cvs commit: jakarta-avalon-logkit/src/java/org/apache/log/output AsyncLogTarget.java

[do...@apache.org]

donaldp     01/03/26 22:10:26

  Added:       src/java/org/apache/log/output AsyncLogTarget.java
  Log:
  First pass at async log target.
  
  Revision  Changes    Path
  1.1                  jakarta-avalon-logkit/src/java/org/apache/log/output/AsyncLogTarget.java
  
  Index: AsyncLogTarget.java
  ===================================================================
  /*
   * Copyright (C) The Apache Software Foundation. All rights reserved.
   *
   * This software is published under the terms of the Apache Software License
   * version 1.1, a copy of which has been included with this distribution in
   * the LICENSE file.
   */
  package org.apache.log.output;
  
  import java.util.LinkedList;
  import org.apache.log.LogEntry;
  import org.apache.log.LogTarget;
  
  /**
   * An asynchronous LogTarget that sends entries on in another thread.
   * It is the responsibility of the user of this class to start 
   * the thread etc.
   *
   * <pre>
   * LogTarget target = ...;
   * AsyncLogTarget asyncTarget = new AsyncLogTarget( target );
   * Thread thread = new Thread( asyncTarget );
   * thread.setPriority( Thread.MIN_PRIORITY );
   * thread.start();
   * LogKit.addLogTarget( "foo", asyncTarget );
   * </pre>
   *
   * @author <a href="mailto:donaldp@apache.org">Peter Donald</a>
   */
  public class AsyncLogTarget 
      implements LogTarget, Runnable
  {
      protected final LinkedList  m_list;
      protected final int         m_queueSize;  
      protected final LogTarget   m_logTarget;  
  
      public AsyncLogTarget( final LogTarget logTarget )
      {
          this( logTarget, 15 );
      }
  
      public AsyncLogTarget( final LogTarget logTarget, final int queueSize )
      {
          m_logTarget = logTarget;
          m_list = new LinkedList();
          m_queueSize = queueSize;
      }
  
      /**
       * Process a log entry by adding it to queue.
       *
       * @param entry the log entry
       */
      public void processEntry( final LogEntry entry )
      {
          synchronized( m_list )
          {
              final int size = m_list.size();
              while( m_queueSize <= size )
              {
                  try { m_list.wait(); }
                  catch( final InterruptedException ie )
                  {
                      //This really should not occur ...
                      //Maybe we should log it though for 
                      //now lets ignore it
                  }
              }
  
              m_list.addFirst( entry );
  
              if( size == 0 )
              {
                  //tell the "server" thread to wake up 
                  //if it is waiting for a queue to contain some items
                  m_list.notify();
              }
          }
      }
  
      public void run()
      {
          //set this variable when thread is interupted
          //so we know we can shutdown thread soon.
          boolean interupted = false;
  
          while( true )
          {
              LogEntry entry = null;
  
              synchronized( m_list )
              {
                  while( null == entry )
                  {
                      final int size = m_list.size();
  
                      if( size > 0 )
                      {
                          entry = (LogEntry)m_list.removeLast();
                          
                          if( size == m_queueSize )
                          {
                              //tell the "client" thread to wake up 
                              //if it is waiting for a queue position to open up
                              m_list.notify();
                          }
  
                      }
                      else if( interupted || Thread.interrupted() )
                      {
                          //ie there is nothing in queue and thread is interrupted
                          //thus we stop thread
                          return;
                      }
                      else
                      {
                          try { m_list.wait(); }
                          catch( final InterruptedException ie )
                          {
                              //Ignore this and let it be dealt in next loop 
                              //Need to set variable as the exception throw cleared status
                              interupted = true;
                          }
                      }
                  }
              }
  
              //actually process an entry
              m_logTarget.processEntry( entry );
          }
      }
  }
  
  
  

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