currenttransaction.html

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<a name="312" href="#312">312</a> 
<a name="313" href="#313">313</a>         <strong>if</strong> (cdbMode) {
<a name="314" href="#314">314</a>             CdbCursors cdbCursors = <strong>null</strong>;
<a name="315" href="#315">315</a>             WeakHashMap cdbCursorsMap = (WeakHashMap) localCdbCursors.get();
<a name="316" href="#316">316</a>             <strong>if</strong> (cdbCursorsMap == <strong>null</strong>) {
<a name="317" href="#317">317</a>                 cdbCursorsMap = <strong>new</strong> WeakHashMap();
<a name="318" href="#318">318</a>                 localCdbCursors.set(cdbCursorsMap);
<a name="319" href="#319">319</a>             } <strong>else</strong> {
<a name="320" href="#320">320</a>                 cdbCursors = (CdbCursors) cdbCursorsMap.get(db);
<a name="321" href="#321">321</a>             }
<a name="322" href="#322">322</a>             <strong>if</strong> (cdbCursors == <strong>null</strong>) {
<a name="323" href="#323">323</a>                 cdbCursors = <strong>new</strong> CdbCursors();
<a name="324" href="#324">324</a>                 cdbCursorsMap.put(db, cdbCursors);
<a name="325" href="#325">325</a>             }
<a name="326" href="#326">326</a> 
<a name="327" href="#327">327</a>             <em class="comment">/*</em>
<a name="328" href="#328">328</a> <em class="comment">             * In CDB mode the cursorConfig specified by the user is ignored</em>
<a name="329" href="#329">329</a> <em class="comment">             * and only the writeCursor parameter is honored.  This is the only</em>
<a name="330" href="#330">330</a> <em class="comment">             * meaningful cursor attribute for CDB, and here we count on</em>
<a name="331" href="#331">331</a> <em class="comment">             * writeCursor flag being set correctly by the caller.</em>
<a name="332" href="#332">332</a> <em class="comment">             */</em>
<a name="333" href="#333">333</a>             List cursors;
<a name="334" href="#334">334</a>             CursorConfig cdbConfig;
<a name="335" href="#335">335</a>             <strong>if</strong> (writeCursor) {
<a name="336" href="#336">336</a>                 <strong>if</strong> (cdbCursors.readCursors.size() > 0) {
<a name="337" href="#337">337</a>                     
<a name="338" href="#338">338</a>                     <em class="comment">/*</em>
<a name="339" href="#339">339</a> <em class="comment">                     * Although CDB allows opening a write cursor when a read</em>
<a name="340" href="#340">340</a> <em class="comment">                     * cursor is open, a self-deadlock will occur if a write is</em>
<a name="341" href="#341">341</a> <em class="comment">                     * attempted for a record that is read-locked; we should</em>
<a name="342" href="#342">342</a> <em class="comment">                     * avoid self-deadlocks at all costs</em>
<a name="343" href="#343">343</a> <em class="comment">                     */</em>
<a name="344" href="#344">344</a>                     <strong>throw</strong> <strong>new</strong> IllegalStateException(
<a name="345" href="#345">345</a>                       <span class="string">"cannot open CDB write cursor when read cursor is open"</span>);
<a name="346" href="#346">346</a>                 }
<a name="347" href="#347">347</a>                 cursors = cdbCursors.writeCursors;
<a name="348" href="#348">348</a>                 cdbConfig = <strong>new</strong> CursorConfig();
<a name="349" href="#349">349</a>                 DbCompat.setWriteCursor(cdbConfig, <strong>true</strong>);
<a name="350" href="#350">350</a>             } <strong>else</strong> {
<a name="351" href="#351">351</a>                 cursors = cdbCursors.readCursors;
<a name="352" href="#352">352</a>                 cdbConfig = <strong>null</strong>;
<a name="353" href="#353">353</a>             }
<a name="354" href="#354">354</a>             Cursor cursor;
<a name="355" href="#355">355</a>             <strong>if</strong> (cursors.size() > 0) {
<a name="356" href="#356">356</a>                 Cursor other = ((Cursor) cursors.get(0));
