C++20 introduced two new attributes--likely and unlikely--that
function as a built-in replacement for __builtin_expect implemented
in various compilers. Since it makes code easier to read and it's
an integral part of the language, there's no reason to not use it
instead.
Closesscylladb/scylladb#24786
these unused includes were identifier by clang-include-cleaner. after
auditing these source files, all of the reports have been confirmed.
please note, because quite a few source files relied on
`utils/to_string.hh` to pull in the specialization of
`fmt::formatter<std::optional<T>>`, after removing
`#include <fmt/std.h>` from `utils/to_string.hh`, we have to
include `fmt/std.h` directly.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
assert() is traditionally disabled in release builds, but not in
scylladb. This hasn't caused problems so far, but the latest abseil
release includes a commit [1] that causes a 1000 insn/op regression when
NDEBUG is not defined.
Clearly, we must move towards a build system where NDEBUG is defined in
release builds. But we can't just define it blindly without vetting
all the assert() calls, as some were written with the expectation that
they are enabled in release mode.
To solve the conundrum, change all assert() calls to a new SCYLLA_ASSERT()
macro in utils/assert.hh. This macro is always defined and is not conditional
on NDEBUG, so we can later (after vetting Seastar) enable NDEBUG in release
mode.
[1] 66ef711d68Closesscylladb/scylladb#20006
as we the functor passed to `invoke()` is not a rvalue, if we specify
the template parameter explicitly, clang errors out like:
```
/home/kefu/.local/bin/clang++ -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/seastar/include -I/home/kefu/dev/scylladb/build/seastar/gen/include -I/home/kefu/dev/scylladb/build/seastar/gen/src -I/home/kefu/dev/scylladb/build -I/home/kefu/dev/scylladb/build/gen -isystem /home/kefu/dev/scylladb/build/rust -isystem /home/kefu/dev/scylladb/abseil -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 transport/CMakeFiles/transport.dir/RelWithDebInfo/server.cc.o -MF transport/CMakeFiles/transport.dir/RelWithDebInfo/server.cc.o.d -o transport/CMakeFiles/transport.dir/RelWithDebInfo/server.cc.o -c /home/kefu/dev/scylladb/transport/server.cc
In file included from /home/kefu/dev/scylladb/transport/server.cc:39:
/home/kefu/dev/scylladb/utils/result_try.hh:210:28: error: no matching function for call to 'invoke'
210 | return Converter::template invoke<const Cb, const Ex&>(_cb, ex);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/kefu/dev/scylladb/utils/result_try.hh:194:143: note: while substituting into a lambda expression here
194 | return [this, cont = std::forward<Continuation>(cont)] (bool& already_caught) mutable -> typename Converter::template wrapped_type<R> {
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:327:40: note: in instantiation of function template specialization 'utils::internal::result_catcher<exceptions::unavailable_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:521:68)>::wrap_in_catch<boost::outcome_v2::basic_result<seastar::foreign_ptr<std::unique_ptr<cql_transport::response>>, utils::exception_container<exceptions::mutation_write_timeout_exception, exceptions::read_timeout_exception, exceptions::read_failure_exception, exceptions::rate_limit_exception>, utils::exception_container_throw_policy>, utils::internal::noop_converter, (lambda at /home/kefu/dev/scylladb/utils/result_try.hh:518:76)>' requested here
327 | first_handler.template wrap_in_catch<R, Converter, Continuation>(std::forward<Continuation>(cont)),
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:518:54: note: in instantiation of function template specialization 'utils::internal::try_catch_chain_impl<boost::outcome_v2::basic_result<seastar::foreign_ptr<std::unique_ptr<cql_transport::response>>, utils::exception_container<exceptions::mutation_write_timeout_exception, exceptions::read_timeout_exception, exceptions::read_failure_exception, exceptions::rate_limit_exception>, utils::exception_container_throw_policy>, utils::internal::noop_converter, utils::internal::result_catcher<exceptions::unavailable_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:521:68)>, utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>, utils::internal::result_catcher<exceptions::read_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:531:69)>, utils::internal::result_catcher<exceptions::mutation_write_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:536:79)>, utils::internal::result_catcher<exceptions::mutation_write_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:541:79)>, utils::internal::result_catcher<exceptions::already_exists_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:546:71)>, utils::internal::result_catcher<exceptions::prepared_query_not_found_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:551:81)>, utils::internal::result_catcher<exceptions::function_execution_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:556:75)>, utils::internal::result_catcher<exceptions::rate_limit_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:561:67)>, utils::internal::result_catcher<exceptions::cassandra_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:566:66)>, utils::internal::result_catcher<std::exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:578:49)>, utils::internal::result_catcher_dots<(lambda