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
Commit aab6b0ee27 introduced the
controversial new IMR format, which relied on a very template-heavy
infrastructure to generate serialization and deserialization code via
template meta-programming. The promise was that this new format, beyond
solving the problems the previous open-coded representation had (working
on linearized buffers), will speed up migrating other components to this
IMR format, as the IMR infrastructure reduces code bloat, makes the code
more readable via declarative type descriptions as well as safer.
However, the results were almost the opposite. The template
meta-programming used by the IMR infrastructure proved very hard to
understand. Developers don't want to read or modify it. Maintainers
don't want to see it being used anywhere else. In short, nobody wants to
touch it.
This commit does a conceptual revert of
aab6b0ee27. A verbatim revert is not
possible because related code evolved a lot since the merge. Also, going
back to the previous code would mean we regress as we'd revert the move
to fragmented buffers. So this revert is only conceptual, it changes the
underlying infrastructure back to the previous open-coded one, but keeps
the fragmented buffers, as well as the interface of the related
components (to the extent possible).
Fixes: #5578
atomic_cell_or_collection is also declared as a friend class further
down, and gcc appears to inject this friend declration into the
global namespace. Clang appears not to, and so complains when
atomic_cell_or_collection is mentioned in the declaration of
merge_column().
Add a forward declaration in the global namespace to satisfy clang.
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 standard printer for atomic_cell prints the value as hex,
because atomic_cell does not include the type. Add a type-aware
printer that allows the user to provide the type.
The classes 'collection_mutation' and 'collection_mutation_view'
were moved to a separate header, collection_mutation.hh.
Implementations of functions that operate on these classes,
including some methods of collection_type_impl, were moved
to a separate compilation unit, collection_mutation.cc.
This makes it easier to modify these structures in future commits
in order to generalize them for non-frozen User Defined Types.
Some additional documentation has been written for collection_mutation.
* seastar d59fcef...b924495 (2):
> build: Fix protobuf generation rules
> Merge "Restructure files" from Jesse
Includes fixup patch from Jesse:
"
Update Seastar `#include`s to reflect restructure
All Seastar header files are now prefixed with "seastar" and the
configure script reflects the new locations of files.
Signed-off-by: Jesse Haber-Kucharsky <jhaberku@scylladb.com>
Message-Id: <5d22d964a7735696fb6bb7606ed88f35dde31413.1542731639.git.jhaberku@scylladb.com>
"
This patch changes the implementation of atomic_cell and
atomic_cell_or_collection to use the data::cell implementation which is
based on the new in-memory representation infrastructure.
Collections are not going to be fully converted to the IMR just yet and
still use the old serialisation format. This means that they still don't
support fragmented values very well. This patch passes the information
when an atomic_cell is created as a member of a collection so that later
we can avoid fragmenting the value in such cases.
As a prepratation for the switch to the new cell representation this
patch changes the type returned by atomic_cell_view::value() to one that
requires explicit linearisation of the cell value. Even though the value
is still implicitly linearised (and only when managed by the LSA) the
new interface is the same as the target one so that no more changes to
its users will be needed.
The general algorithm for merging counter cells involves allocating a
new buffer for the shards. However, it is expected that most of the
applies are just updating the values of existing shards and not adding
new ones, therefore can be done in place.
However, reverting the general and in-place applies requires different
logic, hence the need for an additional flag to differentiate between
them.
This patch attempts to avoid excessive allocations and copies when
constructing counter cells using counter_cell_builder. That involves
adding serializer interface to atomic_cell so that the counter cell can
be directly serialized to the buffer allocated for atomic cell.
counter_cell_builder::from_single_shard() is added as well to avoid
std::vector<> overhead when creating a counter cell from a single shard.
Support for deletion of counters is limited in a way that once deleted
they cannot be used again (i.e. tombstone always wins, regardless of the
timestamp). Logic responsible for merging two counter cells already
makes sure that tombstones are handled properly, but it is also
necessary to ensure that higher level tombstones always cover counters.
Deserialization code is going to use a proxy object that will be casted
to either bytes or bytes_ostream depending on the demand. It cannot be
casted directly to bytes_view though as it won't extend the lifetime of
the buffer appropriately. The simples solution is just to add overloads
that accept const bytes&.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
Add linearize() and unlinearize() methods that allow making an
atomic_cell_or_collection object temporarily contiguous, so we can examine
it as a bytes_view.
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.
