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 2001-2003 by Jeff Heaton (http://www.jeffheaton.com) * * @author Jeff Heaton * @version 1.2 */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)  {            running.remove(url);    if ( error ) {      Log.log(Log.LOG_LEVEL_TRACE,"Spider workload ended in error:" + url);      complete.put(url,"e");    } else {      Log.log(Log.LOG_LEVEL_TRACE,"Spider workload complete:" + url);      complete.put(url,"c");    }     }  /**   * 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();  }}