writerpoolmember.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="159" href="#159">159</a>     <em>/**<em>*</em></em>
<a name="160" href="#160">160</a> <em>     * Constructor.</em>
<a name="161" href="#161">161</a> <em>     *</em>
<a name="162" href="#162">162</a> <em>     * @param serialNo  used to create unique filename sequences</em>
<a name="163" href="#163">163</a> <em>     * @param dirs Where to drop files.</em>
<a name="164" href="#164">164</a> <em>     * @param prefix File prefix to use.</em>
<a name="165" href="#165">165</a> <em>     * @param cmprs Compress the records written. </em>
<a name="166" href="#166">166</a> <em>     * @param maxSize Maximum size for ARC files written.</em>
<a name="167" href="#167">167</a> <em>     * @param suffix File tail to use.  If null, unused.</em>
<a name="168" href="#168">168</a> <em>     * @param extension Extension to give file.</em>
<a name="169" href="#169">169</a> <em>     */</em>
<a name="170" href="#170">170</a>     <strong>public</strong> <a href="../../../org/archive/io/WriterPoolMember.html">WriterPoolMember</a>(AtomicInteger serialNo,
<a name="171" href="#171">171</a>             <strong>final</strong> List&lt;File> dirs, <strong>final</strong> String prefix, 
<a name="172" href="#172">172</a>             <strong>final</strong> String suffix, <strong>final</strong> <strong>boolean</strong> cmprs,
<a name="173" href="#173">173</a>             <strong>final</strong> <strong>int</strong> maxSize, <strong>final</strong> String extension) {
<a name="174" href="#174">174</a>         <strong>this</strong>.suffix = suffix;
<a name="175" href="#175">175</a>         <strong>this</strong>.prefix = prefix;
<a name="176" href="#176">176</a>         <strong>this</strong>.maxSize = maxSize;
<a name="177" href="#177">177</a>         <strong>this</strong>.writeDirs = dirs;
<a name="178" href="#178">178</a>         <strong>this</strong>.compressed = cmprs;
<a name="179" href="#179">179</a>         <strong>this</strong>.extension = extension;
<a name="180" href="#180">180</a>         <strong>this</strong>.serialNo = serialNo;
<a name="181" href="#181">181</a>     }
<a name="182" href="#182">182</a> 
<a name="183" href="#183">183</a> 	<em>/**<em>*</em></em>
<a name="184" href="#184">184</a> <em>	 * Call this method just before/after any significant write.</em>
<a name="185" href="#185">185</a> <em>	 *</em>
<a name="186" href="#186">186</a> <em>	 * Call at the end of the writing of a record or just before we start</em>
<a name="187" href="#187">187</a> <em>	 * writing a new record.  Will close current file and open a new file</em>
<a name="188" href="#188">188</a> <em>	 * if file size has passed out maxSize.</em>
<a name="189" href="#189">189</a> <em>	 * </em>
<a name="190" href="#190">190</a> <em>	 * &lt;p>Creates and opens a file if none already open.  One use of this method</em>
<a name="191" href="#191">191</a> <em>	 * then is after construction, call this method to add the metadata, then</em>
<a name="192" href="#192">192</a> <em>	 * call {@link #getPosition()} to find offset of first record.</em>
<a name="193" href="#193">193</a> <em>	 *</em>
<a name="194" href="#194">194</a> <em>	 * @exception IOException</em>
<a name="195" href="#195">195</a> <em>	 */</em>
<a name="196" href="#196">196</a>     <strong>public</strong> <strong>void</strong> checkSize() throws IOException {
<a name="197" href="#197">197</a>         <strong>if</strong> (<strong>this</strong>.out == <strong>null</strong> ||
<a name="198" href="#198">198</a>                 (<strong>this</strong>.maxSize != -1 &amp;&amp; (<strong>this</strong>.f.length() > <strong>this</strong>.maxSize))) {
<a name="199" href="#199">199</a>             createFile();
<a name="200" href="#200">200</a>         }
<a name="201" href="#201">201</a>     }
<a name="202" href="#202">202</a> 
<a name="203" href="#203">203</a>     <em>/**<em>*</em></em>
<a name="204" href="#204">204</a> <em>     * Create a new file.</em>
<a name="205" href="#205">205</a> <em>     * Rotates off the current Writer and creates a new in its place</em>
<a name="206" href="#206">206</a> <em>     * to take subsequent writes.  Usually called from {@link #checkSize()}.</em>
<a name="207" href="#207">207</a> <em>     * @return Name of file created.</em>
<a name="208" href="#208">208</a> <em>     * @throws IOException</em>
<a name="209" href="#209">209</a> <em>     */</em>
<a name="210" href="#210">210</a>     <strong>protected</strong> String createFile() throws IOException {
<a name="211" href="#211">211</a>         <a href="../../../org/archive/util/TimestampSerialno.html">TimestampSerialno</a> tsn = getTimestampSerialNo();
<a name="212" href="#212">212</a>         String name = <strong>this</strong>.prefix + '-' + getUniqueBasename(tsn) +
<a name="213" href="#213">213</a>             ((<strong>this</strong>.suffix == <strong>null</strong> || <strong>this</strong>.suffix.length() &lt;= 0)?
