checkpointer.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="175" href="#175">175</a>     <em>/**<em>*</em></em>
<a name="176" href="#176">176</a> <em>     * Thread to run the checkpointing.</em>
<a name="177" href="#177">177</a> <em>     * @author stack</em>
<a name="178" href="#178">178</a> <em>     */</em>
<a name="179" href="#179">179</a>     <strong>public</strong> <strong>class</strong> CheckpointingThread <strong>extends</strong> Thread {
<a name="180" href="#180">180</a>         <strong>public</strong> CheckpointingThread(<strong>final</strong> String name) {
<a name="181" href="#181">181</a>             <strong>super</strong>(name);
<a name="182" href="#182">182</a>         }
<a name="183" href="#183">183</a> 
<a name="184" href="#184">184</a>         <strong>public</strong> <a href="../../../../org/archive/crawler/framework/CrawlController.html">CrawlController</a> getController() {
<a name="185" href="#185">185</a>         	<strong>return</strong> Checkpointer.<strong>this</strong>.controller;
<a name="186" href="#186">186</a>         }
<a name="187" href="#187">187</a>         
<a name="188" href="#188">188</a>         <strong>public</strong> <strong>void</strong> run() {
<a name="189" href="#189">189</a>             LOGGER.info(<span class="string">"Started"</span>);
<a name="190" href="#190">190</a>             <em class="comment">// If crawler already paused, don't resume crawling after</em>
<a name="191" href="#191">191</a>             <em class="comment">// finishing checkpointing.</em>
<a name="192" href="#192">192</a>             <strong>final</strong> <strong>boolean</strong> alreadyPaused = getController().isPaused() ||
<a name="193" href="#193">193</a>                 getController().isPausing();
<a name="194" href="#194">194</a>             <strong>try</strong> {
<a name="195" href="#195">195</a>                 getController().requestCrawlPause();
<a name="196" href="#196">196</a>                 <em class="comment">// Clear any checkpoint errors.</em>
<a name="197" href="#197">197</a>                 setCheckpointErrors(false);
<a name="198" href="#198">198</a>                 <strong>if</strong> (!waitOnPaused()) {
<a name="199" href="#199">199</a>                     checkpointFailed(<span class="string">"Failed wait for complete pause."</span>);
<a name="200" href="#200">200</a>                 } <strong>else</strong> {
<a name="201" href="#201">201</a>                     createCheckpointInProgressDirectory();
<a name="202" href="#202">202</a>                     <strong>this</strong>.getController().checkpoint();
<a name="203" href="#203">203</a>                 }
<a name="204" href="#204">204</a>             } <strong>catch</strong> (Exception e) {
<a name="205" href="#205">205</a>                 checkpointFailed(e);
<a name="206" href="#206">206</a>             } <strong>finally</strong> {
<a name="207" href="#207">207</a>                 <strong>if</strong> (!isCheckpointErrors()) {
<a name="208" href="#208">208</a>                     writeValidity();
<a name="209" href="#209">209</a>                 }
<a name="210" href="#210">210</a>                 Checkpointer.<strong>this</strong>.nextCheckpoint++;
<a name="211" href="#211">211</a>                 clearCheckpointInProgressDirectory();
<a name="212" href="#212">212</a>                 LOGGER.info(<span class="string">"Finished"</span>);
<a name="213" href="#213">213</a>                 getController().completePause();
<a name="214" href="#214">214</a>                 <strong>if</strong> (!alreadyPaused) {
<a name="215" href="#215">215</a>                     getController().requestCrawlResume();
<a name="216" href="#216">216</a>                 }
<a name="217" href="#217">217</a>             }
<a name="218" href="#218">218</a>         }
<a name="219" href="#219">219</a>         
<a name="220" href="#220">220</a>         <strong>private</strong> <strong>synchronized</strong> <strong>boolean</strong> waitOnPaused() {
<a name="221" href="#221">221</a>             <em class="comment">// If we're paused we can exit but also exit if the crawl has been</em>
<a name="222" href="#222">222</a>             <em class="comment">// resumed by the operator.</em>
<a name="223" href="#223">223</a>             <strong>while</strong>(!getController().isPaused() &amp;&amp; !getController().isRunning()) {
<a name="224" href="#224">224</a>                 <strong>try</strong> {
<a name="225" href="#225">225</a>                     wait(1000 * 3);
<a name="226" href="#226">226</a>                 } <strong>catch</strong> (InterruptedException e) {
<a name="227" href="#227">227</a>                     <em class="comment">// May be for us.</em>
<a name="228" href="#228">228</a>                 }
<a name="229" href="#229">229</a>             }
