Source Code for Apache Log4j API
Apache Log4j API
provides the interface that applications should code to and provides the adapter
components required for implementers to create a logging implementation.
Apache Log4j API is a required module to use Apache Log4j.
Bytecode (Java 8) for Apache Log4j API is provided in a separate JAR file like log4j-api-2.14.1.jar.
Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.
You can also browse Source Code files for Apache Log4j API 2.14.1 below.
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⏎ org/apache/logging/log4j/message/ParameterFormatter.java
/*
* 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.message;
import org.apache.logging.log4j.util.StringBuilders;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Set;
/**
* Supports parameter formatting as used in ParameterizedMessage and ReusableParameterizedMessage.
*/
final class ParameterFormatter {
/**
* Prefix for recursion.
*/
static final String RECURSION_PREFIX = "[...";
/**
* Suffix for recursion.
*/
static final String RECURSION_SUFFIX = "...]";
/**
* Prefix for errors.
*/
static final String ERROR_PREFIX = "[!!!";
/**
* Separator for errors.
*/
static final String ERROR_SEPARATOR = "=>";
/**
* Separator for error messages.
*/
static final String ERROR_MSG_SEPARATOR = ":";
/**
* Suffix for errors.
*/
static final String ERROR_SUFFIX = "!!!]";
private static final char DELIM_START = '{';
private static final char DELIM_STOP = '}';
private static final char ESCAPE_CHAR = '\\';
private static final ThreadLocal<SimpleDateFormat> SIMPLE_DATE_FORMAT_REF =
ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ"));
private ParameterFormatter() {
}
/**
* Counts the number of unescaped placeholders in the given messagePattern.
*
* @param messagePattern the message pattern to be analyzed.
* @return the number of unescaped placeholders.
*/
static int countArgumentPlaceholders(final String messagePattern) {
if (messagePattern == null) {
return 0;
}
final int length = messagePattern.length();
int result = 0;
boolean isEscaped = false;
for (int i = 0; i < length - 1; i++) {
final char curChar = messagePattern.charAt(i);
if (curChar == ESCAPE_CHAR) {
isEscaped = !isEscaped;
} else if (curChar == DELIM_START) {
if (!isEscaped && messagePattern.charAt(i + 1) == DELIM_STOP) {
result++;
i++;
}
isEscaped = false;
} else {
isEscaped = false;
}
}
return result;
}
/**
* Counts the number of unescaped placeholders in the given messagePattern.
*
* @param messagePattern the message pattern to be analyzed.
* @return the number of unescaped placeholders.
*/
static int countArgumentPlaceholders2(final String messagePattern, final int[] indices) {
if (messagePattern == null) {
return 0;
}
final int length = messagePattern.length();
int result = 0;
boolean isEscaped = false;
for (int i = 0; i < length - 1; i++) {
final char curChar = messagePattern.charAt(i);
if (curChar == ESCAPE_CHAR) {
isEscaped = !isEscaped;
indices[0] = -1; // escaping means fast path is not available...
result++;
} else if (curChar == DELIM_START) {
if (!isEscaped && messagePattern.charAt(i + 1) == DELIM_STOP) {
indices[result] = i;
result++;
i++;
}
isEscaped = false;
} else {
isEscaped = false;
}
}
return result;
}
/**
* Counts the number of unescaped placeholders in the given messagePattern.
*
* @param messagePattern the message pattern to be analyzed.
* @return the number of unescaped placeholders.
*/
static int countArgumentPlaceholders3(final char[] messagePattern, final int length, final int[] indices) {
int result = 0;
boolean isEscaped = false;
for (int i = 0; i < length - 1; i++) {
final char curChar = messagePattern[i];
if (curChar == ESCAPE_CHAR) {
isEscaped = !isEscaped;
} else if (curChar == DELIM_START) {
if (!isEscaped && messagePattern[i + 1] == DELIM_STOP) {
indices[result] = i;
result++;
i++;
}
isEscaped = false;
} else {
isEscaped = false;
}
}
return result;
}
/**
* Replace placeholders in the given messagePattern with arguments.
*
* @param messagePattern the message pattern containing placeholders.
* @param arguments the arguments to be used to replace placeholders.
* @return the formatted message.
