Logger.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.spi.LoggingEvent;
import ch.qos.logback.classic.util.LoggerNameUtil;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.spi.AppenderAttachable;
import ch.qos.logback.core.spi.AppenderAttachableImpl;
import ch.qos.logback.core.spi.FilterReply;
import org.slf4j.LoggerFactory;
import org.slf4j.Marker;
import org.slf4j.spi.LocationAwareLogger;

import java.io.ObjectStreamException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

public final class Logger implements org.slf4j.Logger, LocationAwareLogger,
    AppenderAttachable<ILoggingEvent>, Serializable {

  private static final long serialVersionUID = 5454405123156820674L; //8745934908040027998L;

  /**
   * The fully qualified name of this class. Used in gathering caller
   * information.
   */
  public static final String FQCN = ch.qos.logback.classic.Logger.class
      .getName();

  /**
   * The name of this logger
   */
  private String name;

  // The assigned levelInt of this logger. Can be null.
  transient private Level level;

  // The effective levelInt is the assigned levelInt and if null, a levelInt is
  // inherited form a parent.
  transient private int effectiveLevelInt;

  /**
   * The parent of this category. All categories have at least one ancestor
   * which is the root category.
   */
  transient private Logger parent;

  /**
   * The children of this logger. A logger may have zero or more children.
   */
  transient private List<Logger> childrenList;

  /**
   * It is assumed that once the 'aai' variable is set to a non-null value, it
   * will never be reset to null. it is further assumed that only place where
   * the 'aai'ariable is set is within the addAppender method. This method is
   * synchronized on 'this' (Logger) protecting against simultaneous
   * re-configuration of this logger (a very unlikely scenario).
   *
   * <p>
   * It is further assumed that the AppenderAttachableImpl is responsible for
   * its internal synchronization and thread safety. Thus, we can get away with
   * *not* synchronizing on the 'aai' (check null/ read) because
   * <p>
   * 1) the 'aai' variable is immutable once set to non-null
   * <p>
   * 2) 'aai' is getAndSet only within addAppender which is synchronized
   * <p>
   * 3) all the other methods check whether 'aai' is null
   * <p>
   * 4) AppenderAttachableImpl is thread safe
   */
  transient private AppenderAttachableImpl<ILoggingEvent> aai;
  /**
   * Additivity is set to true by default, that is children inherit the
   * appenders of their ancestors by default. If this variable is set to
   * <code>false</code> then the appenders located in the ancestors of this
   * logger will not be used. However, the children of this logger will inherit
   * its appenders, unless the children have their additivity flag set to
   * <code>false</code> too. See the user manual for more details.
   */
  transient private boolean additive = true;

  final transient LoggerContext loggerContext;

  Logger(String name, Logger parent, LoggerContext loggerContext) {
    this.name = name;
    this.parent = parent;
    this.loggerContext = loggerContext;
  }

  public Level getEffectiveLevel() {
    return Level.toLevel(effectiveLevelInt);
  }

  int getEffectiveLevelInt() {
    return effectiveLevelInt;
  }

  public Level getLevel() {
    return level;
  }

  public String getName() {
    return name;
  }

  private boolean isRootLogger() {
    // only the root logger has a null parent
    return parent == null;
  }

  Logger getChildByName(final String childName) {
    if (childrenList == null) {
      return null;
    } else {
      int len = this.childrenList.size();
      for (int i = 0; i < len; i++) {
        final Logger childLogger_i = (Logger) childrenList.get(i);
        final String childName_i = childLogger_i.getName();

        if (childName.equals(childName_i)) {
          return childLogger_i;
        }
      }
      // no child found
      return null;
    }
  }

  public synchronized void setLevel(Level newLevel) {
    if (level == newLevel) {
      // nothing to do;
      return;
    }
    if (newLevel == null && isRootLogger()) {
      throw new IllegalArgumentException(
          "The level of the root logger cannot be set to null");
    }

    level = newLevel;
    if (newLevel == null) {
      effectiveLevelInt = parent.effectiveLevelInt;
      newLevel = parent.getEffectiveLevel();
    } else {
      effectiveLevelInt = newLevel.levelInt;
    }

    if (childrenList != null) {
      int len = childrenList.size();
      for (int i = 0; i < len; i++) {
        Logger child = (Logger) childrenList.get(i);
        // tell child to handle parent levelInt change
        child.handleParentLevelChange(effectiveLevelInt);
      }
    }
    // inform listeners
    loggerContext.fireOnLevelChange(this, newLevel);
  }

