softsettingshash.html

用JAVA编写的,在做实验的时候留下来的,本来想删的,但是传上来,大家分享吧

<a name="324" href="#324">324</a> <em>     */</em>
<a name="325" href="#325">325</a>     <strong>public</strong> <strong>void</strong> clear() {
<a name="326" href="#326">326</a>         <em class="comment">// clear out ref queue. We don't need to expunge entries</em>
<a name="327" href="#327">327</a>         <em class="comment">// since table is getting cleared.</em>
<a name="328" href="#328">328</a>         <strong>while</strong> (queue.poll() != <strong>null</strong>)
<a name="329" href="#329">329</a>             ;
<a name="330" href="#330">330</a> 
<a name="331" href="#331">331</a>         modCount++;
<a name="332" href="#332">332</a>         SettingsEntry tab[] = table;
<a name="333" href="#333">333</a>         <strong>for</strong> (<strong>int</strong> i = 0; i &lt; tab.length; ++i)
<a name="334" href="#334">334</a>             tab[i] = <strong>null</strong>;
<a name="335" href="#335">335</a>         size = 0;
<a name="336" href="#336">336</a> 
<a name="337" href="#337">337</a>         <em class="comment">// Allocation of array may have caused GC, which may have caused</em>
<a name="338" href="#338">338</a>         <em class="comment">// additional entries to go stale.  Removing these entries from the</em>
<a name="339" href="#339">339</a>         <em class="comment">// reference queue will make them eligible for reclamation.</em>
<a name="340" href="#340">340</a>         <strong>while</strong> (queue.poll() != <strong>null</strong>)
<a name="341" href="#341">341</a>             ;
<a name="342" href="#342">342</a>    }
<a name="343" href="#343">343</a> 
<a name="344" href="#344">344</a>     <em>/**<em>*</em></em>
<a name="345" href="#345">345</a> <em>     * The entries in this hash extend SoftReference, using the host string</em>
<a name="346" href="#346">346</a> <em>     * as the key.</em>
<a name="347" href="#347">347</a> <em>     */</em>
<a name="348" href="#348">348</a>     <strong>static</strong> <strong>class</strong> SettingsEntry <strong>extends</strong> SoftReference {
<a name="349" href="#349">349</a>         <strong>private</strong> <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> settings;
<a name="350" href="#350">350</a>         <strong>private</strong> <strong>final</strong> <strong>int</strong> hash;
<a name="351" href="#351">351</a>         <strong>private</strong> SettingsEntry next;
<a name="352" href="#352">352</a> 
<a name="353" href="#353">353</a>         <em>/**<em>*</em></em>
<a name="354" href="#354">354</a> <em>         * Create new entry.</em>
<a name="355" href="#355">355</a> <em>         */</em>
<a name="356" href="#356">356</a>         SettingsEntry(String key, <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> settings, ReferenceQueue queue,
<a name="357" href="#357">357</a>               <strong>int</strong> hash, SettingsEntry next) {
<a name="358" href="#358">358</a>             <strong>super</strong>(key, queue);
<a name="359" href="#359">359</a>             <strong>this</strong>.settings = settings;
<a name="360" href="#360">360</a>             <strong>this</strong>.hash  = hash;
<a name="361" href="#361">361</a>             <strong>this</strong>.next  = next;
<a name="362" href="#362">362</a>         }
<a name="363" href="#363">363</a> 
<a name="364" href="#364">364</a>         <strong>public</strong> String getKey() {
<a name="365" href="#365">365</a>             <strong>return</strong> (String) <strong>this</strong>.get();
<a name="366" href="#366">366</a>         }
<a name="367" href="#367">367</a> 
<a name="368" href="#368">368</a>         <strong>public</strong> <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> getValue() {
<a name="369" href="#369">369</a>             <strong>return</strong> settings;
<a name="370" href="#370">370</a>         }
<a name="371" href="#371">371</a> 
<a name="372" href="#372">372</a>         <strong>public</strong> <strong>boolean</strong> equals(Object o) {
<a name="373" href="#373">373</a>             <strong>if</strong> (!(o instanceof SettingsEntry))
<a name="374" href="#374">374</a>                 <strong>return</strong> false;
