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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=ISO-8859-1" /><title>SoftSettingsHash xref</title><link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" /></head><body><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> SoftHashMap</em></em><a name="2" href="#2">2</a> <em class="comment"> *</em><a name="3" href="#3">3</a> <em class="comment"> * $Id: SoftSettingsHash.java,v 1.2 2004/05/28 22:33:05 stack-sf Exp $</em><a name="4" href="#4">4</a> <em class="comment"> *</em><a name="5" href="#5">5</a> <em class="comment"> * Created on Mar 18, 2004</em><a name="6" href="#6">6</a> <em class="comment"> *</em><a name="7" href="#7">7</a> <em class="comment"> * Copyright (C) 2004 Internet Archive.</em><a name="8" href="#8">8</a> <em class="comment"> *</em><a name="9" href="#9">9</a> <em class="comment"> * This file is part of the Heritrix web crawler (crawler.archive.org).</em><a name="10" href="#10">10</a> <em class="comment"> *</em><a name="11" href="#11">11</a> <em class="comment"> * Heritrix is free software; you can redistribute it and/or modify</em><a name="12" href="#12">12</a> <em class="comment"> * it under the terms of the GNU Lesser Public License as published by</em><a name="13" href="#13">13</a> <em class="comment"> * the Free Software Foundation; either version 2.1 of the License, or</em><a name="14" href="#14">14</a> <em class="comment"> * any later version.</em><a name="15" href="#15">15</a> <em class="comment"> *</em><a name="16" href="#16">16</a> <em class="comment"> * Heritrix is distributed in the hope that it will be useful,</em><a name="17" href="#17">17</a> <em class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</em><a name="18" href="#18">18</a> <em class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</em><a name="19" href="#19">19</a> <em class="comment"> * GNU Lesser Public License for more details.</em><a name="20" href="#20">20</a> <em class="comment"> *</em><a name="21" href="#21">21</a> <em class="comment"> * You should have received a copy of the GNU Lesser Public License</em><a name="22" href="#22">22</a> <em class="comment"> * along with Heritrix; if not, write to the Free Software</em><a name="23" href="#23">23</a> <em class="comment"> * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA</em><a name="24" href="#24">24</a> <em class="comment"> */</em><a name="25" href="#25">25</a> <strong>package</strong> <a href="../../../../org/archive/crawler/settings/package-summary.html">org.archive.crawler.settings</a>;<a name="26" href="#26">26</a> <a name="27" href="#27">27</a> <strong>import</strong> java.lang.ref.ReferenceQueue;<a name="28" href="#28">28</a> <strong>import</strong> java.lang.ref.SoftReference;<a name="29" href="#29">29</a> <strong>import</strong> java.util.ConcurrentModificationException;<a name="30" href="#30">30</a> <strong>import</strong> java.util.Iterator;<a name="31" href="#31">31</a> <strong>import</strong> java.util.NoSuchElementException;<a name="32" href="#32">32</a> <a name="33" href="#33">33</a> <a name="34" href="#34">34</a> <strong>public</strong> <strong>class</strong> <a href="../../../../org/archive/crawler/settings/SoftSettingsHash.html">SoftSettingsHash</a> {<a name="35" href="#35">35</a> <a name="36" href="#36">36</a> <em>/**<em>*</em></em><a name="37" href="#37">37</a> <em> * The maximum capacity, used if a higher value is implicitly specified</em><a name="38" href="#38">38</a> <em> * by either of the constructors with arguments.</em><a name="39" href="#39">39</a> <em> * MUST be a power of two <= 1<<30.</em><a name="40" href="#40">40</a> <em> */</em><a name="41" href="#41">41</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>int</strong> MAXIMUM_CAPACITY = 1 << 30;<a name="42" href="#42">42</a> <a name="43" href="#43">43</a> <em>/**<em>*</em></em><a name="44" href="#44">44</a> <em> * The load fast used.