The chunk size used in sstable compression can be set when creating a
table, using the "chunk_length_in_kb" parameter. It can be any power-of-two
multiple of 1KB. Very large compression chunks are not useful - they
offer diminishing returns on compression ratio, and require very large
memory buffers and reading a very large amount of disk data just to
read a small row. In fact, small chunks are recommended - Scylla
defaults to 4 KB chunks, and Cassandra lowered their default from 64 KB
(in Cassandra 3) to 16 KB (in Cassandra 4).
Therefore, allowing arbitrarily large chunk sizes is just asking for
trouble. Today, a user can ask for a 1 GB chunk size, and crash or hang
Scylla when it runs out of memory. So in this patch we add a hard limit
of 128 KB for the chunk size - anything larger is refused.
Fixes#9933
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#14267
in C++20, compiler generate operator!=() if the corresponding
operator==() is already defined, the language now understands
that the comparison is symmetric in the new standard.
fortunately, our operator!=() is always equivalent to
`! operator==()`, this matches the behavior of the default
generated operator!=(). so, in this change, all `operator!=`
are removed.
in addition to the defaulted operator!=, C++20 also brings to us
the defaulted operator==() -- it is able to generated the
operator==() if the member-wise lexicographical comparison.
under some circumstances, this is exactly what we need. so,
in this change, if the operator==() is also implemented as
a lexicographical comparison of all memeber variables of the
class/struct in question, it is implemented using the default
generated one by removing its body and mark the function as
`default`. moreover, if the class happen to have other comparison
operators which are implemented using lexicographical comparison,
the default generated `operator<=>` is used in place of
the defaulted `operator==`.
sometimes, we fail to mark the operator== with the `const`
specifier, in this change, to fulfil the need of C++ standard,
and to be more correct, the `const` specifier is added.
also, to generate the defaulted operator==, the operand should
be `const class_name&`, but it is not always the case, in the
class of `version`, we use `version` as the parameter type, to
fulfill the need of the C++ standard, the parameter type is
changed to `const version&` instead. this does not change
the semantic of the comparison operator. and is a more idiomatic
way to pass non-trivial struct as function parameters.
please note, because in C++20, both operator= and operator<=> are
symmetric, some of the operators in `multiprecision` are removed.
they are the symmetric form of the another variant. if they were
not removed, compiler would, for instance, find ambiguous
overloaded operator '=='.
this change is a cleanup to modernize the code base with C++20
features.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13687
`LZ4_compress_default()` was introduced in liblz4 v1.7.3, despite
that the release note (https://github.com/lz4/lz4/releases/tag/v1.7.3)
of v1.7.3 didn't mention this. if we check the commit which added
this API, we can find all releases including it: see
```
$ git tag --contains 1b17bf2ab8cf66dd2b740eca376e2d46f7ad7041
lz4-r130
r129
r130
r131
rc129v0
v1.7.3
v1.7.4
v1.7.4.2
v1.7.5
v1.8.0
v1.8.1
v1.8.1.2
v1.8.2
v1.8.3
v1.9.0
v1.9.1
v1.9.2
v1.9.3
v1.9.4
```
and v1.7.3 was released in Nov 17, 2016. some popular distros
releases also package new enough liblz4:
- fedora 35 ships lz4-devel 1.9.3,
- CentOS 7 ships lz4-devel 1.8.3
- debian 10 ships liblz4-dev 1.8.3
- ubuntu 18.04 ships liblz4-dev r131
so, in this change, we drop the support of liblz4 < 1.7.3 for better
code readability.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#12971
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
Enable creating shared_ptr<BaseClass> in nonstatic_class_registry
using BaseClass::ptr_type and use that for
abstract_replication_strategy.
While at it, also clean up compressor with that respect
to define compressor::ptr_type as shared_ptr<compressor>
thus simplifying compressor_registry.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Cassandra 3.0 deprecated the 'sstable_compression' attribute and added
'class' as a replacement. Follow by supporting both.
The SSTABLE_COMPRESSION variable is renamed to SSTABLE_COMPRESSION_DEPRECATED
to detect all uses and prevent future misuse.
To prevent old-version nodes from seeing the new name, the
compression_parameters class preserves the key name when it is
constructed from an options map, and emits the same key name when
asked to generate an options map.
Existing unit tests are modified to use the new name, and a test
is added to ensure the old name is still supported.
Fixes#8948.
Closes#8949
C++20 introduced `contains` member functions for maps and sets for
checking whether an element is present in the collection. Previously
`count` function was often used in various ways.
`contains` does not only express the intend of the code better but also
does it in more unified way.
This commit replaces all the occurences of the `count` with the
`contains`.
Tests: unit(dev)
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
Message-Id: <b4ef3b4bc24f49abe04a2aba0ddd946009c9fcb2.1597314640.git.piotr@scylladb.com>
Some difference on how exactly the operator== is declared for sstring
versus std::string requires this change if we convert from sstring to
std::string.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
If sstring is made an alias to std::string ADL causes std::make_shared
to be found. Explicitly ask for ::make_shared.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
The existence of LZ4_compress_default is a property of the lz4
library, not seastar.
With this patch scylla does its own configure check instead of
depending on the one done by seastar.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Message-Id: <20190114013737.5395-1-espindola@scylladb.com>
Replace stdx::optional and stdx::string_view with the C++ std
counterparts.
Some instances of boost::variant were also replaced with std::variant,
namely those that called seastar::visit.
Scylla now requires GCC 8 to compile.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20190108111141.5369-1-duarte@scylladb.com>
This patch adds compatibility for Cassandra's "chunk_size_in_kb", as
well as it keeps Scylla's "chunk_size_kb" compression parameter.
Fixes#3669
Tests: unit (release)
v2: use variable instead of array
v3: fix commited files
Signed-off-by: Juliana Oliveira <juliana@scylladb.com>
Message-Id: <20181211215840.GA7379@shenzou.localdomain>
Fixes a regression introduced in
74758c87cd, where tables started to be
created without compression by default (before they were created with
lz4 by default).
Fixes#3926
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
sprint() recently became more strict, throwing on sprint("%s", 5). Replace
with the more modern format().
Mechanically converted with https://github.com/avikivity/unsprint.
Make a "compressor" an actual class, that can be implemented and
registered via class registry.
For "common" compressors, the objects will be shared, but complex
implementors can be semi-stateful.
sstable compression is split into two parts: The "static" config
which is shared across shards, and a "local" one, which holds
a compressor pointer. The latter is encapsulated, along with
actual compressed data writers, in sstables/compress.cc.
For compression (write), compression writer is instansiated
with the settings active in table metadata.
For decompression (read), compression reader is instansiated
with the settings stored in sstable metadata, which can
differ from the currently active table metadata.
v2:
* Structured patch sets differently (dependencies)
* Added more comments/api descs
* Added patch to move all sstable compression into compress.cc,
effectively separating top-level virtual compressor object
from sstable io knowledge
v3:
* Rebased
v4:
* Moved all sstable compression logic/knowledge into
compress.cc (local compression). Merged the two patches
(separation just confuses reader).
