
* @return instance of PropertiesPatternConverter.
*/
public static MdcPatternConverter newInstance(final String[] options) {
return new MdcPatternConverter(options);
}
private static final TriConsumer<String, Object, StringBuilder> WRITE_KEY_VALUES_INTO = new TriConsumer<String, Object, StringBuilder>() {
@Override
public void accept(final String key, final Object value, final StringBuilder sb) {
if (sb.length() > 1) {
sb.append(", ");
}
sb.append(key).append('=');
StringBuilders.appendValue(sb, value);
}
};
/**
* {@inheritDoc}
*/
@Override
public void format(final LogEvent event, final StringBuilder toAppendTo) {
final ReadOnlyStringMap contextData = event.getContextData();
// if there is no additional options, we output every single
// Key/Value pair for the MDC in a similar format to Hashtable.toString()
if (full) {
if (contextData == null || contextData.size() == 0) {
toAppendTo.append("{}");
return;
}
appendFully(contextData, toAppendTo);
} else {
if (keys != null) {
if (contextData == null || contextData.size() == 0) {
toAppendTo.append("{}");
return;
}
appendSelectedKeys(keys, contextData, toAppendTo);
} else if (contextData != null){
// otherwise they just want a single key output
final Object value = contextData.getValue(key);
if (value != null) {
StringBuilders.appendValue(toAppendTo, value);
}
}
}
}
private static void appendFully(final ReadOnlyStringMap contextData, final StringBuilder toAppendTo) {
final StringBuilder sb = getStringBuilder();
sb.append("{");
contextData.forEach(WRITE_KEY_VALUES_INTO, sb);
sb.append('}');
toAppendTo.append(sb);
trimToMaxSize(sb);
}
private static void appendSelectedKeys(final String[] keys, final ReadOnlyStringMap contextData, final StringBuilder toAppendTo) {
// Print all the keys in the array that have a value.
final StringBuilder sb = getStringBuilder();
sb.append("{");
for (int i = 0; i < keys.length; i++) {
final String theKey = keys[i];
final Object value = contextData.getValue(theKey);
if (value != null) { // !contextData.containskey(theKey)
if (sb.length() > 1) {
sb.append(", ");
}
sb.append(theKey).append('=');
StringBuilders.appendValue(sb, value);
}
}
sb.append('}');
toAppendTo.append(sb);
trimToMaxSize(sb);
}
private static StringBuilder getStringBuilder() {
StringBuilder result = threadLocal.get();
if (result == null) {
result = new StringBuilder(DEFAULT_STRING_BUILDER_SIZE);
threadLocal.set(result);
}
result.setLength(0);
return result;
}
private static void trimToMaxSize(final StringBuilder stringBuilder) {
StringBuilders.trimToMaxSize(stringBuilder, Constants.MAX_REUSABLE_MESSAGE_SIZE);
}
}