By the way, if you wanted vary your jdoconfig.xml settings knowing which are impl in appengine, here's a link to appengine datanucleus test code:
http://code.google.com/p/datanucleus-appengine/source/browse/trunk/tests/META-INF/jdoconfig.xml?r=514&spec=svn514 On Jul 18, 8:44 pm, Nichole <[email protected]> wrote: > The answer to the nontransactionalread and write are below, but > meanwhile, if you really do need those updates to be as close > to atomic as possible, then you need them in the same entity > group so they're co-located in the distributed file system. > > On Jul 18, 2:02 am, mscwd01 <[email protected]> wrote: > > > > > > > > > Thanks for the update. It's a pity you cant check to see if the first > > transaction committed before it leaves an "active" state, that'd make > > things so much easier. I really needed the two updates to occur as > > quickly as possible so relying on the second update to continue > > retying via the task queue, is not ideal. Would running the > > PersistenceManagerFactory with 'NontransactionalRead' and > > 'NontransactionalWrite' set to 'true' allow me to do what I want? I > > cant really find any documentation that describes what those two > > values do. > > > Thanks again > > > On Jul 17, 11:46 pm,Nichole<[email protected]> wrote: > > > > Good point, I rewrote the code below to better use the available > > > connections > > > and improve the pattern. > > > > Regarding update 1 being committed and update 2 failing, the > > > first is already committed, yes. I think one has to use a retry for > > > the > > > 2nd update (using the task queue structure) for the 2nd operation to > > > eventually succeed, but on a longer timescale. > > > > Here's a better approach to the problem: > > > > import com.climbwithyourfeet.software.twotransaction.util.PMF; > > > import com.google.appengine.api.datastore.Key; > > > import java.util.ArrayList; > > > import javax.jdo.Transaction; > > > import javax.jdo.PersistenceManager; > > > import java.util.logging.Logger; > > > import com.google.appengine.tools.development.LocalDatastoreTestCase; > > > import java.util.List; > > > import org.junit.After; > > > import org.junit.Before; > > > import org.junit.Test; > > > > /** > > > Goal: > > > * Update 2 entities which reside in 2 different entity groups. > > > * The updates must both pass or both fail. > > > * > > > * Solution: > > > * Use a different transaction for each entity, configurable in > > > jdoconfig.xml. > > > * (Note that it looks like 2 named PersistenceManagerFactory > > > connections are possible, but not more than that, and there > > > is only one transaction for a PMF connection). > > > * > > > * Solution is essentially check that transaction1 succeeds or > > > fails before > > > * committing transaction2. > > > * > > > * The case which needs additional fail-over is the case in which > > > transaction 1 is committed successfully but transaction2 fails. > > > * In this case a retry of transaction2 should be invoked and must > > > eventually succeed. > > > * > > > * For that reason, any code using this pattern should design > > > the logic so that the logic in the 2nd transaction can be > > > consistent > > > on a longer timescale. > > > * > > > * @authornichole > > > */ > > > public class TwoOperationPseudoTransactionTest extends > > > LocalDatastoreTestCase { > > > > private final Logger log = > > > Logger.getLogger(this.getClass().getName()); > > > private String iden1 = "1234567"; > > > private String iden2 = "1123456"; > > > > public TwoOperationPseudoTransactionTest() { > > > super(); > > > } > > > > @Before > > > public void setUp() throws Exception { > > > super.setUp(); > > > > try { > > > PersistenceManager pm = PMF.get().getPersistenceManager(); > > > Transaction tx = pm.currentTransaction(); > > > tx.begin(); > > > UserGameCredits e1 = new