src/java/org/apache/log4j/spi/LocationInfo.java

/*
 * ============================================================================
 *                   The Apache Software License, Version 1.1
 * ============================================================================
 *
 *    Copyright (C) 1999 The Apache Software Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of  source code must  retain the above copyright  notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include  the following  acknowledgment:  "This product includes  software
 *    developed  by the  Apache Software Foundation  (http://www.apache.org/)."
 *    Alternately, this  acknowledgment may  appear in the software itself,  if
 *    and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "log4j" and  "Apache Software Foundation"  must not be used to
 *    endorse  or promote  products derived  from this  software without  prior
 *    written permission. For written permission, please contact
 *    apache@apache.org.
 *
 * 5. Products  derived from this software may not  be called "Apache", nor may
 *    "Apache" appear  in their name,  without prior written permission  of the
 *    Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
 * APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLU-
 * DING, BUT NOT LIMITED TO, PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND ON
 * ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR TORT
 * (INCLUDING  NEGLIGENCE OR  OTHERWISE) ARISING IN  ANY WAY OUT OF THE  USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software  consists of voluntary contributions made  by many individuals
 * on  behalf of the Apache Software  Foundation.  For more  information on the
 * Apache Software Foundation, please see <http://www.apache.org/>.
 *
 */


// Contributors: Mathias Rupprecht <mmathias.rupprecht@fja.com>
package org.apache.log4j.spi;

import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;

import java.io.PrintWriter;
import java.io.StringWriter;


/**
   The internal representation of caller location information.

   @since 0.8.3
*/
public class LocationInfo implements java.io.Serializable {
  private static StringWriter sw = new StringWriter();
  private static PrintWriter pw = new PrintWriter(sw);

  /**
     When location information is not available the constant
     <code>NA</code> is returned. Current value of this string
     constant is <b>?</b>.  */
  public static final String NA = "?";
  static final long serialVersionUID = -1325822038990805636L;

  // Check if we are running in IBM's visual age.
  static boolean inVisualAge = false;

  static {
    try {
      Class dummy = Class.forName("com.ibm.uvm.tools.DebugSupport");
      inVisualAge = true;
      LogLog.debug("Detected IBM VisualAge environment.");
    } catch (Throwable e) {
      ; // nothing to do
    }
  }

  /**
     Caller's line number.
  */
  transient String lineNumber;

  /**
     Caller's file name.
  */
  transient String fileName;

  /**
     Caller's fully qualified class name.
  */
  transient String className;

  /**
     Caller's method name.
  */
  transient String methodName;

  /**
     All available caller information, in the format
     <code>fully.qualified.classname.of.caller.methodName(Filename.java:line)</code>
    */
  public String fullInfo;
  private boolean locationInfoAvailable;

  public LocationInfo(
    String fileName, String className, String methodName, String lineNumber) {
    locationInfoAvailable = true;
    this.fileName = fileName;
    this.className = className;
    this.methodName = methodName;
    this.lineNumber = lineNumber;
  }

  /**
     Instantiate location information based on a Throwable. We
     expect the Throwable <code>t</code>, to be in the format

       <pre>
        java.lang.Throwable
        ...
          at org.apache.log4j.PatternLayout.format(PatternLayout.java:413)
          at org.apache.log4j.FileAppender.doAppend(FileAppender.java:183)
        at org.apache.log4j.Category.callAppenders(Category.java:131)
        at org.apache.log4j.Category.log(Category.java:512)
        at callers.fully.qualified.className.methodName(FileName.java:74)
        ...
       </pre>

       <p>However, we can also deal with JIT compilers that "lose" the
       location information, especially between the parentheses.

