in in {fmt} before v10, it provides the specialization of `fmt::formatter<..>`
for `std::string_view` as well as the specialization of `fmt::formatter<..>`
for `fmt::string_view` which is an implementation builtin in {fmt} for
compatibility of pre-C++17. and this type is used even if the code is
compiled with C++ stadandard greater or equal to C++17. also, before v10,
the `fmt::formatter<std::string_view>::format()` is defined so it accepts
`std::string_view`. after v10, `fmt::formatter<std::string_view>` still
exists, but it is now defined using `format_as()` machinery, so it's
`format()` method does not actually accept `std::string_view`, it
accepts `fmt::string_view`, as the former can be converted to
`fmt::string_view`.
this is why we can inherit from `fmt::formatter<std::string_view>` and
use `formatter<std::string_view>::format(foo, ctx);` to implement the
`format()` method with {fmt} v9, but we cannot do this with {fmt} v10,
and we would have following compilation failure:
```
FAILED: service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o
/home/kefu/.local/bin/clang++ -DFMT_DEPRECATED_OSTREAM -DFMT_SHARED -DSCYLLA_BUILD_MODE=release -DSEASTAR_API_LEVEL=7 -DSEASTAR_LOGGER_COMPILE_TIME_FMT -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_SSTRING -DXXH_PRIVATE_API -DCMAKE_INTDIR=\"RelWithDebInfo\" -I/home/kefu/dev/scylladb -I/home/kefu/dev/scylladb/build/gen -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/seastar/gen/include -I/home/kefu/dev/scylladb/build/seastar/gen/src -ffunction-sections -fdata-sections -O3 -g -gz -std=gnu++20 -fvisibility=hidden -Wall -Werror -Wextra -Wno-error=deprecated-declarations -Wimplicit-fallthrough -Wno-c++11-narrowing -Wno-deprecated-copy -Wno-mismatched-tags -Wno-missing-field-initializers -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-enum-constexpr-conversion -Wno-unused-parameter -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -mllvm -inline-threshold=2500 -fno-slp-vectorize -U_FORTIFY_SOURCE -Werror=unused-result -MD -MT service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -MF service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o.d -o service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -c /home/kefu/dev/scylladb/service/topology_state_machine.cc
/home/kefu/dev/scylladb/service/topology_state_machine.cc:254:41: error: no matching member function for call to 'format'
254 | return formatter<std::string_view>::format(it->second, ctx);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
/usr/include/fmt/core.h:2759:22: note: candidate function template not viable: no known conversion from 'seastar::basic_sstring<char, unsigned int, 15>' to 'const fmt::basic_string_view<char>' for 1st argument
2759 | FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
| ^ ~~~~~~~~~~~~
```
because the inherited `format()` method actually comes from
`fmt::formatter<fmt::string_view>`. to reduce the confusion, in this
change, we just inherit from `fmt::format<string_view>`, where
`string_view` is actually `fmt::string_view`. this follows
the document at
https://fmt.dev/latest/api.html#formatting-user-defined-types,
and since there is less indirection under the hood -- we do not
use the specialization created by `FMT_FORMAT_AS` which inherit
from `formatter<fmt::string_view>`, hopefully this can improve
the compilation speed a little bit. also, this change addresses
the build failure with {fmt} v10.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#18299
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.
in this change, we define formatters for `schema_mutations`,
and drop its operator<< .
Refs #13245
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#17815
Schema digest is calculated by querying for mutations of all schema
tables, then compacting them so that all tombstones in them are
dropped. However, even if the mutation becomes empty after compaction,
we still feed its partition key. If the same mutations were compacted
prior to the query, because the tombstones expire, we won't get any
mutation at all and won't feed the partition key. So schema digest
will change once an empty partition of some schema table is compacted
away.
Tombstones expire 7 days after schema change which introduces them. If
one of the nodes is restarted after that, it will compute a different
table schema digest on boot. This may cause performance problems. When
sending a request from coordinator to replica, the replica needs
schema_ptr of exact schema version request by the coordinator. If it
doesn't know that version, it will request it from the coordinator and
perform a full schema merge. This adds latency to every such request.