UserGameCredits(iden1); > > > pm.makePersistent(e1); > > > pm.flush(); > > > tx.commit(); > > > > PersistenceManager pm2 = > > > PMF.get2().getPersistenceManager(); > > > tx = pm2.currentTransaction(); > > > tx.begin(); > > > UserAccount e2 = new UserAccount(iden2); > > > pm2.makePersistent(e2); > > > pm2.flush(); > > > tx.commit(); > > > } catch (Throwable t) { > > > String msg = t.getMessage(); > > > } > > > } > > > > @After > > > public void tearDown() throws Exception { > > > super.tearDown(); > > > } > > > > @Test > > > public void test2() throws Exception { > > > > PersistenceManager pm = PMF.get().getPersistenceManager(); > > > PersistenceManager pm2 = PMF.get2().getPersistenceManager(); > > > > final Transaction tx = pm.currentTransaction(); > > > final Transaction tx2 = pm2.currentTransaction(); > > > > final List<Boolean> completedOp1 = new ArrayList<Boolean>(); > > > final List<Boolean> completedOp2 = new ArrayList<Boolean>(); > > > > try { > > > > // change to for tests > > > final boolean commit1 = true; > > > final boolean commit2 = false; > > > > tx.setSynchronization(new > > > javax.transaction.Synchronization() { > > > public void beforeCompletion() { > > > log.info("before transaction 1"); > > > } > > > public void afterCompletion(int status) { > > > switch (status) { > > > case > > > javax.transaction.Status.STATUS_MARKED_ROLLBACK : > > > // fall through > > > case > > > javax.transaction.Status.STATUS_ROLLEDBACK : > > > log.severe("rollback transaction 1"); > > > break; > > > case > > > javax.transaction.Status.STATUS_COMMITTED: > > > log.info("committed transaction 1"); > > > completedOp1.add(Boolean.TRUE); > > > break; > > > case javax.transaction.Status.STATUS_UNKNOWN: > > > // treat as rollback both? > > > } > > > } > > > }); > > > tx2.setSynchronization(new > > > javax.transaction.Synchronization() { > > > public void beforeCompletion() { > > > log.info("before transaction 2"); > > > } > > > public void afterCompletion(int status) { > > > > switch (status) { > > > case > > > javax.transaction.Status.STATUS_MARKED_ROLLBACK : > > > // fall through > > > case > > > javax.transaction.Status.STATUS_ROLLEDBACK : > > > log.severe("rollback transaction 2"); > > > if (!completedOp1.isEmpty() && > > > completedOp1.get(0)) { > > > log.severe("1st transaction committed, > > > but 2nd did not"); > > > //TODO this is the case we need to > > > apply application logic for > > > retry2ndOperation(); > > > } > > > break; > > > case > > > javax.transaction.Status.STATUS_COMMITTED: > > > log.info("committed transaction 2"); > > > completedOp2.add(Boolean.TRUE); > > > break; > > > case javax.transaction.Status.STATUS_UNKNOWN: > > > // treat as rollback both? > > > } > > > } > > > }); > > > > tx.begin(); > > > > Key key1 = UserGameCredits.createKey(iden1); > > > UserGameCredits e1 = > > > pm.getObjectById(UserGameCredits.class, key1); > > > e1.setVariable("updated"); > > > > pm.flush(); > > > > if (commit1) { > > > tx.commit(); > > > } > > > > if (!completedOp1.isEmpty() && completedOp1.get(0)) { > > > > tx2.begin(); > > > > Key key2 = UserAccount.createKey(iden2); > > > UserAccount e2 = pm.getObjectById(UserAccount.class, > > > key2); > > > e2.setVariable("updated"); > > > > pm2.flush(); > > > > // test structure that shouldn't be in place for real > > > code! > > > // (the retry is in the sync code above) > > > if (commit2) { > > > tx2.commit(); > > > } else { > > > log.severe("1st transaction committed, but 2nd did > > > not"); > > > //TODO this is the case we need to apply > > > application logic for > > > retry2ndOperation(); > > > } > > > } > > > > } catch (Throwable t) { > > > > String msg = t.getMessage(); > > > > } finally { > > > > boolean > > ... > > read more » -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. 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