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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="content-type" content="text/html; charset=UTF-8" /><title>AdaptiveRevisitFrontier xref</title><link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../../apidocs/org/archive/crawler/frontier/AdaptiveRevisitFrontier.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> AdaptiveRevisitFrontier.java</em></em><a name="2" href="#2">2</a> <em class="comment">*</em><a name="3" href="#3">3</a> <em class="comment">* Created on Sep 13, 2004</em><a name="4" href="#4">4</a> <em class="comment">*</em><a name="5" href="#5">5</a> <em class="comment">* Copyright (C) 2004 Kristinn Sigur?sson.</em><a name="6" href="#6">6</a> <em class="comment">*</em><a name="7" href="#7">7</a> <em class="comment">* This file is part of the Heritrix web crawler (crawler.archive.org).</em><a name="8" href="#8">8</a> <em class="comment">*</em><a name="9" href="#9">9</a> <em class="comment">* Heritrix is free software; you can redistribute it and/or modify</em><a name="10" href="#10">10</a> <em class="comment">* it under the terms of the GNU Lesser Public License as published by</em><a name="11" href="#11">11</a> <em class="comment">* the Free Software Foundation; either version 2.1 of the License, or</em><a name="12" href="#12">12</a> <em class="comment">* any later version.</em><a name="13" href="#13">13</a> <em class="comment">*</em><a name="14" href="#14">14</a> <em class="comment">* Heritrix is distributed in the hope that it will be useful,</em><a name="15" href="#15">15</a> <em class="comment">* but WITHOUT ANY WARRANTY; without even the implied warranty of</em><a name="16" href="#16">16</a> <em class="comment">* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</em><a name="17" href="#17">17</a> <em class="comment">* GNU Lesser Public License for more details.</em><a name="18" href="#18">18</a> <em class="comment">*</em><a name="19" href="#19">19</a> <em class="comment">* You should have received a copy of the GNU Lesser Public License</em><a name="20" href="#20">20</a> <em class="comment">* along with Heritrix; if not, write to the Free Software</em><a name="21" href="#21">21</a> <em class="comment">* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA</em><a name="22" href="#22">22</a> <em class="comment">*/</em><a name="23" href="#23">23</a> <strong>package</strong> <a href="../../../../org/archive/crawler/frontier/package-summary.html">org.archive.crawler.frontier</a>;<a name="24" href="#24">24</a> <a name="25" href="#25">25</a> <strong>import</strong> java.io.File;<a name="26" href="#26">26</a> <strong>import</strong> java.io.IOException;<a name="27" href="#27">27</a> <strong>import</strong> java.io.PrintWriter;<a name="28" href="#28">28</a> <strong>import</strong> java.io.Serializable;<a name="29" href="#29">29</a> <strong>import</strong> java.io.StringWriter;<a name="30" href="#30">30</a> <strong>import</strong> java.io.Writer;<a name="31" href="#31">31</a> <strong>import</strong> java.util.ArrayList;<a name="32" href="#32">32</a> <strong>import</strong> java.util.Date;<a name="33" href="#33">33</a> <strong>import</strong> java.util.Iterator;<a name="34" href="#34">34</a> <strong>import</strong> java.util.List;<a name="35" href="#35">35</a> <strong>import</strong> java.util.logging.Level;<a name="36" href="#36">36</a> <strong>import</strong> java.util.logging.Logger;<a name="37" href="#37">37</a> <a name="38" href="#38">38</a> <strong>import</strong> javax.management.AttributeNotFoundException;<a name="39" href="#39">39</a> <a name="40" href="#40">40</a> <strong>import</strong> org.apache.commons.httpclient.HttpStatus;<a name="41" href="#41">41</a> <strong>import</strong> org.archive.crawler.datamodel.CandidateURI;<a name="42" href="#42">42</a> <strong>import</strong> org.archive.crawler.datamodel.CoreAttributeConstants;<a name="43" href="#43">43</a> <strong>import</strong> org.archive.crawler.datamodel.CrawlServer;<a