</em><a name="45" href="#45">45</a> <em> */</em><a name="46" href="#46">46</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>float</strong> LOAD_FACTOR = 0.75f;<a name="47" href="#47">47</a> <a name="48" href="#48">48</a> <em>/**<em>*</em></em><a name="49" href="#49">49</a> <em> * The table, resized as necessary. Length MUST Always be a power of two.</em><a name="50" href="#50">50</a> <em> */</em><a name="51" href="#51">51</a> <strong>private</strong> SettingsEntry[] table;<a name="52" href="#52">52</a> <a name="53" href="#53">53</a> <em>/**<em>*</em></em><a name="54" href="#54">54</a> <em> * The number of key-value mappings contained in this hash.</em><a name="55" href="#55">55</a> <em> */</em><a name="56" href="#56">56</a> <strong>private</strong> <strong>int</strong> size;<a name="57" href="#57">57</a> <a name="58" href="#58">58</a> <em>/**<em>*</em></em><a name="59" href="#59">59</a> <em> * The next size value at which to resize (capacity * load factor).</em><a name="60" href="#60">60</a> <em> */</em><a name="61" href="#61">61</a> <strong>private</strong> <strong>int</strong> threshold;<a name="62" href="#62">62</a> <a name="63" href="#63">63</a> <em>/**<em>*</em></em><a name="64" href="#64">64</a> <em> * Reference queue for cleared entries</em><a name="65" href="#65">65</a> <em> */</em><a name="66" href="#66">66</a> <strong>private</strong> <strong>final</strong> ReferenceQueue queue = <strong>new</strong> ReferenceQueue();<a name="67" href="#67">67</a> <a name="68" href="#68">68</a> <em>/**<em>*</em></em><a name="69" href="#69">69</a> <em> * The number of times this HashMap has been structurally modified</em><a name="70" href="#70">70</a> <em> * Structural modifications are those that change the number of mappings in</em><a name="71" href="#71">71</a> <em> * the HashMap or otherwise modify its internal structure (e.g.,</em><a name="72" href="#72">72</a> <em> * rehash). This field is used to make iterators on Collection-views of</em><a name="73" href="#73">73</a> <em> * the HashMap fail-fast. (See ConcurrentModificationException).</em><a name="74" href="#74">74</a> <em> */</em><a name="75" href="#75">75</a> <strong>private</strong> <strong>volatile</strong> <strong>int</strong> modCount;<a name="76" href="#76">76</a> <a name="77" href="#77">77</a> <em>/**<em>*</em></em><a name="78" href="#78">78</a> <em> * Constructs a new, empty <tt>SoftSettingsHash</tt> with the given initial</em><a name="79" href="#79">79</a> <em> * capacity.</em><a name="80" href="#80">80</a> <em> *</em><a name="81" href="#81">81</a> <em> * @param initialCapacity The initial capacity of the</em><a name="82" href="#82">82</a> <em> * <tt>SoftSettingsHash</tt></em><a name="83" href="#83">83</a> <em> * @throws IllegalArgumentException If the initial capacity is negative.</em><a name="84" href="#84">84</a> <em> */</em><a name="85" href="#85">85</a> <strong>public</strong> <a href="../../../../org/archive/crawler/settings/SoftSettingsHash.html">SoftSettingsHash</a>(<strong>int</strong> initialCapacity) {<a name="86" href="#86">86</a> <strong>if</strong> (initialCapacity < 0)<a name="87" href="#87">87</a> <strong>throw</strong> <strong>new</strong> IllegalArgumentException(<span class="string">"Illegal Initial Capacity: "</span>+<a name="88" href="#88">88</a> initialCapacity);<a name="89" href="#89">89</a> <strong>if</strong> (initialCapacity > MAXIMUM_CAPACITY)<a name="90" href="#90">90</a> initialCapacity = MAXIMUM_CAPACITY;<a name="91" href="#91">91</a> <a name="92" href="#92">92</a> <strong>int</strong> capacity = 1;<a name="93" href="#93">93</a> <strong>while</strong> (capacity < initialCapacity)<a name="94" href="#94">94</a> capacity <<= 1;<a name="95" href="#95">95</a> table = <strong>new</strong> SettingsEntry[capacity];<a name="96" href="#96">96</a> threshold = (<strong>int</strong>)(capacity * LOAD_FACTOR);<a name="97" href="#97">97</a> }<a name="98" href="#98">98</a> <a name="99" href="#99">99</a> <em>/**<em>*</em></em><a name="100" href="#100">100</a> <em> * Check for equality of non-null reference x and possibly-null y. By</em><a name="101" href="#101">101</a> <em> * default uses Object.equals.