Schema versions which are not referenced are currently kept in cache
for only 1 second, so if request flow has low-enough rate, this
situation results in perpetual schema pulls.
After ae8d2a550d, it is more liekly to
run into this situation, because table creation generates tombstones
for all schema tables relevant to the table, even the ones which
will be otherwise empty for the new table (e.g. computed_columns).
This change inroduces a cluster feature which when enabled will change
digest calculation to be insensitive to expiry by ignoring empty
partitions in digest calculation. When the feature is enabled,
schema_ptrs are reloaded so that the window of discrepancy during
transition is short and no rolling restart is required.
A similar problem was fixed for per-node digest calculation in
18f484cc753d17d1e3658bcb5c73ed8f319d32e8. Per-table digest calculation
was not fixed at that time because we didn't persist enabled features
and they were not enabled early-enough on boot for us to depend on
them in digest calculation. Now they are enabled before non-system
tables are loaded so digest calculation can rely on cluster features.
Fixes#4485.
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
Schema related files are moved there. This excludes schema files that
also interact with mutations, because the mutation module depends on
the schema. Those files will have to go into a separate module.
Closes#12858
Move mutation-related files to a new mutation/ directory. The names
are kept in the global namespace to reduce churn; the names are
unambiguous in any case.
mutation_reader remains in the readers/ module.
mutation_partition_v2.cc was missing from CMakeLists.txt; it's added in this
patch.
This is a step forward towards librarization or modularization of the
source base.
Closes#12788
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
There are two results of this patch:
1. New partitioner name column is persited on node's disk in scylla_tables
2. New partitioner name column is included into schema digest
This is achieved by including this new column in scylla tables mutation.
For that we:
1. Add partitioner name to the result of make_scylla_tables_mutation.
If table does not have a specific partitioner set and uses default
partitioner then we don't include the name of such default partitioner.
Only the name of custom partitioner is added if a table has one.
2. In create_table_from_mutations we check whether scylla tables mutation
has a partitioner name set. If so then we use it as a parameter for
schema_builder.
Note that previous patches have ensured that this new column will be included
into schema digest only after the whole cluster supports per table partitioners.
Before that, during rolling upgrade, new partitioner name column is hidden and
not shared with other nodes.
Signed-off-by: Piotr Jastrzebski <piotr@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>
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>
In the previous patch, we added a "view virtual" flag on columns. In this
patch we add persistance to this flag: I.e., writing it to the on-disk
schema table and reading it back on startup. But the implementation is
not as simple as adding a flag:
In the on-disk system tables, we have a "columns" table listing all the
columns in the database and their types. Cqlsh's "DESCRIBE MATERIALIZED
VIEW" works by reading this "columns" table, and listing all of the
requested view's columns. Therefore, we cannot add "virtual columns" -
which are columns not added by the user and not intended to be seen -
to this list.
We therefore need to create in this patch a separate list for virtual
columns, in a new table "view_virtual_columns". This table is essentially
identical to the existing "columns" table, just separate. We need to write
each column to the appropriate table (columns with the view_virtual flag to
"view_virtual_columns", columns without it to the old "columns"), read
from both on startup, and remember to delete columns from both when a table
is dropped.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
We apply deletion of scylla_tables.version to the incoming schema
mutations so that table schema version is recalculated after merge.
The mutations which we read from local schema tables may not have it
deleted in which case all tables would be considered as differing on
the presence of the version field. Avoid this by deleting the field
from old mutations as well.
Digest only looks like live values, ignoring deletion
information. Equality should be consistent with that, so that schemas
considered equal do not trigger the alter path unnecessarily.
It will be used to store Scylla spcific table metadata. We cannot
store it in the standard "tables" table for compatibility reasons -
Cassandra will fail to read schema if it encounteres columns it is not
expecting.
This patch allows a view schema to be frozen. To unfreeze such a
schema, we add an is_view attribute to the schema idl.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
We must use canonical_mutation form to allow for changes in the schema
of schema tables. The node which deserializes schema mutations may not
have the same version of the schema tables so we cannot use
frozen_mutation, which is a schema dependent form.