  /**
   * This method is invoked by parent logger to let this logger know that the
   * prent's levelInt changed.
   *
   * @param newParentLevelInt
   */
  private synchronized void handleParentLevelChange(int newParentLevelInt) {
    // changes in the parent levelInt affect children only if their levelInt is
    // null
    if (level == null) {
      effectiveLevelInt = newParentLevelInt;

      // propagate the parent levelInt change to this logger's children
      if (childrenList != null) {
        int len = childrenList.size();
        for (int i = 0; i < len; i++) {
          Logger child = (Logger) childrenList.get(i);
          child.handleParentLevelChange(newParentLevelInt);
        }
      }
    }
  }

  /**
   * Remove all previously added appenders from this logger instance.
   * <p>
   * This is useful when re-reading configuration information.
   */
  public void detachAndStopAllAppenders() {
    if (aai != null) {
      aai.detachAndStopAllAppenders();
    }
  }

  public boolean detachAppender(String name) {
    if (aai == null) {
      return false;
    }
    return aai.detachAppender(name);
  }

  // this method MUST be synchronized. See comments on 'aai' field for further
  // details.
  public synchronized void addAppender(Appender<ILoggingEvent> newAppender) {
    if (aai == null) {
      aai = new AppenderAttachableImpl<ILoggingEvent>();
    }
    aai.addAppender(newAppender);
  }

  public boolean isAttached(Appender<ILoggingEvent> appender) {
    if (aai == null) {
      return false;
    }
    return aai.isAttached(appender);
  }

  @SuppressWarnings("unchecked")
  public Iterator<Appender<ILoggingEvent>> iteratorForAppenders() {
    if (aai == null) {
      return Collections.EMPTY_LIST.iterator();
    }
    return aai.iteratorForAppenders();
  }

  public Appender<ILoggingEvent> getAppender(String name) {
    if (aai == null) {
      return null;
    }
    return aai.getAppender(name);
  }

  /**
   * Invoke all the appenders of this logger.
   *
   * @param event
   *          The event to log
   */
  public void callAppenders(ILoggingEvent event) {
    int writes = 0;
    for (Logger l = this; l != null; l = l.parent) {
      writes += l.appendLoopOnAppenders(event);
      if (!l.additive) {
        break;
      }
    }
    // No appenders in hierarchy
    if (writes == 0) {
      loggerContext.noAppenderDefinedWarning(this);
    }
  }

  private int appendLoopOnAppenders(ILoggingEvent event) {
    if (aai != null) {
      return aai.appendLoopOnAppenders(event);
    } else {
      return 0;
    }
  }

  /**
   * Remove the appender passed as parameter form the list of appenders.
   */
  public boolean detachAppender(Appender<ILoggingEvent> appender) {
    if (aai == null) {
      return false;
    }
    return aai.detachAppender(appender);
  }



  /**
   * Create a child of this logger by suffix, that is, the part of the name
   * extending this logger. For example, if this logger is named "x.y" and the
   * lastPart is "z", then the created child logger will be named "x.y.z".
   *
   * <p>
   * IMPORTANT: Calls to this method must be within a synchronized block on this
   * logger.
   *
   * @param lastPart
   *          the suffix (i.e. last part) of the child logger name. This
   *          parameter may not include dots, i.e. the logger separator
   *          character.
   * @return
   */
  Logger createChildByLastNamePart(final String lastPart) {
    int i_index = LoggerNameUtil.getFirstSeparatorIndexOf(lastPart);
    if (i_index != -1) {
      throw new IllegalArgumentException("Child name [" + lastPart
          + " passed as parameter, may not include [" + CoreConstants.DOT + "]");
    }