</em><a name="102" href="#102">102</a> <em> */</em><a name="103" href="#103">103</a> <strong>static</strong> <strong>boolean</strong> eq(Object x, Object y) {<a name="104" href="#104">104</a> <strong>return</strong> x == y || x.equals(y);<a name="105" href="#105">105</a> }<a name="106" href="#106">106</a> <a name="107" href="#107">107</a> <em>/**<em>*</em></em><a name="108" href="#108">108</a> <em> * Return index for hash code h.</em><a name="109" href="#109">109</a> <em> */</em><a name="110" href="#110">110</a> <strong>static</strong> <strong>int</strong> indexFor(<strong>int</strong> h, <strong>int</strong> length) {<a name="111" href="#111">111</a> <strong>return</strong> h & (length-1);<a name="112" href="#112">112</a> }<a name="113" href="#113">113</a> <a name="114" href="#114">114</a> <em>/**<em>*</em></em><a name="115" href="#115">115</a> <em> * Expunge stale entries from the table.</em><a name="116" href="#116">116</a> <em> */</em><a name="117" href="#117">117</a> <strong>private</strong> <strong>void</strong> expungeStaleEntries() {<a name="118" href="#118">118</a> SettingsEntry entry;<a name="119" href="#119">119</a> <strong>while</strong> ( (entry = (SettingsEntry) queue.poll()) != <strong>null</strong>) {<a name="120" href="#120">120</a> <strong>int</strong> h = entry.hash;<a name="121" href="#121">121</a> <strong>int</strong> i = indexFor(h, table.length);<a name="122" href="#122">122</a> <a name="123" href="#123">123</a> SettingsEntry prev = table[i];<a name="124" href="#124">124</a> SettingsEntry p = prev;<a name="125" href="#125">125</a> <strong>while</strong> (p != <strong>null</strong>) {<a name="126" href="#126">126</a> SettingsEntry next = p.next;<a name="127" href="#127">127</a> <strong>if</strong> (p == entry) {<a name="128" href="#128">128</a> <strong>if</strong> (prev == entry)<a name="129" href="#129">129</a> table[i] = next;<a name="130" href="#130">130</a> <strong>else</strong><a name="131" href="#131">131</a> prev.next = next;<a name="132" href="#132">132</a> entry.next = <strong>null</strong>; <em class="comment">// Help GC</em><a name="133" href="#133">133</a> entry.settings = <strong>null</strong>; <em class="comment">// " "</em><a name="134" href="#134">134</a> size--;<a name="135" href="#135">135</a> <strong>break</strong>;<a name="136" href="#136">136</a> }<a name="137" href="#137">137</a> prev = p;<a name="138" href="#138">138</a> p = next;<a name="139" href="#139">139</a> }<a name="140" href="#140">140</a> }<a name="141" href="#141">141</a> }<a name="142" href="#142">142</a> <a name="143" href="#143">143</a> <em>/**<em>*</em></em><a name="144" href="#144">144</a> <em> * Returns the number of key-value mappings in this map.</em><a name="145" href="#145">145</a> <em> * This result is a snapshot, and may not reflect unprocessed</em><a name="146" href="#146">146</a> <em> * entries that will be removed before next attempted access</em><a name="147" href="#147">147</a> <em> * because they are no longer referenced.</em><a name="148" href="#148">148</a> <em> */</em><a name="149" href="#149">149</a> <strong>public</strong> <strong>int</strong> size() {<a name="150" href="#150">150</a> <strong>if</strong> (size == 0)<a name="151" href="#151">151</a> <strong>return</strong> 0;<a name="152" href="#152">152</a> expungeStaleEntries();<a name="153" href="#153">153</a> <strong>return</strong> size;<a name="154" href="#154">154</a> }<a name="155" href="#155">155</a> <a name="156" href="#156">156</a> <em>/**<em>*</em></em><a name="157" href="#157">157</a> <em> * Returns the value to which the specified key is mapped in this weak</em>⌨️ 快捷键说明
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