name="44" href="#44">44</a> <strong>import</strong> org.archive.crawler.datamodel.CrawlURI;<a name="45" href="#45">45</a> <strong>import</strong> org.archive.crawler.datamodel.FetchStatusCodes;<a name="46" href="#46">46</a> <strong>import</strong> org.archive.crawler.datamodel.UriUniqFilter;<a name="47" href="#47">47</a> <strong>import</strong> org.archive.crawler.datamodel.UriUniqFilter.HasUriReceiver;<a name="48" href="#48">48</a> <strong>import</strong> org.archive.crawler.event.CrawlStatusListener;<a name="49" href="#49">49</a> <strong>import</strong> org.archive.crawler.framework.CrawlController;<a name="50" href="#50">50</a> <strong>import</strong> org.archive.crawler.framework.Frontier;<a name="51" href="#51">51</a> <strong>import</strong> org.archive.crawler.framework.FrontierMarker;<a name="52" href="#52">52</a> <strong>import</strong> org.archive.crawler.framework.exceptions.EndedException;<a name="53" href="#53">53</a> <strong>import</strong> org.archive.crawler.framework.exceptions.FatalConfigurationException;<a name="54" href="#54">54</a> <strong>import</strong> org.archive.crawler.framework.exceptions.InvalidFrontierMarkerException;<a name="55" href="#55">55</a> <strong>import</strong> org.archive.crawler.settings.ModuleType;<a name="56" href="#56">56</a> <strong>import</strong> org.archive.crawler.settings.RegularExpressionConstraint;<a name="57" href="#57">57</a> <strong>import</strong> org.archive.crawler.settings.SimpleType;<a name="58" href="#58">58</a> <strong>import</strong> org.archive.crawler.settings.Type;<a name="59" href="#59">59</a> <strong>import</strong> org.archive.crawler.url.Canonicalizer;<a name="60" href="#60">60</a> <strong>import</strong> org.archive.crawler.util.BdbUriUniqFilter;<a name="61" href="#61">61</a> <strong>import</strong> org.archive.net.UURI;<a name="62" href="#62">62</a> <strong>import</strong> org.archive.queue.MemQueue;<a name="63" href="#63">63</a> <strong>import</strong> org.archive.queue.Queue;<a name="64" href="#64">64</a> <strong>import</strong> org.archive.util.ArchiveUtils;<a name="65" href="#65">65</a> <a name="66" href="#66">66</a> <a name="67" href="#67">67</a> <em>/**<em>*</em></em><a name="68" href="#68">68</a> <em> * A Frontier that will repeatedly visit all encountered URIs. </em><a name="69" href="#69">69</a> <em> * <p></em><a name="70" href="#70">70</a> <em> * Wait time between visits is configurable and varies based on observed </em><a name="71" href="#71">71</a> <em> * changes of documents.</em><a name="72" href="#72">72</a> <em> * <p></em><a name="73" href="#73">73</a> <em> * The Frontier borrows many things from HostQueuesFrontier, but implements </em><a name="74" href="#74">74</a> <em> * an entirely different strategy in issuing URIs and consequently in keeping a</em><a name="75" href="#75">75</a> <em> * record of discovered URIs.</em><a name="76" href="#76">76</a> <em> *</em><a name="77" href="#77">77</a> <em> * @author Kristinn Sigurdsson</em><a name="78" href="#78">78</a> <em> */</em><a name="79" href="#79">79</a> <strong>public</strong> <strong>class</strong> <a href="../../../../org/archive/crawler/frontier/AdaptiveRevisitFrontier.html">AdaptiveRevisitFrontier</a> <strong>extends</strong> <a href="../../../../org/archive/crawler/settings/ModuleType.html">ModuleType</a> <a name="80" href="#80">80</a> implements Frontier, FetchStatusCodes, CoreAttributeConstants,<a name="81" href="#81">81</a> AdaptiveRevisitAttributeConstants, CrawlStatusListener, HasUriReceiver {<a name="82" href="#82">82</a> <a name="83" href="#83">83</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>long</strong> serialVersionUID = -8666872690438543671L;<a name="84" href="#84">84</a> <a name="85" href="#85">85</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> Logger logger =<a name="86" href="#86">86</a> Logger.getLogger(AdaptiveRevisitFrontier.