    if (childrenList == null) {
      childrenList = new ArrayList<Logger>();
    }
    Logger childLogger;
    if (this.isRootLogger()) {
      childLogger = new Logger(lastPart, this, this.loggerContext);
    } else {
      childLogger = new Logger(name + CoreConstants.DOT + lastPart, this,
          this.loggerContext);
    }
    childrenList.add(childLogger);
    childLogger.effectiveLevelInt = this.effectiveLevelInt;
    return childLogger;
  }

  private void localLevelReset() {
    effectiveLevelInt = Level.DEBUG_INT;
    if (isRootLogger()) {
      level = Level.DEBUG;
    } else {
      level = null;
    }
  }

  void recursiveReset() {
    detachAndStopAllAppenders();
    localLevelReset();
    additive = true;
    if (childrenList == null) {
      return;
    }
    for (Logger childLogger : new CopyOnWriteArrayList<Logger>(childrenList)) {
      childLogger.recursiveReset();
    }
  }

  /**
   * The default size of child list arrays. The JDK 1.5 default is 10. We use a
   * smaller value to save a little space.
   */
  private static final int DEFAULT_CHILD_ARRAY_SIZE = 5;

  Logger createChildByName(final String childName) {
    int i_index = LoggerNameUtil.getSeparatorIndexOf(childName, this.name.length() + 1);
    if (i_index != -1) {
      throw new IllegalArgumentException("For logger [" + this.name
          + "] child name [" + childName
          + " passed as parameter, may not include '.' after index"
          + (this.name.length() + 1));
    }

    if (childrenList == null) {
      childrenList = new ArrayList<Logger>(DEFAULT_CHILD_ARRAY_SIZE);
    }
    Logger childLogger;
    childLogger = new Logger(childName, this, this.loggerContext);
    childrenList.add(childLogger);
    childLogger.effectiveLevelInt = this.effectiveLevelInt;
    return childLogger;
  }

  /**
   * The next methods are not merged into one because of the time we gain by not
   * creating a new Object[] with the params. This reduces the cost of not
   * logging by about 20 nanoseconds.
   */

  private void filterAndLog_0_Or3Plus(final String localFQCN,
      final Marker marker, final Level level, final String msg,
      final Object[] params, final Throwable t) {

    final FilterReply decision = loggerContext
        .getTurboFilterChainDecision_0_3OrMore(marker, this, level, msg,
            params, t);

    if (decision == FilterReply.NEUTRAL) {
      if (effectiveLevelInt > level.levelInt) {
        return;
      }
    } else if (decision == FilterReply.DENY) {
      return;
    }

    buildLoggingEventAndAppend(localFQCN, marker, level, msg, params, t);
  }

  private void filterAndLog_1(final String localFQCN,
      final Marker marker, final Level level, final String msg,
      final Object param, final Throwable t) {

    final FilterReply decision = loggerContext.getTurboFilterChainDecision_1(
        marker, this, level, msg, param, t);

    if (decision == FilterReply.NEUTRAL) {
      if (effectiveLevelInt > level.levelInt) {
        return;
      }
    } else if (decision == FilterReply.DENY) {
      return;
    }

    buildLoggingEventAndAppend(localFQCN, marker, level, msg,
        new Object[] { param }, t);
  }

  private void filterAndLog_2(final String localFQCN,
      final Marker marker, final Level level, final String msg,
      final Object param1, final Object param2, final Throwable t) {

    final FilterReply decision = loggerContext.getTurboFilterChainDecision_2(
        marker, this, level, msg, param1, param2, t);

    if (decision == FilterReply.NEUTRAL) {
      if (effectiveLevelInt > level.levelInt) {
        return;
      }
    } else if (decision == FilterReply.DENY) {
      return;
    }

    buildLoggingEventAndAppend(localFQCN, marker, level, msg, new Object[] {
        param1, param2 }, t);
  }

  private void buildLoggingEventAndAppend(final String localFQCN,
      final Marker marker, final Level level, final String msg,
      final Object[] params, final Throwable t) {
    LoggingEvent le = new LoggingEvent(localFQCN, this, level, msg, t, params);
    le.setMarker(marker);
    callAppenders(le);
  }