<a name="214" href="#214">214</a>                 <span class="string">""</span>: <span class="string">"-"</span> + <strong>this</strong>.suffix) + '.' + <strong>this</strong>.extension  +
<a name="215" href="#215">215</a>             ((<strong>this</strong>.compressed)? '.' + COMPRESSED_FILE_EXTENSION: <span class="string">""</span>) +
<a name="216" href="#216">216</a>             OCCUPIED_SUFFIX;
<a name="217" href="#217">217</a>         <strong>this</strong>.createTimestamp = tsn.getTimestamp();
<a name="218" href="#218">218</a>         File dir = getNextDirectory(<strong>this</strong>.writeDirs);
<a name="219" href="#219">219</a>         <strong>return</strong> createFile(<strong>new</strong> File(dir, name));
<a name="220" href="#220">220</a>     }
<a name="221" href="#221">221</a>     
<a name="222" href="#222">222</a>     <strong>protected</strong> String createFile(<strong>final</strong> File file) throws IOException {
<a name="223" href="#223">223</a>     	close();
<a name="224" href="#224">224</a>         <strong>this</strong>.f = file;
<a name="225" href="#225">225</a>         <strong>this</strong>.fos = <strong>new</strong> FileOutputStream(<strong>this</strong>.f);
<a name="226" href="#226">226</a>         <strong>this</strong>.out = <strong>new</strong> FastBufferedOutputStream(<strong>this</strong>.fos);
<a name="227" href="#227">227</a>         logger.info(<span class="string">"Opened "</span> + <strong>this</strong>.f.getAbsolutePath());
<a name="228" href="#228">228</a>         <strong>return</strong> <strong>this</strong>.f.getName();
<a name="229" href="#229">229</a>     }
<a name="230" href="#230">230</a>     
<a name="231" href="#231">231</a>     <em>/**<em>*</em></em>
<a name="232" href="#232">232</a> <em>     * @param dirs List of File objects that point at directories.</em>
<a name="233" href="#233">233</a> <em>     * @return Find next directory to write an arc too.  If more</em>
<a name="234" href="#234">234</a> <em>     * than one, it tries to round-robin through each in turn.</em>
<a name="235" href="#235">235</a> <em>     * @throws IOException</em>
<a name="236" href="#236">236</a> <em>     */</em>
<a name="237" href="#237">237</a>     <strong>protected</strong> File getNextDirectory(List&lt;File> dirs)
<a name="238" href="#238">238</a>     throws IOException {
<a name="239" href="#239">239</a>         <strong>if</strong> (WriterPoolMember.roundRobinIndex >= dirs.size()) {
<a name="240" href="#240">240</a>             WriterPoolMember.roundRobinIndex = 0;
<a name="241" href="#241">241</a>         }
<a name="242" href="#242">242</a>         File d = <strong>null</strong>;
<a name="243" href="#243">243</a>         <strong>try</strong> {
<a name="244" href="#244">244</a>             d = checkWriteable((File)dirs.
<a name="245" href="#245">245</a>                 get(WriterPoolMember.roundRobinIndex));
<a name="246" href="#246">246</a>         } <strong>catch</strong> (IndexOutOfBoundsException e) {
<a name="247" href="#247">247</a>             <em class="comment">// Dirs list might be altered underneath us.</em>
<a name="248" href="#248">248</a>             <em class="comment">// If so, we get this exception -- just keep on going.</em>
<a name="249" href="#249">249</a>         }
<a name="250" href="#250">250</a>         <strong>if</strong> (d == <strong>null</strong> &amp;&amp; dirs.size() > 1) {
<a name="251" href="#251">251</a>             <strong>for</strong> (Iterator i = dirs.iterator(); d == <strong>null</strong> &amp;&amp; i.hasNext();) {
<a name="252" href="#252">252</a>                 d = checkWriteable((File)i.next());
<a name="253" href="#253">253</a>             }
<a name="254" href="#254">254</a>         } <strong>else</strong> {
<a name="255" href="#255">255</a>             WriterPoolMember.roundRobinIndex++;
<a name="256" href="#256">256</a>         }
<a name="257" href="#257">257</a>         <strong>if</strong> (d == <strong>null</strong>) {
<a name="258" href="#258">258</a>             <strong>throw</strong> <strong>new</strong> IOException(<span class="string">"Directories unusable."</span>);
<a name="259" href="#259">259</a>         }
<a name="260" href="#260">260</a>         <strong>return</strong> d;
<a name="261" href="#261">261</a>     }
<a name="262" href="#262">262</a>         
<a name="263" href="#263">263</a>     <strong>protected</strong> File checkWriteable(File d) {
<a name="264" href="#264">264</a>         <strong>if</strong> (d == <strong>null</strong>) {
<a name="265" href="#265">265</a>             <strong>return</strong> d;
<a name="266" href="#266">266</a>         }
<a name="267" href="#267">267</a>         
<a name="268" href="#268">268</a>         <strong>try</strong> {
<a name="269" href="#269">269</a>             IoUtils.ensureWriteableDirectory(d);