<strong>class</strong>.getName());<a name="87" href="#87">87</a> <a name="88" href="#88">88</a> <em>/**<em>* How many multiples of last fetch elapsed time to wait before recontacting</em></em><a name="89" href="#89">89</a> <em> * same server */</em><a name="90" href="#90">90</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_DELAY_FACTOR = <span class="string">"delay-factor"</span>;<a name="91" href="#91">91</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Float DEFAULT_DELAY_FACTOR = <strong>new</strong> Float(5);<a name="92" href="#92">92</a> <a name="93" href="#93">93</a> <em>/**<em>* Always wait this long after one completion before recontacting</em></em><a name="94" href="#94">94</a> <em> * same server, regardless of multiple */</em><a name="95" href="#95">95</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_MIN_DELAY = <span class="string">"min-delay-ms"</span>;<a name="96" href="#96">96</a> <a name="97" href="#97">97</a> <em class="comment">// 2 seconds</em><a name="98" href="#98">98</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Integer DEFAULT_MIN_DELAY = <strong>new</strong> Integer(2000);<a name="99" href="#99">99</a> <a name="100" href="#100">100</a> <em>/**<em>* Never wait more than this long, regardless of multiple */</em></em><a name="101" href="#101">101</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_MAX_DELAY = <span class="string">"max-delay-ms"</span>;<a name="102" href="#102">102</a> <a name="103" href="#103">103</a> <em class="comment">// 30 seconds</em><a name="104" href="#104">104</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Integer DEFAULT_MAX_DELAY = <strong>new</strong> Integer(30000);<a name="105" href="#105">105</a> <a name="106" href="#106">106</a> <em>/**<em>* Maximum times to emit a <a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> without final disposition */</em></em><a name="107" href="#107">107</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_MAX_RETRIES = <span class="string">"max-retries"</span>;<a name="108" href="#108">108</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Integer DEFAULT_MAX_RETRIES = <strong>new</strong> Integer(30);<a name="109" href="#109">109</a> <a name="110" href="#110">110</a> <em>/**<em>* For retryable problems, seconds to wait before a retry */</em></em><a name="111" href="#111">111</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_RETRY_DELAY = <span class="string">"retry-delay-seconds"</span>;<a name="112" href="#112">112</a> <a name="113" href="#113">113</a> <em class="comment">// 15 minutes</em><a name="114" href="#114">114</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Long DEFAULT_RETRY_DELAY = <strong>new</strong> Long(900);<a name="115" href="#115">115</a> <a name="116" href="#116">116</a> <em>/**<em>* Maximum simultaneous requests in process to a host (queue) */</em></em><a name="117" href="#117">117</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_HOST_VALENCE = <span class="string">"host-valence"</span>;<a name="118" href="#118">118</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Integer DEFAULT_HOST_VALENCE = <strong>new</strong> Integer(1); <a name="119" href="#119">119</a> <a name="120" href="#120">120</a> <em>/**<em>* Number of hops of embeds (ERX) to bump to front of host queue */</em></em><a name="121" href="#121">121</a> <strong>public</strong> <strong>final</strong> <strong>static</strong> String ATTR_PREFERENCE_EMBED_HOPS =<a name="122" href="#122">122</a> <span class="string">"preference-embed-hops"</span>;<a name="123" href="#123">123</a> <strong>private</strong> <strong>final</strong> <strong>static</strong> Integer DEFAULT_PREFERENCE_EMBED_HOPS = <strong>new</strong> Integer(0); <a name="124" href="#124">124</a> <a name="125" href="#125">125</a> <em>/**<em>* Queue assignment to force on CrawlURIs. Intended to be used </em></em><a name="126" href="#126">126</a> <em> * via overrides*/</em>?? 快捷鍵說明
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