  public void trace(String msg) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.TRACE, msg, null, null);
  }

  public void trace(String format, Object arg) {
    filterAndLog_1(FQCN, null, Level.TRACE, format, arg, null);
  }

  public void trace(String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, null, Level.TRACE, format, arg1, arg2, null);
  }

  public void trace(String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.TRACE, format, argArray, null);
  }

  public void trace(String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.TRACE, msg, null, t);
  }

  public void trace(Marker marker, String msg) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.TRACE, msg, null, null);
  }

  public void trace(Marker marker, String format, Object arg) {
    filterAndLog_1(FQCN, marker, Level.TRACE, format, arg, null);
  }

  public void trace(Marker marker, String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, marker, Level.TRACE, format, arg1, arg2, null);
  }

  public void trace(Marker marker, String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.TRACE, format, argArray, null);
  }

  public void trace(Marker marker, String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.TRACE, msg, null, t);
  }

  public boolean isDebugEnabled() {
    return isDebugEnabled(null);
  }

  public boolean isDebugEnabled(Marker marker) {
    final FilterReply decision = callTurboFilters(marker, Level.DEBUG);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= Level.DEBUG_INT;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }
  }

  public void debug(String msg) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.DEBUG, msg, null, null);
  }

  public void debug(String format, Object arg) {
    filterAndLog_1(FQCN, null, Level.DEBUG, format, arg, null);
  }

  public void debug(String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, null, Level.DEBUG, format, arg1, arg2, null);
  }

  public void debug(String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.DEBUG, format, argArray, null);
  }

  public void debug(String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.DEBUG, msg, null, t);
  }

  public void debug(Marker marker, String msg) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.DEBUG, msg, null, null);
  }

  public void debug(Marker marker, String format, Object arg) {
    filterAndLog_1(FQCN, marker, Level.DEBUG, format, arg, null);
  }

  public void debug(Marker marker, String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, marker, Level.DEBUG, format, arg1, arg2, null);
  }

  public void debug(Marker marker, String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.DEBUG, format, argArray, null);
  }

  public void debug(Marker marker, String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.DEBUG, msg, null, t);
  }

  public void error(String msg) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.ERROR, msg, null, null);
  }

  public void error(String format, Object arg) {
    filterAndLog_1(FQCN, null, Level.ERROR, format, arg, null);
  }

  public void error(String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, null, Level.ERROR, format, arg1, arg2, null);
  }

  public void error(String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.ERROR, format, argArray, null);
  }

  public void error(String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.ERROR, msg, null, t);
  }

  public void error(Marker marker, String msg) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.ERROR, msg, null, null);
  }

  public void error(Marker marker, String format, Object arg) {
    filterAndLog_1(FQCN, marker, Level.ERROR, format, arg, null);
  }

  public void error(Marker marker, String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, marker, Level.ERROR, format, arg1, arg2, null);
  }

  public void error(Marker marker, String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.ERROR, format, argArray, null);
  }

  public void error(Marker marker, String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.ERROR, msg, null, t);
  }

  public boolean isInfoEnabled() {
    return isInfoEnabled(null);
  }

  public boolean isInfoEnabled(Marker marker) {
    FilterReply decision = callTurboFilters(marker, Level.INFO);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= Level.INFO_INT;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }
  }

  public void info(String msg) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.INFO, msg, null, null);
  }

  public void info(String format, Object arg) {
    filterAndLog_1(FQCN, null, Level.INFO, format, arg, null);
  }

  public void info(String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, null, Level.INFO, format, arg1, arg2, null);
  }

  public void info(String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.INFO, format, argArray, null);
  }

  public void info(String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.INFO, msg, null, t);
  }

  public void info(Marker marker, String msg) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.INFO, msg, null, null);
  }

  public void info(Marker marker, String format, Object arg) {
    filterAndLog_1(FQCN, marker, Level.INFO, format, arg, null);
  }

  public void info(Marker marker, String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, marker, Level.INFO, format, arg1, arg2, null);
  }