<a name="357" href="#357">357</a>                 cursor = other.dup(false);
<a name="358" href="#358">358</a>             } <strong>else</strong> {
<a name="359" href="#359">359</a>                 cursor = db.openCursor(<strong>null</strong>, cdbConfig);
<a name="360" href="#360">360</a>             }
<a name="361" href="#361">361</a>             cursors.add(cursor);
<a name="362" href="#362">362</a>             <strong>return</strong> cursor;
<a name="363" href="#363">363</a>         } <strong>else</strong> {
<a name="364" href="#364">364</a>             <strong>return</strong> db.openCursor(txn, cursorConfig);
<a name="365" href="#365">365</a>         }
<a name="366" href="#366">366</a>     }
<a name="367" href="#367">367</a> 
<a name="368" href="#368">368</a>     <em>/**<em>*</em></em>
<a name="369" href="#369">369</a> <em>     * Duplicates a cursor for a given database.</em>
<a name="370" href="#370">370</a> <em>     *</em>
<a name="371" href="#371">371</a> <em>     * @param writeCursor true to open a write cursor in a CDB environment, and</em>
<a name="372" href="#372">372</a> <em>     * ignored for other environments.</em>
<a name="373" href="#373">373</a> <em>     *</em>
<a name="374" href="#374">374</a> <em>     * @param samePosition is passed through to Cursor.dup().</em>
<a name="375" href="#375">375</a> <em>     *</em>
<a name="376" href="#376">376</a> <em>     * @return the open cursor.</em>
<a name="377" href="#377">377</a> <em>     *</em>
<a name="378" href="#378">378</a> <em>     * @throws DatabaseException if a database problem occurs.</em>
<a name="379" href="#379">379</a> <em>     */</em>
<a name="380" href="#380">380</a>     Cursor dupCursor(Cursor cursor, <strong>boolean</strong> writeCursor, <strong>boolean</strong> samePosition)
<a name="381" href="#381">381</a>         throws DatabaseException {
<a name="382" href="#382">382</a> 
<a name="383" href="#383">383</a>         <strong>if</strong> (cdbMode) {
<a name="384" href="#384">384</a>             WeakHashMap cdbCursorsMap = (WeakHashMap) localCdbCursors.get();
<a name="385" href="#385">385</a>             <strong>if</strong> (cdbCursorsMap != <strong>null</strong>) {
<a name="386" href="#386">386</a>                 Database db = cursor.getDatabase();
<a name="387" href="#387">387</a>                 CdbCursors cdbCursors = (CdbCursors) cdbCursorsMap.get(db);
<a name="388" href="#388">388</a>                 <strong>if</strong> (cdbCursors != <strong>null</strong>) {
<a name="389" href="#389">389</a>                     List cursors = writeCursor ? cdbCursors.writeCursors
<a name="390" href="#390">390</a>                                                : cdbCursors.readCursors;
<a name="391" href="#391">391</a>                     <strong>if</strong> (cursors.contains(cursor)) {
<a name="392" href="#392">392</a>                         Cursor newCursor = cursor.dup(samePosition);
<a name="393" href="#393">393</a>                         cursors.add(newCursor);
<a name="394" href="#394">394</a>                         <strong>return</strong> newCursor;
<a name="395" href="#395">395</a>                     }
<a name="396" href="#396">396</a>                 }
<a name="397" href="#397">397</a>             }
<a name="398" href="#398">398</a>             <strong>throw</strong> <strong>new</strong> IllegalStateException(<span class="string">"cursor to dup not tracked"</span>);
<a name="399" href="#399">399</a>         } <strong>else</strong> {
<a name="400" href="#400">400</a>             <strong>return</strong> cursor.dup(samePosition);
<a name="401" href="#401">401</a>         }
<a name="402" href="#402">402</a>     }
<a name="403" href="#403">403</a> 
<a name="404" href="#404">404</a>     <em>/**<em>*</em></em>
<a name="405" href="#405">405</a> <em>     * Closes a cursor.</em>
<a name="406" href="#406">406</a> <em>     *</em>
<a name="407" href="#407">407</a> <em>     * @param cursor the cursor to close.</em>
<a name="408" href="#408">408</a> <em>     *</em>
<a name="409" href="#409">409</a> <em>     * @throws DatabaseException if a database problem occurs.</em>
<a name="410" href="#410">410</a> <em>     */</em>