<a name="375" href="#375">375</a>             SettingsEntry e = (SettingsEntry)o;
<a name="376" href="#376">376</a>             String key1 = getKey();
<a name="377" href="#377">377</a>             String key2 = e.getKey();
<a name="378" href="#378">378</a>             <strong>if</strong> (key1 == key2 || (key1 != <strong>null</strong> &amp;&amp; key1.equals(key2))) {
<a name="379" href="#379">379</a>                 <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> setting1 = getValue();
<a name="380" href="#380">380</a>                 <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> setting2 = e.getValue();
<a name="381" href="#381">381</a>                 <strong>if</strong> (setting1 == setting2 || (setting1 != <strong>null</strong> &amp;&amp; setting1.equals(setting2)))
<a name="382" href="#382">382</a>                     <strong>return</strong> <strong>true</strong>;
<a name="383" href="#383">383</a>             }
<a name="384" href="#384">384</a>             <strong>return</strong> false;
<a name="385" href="#385">385</a>         }
<a name="386" href="#386">386</a>     }
<a name="387" href="#387">387</a> 
<a name="388" href="#388">388</a>     <em>/**<em>* Iterator over all elements in hash.</em></em>
<a name="389" href="#389">389</a> <em>     */</em>
<a name="390" href="#390">390</a>     <strong>class</strong> EntryIterator implements Iterator {
<a name="391" href="#391">391</a>         <strong>int</strong> index;
<a name="392" href="#392">392</a>         SettingsEntry entry = <strong>null</strong>;
<a name="393" href="#393">393</a>         SettingsEntry lastReturned = <strong>null</strong>;
<a name="394" href="#394">394</a>         <strong>int</strong> expectedModCount = modCount;
<a name="395" href="#395">395</a> 
<a name="396" href="#396">396</a>         <em>/**<em>*</em></em>
<a name="397" href="#397">397</a> <em>         * Strong reference needed to avoid disappearance of key</em>
<a name="398" href="#398">398</a> <em>         * between hasNext and next</em>
<a name="399" href="#399">399</a> <em>         */</em>
<a name="400" href="#400">400</a>         String nextKey = <strong>null</strong>;
<a name="401" href="#401">401</a> 
<a name="402" href="#402">402</a>         <em>/**<em>*</em></em>
<a name="403" href="#403">403</a> <em>         * Strong reference needed to avoid disappearance of key</em>
<a name="404" href="#404">404</a> <em>         * between nextEntry() and any use of the entry</em>
<a name="405" href="#405">405</a> <em>         */</em>
<a name="406" href="#406">406</a>         String currentKey = <strong>null</strong>;
<a name="407" href="#407">407</a> 
<a name="408" href="#408">408</a>         EntryIterator() {
<a name="409" href="#409">409</a>             index = (size() != 0 ? table.length : 0);
<a name="410" href="#410">410</a>         }
<a name="411" href="#411">411</a> 
<a name="412" href="#412">412</a>         <strong>public</strong> <strong>boolean</strong> hasNext() {
<a name="413" href="#413">413</a>             SettingsEntry[] t = table;
<a name="414" href="#414">414</a> 
<a name="415" href="#415">415</a>             <strong>while</strong> (nextKey == <strong>null</strong>) {
<a name="416" href="#416">416</a>                 SettingsEntry e = entry;
<a name="417" href="#417">417</a>                 <strong>int</strong> i = index;
<a name="418" href="#418">418</a>                 <strong>while</strong> (e == <strong>null</strong> &amp;&amp; i > 0)
<a name="419" href="#419">419</a>                     e = t[--i];
<a name="420" href="#420">420</a>                 entry = e;
<a name="421" href="#421">421</a>                 index = i;
<a name="422" href="#422">422</a>                 <strong>if</strong> (e == <strong>null</strong>) {
<a name="423" href="#423">423</a>                     currentKey = <strong>null</strong>;
<a name="424" href="#424">424</a>                     <strong>return</strong> false;
<a name="425" href="#425">425</a>                 }
<a name="426" href="#426">426</a>                 nextKey = (String) e.get(); <em class="comment">// hold on to key in strong ref</em>
<a name="427" href="#427">427</a>                 <strong>if</strong> (nextKey == <strong>null</strong>)
