Hazelcast IMap以二进制形式获取

Question

Is there any way I can retrieve the entry as bytes from a Hazelcast map? We have an intermediate (Hz) message queue, where we would offer the map entry (value) through a local entry listener.

To reduce the (de)serialization cost, we are passing byte[] to the Hz queue. However, in order to do so we have to manually deserialize the entry object again before adding to the queue. It is the same object that is being passed and I was thinking of some way to reduce this 'redundant' deserialization.

Answer 1

You can do it by using internal APIs but those might change at any time in the future. I can give you an example but I'm not sure this is what you want to use.

edit: As mentioned before this uses a lot of internal APIs so PLEASE be aware of the fact it might change at any time (even without mentioning):

public class Test {
  public static void main(String[] args) throws Exception {
    HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();

    IMap<String, String> map = hazelcastInstance.getMap("myMapName");

    String key = "mySearchedKey";
    map.put(key, "foo");

    SerializationService serializationService = getSerializationService(map);
    Data keyData = serializationService.toData(key);

    RecordStore recordStore = getRecordStore(map, key);
    Record record = recordStore.getRecord(keyData);

    // This will do no serialization in most cases since Data is a DataRecord
    // only for InMemoryFormat::OBJECT this will serialize the object to a Data
    // instance
    Data serializedValue = serializationService.toData(record.getValue());
  }

  /**
   * This method handles internal APIs!!!
   */
  private static SerializationService getSerializationService(IMap<String, String> map) {
    MapProxyImpl<String, String> proxy = (MapProxyImpl<String, String>) map;
    return proxy.getNodeEngine().getSerializationService();
  }

  /**
   * This method handles internal APIs!!!
   */
  private static RecordStore getRecordStore(IMap<String, String> map, String key) throws Exception {
    MapProxyImpl<String, String> proxy = (MapProxyImpl<String, String>) map;
    HazelcastInstance hazelcastInstance = proxy.getNodeEngine().getHazelcastInstance();

    MapService mapService = proxy.getService();
    MapServiceContext mapServiceContext = mapService.getMapServiceContext();

    PartitionService partitionService = hazelcastInstance.getPartitionService();
    Partition partition = partitionService.getPartition(key);

    PartitionContainer partitionContainer = mapServiceContext.getPartitionContainer(partition.getPartitionId());
    return partitionContainer.getRecordStore("myMapName");
  }
}