helenus/NOTES

--- Cache

cache entites (2 methods) marked @Cacheable
cache entites in txn context
cache results when .cache() chained before .{a}sync() call, return a EvictableCacheItem<E> that has an .evict() method
fix txn .andThen() chains




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);
            }
        });
	}