Currently, the code is using bytes_opt and bytes_view_opt to represent
CQL values, which can hold a value or null. In preparation for
supporting a third state, unset value introduced in CQL v4, introduce
new raw_value and raw_value_view types and use them instead.
The new types are based on boost::variant<> and are capable of holding
null, unset values, and blobs that represent a value.
Every native scalar function is already tagged whether they're pure or
not but because we don't implement the is_pure() function, all functions
end up being advertised as pure. This means that functions like now()
that are *not* pure, end up being evaluated only once.
Fixes#571.
Message-Id: <1456227171-461-1-git-send-email-penberg@scylladb.com>
serialize() and from_bytes() is a low level interface, which in this
case can be replaced with a partition_key static factory method
resulting in cleaner code.
We use boost::any to convert to and from database values (stored in
serlialized form) and native C++ values. boost::any captures information
about the data type (how to copy/move/delete etc.) and stores it inside
the boost::any instance. We later retrieve the real value using
boost::any_cast.
However, data_value (which has a boost::any member) already has type
information as a data_type instance. By teaching data_type intances about
the corresponding native type, we can elimiante the use of boost::any.
While boost::any is evil and eliminating it improves efficiency somewhat,
the real goal is growing native type support in data_type. We will use that
later to store native types in the cache, enabling O(log n) access to
collections, O(1) access to tuples, and more efficient large blob support.
We need a container which can be used with compacting
allocators. "bytes" can't be used with compacting allocator because it
can't handle its external storage being moved.
Convert code to use the deserialize() function and drop the duplicate
compose() wrapper that we inherited from Origin.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
There's no benefit to using C include guards so switch to pragma once
everywhere for consistency.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Also replace derived types (map_type, collection_type, etc.).
As we'll change data_type's definition, this reduces the number of places
that need to be modified later, and is more readable.
To prepare a user-defined type, we need to look up its name in the keyspace.
While we get the keyspace name as an argument to prepare(), it is useless
without the database instance.
Fix the problem by passing a database reference along with the keyspace.
This precolates through the class structure, so most cql3 raw types end up
receiving this treatment.
Origin gets along without it by using a singleton. We can't do this due
to sharding (we could use a thread-local instance, but that's ugly too).
Hopefully the transition to a visitor will clean this up.
Change function argument types and return values to bytes_opt.
Note: a comment in the code says that NULL arguments are not supported,
but it seems prudent to prepare for the day they will be.
Registration was done with a null shared_ptr<> instead of make_shared(),
and as a result the max template wasn't even instantiated, so it did not
even build.
cql3_type is a wrapper around data_type, so there's no need for a class
hierarchy -- anything that depends on the actual type can be forwarded
to abstract_type_impl.
We can now use this as a value type (dropping shared_ptr<cql3_type>), but
that is left for later.
The Functions class wants to store functions in a map and hand them out later,
so we need a shared_ptr.
(could have had a map of name -> function factory, maybe one day)
