helenus/NOTES

Operation/
|-- AbstractStatementOperation
|   |-- AbstractOperation
|   |   |-- AbstractFilterOperation
|   |   |   |-- CountOperation
|   |   |   |-- DeleteOperation
|   |   |   `-- UpdateOperation
|   |   |-- BoundOperation
|   |   `-- InsertOperation
|   |-- AbstractOptionalOperation
|   |   |-- AbstractFilterOptionalOperation
|   |   |   |-- SelectFirstOperation
|   |   |   `-- SelectFirstTransformingOperation
|   |   `-- BoundOptionalOperation
|   `-- AbstractStreamOperation
|       |-- AbstractFilterStreamOperation
|       |   |-- SelectOperation
|       |   `-- SelectTransformingOperation
|       `-- BoundStreamOperation
|-- PreparedOperation
|-- PreparedOptionalOperation
`-- PreparedStreamOperation


    // TODO(gburd): create a statement that matches one that wasn't prepared
    //String key =
    //    "use " + preparedStatement.getQueryKeyspace() + "; " + preparedStatement.getQueryString();
    //for (Object param : params) {
    //  key = key.replaceFirst(Pattern.quote("?"), param.toString());
    //}




primitive types have default values, (e.g. boolean, int, ...) but primative wrapper classes do not and can be null (e.g. Boolean, Integer, ...)

create table wal {
  id timeuuid,
  follows timeuuid,
  read <Counting Quotient Filter, Set<{keyspace, col, schema generation, timestamp}>>
  write <Counting Quotient Filter, Set<{keyspace, col, schema generation, timestamp}>>
  primary key (id, follows)
}
begin:
  - insert into wal (timeuuid, parent timeuuid,



        // NOTE: Update operations have no meaning when they only contain primary key components, so
        // given that `properties` is ordered with the keys first if we find that the last element
        // is either a partition key or clustering column then we know we should just skip this operation.
        ColumnType ct = ((HelenusProperty) properties.toArray()[properties.size() - 1]).getColumnType();
        if (ct != ColumnType.PARTITION_KEY && ct != ColumnType.CLUSTERING_COLUMN) {
            return;
        }



	public Stream<E> sync() {
	    ListenableFuture<Stream<E>> future = async();
        Futures.addCallback(future, new FutureCallback<String>() {
            @Override
            public void onSuccess(String contents) {
                //...process web site contents
            }

            @Override
            public void onFailure(Throwable throwable) {
                log.error("Exception in task", throwable);
            }
        });
	}
-------
  private mergeCache(Map<String, Set<Object>>

  private static <E> Iterable<E> concat(
          Iterable<? extends E> i1,
          Iterable<? extends E> i2) {
    return new Iterable<E>() {
      public Iterator<E> iterator() {
        return new Iterator<E>() {
          Iterator<? extends E> listIterator = i1.iterator();
          Boolean checkedHasNext;
          E nextValue;
          private boolean startTheSecond;

          void theNext() {
            if (listIterator.hasNext()) {
              checkedHasNext = true;
              nextValue = listIterator.next();
            } else if (startTheSecond)
              checkedHasNext = false;
            else {
              startTheSecond = true;
              listIterator = i2.iterator();
              theNext();
            }
          }

          public boolean hasNext() {
            if (checkedHasNext == null)
              theNext();
            return checkedHasNext;
          }

          public E next() {
            if (!hasNext())
              throw new NoSuchElementException();
            checkedHasNext = null;
            return nextValue;
          }

          public void remove() {
            listIterator.remove();
          }
        };
      }
    };
  }
----------------------------------
      if ("ttl".equals(methodName) && method.getParameterCount() == 1 && method.getReturnType() == int.class) {
          Getter getter = (Getter) args[0];
          if (getter == null) {
              return false;
          }
          HelenusProperty prop = MappingUtil.resolveMappingProperty(getter).getProperty();
          String getterName = prop.getPropertyName();
          String ttlKeyForProperty = prop.getColumnName().toCql() + "_ttl";
          if (src.containsKey(ttlKeyForProperty)) {
              return src.get(ttlKeyForProperty);
          } else {
              return 0;
          }
      }

      if ("written".equals(methodName) && method.getParameterCount() == 1 && method.getReturnType() == int.class) {
          Getter getter = (Getter) args[0];
          if (getter == null) {
              return false;
          }
          HelenusProperty prop = MappingUtil.resolveMappingProperty(getter).getProperty();
          String getterName = prop.getPropertyName();
          String ttlKeyForProperty = prop.getColumnName().toCql() + "_ttl";
          if (src.containsKey(ttlKeyForProperty)) {
              return src.get(ttlKeyForProperty);
          } else {
              return 0;
          }
      }



-----------------


/*else {
			    Cache<String, Object> cache = session.getSessionCache();
				Map<String, Object> rowMap = this.cache.rowMap();
				for (String rowKey : rowMap.keySet()) {
					String keys = flattenFacets(facets);
					for (String key : keys) {
						Object value = cache.getIfPresent(key);
						if (value != null) {
							result = Optional.of(value);
							break;
						}
					}
				}
			    cache.put
            }
			*/