  public void info(Marker marker, String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.INFO, format, argArray, null);
  }

  public void info(Marker marker, String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.INFO, msg, null, t);
  }

  public boolean isTraceEnabled() {
    return isTraceEnabled(null);
  }

  public boolean isTraceEnabled(Marker marker) {
    final FilterReply decision = callTurboFilters(marker, Level.TRACE);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= Level.TRACE_INT;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }
  }

  public boolean isErrorEnabled() {
    return isErrorEnabled(null);
  }

  public boolean isErrorEnabled(Marker marker) {
    FilterReply decision = callTurboFilters(marker, Level.ERROR);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= Level.ERROR_INT;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }
  }

  public boolean isWarnEnabled() {
    return isWarnEnabled(null);
  }

  public boolean isWarnEnabled(Marker marker) {
    FilterReply decision = callTurboFilters(marker, Level.WARN);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= Level.WARN_INT;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }

  }

  public boolean isEnabledFor(Marker marker, Level level) {
    FilterReply decision = callTurboFilters(marker, level);
    if (decision == FilterReply.NEUTRAL) {
      return effectiveLevelInt <= level.levelInt;
    } else if (decision == FilterReply.DENY) {
      return false;
    } else if (decision == FilterReply.ACCEPT) {
      return true;
    } else {
      throw new IllegalStateException("Unknown FilterReply value: " + decision);
    }
  }

  public boolean isEnabledFor(Level level) {
    return isEnabledFor(null, level);
  }

  public void warn(String msg) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.WARN, msg, null, null);
  }

  public void warn(String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.WARN, msg, null, t);
  }

  public void warn(String format, Object arg) {
    filterAndLog_1(FQCN, null, Level.WARN, format, arg, null);
  }

  public void warn(String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, null, Level.WARN, format, arg1, arg2, null);
  }

  public void warn(String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, null, Level.WARN, format, argArray, null);
  }

  public void warn(Marker marker, String msg) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.WARN, msg, null, null);
  }

  public void warn(Marker marker, String format, Object arg) {
    filterAndLog_1(FQCN, marker, Level.WARN, format, arg, null);
  }

  public void warn(Marker marker, String format, Object[] argArray) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.WARN, format, argArray, null);
  }

  public void warn(Marker marker, String format, Object arg1, Object arg2) {
    filterAndLog_2(FQCN, marker, Level.WARN, format, arg1, arg2, null);
  }

  public void warn(Marker marker, String msg, Throwable t) {
    filterAndLog_0_Or3Plus(FQCN, marker, Level.WARN, msg, null, t);
  }

  public boolean isAdditive() {
    return additive;
  }

  public void setAdditive(boolean additive) {
    this.additive = additive;
  }

  public String toString() {
    return "Logger[" + name + "]";
  }

  /**
   * Method that calls the attached TurboFilter objects based on the logger and
   * the level.
   *
   * It is used by isYYYEnabled() methods.
   *
   * It returns the typical FilterReply values: ACCEPT, NEUTRAL or DENY.
   *
   * @param level
   * @return the reply given by the TurboFilters
   */
  private FilterReply callTurboFilters(Marker marker, Level level) {
    return loggerContext.getTurboFilterChainDecision_0_3OrMore(marker, this,
        level, null, null, null);
  }

  /**
   * Return the context for this logger.
   *
   * @return the context
   */
  public LoggerContext getLoggerContext() {
    return loggerContext;
  }

  public void log(Marker marker, String fqcn, int levelInt, String message,
      Object[] argArray, Throwable t) {
    Level level = Level.fromLocationAwareLoggerInteger(levelInt);
    filterAndLog_0_Or3Plus(fqcn, marker, level, message, argArray, t);
  }

  /**
   * After serialization, the logger instance does not know its LoggerContext.
   * The best we can do here, is to return a logger with the same name
   * returned by org.slf4j.LoggerFactory.
   *
   * @return Logger instance with the same name
   * @throws ObjectStreamException
   */
  protected Object readResolve() throws ObjectStreamException {
    return LoggerFactory.getLogger(getName());
  }
}