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    1   /* BeanShellDecideRule
    2   *
    3   * $Id: BeanShellDecideRule.java 4649 2006-09-25 17:16:55Z paul_jack $
    4   *
    5   * Created on Aug 7, 2006
    6   *
    7   * Copyright (C) 2006 Internet Archive.
    8   *
    9   * This file is part of the Heritrix web crawler (crawler.archive.org).
    10  *
    11  * Heritrix is free software; you can redistribute it and/or modify
    12  * it under the terms of the GNU Lesser Public License as published by
    13  * the Free Software Foundation; either version 2.1 of the License, or
    14  * any later version.
    15  *
    16  * Heritrix is distributed in the hope that it will be useful,
    17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    19  * GNU Lesser Public License for more details.
    20  *
    21  * You should have received a copy of the GNU Lesser Public License
    22  * along with Heritrix; if not, write to the Free Software
    23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    24  */
    25  package org.archive.crawler.deciderules;
    26
    27  import java.io.File;
    28  import java.io.IOException;
    29  import java.util.Collections;
    30  import java.util.HashMap;
    31  import java.util.Map;
    32  import java.util.logging.Level;
    33  import java.util.logging.Logger;
    34
    35  import org.archive.crawler.settings.SimpleType;
    36  import org.archive.crawler.settings.Type;
    37
    38  import bsh.EvalError;
    39  import bsh.Interpreter;
    40
    41
    42  /***
    43   * Rule which runs a groovy script to make its decision.
    44   *
    45   * Script source may be provided via a file local to the crawler.
    46   *
    47   * Variables available to the script include 'object' (the object to be
    48   * evaluated, typically a CandidateURI or CrawlURI), 'self'
    49   * (this GroovyDecideRule instance), and 'controller' (the crawl's
    50   * CrawlController instance).
    51   *
    52   * TODO: reduce copy & paste with GroovyProcessor
    53   *
    54   * @author gojomo
    55   */
    56  public class BeanShellDecideRule extends DecideRule {
    57
    58      private static final long serialVersionUID = -8433859929199308527L;
    59
    60      private static final Logger logger =
    61          Logger.getLogger(BeanShellDecideRule.class.getName());
    62
    63      /*** setting for script file */
    64      public final static String ATTR_SCRIPT_FILE = "script-file";
    65
    66      /*** whether each thread should have its own script runner (true), or
    67       * they should share a single script runner with synchronized access */
    68      public final static String ATTR_ISOLATE_THREADS = "isolate-threads";
    69
    70      protected ThreadLocal<Interpreter> threadInterpreter =
    71          new ThreadLocal<Interpreter>();;
    72      protected Interpreter sharedInterpreter;
    73      public Map<Object,Object> sharedMap =
    74          Collections.synchronizedMap(new HashMap<Object,Object>());
    75      protected boolean initialized = false;
    76
    77      public BeanShellDecideRule(String name) {
    78          super(name);
    79          setDescription("BeanShellDecideRule. Runs the BeanShell script " +
    80                  "source (supplied via a file path) against " +
    81                  "the current URI. Source should define a script method " +
    82                  "'decisionFor(object)' which will be passed the object" +
    83                  "to be evaluated and returns one of self.ACCEPT, " +
    84                  "self.REJECT, or self.PASS. " +
    85                  "The script may access this BeanShellDecideRule via" +
    86                  "the 'self' variable and the CrawlController via the " +
    87                  "'controller' variable. Runs the groovy script source " +
    88                  "(supplied via a file path) against the " +
    89                  "current URI.");
    90          Type t = addElementToDefinition(new SimpleType(ATTR_SCRIPT_FILE,
    91                  "BeanShell script file", ""));
    92          t.setOverrideable(false);
    93          t = addElementToDefinition(new SimpleType(ATTR_ISOLATE_THREADS,
    94                  "Whether each ToeThread should get its own independent " +
    95                  "script context, or they should share synchronized access " +
    96                  "to one context. Default is true, meaning each threads " +
    97                  "gets its own isolated context.", true));
    98          t.setOverrideable(false);
    99      }
    100
    101     public synchronized Object decisionFor(Object object) {
    102         // depending on previous configuration, interpreter may
    103         // be local to this thread or shared
    104         Interpreter interpreter = getInterpreter();
    105         synchronized(interpreter) {
    106             // synchronization is harmless for local thread interpreter,
    107             // necessary for shared interpreter
    108             try {
    109                 interpreter.set("object",object);
    110                 return interpreter.eval("decisionFor(object)");
    111             } catch (EvalError e) {
    112                 // TODO Auto-generated catch block
    113                 e.printStackTrace();
    114                 return PASS;
    115             }
    116         }
    117     }
    118
    119     /***
    120      * Get the proper Interpreter instance -- either shared or local
    121      * to this thread.
    122      * @return Interpreter to use
    123      */
    124     protected Interpreter getInterpreter() {
    125         if(sharedInterpreter==null
    126            && !(Boolean)getUncheckedAttribute(null,ATTR_ISOLATE_THREADS)) {
    127             // initialize
    128             sharedInterpreter = newInterpreter();
    129         }
    130         if(sharedInterpreter!=null) {
    131             return sharedInterpreter;
    132         }
    133         Interpreter interpreter = threadInterpreter.get();
    134         if(interpreter==null) {
    135             interpreter = newInterpreter();
    136             threadInterpreter.set(interpreter);
    137         }
    138         return interpreter;
    139     }
    140
    141     /***
    142      * Create a new Interpreter instance, preloaded with any supplied
    143      * source file and the variables 'self' (this
    144      * BeanShellProcessor) and 'controller' (the CrawlController).
    145      *
    146      * @return  the new Interpreter instance
    147      */
    148     protected Interpreter newInterpreter() {
    149         Interpreter interpreter = new Interpreter();
    150         try {
    151             interpreter.set("self", this);
    152             interpreter.set("controller", getController());
    153
    154             String filePath = (String) getUncheckedAttribute(null, ATTR_SCRIPT_FILE);
    155             if(filePath.length()>0) {
    156                 try {
    157                     File file = getSettingsHandler().getPathRelativeToWorkingDirectory(filePath);
    158                     interpreter.source(file.getPath());
    159                 } catch (IOException e) {
    160                     logger.log(Level.SEVERE,"unable to read script file",e);
    161                 }
    162             }
    163         } catch (EvalError e) {
    164             // TODO Auto-generated catch block
    165             e.printStackTrace();
    166         }
    167
    168         return interpreter;
    169     }
    170
    171
    172     /***
    173      * Setup (or reset) Intepreter variables, as appropraite based on
    174      * thread-isolation setting.
    175      */
    176     public void kickUpdate() {
    177         // TODO make it so running state (tallies, etc.) isn't lost on changes
    178         // unless unavoidable
    179         if((Boolean)getUncheckedAttribute(null,ATTR_ISOLATE_THREADS)) {
    180             sharedInterpreter = null;
    181             threadInterpreter = new ThreadLocal<Interpreter>();
    182         } else {
    183             sharedInterpreter = newInterpreter();
    184             threadInterpreter = null;
    185         }
    186     }
    187 }