*/
static String format(final String messagePattern, final Object[] arguments) {
final StringBuilder result = new StringBuilder();
final int argCount = arguments == null ? 0 : arguments.length;
formatMessage(result, messagePattern, arguments, argCount);
return result.toString();
}
/**
* Replace placeholders in the given messagePattern with arguments.
*
* @param buffer the buffer to write the formatted message into
* @param messagePattern the message pattern containing placeholders.
* @param arguments the arguments to be used to replace placeholders.
*/
static void formatMessage2(final StringBuilder buffer, final String messagePattern,
final Object[] arguments, final int argCount, final int[] indices) {
if (messagePattern == null || arguments == null || argCount == 0) {
buffer.append(messagePattern);
return;
}
int previous = 0;
for (int i = 0; i < argCount; i++) {
buffer.append(messagePattern, previous, indices[i]);
previous = indices[i] + 2;
recursiveDeepToString(arguments[i], buffer);
}
buffer.append(messagePattern, previous, messagePattern.length());
}
/**
* Replace placeholders in the given messagePattern with arguments.
*
* @param buffer the buffer to write the formatted message into
* @param messagePattern the message pattern containing placeholders.
* @param arguments the arguments to be used to replace placeholders.
*/
static void formatMessage3(final StringBuilder buffer, final char[] messagePattern, final int patternLength,
final Object[] arguments, final int argCount, final int[] indices) {
if (messagePattern == null) {
return;
}
if (arguments == null || argCount == 0) {
buffer.append(messagePattern);
return;
}
int previous = 0;
for (int i = 0; i < argCount; i++) {
buffer.append(messagePattern, previous, indices[i]);
previous = indices[i] + 2;
recursiveDeepToString(arguments[i], buffer);
}
buffer.append(messagePattern, previous, patternLength);
}
/**
* Replace placeholders in the given messagePattern with arguments.
*
* @param buffer the buffer to write the formatted message into
* @param messagePattern the message pattern containing placeholders.
* @param arguments the arguments to be used to replace placeholders.
*/
static void formatMessage(final StringBuilder buffer, final String messagePattern,
final Object[] arguments, final int argCount) {
if (messagePattern == null || arguments == null || argCount == 0) {
buffer.append(messagePattern);
return;
}
int escapeCounter = 0;
int currentArgument = 0;
int i = 0;
final int len = messagePattern.length();
for (; i < len - 1; i++) { // last char is excluded from the loop
final char curChar = messagePattern.charAt(i);
if (curChar == ESCAPE_CHAR) {
escapeCounter++;
} else {
if (isDelimPair(curChar, messagePattern, i)) { // looks ahead one char
i++;
// write escaped escape chars
writeEscapedEscapeChars(escapeCounter, buffer);
if (isOdd(escapeCounter)) {
// i.e. escaped: write escaped escape chars
writeDelimPair(buffer);
} else {
// unescaped
writeArgOrDelimPair(arguments, argCount, currentArgument, buffer);
currentArgument++;
}
} else {
handleLiteralChar(buffer, escapeCounter, curChar);
}
escapeCounter = 0;
}
}
handleRemainingCharIfAny(messagePattern, len, buffer, escapeCounter, i);
}
/**
* Returns {@code true} if the specified char and the char at {@code curCharIndex + 1} in the specified message
* pattern together form a "{}" delimiter pair, returns {@code false} otherwise.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 22 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static boolean isDelimPair(final char curChar, final String messagePattern, final int curCharIndex) {
return curChar == DELIM_START && messagePattern.charAt(curCharIndex + 1) == DELIM_STOP;
}
/**
* Detects whether the message pattern has been fully processed or if an unprocessed character remains and processes
* it if necessary, returning the resulting position in the result char array.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 28 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void handleRemainingCharIfAny(final String messagePattern, final int len,
final StringBuilder buffer, final int escapeCounter, final int i) {
if (i == len - 1) {
final char curChar = messagePattern.charAt(i);
handleLastChar(buffer, escapeCounter, curChar);
}
}
/**
* Processes the last unprocessed character and returns the resulting position in the result char array.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 28 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void handleLastChar(final StringBuilder buffer, final int escapeCounter, final char curChar) {
if (curChar == ESCAPE_CHAR) {
writeUnescapedEscapeChars(escapeCounter + 1, buffer);
} else {
handleLiteralChar(buffer, escapeCounter, curChar);
}
}
/**
* Processes a literal char (neither an '\' escape char nor a "{}" delimiter pair) and returns the resulting