<a name="428" href="#428">428</a>                     entry = entry.next;
<a name="429" href="#429">429</a>             }
<a name="430" href="#430">430</a>             <strong>return</strong> <strong>true</strong>;
<a name="431" href="#431">431</a>         }
<a name="432" href="#432">432</a> 
<a name="433" href="#433">433</a>         <em>/**<em>* The common parts of next() across different types of iterators */</em></em>
<a name="434" href="#434">434</a>         <strong>public</strong> Object next() {
<a name="435" href="#435">435</a>             <strong>return</strong> nextEntry();
<a name="436" href="#436">436</a>         }
<a name="437" href="#437">437</a> 
<a name="438" href="#438">438</a>         <strong>public</strong> SettingsEntry nextEntry() {
<a name="439" href="#439">439</a>             <strong>if</strong> (modCount != expectedModCount)
<a name="440" href="#440">440</a>                 <strong>throw</strong> <strong>new</strong> ConcurrentModificationException();
<a name="441" href="#441">441</a>             <strong>if</strong> (nextKey == <strong>null</strong> &amp;&amp; !hasNext())
<a name="442" href="#442">442</a>                 <strong>throw</strong> <strong>new</strong> NoSuchElementException();
<a name="443" href="#443">443</a> 
<a name="444" href="#444">444</a>             lastReturned = entry;
<a name="445" href="#445">445</a>             entry = entry.next;
<a name="446" href="#446">446</a>             currentKey = nextKey;
<a name="447" href="#447">447</a>             nextKey = <strong>null</strong>;
<a name="448" href="#448">448</a>             <strong>return</strong> lastReturned;
<a name="449" href="#449">449</a>         }
<a name="450" href="#450">450</a> 
<a name="451" href="#451">451</a>         <strong>public</strong> <strong>void</strong> remove() {
<a name="452" href="#452">452</a>             <strong>if</strong> (lastReturned == <strong>null</strong>)
<a name="453" href="#453">453</a>                 <strong>throw</strong> <strong>new</strong> IllegalStateException();
<a name="454" href="#454">454</a>             <strong>if</strong> (modCount != expectedModCount)
<a name="455" href="#455">455</a>                 <strong>throw</strong> <strong>new</strong> ConcurrentModificationException();
<a name="456" href="#456">456</a> 
<a name="457" href="#457">457</a>             SoftSettingsHash.<strong>this</strong>.remove(currentKey);
<a name="458" href="#458">458</a>             expectedModCount = modCount;
<a name="459" href="#459">459</a>             lastReturned = <strong>null</strong>;
<a name="460" href="#460">460</a>             currentKey = <strong>null</strong>;
<a name="461" href="#461">461</a>         }
<a name="462" href="#462">462</a> 
<a name="463" href="#463">463</a>     }
<a name="464" href="#464">464</a> 
<a name="465" href="#465">465</a>     <em>/**<em>* Make hash value from a String.</em></em>
<a name="466" href="#466">466</a> <em>     *</em>
<a name="467" href="#467">467</a> <em>     * @param key the string for which to create hash value.</em>
<a name="468" href="#468">468</a> <em>     * @return the hash value.</em>
<a name="469" href="#469">469</a> <em>     */</em>
<a name="470" href="#470">470</a>     <strong>static</strong> <strong>int</strong> hash(String key) {
<a name="471" href="#471">471</a>         <strong>int</strong> hash = key.hashCode();
<a name="472" href="#472">472</a> 
<a name="473" href="#473">473</a>         hash += ~(hash &lt;&lt; 9);
<a name="474" href="#474">474</a>         hash ^=  (hash >>> 14);
<a name="475" href="#475">475</a>         hash +=  (hash &lt;&lt; 4);
<a name="476" href="#476">476</a>         hash ^=  (hash >>> 10);
<a name="477" href="#477">477</a>         <strong>return</strong> hash;
<a name="478" href="#478">478</a>     }
<a name="479" href="#479">479</a> 
<a name="480" href="#480">480</a>     <strong>public</strong> EntryIterator iterator() {
<a name="481" href="#481">481</a>         <strong>return</strong> <strong>new</strong> EntryIterator();
<a name="482" href="#482">482</a>     }
<a name="483" href="#483">483</a> 
<a name="484" href="#484">484</a> }
</pre>
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