This patch adds a new `LWT` flag to `cql3::prepared_metadata`.
That allows clients to clearly distinguish betwen lwt and
non-lwt statements without need to execute some custom parsing
logic (e.g. parsing the prepared query with regular expressions),
which is obviously quite fragile.
The feature is meant to be further utilized by client drivers
to use primary replicas consistently when dealing with conditional
statements.
Whether to use lwt optimization flag or not is handled by negotiation
procedure between scylla server and client library via SUPPORTED/STARTUP
messages (`LWT_ADD_METADATA_MARK` extension).
Tests: unit(dev, debug), manual testing with modified scylla/gocql driver
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
cql_statement is a class representing a prepared statement in Scylla.
It is used concurrently during execution, so it is important that its
change is not changed by execution.
Add const qualifier to the execution methods family, throghout the
cql hierarchy.
Mark a few places which do mutate prepared statement state during
execution as mutable. While these are not affecting production today,
as code ages, they may become a source of latent bugs and should be
moved out of the prepared state or evaluated at prepare eventually:
cf_property_defs::_compaction_strategy_class
list_permissions_statement::_resource
permission_altering_statement::_resource
property_definitions::_properties
select_statement::_opts
cql_statement_opt_metadata is an interim node
in cql (prepared) statement hierarchy parenting
modification_statement and batch_statement. If there
is IF condition in such statements, they return a result set,
and thus have a result set metadata.
The metadata itself is filled in a subsequent patch.
Determine which timeout we need to apply at prepare time. We
don't know the numerical value (since it depends on whoever is
executing the query, not just the statement type), but we know
which member of timeout_config we need, so determine and remember
that.
The storage_proxy represents the entire cluster, so there's never a need
to access it on a remote shard; the local shard instance will contact
remote shard or remote nodes as needed.
Simplify the API by passing storage_proxy references instead of
seastar::sharded<storage_proxy> references. query_processor and
other callers are adjusted to call seastar::sharded::local() first.
Message-Id: <20180415142656.25370-2-avi@scylladb.com>
- introcduced "seastarx.hh" header, which does a "using namespace seastar";
- 'net' namespace conflicts with seastar::net, renamed to 'netw'.
- 'transport' namespace conflicts with seastar::transport, renamed to
cql_transport.
- "logger" global variables now conflict with logger global type, renamed
to xlogger.
- other minor changes
Metadata usually doesn't change after it is created; make that visible in
the code, allowing further optimizations to be applied later.
Message-Id: <1464334638-7971-3-git-send-email-avi@scylladb.com>
Rather than dynamic_cast<>ing the statement to see whether it is a
select statement, add a virtual function to cql_statement to get the
result metadata.
This is faster and easier to follow.
Message-Id: <1464334638-7971-2-git-send-email-avi@scylladb.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>
There's a cyclic dependency between cql3 and transport namespaces when
we introduce prepared statements. The latter pulls
parsed_statement::prepared from the former. Break the cycle by using
a forward delcaration in cql_statement.hh.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
It's compared with size_t and is set from size_t. To avoid ugly casts
we can store it as unsigned int. It's always positive anyway. Origin
uses signed int ("int") because there is no unsigned int in Java.
The method may defer so the result is wrapped in future<>.
I think we don't need to wrap arguments in shared_ptr<> because they
may come from the request state object.