* position.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 16 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void handleLiteralChar(final StringBuilder buffer, final int escapeCounter, final char curChar) {
// any other char beside ESCAPE or DELIM_START/STOP-combo
// write unescaped escape chars
writeUnescapedEscapeChars(escapeCounter, buffer);
buffer.append(curChar);
}
/**
* Writes "{}" to the specified result array at the specified position and returns the resulting position.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 18 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void writeDelimPair(final StringBuilder buffer) {
buffer.append(DELIM_START);
buffer.append(DELIM_STOP);
}
/**
* Returns {@code true} if the specified parameter is odd.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 11 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static boolean isOdd(final int number) {
return (number & 1) == 1;
}
/**
* Writes a '\' char to the specified result array (starting at the specified position) for each <em>pair</em> of
* '\' escape chars encountered in the message format and returns the resulting position.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 11 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void writeEscapedEscapeChars(final int escapeCounter, final StringBuilder buffer) {
final int escapedEscapes = escapeCounter >> 1; // divide by two
writeUnescapedEscapeChars(escapedEscapes, buffer);
}
/**
* Writes the specified number of '\' chars to the specified result array (starting at the specified position) and
* returns the resulting position.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 20 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void writeUnescapedEscapeChars(int escapeCounter, final StringBuilder buffer) {
while (escapeCounter > 0) {
buffer.append(ESCAPE_CHAR);
escapeCounter--;
}
}
/**
* Appends the argument at the specified argument index (or, if no such argument exists, the "{}" delimiter pair) to
* the specified result char array at the specified position and returns the resulting position.
*/
// Profiling showed this method is important to log4j performance. Modify with care!
// 25 bytes (allows immediate JVM inlining: < 35 bytes) LOG4J2-1096
private static void writeArgOrDelimPair(final Object[] arguments, final int argCount, final int currentArgument,
final StringBuilder buffer) {
if (currentArgument < argCount) {
recursiveDeepToString(arguments[currentArgument], buffer);
} else {
writeDelimPair(buffer);
}
}
/**
* This method performs a deep toString of the given Object.
* Primitive arrays are converted using their respective Arrays.toString methods while
* special handling is implemented for "container types", i.e. Object[], Map and Collection because those could
* contain themselves.
* <p>
* It should be noted that neither AbstractMap.toString() nor AbstractCollection.toString() implement such a
* behavior. They only check if the container is directly contained in itself, but not if a contained container
* contains the original one. Because of that, Arrays.toString(Object[]) isn't safe either.
* Confusing? Just read the last paragraph again and check the respective toString() implementation.
* </p>
* <p>
* This means, in effect, that logging would produce a usable output even if an ordinary System.out.println(o)
* would produce a relatively hard-to-debug StackOverflowError.
* </p>
* @param o The object.
* @return The String representation.
*/
static String deepToString(final Object o) {
if (o == null) {
return null;
}
// Check special types to avoid unnecessary StringBuilder usage
if (o instanceof String) {
return (String) o;
}
if (o instanceof Integer) {
return Integer.toString((Integer) o);
}
if (o instanceof Long) {
return Long.toString((Long) o);
}
if (o instanceof Double) {
return Double.toString((Double) o);
}
if (o instanceof Boolean) {
return Boolean.toString((Boolean) o);
}
if (o instanceof Character) {
return Character.toString((Character) o);
}
if (o instanceof Short) {
return Short.toString((Short) o);
}
if (o instanceof Float) {
return Float.toString((Float) o);
}
if (o instanceof Byte) {
return Byte.toString((Byte) o);
}
final StringBuilder str = new StringBuilder();
recursiveDeepToString(o, str);
return str.toString();
}
/**
* This method performs a deep {@code toString()} of the given {@code Object}.
* <p>
* Primitive arrays are converted using their respective {@code Arrays.toString()} methods, while
* special handling is implemented for <i>container types</i>, i.e. {@code Object[]}, {@code Map} and {@code Collection},
* because those could contain themselves.
* <p>
* It should be noted that neither {@code AbstractMap.toString()} nor {@code AbstractCollection.toString()} implement such a behavior.
* They only check if the container is directly contained in itself, but not if a contained container contains the original one.
