mirror of
https://github.com/scylladb/scylladb.git
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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>
Closes scylladb/scylladb#18299
98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
#pragma once
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#include "repair/decorated_key_with_hash.hh"
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#include "readers/evictable.hh"
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#include "dht/sharder.hh"
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#include "reader_permit.hh"
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#include "utils/phased_barrier.hh"
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#include "readers/mutation_fragment_v1_stream.hh"
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#include <fmt/core.h>
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class repair_reader {
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public:
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enum class read_strategy {
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local,
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multishard_split,
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multishard_filter
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};
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private:
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schema_ptr _schema;
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reader_permit _permit;
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dht::partition_range _range;
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// Used to find the range that repair master will work on
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dht::selective_token_range_sharder _sharder;
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// Seed for the repair row hashing
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uint64_t _seed;
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// Pin the table while the reader is alive.
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// Only needed for local readers, the multishard reader takes care
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// of pinning tables on used shards.
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std::optional<utils::phased_barrier::operation> _local_read_op;
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std::optional<evictable_reader_handle_v2> _reader_handle;
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// Fragment stream of either local or multishard reader for the range
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mutation_fragment_v1_stream _reader;
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// Current partition read from disk
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lw_shared_ptr<const decorated_key_with_hash> _current_dk;
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uint64_t _reads_issued = 0;
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uint64_t _reads_finished = 0;
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flat_mutation_reader_v2 make_reader(
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seastar::sharded<replica::database>& db,
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replica::column_family& cf,
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read_strategy strategy,
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const dht::sharder& remote_sharder,
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unsigned remote_shard,
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gc_clock::time_point compaction_time);
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public:
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repair_reader(
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seastar::sharded<replica::database>& db,
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replica::column_family& cf,
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schema_ptr s,
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reader_permit permit,
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dht::token_range range,
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const dht::sharder& remote_sharder,
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unsigned remote_shard,
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uint64_t seed,
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read_strategy strategy,
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gc_clock::time_point compaction_time);
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future<mutation_fragment_opt>
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read_mutation_fragment();
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future<> on_end_of_stream() noexcept;
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future<> close() noexcept;
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lw_shared_ptr<const decorated_key_with_hash>& get_current_dk() {
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return _current_dk;
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}
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void set_current_dk(const dht::decorated_key& key);
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void clear_current_dk();
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void check_current_dk();
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void pause();
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};
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template <> struct fmt::formatter<repair_reader::read_strategy> : fmt::formatter<string_view> {
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auto format(repair_reader::read_strategy s, fmt::format_context& ctx) const {
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using enum repair_reader::read_strategy;
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std::string_view name = "unknown";
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switch (s) {
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case local:
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name = "local";
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break;
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case multishard_split:
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name = "multishard_split";
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break;
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case multishard_filter:
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name = "multishard_filter";
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break;
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};
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return formatter<string_view>::format(name, ctx);
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}
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};
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