[infinispan-issues] [JBoss JIRA] (ISPN-3163) Replacing entry via HotRod which was initially stored via Memcached does not change CAS

[Martin Gencur (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-3163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12778414#comment-12778414 ] 

Martin Gencur commented on ISPN-3163:
-------------------------------------

If I change the value via REST, the subsequent .gets() operation (which returns CASValue) fails with an exception:
{code}
 Reconnection due to exception handling a memcached operation on {QA sa=/127.0.0.1:16211, #Rops=1, #Wops=0, #iq=0, topRop=net.spy.memcached.protocol.ascii.GetsOperationImpl at f89761c, topWop=null, toWrite=0, interested=1}.  This may be due to an authentication failure.
OperationException: SERVER: SERVER_ERROR java.lang.NullPointerException
	at net.spy.memcached.protocol.BaseOperationImpl.handleError(BaseOperationImpl.java:123)
	at net.spy.memcached.protocol.ascii.OperationImpl.readFromBuffer(OperationImpl.java:130)
	at net.spy.memcached.MemcachedConnection.handleReads(MemcachedConnection.java:401)
	at net.spy.memcached.MemcachedConnection.handleIO(MemcachedConnection.java:333)
	at net.spy.memcached.MemcachedConnection.handleIO(MemcachedConnection.java:219)
	at net.spy.memcached.MemcachedClient.run(MemcachedClient.java:1591)
{code}

OTOH, the .get() operation (note the missing "s" in the name) works correctly
                
> Replacing entry via HotRod which was initially stored via Memcached does not change CAS
> ---------------------------------------------------------------------------------------
>
>                 Key: ISPN-3163
>                 URL: https://issues.jboss.org/browse/ISPN-3163
>             Project: Infinispan
>          Issue Type: Bug
>    Affects Versions: 5.3.0.CR1
>            Reporter: Martin Gencur
>            Assignee: Galder Zamarreño
>             Fix For: 5.3.0.Final
>
>
> Users might expect that CAS (check-and-set) operation will work even in compatibility mode which is currently not true in the following scenario:
> 1) store a key/value via Memcached
> 2) change the value via HotRod or Embedded 
> 3) use Memcached's CAS operation
> In step #3 the memcached client will update the value even though the value was changed by another client in the meantime. The memcached client was supposed to change it only if it had not been changed in the meantime.
> The following test snippet shows the problem:
> {code:java}
> public void testMemcachedPutHotRodEmbbeddedReplaceMemcachedCASTest() throws Exception {
>       final String key1 = "5";
>       // 1. Put with Memcached
>       Future<Boolean> f = cacheFactory.getMemcachedClient().set(key1, 0, "v1");
>       assertTrue(f.get(60, TimeUnit.SECONDS));
>       CASValue oldValue = cacheFactory.getMemcachedClient().gets(key1);
>       // 2. Replace with Hot Rod
>       VersionedValue versioned = cacheFactory.getHotRodCache().getVersioned(key1);
>       assertTrue(cacheFactory.getHotRodCache().replaceWithVersion(key1, "v2", versioned.getVersion()));
>       // 3. Replace with Embedded
>       assertTrue(cacheFactory.getEmbeddedCache().replace(key1, "v2", "v3"));
>       // 4. Get with Memcached and verify value/CAS
>       CASValue newValue = cacheFactory.getMemcachedClient().gets(key1);
>       assertEquals("v3", newValue.getValue());
>       assertTrue("The version (CAS) should have changed", oldValue.getCas() != newValue.getCas()); 
> //<---- fails here
>    }
> {code}

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