* Because of that, {@code Arrays.toString(Object[])} isn't safe either.
* Confusing? Just read the last paragraph again and check the respective {@code toString()} implementation.
* <p>
* This means, in effect, that logging would produce a usable output even if an ordinary {@code System.out.println(o)}
* would produce a relatively hard-to-debug {@code StackOverflowError}.
*
* @param o the {@code Object} to convert into a {@code String}
* @param str the {@code StringBuilder} that {@code o} will be appended to
*/
static void recursiveDeepToString(final Object o, final StringBuilder str) {
recursiveDeepToString(o, str, null);
}
/**
* This method performs a deep {@code toString()} of the given {@code Object}.
* <p>
* Primitive arrays are converted using their respective {@code Arrays.toString()} methods, while
* special handling is implemented for <i>container types</i>, i.e. {@code Object[]}, {@code Map} and {@code Collection},
* because those could contain themselves.
* <p>
* {@code dejaVu} is used in case of those container types to prevent an endless recursion.
* <p>
* It should be noted that neither {@code AbstractMap.toString()} nor {@code AbstractCollection.toString()} implement such a behavior.
* They only check if the container is directly contained in itself, but not if a contained container contains the original one.
* Because of that, {@code Arrays.toString(Object[])} isn't safe either.
* Confusing? Just read the last paragraph again and check the respective {@code toString()} implementation.
* <p>
* This means, in effect, that logging would produce a usable output even if an ordinary {@code System.out.println(o)}
* would produce a relatively hard-to-debug {@code StackOverflowError}.
*
* @param o the {@code Object} to convert into a {@code String}
* @param str the {@code StringBuilder} that {@code o} will be appended to
* @param dejaVu a set of container objects directly or transitively containing {@code o}
*/
private static void recursiveDeepToString(final Object o, final StringBuilder str, final Set<Object> dejaVu) {
if (appendSpecialTypes(o, str)) {
return;
}
if (isMaybeRecursive(o)) {
appendPotentiallyRecursiveValue(o, str, dejaVu);
} else {
tryObjectToString(o, str);
}
}
private static boolean appendSpecialTypes(final Object o, final StringBuilder str) {
return StringBuilders.appendSpecificTypes(str, o) || appendDate(o, str);
}
private static boolean appendDate(final Object o, final StringBuilder str) {
if (!(o instanceof Date)) {
return false;
}
final Date date = (Date) o;
final SimpleDateFormat format = SIMPLE_DATE_FORMAT_REF.get();
str.append(format.format(date));
return true;
}
/**
* Returns {@code true} if the specified object is an array, a Map or a Collection.
*/
private static boolean isMaybeRecursive(final Object o) {
return o.getClass().isArray() || o instanceof Map || o instanceof Collection;
}
private static void appendPotentiallyRecursiveValue(
final Object o,
final StringBuilder str,
final Set<Object> dejaVu) {
final Class<?> oClass = o.getClass();
if (oClass.isArray()) {
appendArray(o, str, dejaVu, oClass);
} else if (o instanceof Map) {
appendMap(o, str, dejaVu);
} else if (o instanceof Collection) {
appendCollection(o, str, dejaVu);
} else {
throw new IllegalArgumentException("was expecting a container, found " + oClass);
}
}
private static void appendArray(
final Object o,
final StringBuilder str,
final Set<Object> dejaVu,
final Class<?> oClass) {
if (oClass == byte[].class) {
str.append(Arrays.toString((byte[]) o));
} else if (oClass == short[].class) {
str.append(Arrays.toString((short[]) o));
} else if (oClass == int[].class) {
str.append(Arrays.toString((int[]) o));
} else if (oClass == long[].class) {
str.append(Arrays.toString((long[]) o));
} else if (oClass == float[].class) {
str.append(Arrays.toString((float[]) o));
} else if (oClass == double[].class) {
str.append(Arrays.toString((double[]) o));
} else if (oClass == boolean[].class) {
str.append(Arrays.toString((boolean[]) o));
} else if (oClass == char[].class) {
str.append(Arrays.toString((char[]) o));
} else {
// special handling of container Object[]
final Set<Object> effectiveDejaVu = getOrCreateDejaVu(dejaVu);
final boolean seen = !effectiveDejaVu.add(o);
if (seen) {
final String id = identityToString(o);
str.append(RECURSION_PREFIX).append(id).append(RECURSION_SUFFIX);
} else {
final Object[] oArray = (Object[]) o;
str.append('[');
boolean first = true;
for (final Object current : oArray) {
if (first) {
first = false;
} else {
str.append(", ");
}
recursiveDeepToString(current, str, cloneDejaVu(effectiveDejaVu));
}
str.append(']');
}
}
}
/**
* Specialized handler for {@link Map}s.
