Trace.java

/**
 * C-JDBC: Clustered JDBC.
 * Copyright (C) 2002-2004 French National Institute For Research In Computer
 * Science And Control (INRIA).
 * Contact: c-jdbc@objectweb.org
 * 
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation; either version 2.1 of the License, or any later
 * version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * Initial developer(s): Emmanuel Cecchet.
 * Contributor(s): __________________.
 */

package org.objectweb.cjdbc.common.log;

import org.apache.log4j.Logger;
import org.apache.log4j.Priority;

/**
 * This a wrapper to the log4j logging system. We provide additional features
 * to statically remove tracing.
 * 
 * @author <a href="mailto:Emmanuel.Cecchet@inria.fr">Emmanuel Cecchet</a>
 * @version 1.0
 */
public class Trace
{
  /** Log4j logger instance. */
  private Logger log4jLogger;

  /**
   * Creates a new <code>Trace</code> object from a given log4j <code>Logger</code>.
   * 
   * @param log4jLogger the log4j <code>Logger</code>
   */
  protected Trace(Logger log4jLogger)
  {
    this.log4jLogger = log4jLogger;
  }

  /**
   * Retrieves a logger by its name.
   * 
   * @param name logger name
   * @return trace a <code>Trace</code> instance
   */
  public static Trace getLogger(String name)
  {
    return LogManager.getLogger(name);
  }

  /**
   * Logs a message object with the <code>DEBUG</code> <code>Level</code>.
   * 
   * @param message the message object to log
   */
  public void debug(Object message)
  {
    log4jLogger.debug(message);
  }

  /**
   * Logs a message object with the <code>DEBUG</code> <code>Level</code>
   * including the stack trace of the {@link Throwable}<code>error</code>
   * passed as parameter.
   * 
   * @param message the message object to log
   * @param error the exception to log, including its stack trace
   */
  public void debug(Object message, Throwable error)
  {
    log4jLogger.debug(message, error);
  }

  /**
   * Logs a message object with the <code>ERROR</code> <code>Level</code>.
   * 
   * @param message the message object to log
   */
  public void error(Object message)
  {
    log4jLogger.error(message);
  }

  /**
   * Logs a message object with the <code>ERROR</code> <code>Level</code>
   * including the stack trace of the {@link Throwable}<code>error</code>
   * passed as parameter.
   * 
   * @param message the message object to log.
   * @param error the exception to log, including its stack trace.
   */
  public void error(Object message, Throwable error)
  {
    log4jLogger.error(message, error);
  }

  /**
   * Logs a message object with the <code>FATAL</code> <code>Level</code>.
   * 
   * @param message the message object to log.
   */
  public void fatal(Object message)
  {
    log4jLogger.fatal(message);
  }

  /**
   * Logs a message object with the <code>FATAL</code> <code>Level</code>
   * including the stack trace of the {@link Throwable}<code>error</code>
   * passed as parameter.
   * 
   * @param message the message object to log.
   * @param error the exception to log, including its stack trace.
   */
  public void fatal(Object message, Throwable error)
  {
    log4jLogger.fatal(message, error);
  }

  /**
   * Logs a message object with the <code>INFO</code> <code>Level</code>.
   * 
   * @param message the message object to log.
   */
  public void info(Object message)
  {
    log4jLogger.info(message);
  }

  /**
   * Logs a message object with the <code>INFO</code> <code>Level</code>
   * including the stack trace of the {@link Throwable}<code>error</code>
   * passed as parameter.
   * 
   * @param message the message object to log.
   * @param error the exception to log, including its stack trace.
   */
  public void info(Object message, Throwable error)
  {
    log4jLogger.info(message, error);
  }

  /**
   * Logs a message object with the <code>WARN</code> <code>Level</code>.
   * 
   * @param message the message object to log.
   */
  public void warn(Object message)
  {
    log4jLogger.warn(message);
  }

  /**
   * Logs a message object with the <code>WARN</code> <code>Level</code>
   * including the stack trace of the {@link Throwable}<code>error</code>
   * passed as parameter.
   * 
   * @param message the message object to log.
   * @param error the exception to log, including its stack trace.
   */
  public void warn(Object message, Throwable error)
  {
    log4jLogger.warn(message, error);
  }

  /**
   * Checks whether this category is enabled for the <code>DEBUG</code> <code>Level</code>.
   * 
   * <p>
   * This function is intended to lessen the computational cost of disabled log
   * debug statements.
   * 
   * <p>
   * For some <code>cat</code> Category object, when you write,
   * 
   * <pre>
   *  cat.debug("This is entry number: " + i );
   * </pre>
   * 
   * 
   * <p>
   * You incur the cost constructing the message, concatenatiion in this case,
   * regardless of whether the message is logged or not.
   * 
   * <p>
   * If you are worried about speed, then you should write
   * 
   * <pre>
   *  if(cat.isDebugEnabled()) { cat.debug("This is entry number: " + i ); }
   * </pre>
   * 
   * 
   * <p>
   * This way you will not incur the cost of parameter construction if
   * debugging is disabled for <code>cat</code>. On the other hand, if the
   * <code>cat</code> is debug enabled, you will incur the cost of evaluating
   * whether the category is debug enabled twice. Once in <code>isDebugEnabled</code>
   * and once in the <code>debug</code>. This is an insignificant overhead
   * since evaluating a category takes about 1%% of the time it takes to
   * actually log.
   * 
   * @return <code>true</code> if this category is debug enabled, <code>false</code>
   *         otherwise.
   */
  public boolean isDebugEnabled()
  {
    return log4jLogger.isDebugEnabled();
  }

  /**
   * Checks whether this category is enabled for the <code>INFO</code>
   * <code>Level</code>.
   * See also {@link #isDebugEnabled}.
   * 
   * @return <code>true</code> if this category is enabled for <code>Level</code> <code>INFO</code>,
   *         <code>false</code> otherwise.
   */
  public boolean isInfoEnabled()
  {
    return log4jLogger.isInfoEnabled();
  }

  /**
   * Checks whether this category is enabled for the <code>INFO</code> 
   * <code>Level</code>.
   * See also {@link #isDebugEnabled}.
   * 
   * @return <code>true</code> if this category is enabled for <code>INFO</code> <code>Level</code>,
   *         <code>false</code> otherwise.
   */
  public boolean isWarnEnabled()
  {
    return log4jLogger.isEnabledFor(Priority.WARN);
  }

  /**
   * Checks whether this category is enabled for the <code>INFO</code>
   * <code>Level</code>.
   * See also {@link #isDebugEnabled}.
   * 
   * @return <code>true</code> if this category is enabled for <code>INFO</code> <code>Level</code>,
   *         <code>false</code> otherwise.
   */
  public boolean isErrorEnabled()
  {
    return log4jLogger.isEnabledFor(Priority.ERROR);
  }

  /**
   * Checks whether this category is enabled for the <code>INFO</code> 
   * <code>Level</code>.
   * See also {@link #isDebugEnabled}.
   * 
   * @return <code>true</code> if this category is enabled for <code>INFO</code> <code>Level</code>,
   *         <code>false</code> otherwise.
   */
  public boolean isFatalEnabled()
  {
    return log4jLogger.isEnabledFor(Priority.FATAL);
  }
}

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