Examples of org.infinispan.distribution.ch.impl.SyncConsistentHashFactory

Package org.infinispan.distribution.ch.impl

Examples of org.infinispan.distribution.ch.impl.SyncConsistentHashFactory

org.infinispan.distribution.ch.impl.SyncConsistentHashFactory
One of the assumptions people made on consistent hashing involves thinking that given a particular key and same topology, it would produce the same consistent hash value no matter which cache it was stored in. However, that's not exactly the case in Infinispan. In order to the optimise the number of segments moved on join/leave, Infinispan uses a consistent hash that depends on the previous consistent hash. Given two caches, even if they contain exactly the same keyset, it's very easy for the consistent hash history to differ, e.g. if 2 nodes join you might see two separate topology change in one cache and a single topology change in the other. The reason for that each node has to send a {@link org.infinispan.topology.CacheTopologyControlCommand} for each cacheit wants to join and Infinispan can and does batch cache topology changes. For example, if a rebalance is in progress, joins are queued and send in one go when the rebalance has finished. This {@link org.infinispan.distribution.ch.ConsistentHashFactory} implementation avois any of the issuesmentioned and guarantees that multiple caches with the same members will have the same consistent hash. It has a drawback compared to {@link org.infinispan.distribution.ch.impl.DefaultConsistentHashFactory} though:it can potentially move a lot more segments during a rebalance than strictly necessary because it's not taking advantage of the optimisation mentioned above. @author Dan Berindei @since 5.2

   // percentiles to print
   public static final double[] PERCENTILES = { .999 };


   private DefaultConsistentHash createConsistentHash(int numSegments, int numOwners, int numNodes) {
      MurmurHash3 hash = new MurmurHash3();
      SyncConsistentHashFactory chf = new SyncConsistentHashFactory();
      DefaultConsistentHash ch = chf.create(hash, numOwners, numSegments, createAddresses(numNodes), null);
      return ch;
   }

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      cb.clustering().cacheMode(CacheMode.DIST_SYNC);


      Configuration c = cb.build();
      Assert.assertNull(c.clustering().hash().consistentHashFactory());


      SyncConsistentHashFactory consistentHashFactory = new SyncConsistentHashFactory();
      cb.clustering().hash().consistentHashFactory(consistentHashFactory);
      c = cb.build();
      Assert.assertSame(c.clustering().hash().consistentHashFactory(), consistentHashFactory);
   }

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   // percentiles to print
   public static final double[] PERCENTILES = { .999 };


   protected DefaultConsistentHash createConsistentHash(int numSegments, int numOwners, List<Address> members) {
      MurmurHash3 hash = new MurmurHash3();
      ConsistentHashFactory<DefaultConsistentHash> chf = new SyncConsistentHashFactory();
      DefaultConsistentHash ch = chf.create(hash, numOwners, numSegments, members, null);
      return ch;
   }

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 */
@Test(groups = "unit", testName = "distribution.ch.SyncConsistentHashFactoryTest")
public class SyncConsistentHashFactoryTest extends DefaultConsistentHashFactoryTest {
   @Override
   protected ConsistentHashFactory createConsistentHashFactory() {
      return new SyncConsistentHashFactory();
   }

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org.infinispan.configuration.HashConfigurationBuilderTest

org.infinispan.distribution.ch.SyncConsistentHashFactoryKeyDistributionTest

org.infinispan.distribution.ch.SyncConsistentHashFactoryTest

org.infinispan.remoting.transport.Address

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