<a name="411" href="#411">411</a>     <strong>void</strong> closeCursor(Cursor cursor)
<a name="412" href="#412">412</a>         throws DatabaseException {
<a name="413" href="#413">413</a> 
<a name="414" href="#414">414</a>         <strong>if</strong> (cursor == <strong>null</strong>) {
<a name="415" href="#415">415</a>             <strong>return</strong>;
<a name="416" href="#416">416</a>         }
<a name="417" href="#417">417</a>         <strong>if</strong> (cdbMode) {
<a name="418" href="#418">418</a>             WeakHashMap cdbCursorsMap = (WeakHashMap) localCdbCursors.get();
<a name="419" href="#419">419</a>             <strong>if</strong> (cdbCursorsMap != <strong>null</strong>) {
<a name="420" href="#420">420</a>                 Database db = cursor.getDatabase();
<a name="421" href="#421">421</a>                 CdbCursors cdbCursors = (CdbCursors) cdbCursorsMap.get(db);
<a name="422" href="#422">422</a>                 <strong>if</strong> (cdbCursors != <strong>null</strong>) {
<a name="423" href="#423">423</a>                     <strong>if</strong> (cdbCursors.readCursors.remove(cursor) ||
<a name="424" href="#424">424</a>                         cdbCursors.writeCursors.remove(cursor)) {
<a name="425" href="#425">425</a>                         cursor.close();
<a name="426" href="#426">426</a>                         <strong>return</strong>;
<a name="427" href="#427">427</a>                     }
<a name="428" href="#428">428</a>                 }
<a name="429" href="#429">429</a>             }
<a name="430" href="#430">430</a>             <strong>throw</strong> <strong>new</strong> IllegalStateException(
<a name="431" href="#431">431</a>               <span class="string">"closing CDB cursor that was not known to be open"</span>);
<a name="432" href="#432">432</a>         } <strong>else</strong> {
<a name="433" href="#433">433</a>             cursor.close();
<a name="434" href="#434">434</a>         }
<a name="435" href="#435">435</a>     }
<a name="436" href="#436">436</a> 
<a name="437" href="#437">437</a>     <em>/**<em>*</em></em>
<a name="438" href="#438">438</a> <em>     * Returns true if a CDB cursor is open and therefore a Database write</em>
<a name="439" href="#439">439</a> <em>     * operation should not be attempted since a self-deadlock may result.</em>
<a name="440" href="#440">440</a> <em>     */</em>
<a name="441" href="#441">441</a>     <strong>boolean</strong> isCDBCursorOpen(Database db)
<a name="442" href="#442">442</a>         throws DatabaseException {
<a name="443" href="#443">443</a> 
<a name="444" href="#444">444</a>         <strong>if</strong> (cdbMode) {
<a name="445" href="#445">445</a>             WeakHashMap cdbCursorsMap = (WeakHashMap) localCdbCursors.get();
<a name="446" href="#446">446</a>             <strong>if</strong> (cdbCursorsMap != <strong>null</strong>) {
<a name="447" href="#447">447</a>                 CdbCursors cdbCursors = (CdbCursors) cdbCursorsMap.get(db);
<a name="448" href="#448">448</a> 
<a name="449" href="#449">449</a>                 <strong>if</strong> (cdbCursors != <strong>null</strong> &amp;&amp;
<a name="450" href="#450">450</a>                     (cdbCursors.readCursors.size() > 0 ||
<a name="451" href="#451">451</a>                      cdbCursors.writeCursors.size() > 0)) {
<a name="452" href="#452">452</a>                     <strong>return</strong> <strong>true</strong>;
<a name="453" href="#453">453</a>                 }
<a name="454" href="#454">454</a>             }
<a name="455" href="#455">455</a>         }
<a name="456" href="#456">456</a>         <strong>return</strong> false;
<a name="457" href="#457">457</a>     }
<a name="458" href="#458">458</a> 
<a name="459" href="#459">459</a>     <strong>static</strong> <strong>final</strong> <strong>class</strong> CdbCursors {
<a name="460" href="#460">460</a> 
<a name="461" href="#461">461</a>         List writeCursors = <strong>new</strong> ArrayList();
<a name="462" href="#462">462</a>         List readCursors = <strong>new</strong> ArrayList();
<a name="463" href="#463">463</a>     }
<a name="464" href="#464">464</a> }
</pre>
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