*/
private static void appendMap(
final Object o,
final StringBuilder str,
final Set<Object> dejaVu) {
final Set<Object> effectiveDejaVu = getOrCreateDejaVu(dejaVu);
final boolean seen = !effectiveDejaVu.add(o);
if (seen) {
final String id = identityToString(o);
str.append(RECURSION_PREFIX).append(id).append(RECURSION_SUFFIX);
} else {
final Map<?, ?> oMap = (Map<?, ?>) o;
str.append('{');
boolean isFirst = true;
for (final Object o1 : oMap.entrySet()) {
final Map.Entry<?, ?> current = (Map.Entry<?, ?>) o1;
if (isFirst) {
isFirst = false;
} else {
str.append(", ");
}
final Object key = current.getKey();
final Object value = current.getValue();
recursiveDeepToString(key, str, cloneDejaVu(effectiveDejaVu));
str.append('=');
recursiveDeepToString(value, str, cloneDejaVu(effectiveDejaVu));
}
str.append('}');
}
}
/**
* Specialized handler for {@link Collection}s.
*/
private static void appendCollection(
final Object o,
final StringBuilder str,
final Set<Object> dejaVu) {
final Set<Object> effectiveDejaVu = getOrCreateDejaVu(dejaVu);
final boolean seen = !effectiveDejaVu.add(o);
if (seen) {
final String id = identityToString(o);
str.append(RECURSION_PREFIX).append(id).append(RECURSION_SUFFIX);
} else {
final Collection<?> oCol = (Collection<?>) o;
str.append('[');
boolean isFirst = true;
for (final Object anOCol : oCol) {
if (isFirst) {
isFirst = false;
} else {
str.append(", ");
}
recursiveDeepToString(anOCol, str, cloneDejaVu(effectiveDejaVu));
}
str.append(']');
}
}
private static Set<Object> getOrCreateDejaVu(Set<Object> dejaVu) {
return dejaVu == null
? createDejaVu()
: dejaVu;
}
private static Set<Object> createDejaVu() {
return Collections.newSetFromMap(new IdentityHashMap<>());
}
private static Set<Object> cloneDejaVu(Set<Object> dejaVu) {
Set<Object> clonedDejaVu = createDejaVu();
clonedDejaVu.addAll(dejaVu);
return clonedDejaVu;
}
private static void tryObjectToString(final Object o, final StringBuilder str) {
// it's just some other Object, we can only use toString().
try {
str.append(o.toString());
} catch (final Throwable t) {
handleErrorInObjectToString(o, str, t);
}
}
private static void handleErrorInObjectToString(final Object o, final StringBuilder str, final Throwable t) {
str.append(ERROR_PREFIX);
str.append(identityToString(o));
str.append(ERROR_SEPARATOR);
final String msg = t.getMessage();
final String className = t.getClass().getName();
str.append(className);
if (!className.equals(msg)) {
str.append(ERROR_MSG_SEPARATOR);
str.append(msg);
}
str.append(ERROR_SUFFIX);
}
/**
* This method returns the same as if Object.toString() would not have been
* overridden in obj.
* <p>
* Note that this isn't 100% secure as collisions can always happen with hash codes.
* </p>
* <p>
* Copied from Object.hashCode():
* </p>
* <blockquote>
* As much as is reasonably practical, the hashCode method defined by
* class {@code Object} does return distinct integers for distinct
* objects. (This is typically implemented by converting the internal
* address of the object into an integer, but this implementation
* technique is not required by the Java™ programming language.)
* </blockquote>
*
* @param obj the Object that is to be converted into an identity string.
* @return the identity string as also defined in Object.toString()
*/
static String identityToString(final Object obj) {
if (obj == null) {
return null;
}
return obj.getClass().getName() + '@' + Integer.toHexString(System.identityHashCode(obj));
}
}
⏎ org/apache/logging/log4j/message/ParameterFormatter.java
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