<a name="230" href="#230">230</a>             <strong>return</strong> getController().isPaused();
<a name="231" href="#231">231</a>         }
<a name="232" href="#232">232</a>     }
<a name="233" href="#233">233</a>     
<a name="234" href="#234">234</a>     <strong>protected</strong> File createCheckpointInProgressDirectory() {
<a name="235" href="#235">235</a>         <strong>this</strong>.checkpointInProgressDir =
<a name="236" href="#236">236</a>             <strong>new</strong> File(Checkpointer.<strong>this</strong>.controller.getCheckpointsDisk(),
<a name="237" href="#237">237</a>                 getNextCheckpointName());
<a name="238" href="#238">238</a>         <strong>this</strong>.checkpointInProgressDir.mkdirs();
<a name="239" href="#239">239</a>         <strong>return</strong> <strong>this</strong>.checkpointInProgressDir;
<a name="240" href="#240">240</a>     }
<a name="241" href="#241">241</a>     
<a name="242" href="#242">242</a>     <strong>protected</strong> <strong>void</strong> clearCheckpointInProgressDirectory() {
<a name="243" href="#243">243</a>         <strong>this</strong>.checkpointInProgressDir = <strong>null</strong>;
<a name="244" href="#244">244</a>     }
<a name="245" href="#245">245</a>     
<a name="246" href="#246">246</a>     <strong>protected</strong> <a href="../../../../org/archive/crawler/framework/CrawlController.html">CrawlController</a> getController() {
<a name="247" href="#247">247</a>         <strong>return</strong> <strong>this</strong>.controller;
<a name="248" href="#248">248</a>     }
<a name="249" href="#249">249</a>     
<a name="250" href="#250">250</a>     <em>/**<em>*</em></em>
<a name="251" href="#251">251</a> <em>     * @return next checkpoint name (zero-padding string).</em>
<a name="252" href="#252">252</a> <em>     */</em>
<a name="253" href="#253">253</a>     <strong>public</strong> String getNextCheckpointName() {
<a name="254" href="#254">254</a>         <strong>return</strong> formatCheckpointName(<strong>this</strong>.checkpointPrefix, <strong>this</strong>.nextCheckpoint);
<a name="255" href="#255">255</a>     }
<a name="256" href="#256">256</a>     
<a name="257" href="#257">257</a>     <strong>public</strong> <strong>static</strong> String formatCheckpointName(<strong>final</strong> String prefix,
<a name="258" href="#258">258</a>     		<strong>final</strong> <strong>int</strong> index) {
<a name="259" href="#259">259</a>     	<strong>return</strong> prefix + INDEX_FORMAT.format(index);
<a name="260" href="#260">260</a>     }
<a name="261" href="#261">261</a> 
<a name="262" href="#262">262</a>     <strong>protected</strong> <strong>void</strong> writeValidity() {
<a name="263" href="#263">263</a>         File valid = <strong>new</strong> File(<strong>this</strong>.checkpointInProgressDir,
<a name="264" href="#264">264</a>             Checkpoint.VALIDITY_STAMP_FILENAME);
<a name="265" href="#265">265</a>         <strong>try</strong> {
<a name="266" href="#266">266</a>             FileOutputStream fos = <strong>new</strong> FileOutputStream(valid);
<a name="267" href="#267">267</a>             fos.write(ArchiveUtils.get14DigitDate().getBytes());
<a name="268" href="#268">268</a>             fos.close();
<a name="269" href="#269">269</a>         } <strong>catch</strong> (IOException e) {
<a name="270" href="#270">270</a>             valid.delete();
<a name="271" href="#271">271</a>         }
<a name="272" href="#272">272</a>     }
<a name="273" href="#273">273</a> 
<a name="274" href="#274">274</a>     <em>/**<em>*</em></em>
<a name="275" href="#275">275</a> <em>     * @return Checkpoint directory. Name of the directory is the name of this</em>
<a name="276" href="#276">276</a> <em>     * current checkpoint.  Null if no checkpoint in progress.</em>
<a name="277" href="#277">277</a> <em>     */</em>
<a name="278" href="#278">278</a>     <strong>public</strong> File getCheckpointInProgressDirectory() {
<a name="279" href="#279">279</a>         <strong>return</strong> <strong>this</strong>.checkpointInProgressDir;
<a name="280" href="#280">280</a>     }
<a name="281" href="#281">281</a>     
<a name="282" href="#282">282</a>     <em>/**<em>*</em></em>
<a name="283" href="#283">283</a> <em>     * @return True if a checkpoint is in progress.</em>
<a name="284" href="#284">284</a> <em>     */</em>
<a name="285" href="#285">285</a>     <strong>public</strong> <strong>boolean</strong> isCheckpointing() {
<a name="286" href="#286">286</a>         <strong>return</strong> <strong>this</strong>.checkpointThread != <strong>null</strong> &amp;&amp; <strong>this</strong>.checkpointThread.isAlive();
<a name="287" href="#287">287</a>     }
<a name="288" href="#288">288</a> 
<a name="289" href="#289">289</a>     <em>/**<em>*</em></em>
<a name="290" href="#290">290</a> <em>     * Note that a checkpoint failed</em>
