ClassNotFoundException: byte[] for serialized valued.

[vahid-01]

Hi. I have some problem with play-redis and I think this is a bug.
This Plugin is work fine if we didn't use custom serialization.
This is our scenario. The value serialized before set and deserialized after get.
The value after serialization is byte[] and the ClassTag stored in Redis is byte[].
When we called get we got this exception:

Caused by: java.lang.ClassNotFoundException: byte[]
	at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:466)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:566)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
	at play.api.cache.redis.impl.JavaRedis.decodeClassTag$1(JavaRedis.scala:60)
	at play.api.cache.redis.impl.JavaRedis.$anonfun$getOrElse$1(JavaRedis.scala:61)
	at scala.Option.map(Option.scala:146)
	at play.api.cache.redis.impl.JavaRedis.decodedClassTag$1(JavaRedis.scala:61)
	at play.api.cache.redis.impl.JavaRedis.$anonfun$getOrElse$2(JavaRedis.scala:63)
	at scala.util.Success.$anonfun$map$1(Try.scala:251)
	at scala.util.Success.map(Try.scala:209) 

If the byte[] is incorrect type for value, this method should be fix :

  def set( key: String, value: scala.Any, duration: Duration ): Future[ Done ] = {
    import dsl._

    Future.sequence(
      Seq(
        // set the value
        internal.set( key, value, duration ),
        // and set its type to be able to read it
        internal.set( s"classTag::$key", if ( value == null ) "" else value.getClass.getCanonicalName, duration )
      )
    ).map {
      case Seq( done, _ ) => done
    }
  }

Maybe if you define another set method that get class type our problem resolved!

Version of play-redis = 2.1.2
Version of Scala = 2.12.6
Version of Play = 2.6.15

[KarelCemus]

I am not sure I understand your issue. Can you implement a test to reproduce it?

I sounds like deserialization does not support type byte[].

The value serialized before set and deserialized after get.

Why? Akka provides a mechanism for custom serialization, why don't you use it?

[vahid-01]

Thanks for reply. We have custom Kryo serialization that work fine. I found akka kryo serialization that implement Kryo for akka but this plugin has bug for multi threading. So we have 2 option: 1- implement custom Kryo serialization for akka. 2- used old custom Kryo serialization with above scenario.

[KarelCemus]

What about this issue? Can you confirm the cause? I am not sure I understand it correctly.

And regarding Kryo, you can use explicit strategy instead of incremental. It works nice, I use it in tens of projects.

[vahid-01]

I write simple module in play that run this code :

package services;

import play.Logger;
import play.cache.SyncCacheApi;

import javax.inject.Inject;
import javax.inject.Singleton;

/**
 * @author vahid
 */
@Singleton
public class KryoBindService {

    private final SyncCacheApi syncCacheApi;
    protected final Logger.ALogger logger = Logger.of(getClass());


    @Inject
    public KryoBindService(SyncCacheApi syncCacheApi) {
        this.syncCacheApi = syncCacheApi;
        logger.info("start get and set byte[] to play redis");

        try {


            syncCacheApi.set("string", "vahid");
            System.out.println("string:" + syncCacheApi.get("string"));

            syncCacheApi.set("bytes", new byte[0]);
            System.out.println("bytes:" + String.valueOf(syncCacheApi.get("bytes")));

            logger.info("finish get and set byte[] to play redis");
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }
}

and got this error :

