Could you please guide be through the process? Should I create just a simple 
project anywhere and share it here or I should create a test case in the Ignite 
project?

From: Ilya Kasnacheev <[email protected]>
Reply-To: "[email protected]" <[email protected]>
Date: Tuesday, October 6, 2020 at 3:44 PM
To: "[email protected]" <[email protected]>
Subject: Re: Ignite 2.8.1 ContinuousQueryWithTransformer: ClassCastException on 
PME

Hello!

Do you have a reproducer for this issue? I think I could validate it and create 
an issue if you do.

Can you please also check if it works or not on e.g. Apache Ignite 2.9RC2?

Regards,
--
Ilya Kasnacheev


вт, 6 окт. 2020 г. в 14:30, 
<[email protected]<mailto:[email protected]>>:
Hi everyone!

I am getting the ClassCastException when a node from my cluster fails over. It 
looks like the root cause is that nodes are loading some keys from their 
backups and the CacheContinousQueryHandler is assuming that the entries are 
already converted by the remote side which is a false expectation.

The stacktrace is:

Caused by: java.lang.ClassCastException: 
org.apache.ignite.internal.binary.BinaryObjectImpl cannot be cast to 
java.lang.String

...

        at 
org.apache.ignite.internal.processors.cache.query.continuous.CacheContinuousQueryHandler.notifyLocalListener(CacheContinuousQueryHandler.java:1114)

        at 
org.apache.ignite.internal.processors.cache.query.continuous.CacheContinuousQueryHandler.notifyCallback0(CacheContinuousQueryHandler.java:940)

        at 
org.apache.ignite.internal.processors.cache.query.continuous.CacheContinuousQueryHandler.notifyCallback(CacheContinuousQueryHandler.java:881)

        at 
org.apache.ignite.internal.processors.continuous.GridContinuousProcessor.addBackupNotification(GridContinuousProcessor.java:1161)

        at 
org.apache.ignite.internal.processors.cache.query.continuous.CacheContinuousQueryHandler$2.flushBackupQueue(CacheContinuousQueryHandler.java:498)

        at 
org.apache.ignite.internal.processors.cache.query.continuous.CacheContinuousQueryManager.flushBackupQueue(CacheContinuousQueryManager.java:687)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture.onDone(GridDhtPartitionsExchangeFuture.java:2261)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture.processFullMessage(GridDhtPartitionsExchangeFuture.java:4375)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture.access$1500(GridDhtPartitionsExchangeFuture.java:148)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture$4.apply(GridDhtPartitionsExchangeFuture.java:4054)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture$4.apply(GridDhtPartitionsExchangeFuture.java:4042)

        at 
org.apache.ignite.internal.util.future.GridFutureAdapter.notifyListener(GridFutureAdapter.java:399)

        at 
org.apache.ignite.internal.util.future.GridFutureAdapter.listen(GridFutureAdapter.java:354)

        at 
org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture.onReceiveFullMessage(GridDhtPartitionsExchangeFuture.java:4042)

        at 
org.apache.ignite.internal.processors.cache.GridCachePartitionExchangeManager.processFullPartitionUpdate(GridCachePartitionExchangeManager.java:1886)

        at 
org.apache.ignite.internal.processors.cache.GridCachePartitionExchangeManager$3.onMessage(GridCachePartitionExchangeManager.java:429)

        at 
org.apache.ignite.internal.processors.cache.GridCachePartitionExchangeManager$3.onMessage(GridCachePartitionExchangeManager.java:416)

        at 
org.apache.ignite.internal.processors.cache.GridCachePartitionExchangeManager$MessageHandler.apply(GridCachePartitionExchangeManager.java:3667)

        at 
org.apache.ignite.internal.processors.cache.GridCachePartitionExchangeManager$MessageHandler.apply(GridCachePartitionExchangeManager.java:3646)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager.processMessage(GridCacheIoManager.java:1142)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager.onMessage0(GridCacheIoManager.java:591)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager.handleMessage(GridCacheIoManager.java:392)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager.handleMessage(GridCacheIoManager.java:318)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager.access$100(GridCacheIoManager.java:109)

        at 
org.apache.ignite.internal.processors.cache.GridCacheIoManager$1.onMessage(GridCacheIoManager.java:308)

        at 
org.apache.ignite.internal.managers.communication.GridIoManager.invokeListener(GridIoManager.java:1847)

        at 
org.apache.ignite.internal.managers.communication.GridIoManager.processRegularMessage0(GridIoManager.java:1472)

        at 
org.apache.ignite.internal.managers.communication.GridIoManager.access$5200(GridIoManager.java:229)

        at 
org.apache.ignite.internal.managers.communication.GridIoManager$9.run(GridIoManager.java:1367)

The workaround is:

public abstract class CqWithTransformerLocalListenerAdapter<T>
   implements ContinuousQueryWithTransformer.EventListener<T>
{
   private final Function<BinaryObject, T> localTransformer;

   protected CqWithTransformerLocalListenerAdapter(Function<BinaryObject, T> 
localTransformer) {
      this.localTransformer = localTransformer;
   }

   /**
    * The same as {@link 
ContinuousQueryWithTransformer.EventListener#onUpdated(Iterable)},
    * but guarantees that entities are transformed.
    */
   protected abstract void onUpdatedTransformed(Iterable<T> entities);

   @Override
   public final void onUpdated(Iterable entities) {
      onUpdatedTransformed(new IterableAdapter(entities));
   }

   private class IterableAdapter implements Iterable<T> {
      private final Iterable<?> entities;

      public IterableAdapter(Iterable<?> entities) {
         this.entities = entities;
      }

      @NotNull
      @Override
      public Iterator<T> iterator() {
         return new IteratorWrapper(entities.iterator());
      }
   }

   private class IteratorWrapper implements Iterator<T> {
      private final Iterator<?> underlying;

      public IteratorWrapper(Iterator<?> underlying) {
         this.underlying = underlying;
      }

      @Override
      public boolean hasNext() {
         return underlying.hasNext();
      }

      @Override
      public T next() {
         Object o = underlying.next();
         // Sometimes an entity may be in a binary form (see javadoc of the 
enclosing class).
         if (o instanceof BinaryObject) {
            return localTransformer.apply((BinaryObject) o);
         }
         // The entity has been converted by a remote transformer
         return (T) o;
      }
   }
}

Best regards,
Ivan Fedorenkov

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