    */
  public LocationInfo(Throwable t, String fqnOfCallingClass) {
    if (t == null) {
      return;
    }

    String s;

    // Protect against multiple access to sw.
    synchronized (sw) {
      t.printStackTrace(pw);
      s = sw.toString();
      sw.getBuffer().setLength(0);
    }

    //System.out.println("s is ["+s+"].");
    int ibegin;

    //System.out.println("s is ["+s+"].");
    int iend;

    // Given the current structure of the package, the line
    // containing "org.apache.log4j.Category." should be printed just
    // before the caller.
    // This method of searching may not be fastest but it's safer
    // than counting the stack depth which is not guaranteed to be
    // constant across JVM implementations.
    ibegin = s.lastIndexOf(fqnOfCallingClass);

    if (ibegin == -1) {
      return;
    }

    ibegin = s.indexOf(Layout.LINE_SEP, ibegin);

    if (ibegin == -1) {
      return;
    }

    ibegin += Layout.LINE_SEP_LEN;

    // determine end of line
    iend = s.indexOf(Layout.LINE_SEP, ibegin);

    if (iend == -1) {
      return;
    }

    // VA has a different stack trace format which doesn't
    // need to skip the inital 'at'
    if (!inVisualAge) {
      // back up to first blank character
      ibegin = s.lastIndexOf("at ", iend);

      if (ibegin == -1) {
        return;
      }

      // Add 3 to skip "at ";
      ibegin += 3;
    }

    // everything between is the requested stack item
    this.fullInfo = s.substring(ibegin, iend);
    
    locationInfoAvailable = true;
  }

  /**
     Return the fully qualified class name of the caller making the
     logging request.
  */
  public String getClassName() {
    if (!locationInfoAvailable) {
      return NA;
    }

    if (className == null) {
      // Starting the search from '(' is safer because there is
      // potentially a dot between the parentheses.
      int iend = fullInfo.lastIndexOf('(');

      if (iend == -1) {
        className = NA;
      } else {
        iend = fullInfo.lastIndexOf('.', iend);

        // This is because a stack trace in VisualAge looks like:
        //java.lang.RuntimeException
        //  java.lang.Throwable()
        //  java.lang.Exception()
        //  java.lang.RuntimeException()
        //  void test.test.B.print()
        //  void test.test.A.printIndirect()
        //  void test.test.Run.main(java.lang.String [])
        int ibegin = 0;

        if (inVisualAge) {
          ibegin = fullInfo.lastIndexOf(' ', iend) + 1;
        }

        if (iend == -1) {
          className = NA;
        } else {
          className = this.fullInfo.substring(ibegin, iend);
        }
      }
    }

    return className;
  }

  /**
     Return the file name of the caller.

     <p>This information is not always available.
  */
  public String getFileName() {
    if (!locationInfoAvailable) {
      return NA;
    }

    if (fileName == null) {
      int iend = fullInfo.lastIndexOf(':');

      if (iend == -1) {
        fileName = NA;
      } else {
        int ibegin = fullInfo.lastIndexOf('(', iend - 1);
        fileName = this.fullInfo.substring(ibegin + 1, iend);
      }
    }

    return fileName;
  }

  /**
     Returns the line number of the caller.

     <p>This information is not always available.
  */
  public String getLineNumber() {
    if (!locationInfoAvailable) {
      return NA;
    }

    if (lineNumber == null) {
      int iend = fullInfo.lastIndexOf(')');
      int ibegin = fullInfo.lastIndexOf(':', iend - 1);

      if (ibegin == -1) {
        lineNumber = NA;
      } else {
        lineNumber = this.fullInfo.substring(ibegin + 1, iend);
      }
    }

    return lineNumber;
  }

  /**
     Returns the method name of the caller.
  */
  public String getMethodName() {
    if (!locationInfoAvailable) {
      return NA;
    }

    if (methodName == null) {
      int iend = fullInfo.lastIndexOf('(');
      int ibegin = fullInfo.lastIndexOf('.', iend);

      if (ibegin == -1) {
        methodName = NA;
      } else {
        methodName = this.fullInfo.substring(ibegin + 1, iend);
      }
    }

    return methodName;
  }
}