[info] 2018-07-03 14:13:18,099 s.KryoBindService - start get and set byte[] to play redis
string:vahid
java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.ClassNotFoundException: byte[]
	at play.cache.DefaultSyncCacheApi.blocking(DefaultSyncCacheApi.java:92)
	at play.cache.DefaultSyncCacheApi.get(DefaultSyncCacheApi.java:35)
	at services.KryoBindService.<init>(KryoBindService.java:31)
	at services.KryoBindService$$FastClassByGuice$$be9a370b.newInstance(<generated>)
	at com.google.inject.internal.DefaultConstructionProxyFactory$FastClassProxy.newInstance(DefaultConstructionProxyFactory.java:89)
	at com.google.inject.internal.ConstructorInjector.provision(ConstructorInjector.java:111)
	at com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:90)
	at com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:268)
	at com.google.inject.internal.ProviderToInternalFactoryAdapter$1.call(ProviderToInternalFactoryAdapter.java:46)
	at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1092)
	at com.google.inject.internal.ProviderToInternalFactoryAdapter.get(ProviderToInternalFactoryAdapter.java:40)
	at com.google.inject.internal.SingletonScope$1.get(SingletonScope.java:194)
	at com.google.inject.internal.InternalFactoryToProviderAdapter.get(InternalFactoryToProviderAdapter.java:41)
	at com.google.inject.internal.InternalInjectorCreator$1.call(InternalInjectorCreator.java:205)
	at com.google.inject.internal.InternalInjectorCreator$1.call(InternalInjectorCreator.java:199)
	at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1085)
	at com.google.inject.internal.InternalInjectorCreator.loadEagerSingletons(InternalInjectorCreator.java:199)
	at com.google.inject.internal.InternalInjectorCreator.injectDynamically(InternalInjectorCreator.java:180)
	at com.google.inject.internal.InternalInjectorCreator.build(InternalInjectorCreator.java:110)
	at com.google.inject.Guice.createInjector(Guice.java:99)
	at com.google.inject.Guice.createInjector(Guice.java:84)
	at play.api.inject.guice.GuiceBuilder.injector(GuiceInjectorBuilder.scala:185)
	at play.api.inject.guice.GuiceApplicationBuilder.build(GuiceApplicationBuilder.scala:137)
	at play.api.inject.guice.GuiceApplicationLoader.load(GuiceApplicationLoader.scala:21)
	at play.core.server.DevServerStart$$anon$1.$anonfun$reload$3(DevServerStart.scala:174)
	at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
	at play.core.server.DevServerStart$$anon$1.reload(DevServerStart.scala:171)
	at play.core.server.DevServerStart$$anon$1.get(DevServerStart.scala:124)
	at play.core.server.AkkaHttpServer.handleRequest(AkkaHttpServer.scala:222)
	at play.core.server.AkkaHttpServer.$anonfun$createServerBinding$1(AkkaHttpServer.scala:137)
	at akka.stream.impl.fusing.MapAsync$$anon$25.onPush(Ops.scala:1194)
	at akka.stream.impl.fusing.GraphInterpreter.processPush(GraphInterpreter.scala:519)
	at akka.stream.impl.fusing.GraphInterpreter.execute(GraphInterpreter.scala:411)
	at akka.stream.impl.fusing.GraphInterpreterShell.runBatch(ActorGraphInterpreter.scala:585)
	at akka.stream.impl.fusing.GraphInterpreterShell$AsyncInput.execute(ActorGraphInterpreter.scala:469)
	at akka.stream.impl.fusing.GraphInterpreterShell.processEvent(ActorGraphInterpreter.scala:560)
	at akka.stream.impl.fusing.ActorGraphInterpreter.akka$stream$impl$fusing$ActorGraphInterpreter$$processEvent(ActorGraphInterpreter.scala:742)
	at akka.stream.impl.fusing.ActorGraphInterpreter$$anonfun$receive$1.applyOrElse(ActorGraphInterpreter.scala:757)
	at akka.actor.Actor.aroundReceive(Actor.scala:517)
	at akka.actor.Actor.aroundReceive$(Actor.scala:515)
	at akka.stream.impl.fusing.ActorGraphInterpreter.aroundReceive(ActorGraphInterpreter.scala:667)
	at akka.actor.ActorCell.receiveMessage(ActorCell.scala:590)
	at akka.actor.ActorCell.invoke(ActorCell.scala:559)
	at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
	at akka.dispatch.Mailbox.run(Mailbox.scala:224)
	at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
	at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
	at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
	at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
	at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: java.util.concurrent.ExecutionException: java.lang.ClassNotFoundException: byte[]
	at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:395)
	at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2022)
	at scala.concurrent.java8.FuturesConvertersImpl$CF.super$get(FutureConvertersImpl.scala:84)
	at scala.concurrent.java8.FuturesConvertersImpl$CF.$anonfun$get$2(FutureConvertersImpl.scala:84)
	at akka.dispatch.MonitorableThreadFactory$AkkaForkJoinWorkerThread$$anon$3.block(ThreadPoolBuilder.scala:167)
	at akka.dispatch.forkjoin.ForkJoinPool.managedBlock(ForkJoinPool.java:3641)
	at akka.dispatch.MonitorableThreadFactory$AkkaForkJoinWorkerThread.blockOn(ThreadPoolBuilder.scala:165)
	at scala.concurrent.package$.blocking(package.scala:142)
	at scala.concurrent.java8.FuturesConvertersImpl$CF.get(FutureConvertersImpl.scala:84)
	at play.cache.DefaultSyncCacheApi.blocking(DefaultSyncCacheApi.java:86)
	... 49 more
Caused by: java.lang.ClassNotFoundException: byte[]
	at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:466)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:566)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
	at play.api.cache.redis.impl.JavaRedis.decodeClassTag$1(JavaRedis.scala:60)
	at play.api.cache.redis.impl.JavaRedis.$anonfun$getOrElse$1(JavaRedis.scala:61)
	at scala.Option.map(Option.scala:146)
	at play.api.cache.redis.impl.JavaRedis.decodedClassTag$1(JavaRedis.scala:61)
	at play.api.cache.redis.impl.JavaRedis.$anonfun$getOrElse$2(JavaRedis.scala:63)
	at scala.util.Success.$anonfun$map$1(Try.scala:251)
	at scala.util.Success.map(Try.scala:209)
	at scala.concurrent.Future.$anonfun$map$1(Future.scala:288)
	at scala.concurrent.impl.Promise.liftedTree1$1(Promise.scala:29)
	at scala.concurrent.impl.Promise.$anonfun$transform$1(Promise.scala:29)
	at scala.concurrent.impl.CallbackRunnable.run$$$capture(Promise.scala:60)
	at scala.concurrent.impl.CallbackRunnable.run(Promise.scala)
	at play.core.j.HttpExecutionContext$$anon$2.run(HttpExecutionContext.scala:56)
	at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:844)

The"classTag::bytes" for bytes key is byte[].
The error is exist.
I used incremental and default strategy and the problem exist for Kryo.

[KarelCemus]

Well, the workaround is quire simple, since you already handle (de)serialization yourself. Just produce a string instead of byte[] as Redis does not support bytes if I'm not wrong. So basically, the fix will serialize bytes probably into base64 or similar and you can do it yourself directly. I believe byte[] is not good data type for caching in redis. I agree that it is a bug but raised from discouraged use.