public Object get(Object key) {
    byte[] byteKey = keySerde.toBytes(key);
    byte[] result = null;
    try {
      result = db.get(byteKey);
    } catch (RocksDBException e) {
      log.error("can not get the value for key: " + key);
    }

    if (result == null) {
      log.info(key + " does not exist in the rocksDb");
      return null;
    } else {
      return valueSerde.fromBytes(result);
    }
  }
get the value from the key. This key will be serialized to bytes using the
serde defined in <i>systems.system-name.samza.key.serde</i>. The result
will be deserialized back to the object using the serde in
<i>systems.system-name.samza.msg.serde</i>. If the value does not exist in
the db, it return null.

@param key the key of the value you want to get
@return deserialized value for the key
        Returns null, if the value doesn't exist
samza-kv-rocksdb/src/main/java/org/apache/samza/storage/kv/RocksDbKeyValueReader.java