<a name="291" href="#291">291</a> <em>     *</em>
<a name="292" href="#292">292</a> <em>     * @param e Exception checkpoint failed on.</em>
<a name="293" href="#293">293</a> <em>     */</em>
<a name="294" href="#294">294</a>     <strong>protected</strong> <strong>void</strong> checkpointFailed(Exception e) {
<a name="295" href="#295">295</a>         LOGGER.log(Level.WARNING, <span class="string">" Checkpoint failed"</span>, e);
<a name="296" href="#296">296</a>         checkpointFailed();
<a name="297" href="#297">297</a>     }
<a name="298" href="#298">298</a>     
<a name="299" href="#299">299</a>     <strong>protected</strong> <strong>void</strong> checkpointFailed(<strong>final</strong> String message) {
<a name="300" href="#300">300</a>         LOGGER.warning(message);
<a name="301" href="#301">301</a>         checkpointFailed();
<a name="302" href="#302">302</a>     }
<a name="303" href="#303">303</a>     
<a name="304" href="#304">304</a>     <strong>protected</strong> <strong>void</strong> checkpointFailed() {
<a name="305" href="#305">305</a>         <strong>this</strong>.checkpointErrors = <strong>true</strong>;
<a name="306" href="#306">306</a>     }
<a name="307" href="#307">307</a>     
<a name="308" href="#308">308</a>     <em>/**<em>*</em></em>
<a name="309" href="#309">309</a> <em>     * @return True if current/last checkpoint failed.</em>
<a name="310" href="#310">310</a> <em>     */</em>
<a name="311" href="#311">311</a>     <strong>public</strong> <strong>boolean</strong> isCheckpointFailed() {
<a name="312" href="#312">312</a>         <strong>return</strong> <strong>this</strong>.checkpointErrors;
<a name="313" href="#313">313</a>     }
<a name="314" href="#314">314</a> 
<a name="315" href="#315">315</a>     <em>/**<em>*</em></em>
<a name="316" href="#316">316</a> <em>     * @return Return whether this context is at a new crawl, never-</em>
<a name="317" href="#317">317</a> <em>     * checkpointed state.</em>
<a name="318" href="#318">318</a> <em>     */</em>
<a name="319" href="#319">319</a>     <strong>public</strong> <strong>boolean</strong> isAtBeginning() {
<a name="320" href="#320">320</a>         <strong>return</strong> nextCheckpoint == 1;
<a name="321" href="#321">321</a>     }
<a name="322" href="#322">322</a> 
<a name="323" href="#323">323</a>     <em>/**<em>*</em></em>
<a name="324" href="#324">324</a> <em>     * Call when recovering from a checkpoint.</em>
<a name="325" href="#325">325</a> <em>     * Call this after instance has been revivifyied post-serialization to</em>
<a name="326" href="#326">326</a> <em>     * amend counters and directories that effect where checkpoints get stored</em>
<a name="327" href="#327">327</a> <em>     * from here on out.</em>
<a name="328" href="#328">328</a> <em>     * @param cc CrawlController instance.</em>
<a name="329" href="#329">329</a> <em>     */</em>
<a name="330" href="#330">330</a>     <strong>public</strong> <strong>void</strong> recover(<strong>final</strong> <a href="../../../../org/archive/crawler/framework/CrawlController.html">CrawlController</a> cc) {
<a name="331" href="#331">331</a>         <em class="comment">// Prepend the checkpoint name with a little 'r' so we tell apart</em>
<a name="332" href="#332">332</a>         <em class="comment">// checkpoints made from a recovery.  Allow for there being</em>
<a name="333" href="#333">333</a>         <em class="comment">// multiple 'r' prefixes.</em>
<a name="334" href="#334">334</a>         initialize(cc, 'r' + <strong>this</strong>.checkpointPrefix);
<a name="335" href="#335">335</a>     }
<a name="336" href="#336">336</a>     
<a name="337" href="#337">337</a>     <em>/**<em>*</em></em>
<a name="338" href="#338">338</a> <em>     * @return Returns the predecessorCheckpoints.</em>
<a name="339" href="#339">339</a> <em>     */</em>
<a name="340" href="#340">340</a>     <strong>public</strong> List getPredecessorCheckpoints() {
<a name="341" href="#341">341</a>         <strong>return</strong> <strong>this</strong>.predecessorCheckpoints;
<a name="342" href="#342">342</a>     }
<a name="343" href="#343">343</a> 
<a name="344" href="#344">344</a>     <strong>protected</strong> <strong>boolean</strong> isCheckpointErrors() {
<a name="345" href="#345">345</a>         <strong>return</strong> <strong>this</strong>.checkpointErrors;
<a name="346" href="#346">346</a>     }
<a name="347" href="#347">347</a> 
<a name="348" href="#348">348</a>     <strong>protected</strong> <strong>void</strong> setCheckpointErrors(<strong>boolean</strong> checkpointErrors) {
<a name="349" href="#349">349</a>         <strong>this</strong>.checkpointErrors = checkpointErrors;
<a name="350" href="#350">350</a>     }
<a name="351" href="#351">351</a> }
</pre>
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