package com.heaton.bot;import java.util.*;/** * This class is used to maintain an internal, * memory based workload store for a spider. This * workload store will be used by default, if no * other is specified. * * Copyright 2001 by Jeff Heaton * * @author Jeff Heaton * @version 1.0 */public class SpiderInternalWorkload implements IWorkloadStorable {  /**   * A list of complete workload items.   */  Hashtable _complete = new Hashtable();  /**   * A list of waiting workload items.   */  Vector _waiting = new Vector();  /**   * A list of running workload items.   */  Vector _running = new Vector();  /**   * Call this method to request a URL   * to process. This method will return   * a WAITING URL and mark it as RUNNING.   *   * @return The URL that was assigned.   */  synchronized public String assignWorkload()  {    if ( _waiting.size()<1 )      return null;    String w=(String)_waiting.firstElement();    if ( w!=null ) {      _waiting.remove(w);      _running.addElement(w);    }    Log.log(Log.LOG_LEVEL_TRACE,"Spider workload assigned:" + w);    return w;  }  /**   * Add a new URL to the workload, and   * assign it a status of WAITING.   *   * @param url The URL to be added.   */  synchronized public void addWorkload(String url)  {    if ( getURLStatus(url) != IWorkloadStorable.UNKNOWN )      return;    _waiting.addElement(url);    Log.log(Log.LOG_LEVEL_TRACE,"Spider workload added:" + url);  }  /**   * Called to mark this URL as either   * COMPLETE or ERROR.   *   * @param url The URL to complete.   * @param error true - assign this workload a status of ERROR.   * false - assign this workload a status of COMPLETE.   */  synchronized public void completeWorkload(String url,boolean error)  {    if ( _running.size()>0 ) {      for ( Enumeration e = _running.elements() ; e.hasMoreElements() ; ) {        String w = (String)e.nextElement();        if ( w.equals(url) ) {          _running.remove(w);          if ( error ) {            Log.log(Log.LOG_LEVEL_TRACE,"Spider workload ended in error:" + url);            _complete.put(w,"e");          } else {            Log.log(Log.LOG_LEVEL_TRACE,"Spider workload complete:" + url);            _complete.put(w,"c");          }          return;        }      }    }    Log.log(Log.LOG_LEVEL_ERROR,"Spider workload LOST:" + url);  }  /**   * Get the status of a URL.   *   * @param url Returns either RUNNING, ERROR   * WAITING, or COMPLETE. If the URL   * does not exist in the database,   * the value of UNKNOWN is returned.   * @return Returns either RUNNING,ERROR,   * WAITING,COMPLETE or UNKNOWN.   */  synchronized public char getURLStatus(String url)  {    if ( _complete.get(url)!=null )      return COMPLETE;    if ( _waiting.size()>0 ) {      for ( Enumeration e = _waiting.elements() ; e.hasMoreElements() ; ) {        String w = (String)e.nextElement();        if ( w.equals(url) )          return WAITING;      }    }    if ( _running.size()>0 ) {      for ( Enumeration e = _running.elements() ; e.hasMoreElements() ; ) {        String w = (String)e.nextElement();        if ( w.equals(url) )          return RUNNING;      }    }    return UNKNOWN;  }  /**   * Clear the contents of the workload store.   */  synchronized public void clear()  {    _waiting.clear();    _complete.clear();    _running.clear();  }}