Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
_rows uses a deque, but doesn't need any special functionality.
Switch to chunked_vector, which uses one less allocation in the
common case (std::deque has an extra allocation for managing its
chunks).
Closes#8679
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>
The patch introduces two new features to aid with negotiating
protocol extensions for the CQL protocol:
- `cql_protocol_extensions` enum, which holds all supported
extensions for the CQL protocol (currently contains only
`LWT_ADD_METADATA_MARK` extension, which will be mentioned
below).
- An additional mechainsm of negotiating cql protocol extensions
to be used in a client connection between a scylla server
and a client driver.
These extensions are propagated in SUPPORTED message sent from the
server side with "SCYLLA_" prefix and received back as a response
from the client driver in order to determine intersection between
the cql extensions that are both supported by the server and
acknowledged by a client driver.
This intersection of features is later determined to be a working
set of cql protocol extensions in use for the current `client_state`,
which is associated with a particular client connection.
This way we can easily settle on the used extensions set on
both sides of the connection.
Currently there is only one value: `LWT_ADD_METADATA_MARK`, which
regulates whether to set a designated bit in prepared statement
metadata indicating if the statement at hand is an lwt statement
or not (actual implementation for the feature will be in a later
patch).
Each extension can also propagate some custom parameters to the
corresponding key. CQL protocol specification allows to send
a list of values with each key in the SUPPORTED message, we use
that to pass parameters to extensions as `PARAM=VALUE` strings.
In case of `LWT_ADD_METADATA_MARK` it's
`SCYLLA_LWT_OPTIMIZATION_META_BIT_MASK` which designates the
bitmask for LWT flag in prepared statement metadata in order to be
used for lookup in a client library. The associated bits of code in
`cql3::prepared_metadata` are adjusted to accomodate the feature.
The value for the flag is chosen on purpose to be the last bit
in the flags bitset since we don't want to possibly clash with
C* implementation in case they add more possible flag values to
prepared metadata (though there is an issue regarding that:
https://issues.apache.org/jira/browse/CASSANDRA-15746).
If it's fixed in upstream Cassandra, then we could synchronize
the value for the flag with them.
Also extend the underlying type of `flag` enum in
`cql3::prepared_metadata` to be `uint32_t` instead of `uint8_t`
because in either case flags mask is serialized as 32-bit integer.
In theory, shard-awareness extension support also should be
reworked in terms of provided minimal infrastructure, but for the
sake of simplicity, this is left to be done in a follow-up some
time later.
This solution eliminates the need to assume that all the client
drivers follow the CQL spec carefully because scylla-specific
features and protocol extensions could be enabled only in case both
server and client driver negotiate the supported feature set.
Tests: unit(dev, debug)
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Seastar recently lost support for the experimental Concepts Technical
Specification (TS) and gained support for C++20 concepts. Re-enable
concepts in Scylla by updating our use of concepts to the C++20
standard.
This change:
- peels off uses of the GCC6_CONCEPT macro
- removes inclusions of <seastar/gcc6-concepts.hh>
- replaces function-style concepts (no longer supported) with
equation-style concepts
- semicolons added and removed as needed
- deprecated std::is_pod replaced by recommended replacement
- updates return type constraints to use concepts instead of
type names (either std::same_as or std::convertible_to, with
std::same_as chosen when possible)
No attempt is made to improve the concepts; this is a specification
update only.
Message-Id: <20200531110254.2555854-1-avi@scylladb.com>
The header sits in many other headers, but there's a handy
schema_fwd.hh that's tiny and contains needed declarations
for other headers. So replace shema.hh with schema_fwd.hh
in most of the headers (and remove completely from some).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20200303102050.18462-1-xemul@scylladb.com>
Change the way `service::pager::paging_state` is passed around
from `shared_ptr` to `lw_shared_ptr`. It's safe since
`paging_state` is final.
Tests: unit(dev, debug)
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Changes summary:
* make `cql3::result_set` movable-only
* change signature of `cql3::result::result_set` to return by cref
* adjust available call sites to the aforementioned method to accept cref
Motivation behind this change is elimination of dangerous API,
which can easily set a trap for developers who don't expect that
result_set would be returned by value.
There is no point in copying the `result_set` around, so make
`cql3::result::result_set` to cache `result_set` internally in a
`unique_ptr` member variable and return a const reference so to
minimize unnecessary copies here and there.
Tests: unit(debug)
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Message-Id: <20191220115100.21528-1-pa.solodovnikov@scylladb.com>
The column-related metadata is shared by all requests done with the same
perpared query. However, metadata class contains also some additional
flags and paging state which may differ. This patch allows sharing
column information among multiple instances of the metadata class.
cql3::result can now hold either a result_set or a result_generator.
Some code that is not performance critical expects to get result_set so
a way of converting the result_generator to a result_set is added.
So far the only way of returing a result of a CQL query was to build a
result_set. An alternative lazy result generator is going to be
introduced for the simple cases when no transformations at CQL layer are
needed. To do that we need to hide the fact that there are going to be
multiple representations of a cql results from the users.
This visiting interface for result_set satisfies most of its users (at
least all of those which are in the hot path). It will allow having an
alternative of result_set (i.e. lazy result generator) which would
provide exaclty the same interface.
We both move names_ to its destination, and call names_.size() in the same
expression; this has undefined evaluation order, and fails with clang.
With this patch as well as the clang build fixes, Scylla starts and is
able to serve requests (light cassandra-stress load).
Message-Id: <20170423121727.1948-1-avi@scylladb.com>
Clang complains about some error without it, I could not understand it, but
I'm not going to argue with it.
Since std::sort() will copy the comparator, it's better to pass using an
std::ref(), and everyone is happy.
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>
Introduce a new prepared_metadata class that holds prepared statement
metadata and implement CQL binary protocol serialization that works for
all versions.
The gocql driver assumes that there's a result metadata section in the
PREPARED message. Technically, Scylla is not at fault here as the CQL
specification explicitly states in Section 4.2.5.4. ("Prepared") that the
section may be empty:
- <result_metadata> is defined exactly as <metadata> but correspond to the
metadata for the resultSet that execute this query will yield. Note that
<result_metadata> may be empty (have the No_metadata flag and 0 columns, See
section 4.2.5.2) and will be for any query that is not a Select. There is
in fact never a guarantee that this will non-empty so client should protect
themselves accordingly. The presence of this information is an
However, Cassandra always populates the section so lets do that as well.
Fixes#912.
Message-Id: <1456317082-31688-1-git-send-email-penberg@scylladb.com>