<a name="270" href="#270">270</a>         } <strong>catch</strong>(IOException e) {
<a name="271" href="#271">271</a>             logger.warning(<span class="string">"Directory "</span> + d.getPath() + <span class="string">" is not"</span> +
<a name="272" href="#272">272</a>                 <span class="string">" writeable or cannot be created: "</span> + e.getMessage());
<a name="273" href="#273">273</a>             d = <strong>null</strong>;
<a name="274" href="#274">274</a>         }
<a name="275" href="#275">275</a>         <strong>return</strong> d;
<a name="276" href="#276">276</a>     }
<a name="277" href="#277">277</a>     
<a name="278" href="#278">278</a>     <strong>protected</strong> <strong>synchronized</strong> <a href="../../../org/archive/util/TimestampSerialno.html">TimestampSerialno</a> getTimestampSerialNo() {
<a name="279" href="#279">279</a>         <strong>return</strong> getTimestampSerialNo(<strong>null</strong>);
<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>     * Do static synchronization around getting of counter and timestamp so</em>
<a name="284" href="#284">284</a> <em>     * no chance of a thread getting in between the getting of timestamp and</em>
<a name="285" href="#285">285</a> <em>     * allocation of serial number throwing the two out of alignment.</em>
<a name="286" href="#286">286</a> <em>     * </em>
<a name="287" href="#287">287</a> <em>     * @param timestamp If non-null, use passed timestamp (must be 14 digit</em>
<a name="288" href="#288">288</a> <em>     * ARC format), else if null, timestamp with now.</em>
<a name="289" href="#289">289</a> <em>     * @return Instance of data structure that has timestamp and serial no.</em>
<a name="290" href="#290">290</a> <em>     */</em>
<a name="291" href="#291">291</a>     <strong>protected</strong> <strong>synchronized</strong> <a href="../../../org/archive/util/TimestampSerialno.html">TimestampSerialno</a>
<a name="292" href="#292">292</a>             getTimestampSerialNo(<strong>final</strong> String timestamp) {
<a name="293" href="#293">293</a>         <strong>return</strong> <strong>new</strong> <a href="../../../org/archive/util/TimestampSerialno.html">TimestampSerialno</a>((timestamp != <strong>null</strong>)?
<a name="294" href="#294">294</a>                 timestamp: ArchiveUtils.get14DigitDate(),
<a name="295" href="#295">295</a>                 serialNo.getAndIncrement());
<a name="296" href="#296">296</a>     }
<a name="297" href="#297">297</a> 
<a name="298" href="#298">298</a>     <em>/**<em>*</em></em>
<a name="299" href="#299">299</a> <em>     * Return a unique basename.</em>
<a name="300" href="#300">300</a> <em>     *</em>
<a name="301" href="#301">301</a> <em>     * Name is timestamp + an every increasing sequence number.</em>
<a name="302" href="#302">302</a> <em>     *</em>
<a name="303" href="#303">303</a> <em>     * @param tsn Structure with timestamp and serial number.</em>
<a name="304" href="#304">304</a> <em>     *</em>
<a name="305" href="#305">305</a> <em>     * @return Unique basename.</em>
<a name="306" href="#306">306</a> <em>     */</em>
<a name="307" href="#307">307</a>     <strong>private</strong> String getUniqueBasename(<a href="../../../org/archive/util/TimestampSerialno.html">TimestampSerialno</a> tsn) {
<a name="308" href="#308">308</a>         <strong>return</strong> tsn.getTimestamp() + <span class="string">"-"</span> +
<a name="309" href="#309">309</a>            WriterPoolMember.serialNoFormatter.format(tsn.getSerialNumber());
<a name="310" href="#310">310</a>     }
<a name="311" href="#311">311</a> 
<a name="312" href="#312">312</a> 
<a name="313" href="#313">313</a>     <em>/**<em>*</em></em>
<a name="314" href="#314">314</a> <em>     * Get the file name</em>
<a name="315" href="#315">315</a> <em>     * </em>
<a name="316" href="#316">316</a> <em>     * @return the filename, as if uncompressed</em>
<a name="317" href="#317">317</a> <em>     */</em>
<a name="318" href="#318">318</a>     <strong>protected</strong> String getBaseFilename() {
<a name="319" href="#319">319</a>         String name = <strong>this</strong>.f.getName();
<a name="320" href="#320">320</a>         <strong>if</strong> (<strong>this</strong>.compressed &amp;&amp; name.endsWith(DOT_COMPRESSED_FILE_EXTENSION)) {
<a name="321" href="#321">321</a>             <strong>return</strong> name.substring(0,name.length() - 3);
<a name="322" href="#322">322</a>         } <strong>else</strong> <strong>if</strong>(<strong>this</strong>.compressed &amp;&amp;
<a name="323" href="#323">323</a>                 name.endsWith(DOT_COMPRESSED_FILE_EXTENSION +
<a name="324" href="#324">324</a>                     OCCUPIED_SUFFIX)) {
<a name="325" href="#325">325</a>             <strong>return</strong> name.substring(0, name.length() -