at /home/kefu/dev/scylladb/transport/server.cc:591:38)>>::invoke_in_try_catch<(lambda at /home/kefu/dev/scylladb/utils/result_try.hh:518:76)>' requested here
518 | result_type res = try_catch_chain_type::template invoke_in_try_catch<>([&fun] (bool&) { return fun(); }, handlers...);
| ^
/home/kefu/dev/scylladb/transport/server.cc:484:83: note: in instantiation of function template specialization 'utils::result_try<(lambda at /home/kefu/dev/scylladb/transport/server.cc:484:94), utils::internal::result_catcher<exceptions::unavailable_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:521:68)>, utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>, utils::internal::result_catcher<exceptions::read_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:531:69)>, utils::internal::result_catcher<exceptions::mutation_write_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:536:79)>, utils::internal::result_catcher<exceptions::mutation_write_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:541:79)>, utils::internal::result_catcher<exceptions::already_exists_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:546:71)>, utils::internal::result_catcher<exceptions::prepared_query_not_found_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:551:81)>, utils::internal::result_catcher<exceptions::function_execution_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:556:75)>, utils::internal::result_catcher<exceptions::rate_limit_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:561:67)>, utils::internal::result_catcher<exceptions::cassandra_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:566:66)>, utils::internal::result_catcher<std::exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:578:49)>, utils::internal::result_catcher_dots<(lambda at /home/kefu/dev/scylladb/transport/server.cc:591:38)>>' requested here
484 | return utils::result_into_future<result_with_foreign_response_ptr>(utils::result_try([&] () -> result_with_foreign_response_ptr {
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:33:5: note: candidate function template not viable: expects an rvalue for 1st argument
33 | invoke(F&& f, Args&&... args) {
| ^ ~~~~~
/home/kefu/dev/scylladb/utils/result_try.hh:210:28: error: no matching function for call to 'invoke'
210 | return Converter::template invoke<const Cb, const Ex&>(_cb, ex);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/kefu/dev/scylladb/utils/result_try.hh:194:143: note: while substituting into a lambda expression here
194 | return [this, cont = std::forward<Continuation>(cont)] (bool& already_caught) mutable -> typename Converter::template wrapped_type<R> {
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:327:40: note: in instantiation of function template specialization 'utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>::wrap_in_catch<boost::outcome_v2::basic_result<seastar::foreign_ptr<std::unique_ptr<cql_transport::response>>, utils::exception_container<exceptions::mutation_write_timeout_exception, exceptions::read_timeout_exception, exceptions::read_failure_exception, exceptions::rate_limit_exception>, utils::exception_container_throw_policy>, utils::internal::noop_converter, (lambda at /home/kefu/dev/scylladb/utils/result_try.hh:194:16)>' requested here
327 | first_handler.template wrap_in_catch<R, Converter, Continuation>(std::forward<Continuation>(cont)),
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:326:79: note: in instantiation of function template specialization 'utils::internal::try_catch_chain_impl<boost::outcome_v2::basic_result<seastar::foreign_ptr<std::unique_ptr<cql_transport::response>>, utils::exception_container<exceptions::mutation_write_timeout_exception, exceptions::read_timeout_exception, exceptions::read_failure_exception, exceptions::rate_limit_exception>, utils::exception_container_throw_policy>, utils::internal::noop_converter, utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>, utils::internal::result_catcher<exceptions::read_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:531:69)>, utils::internal::result_catcher<exceptions::mutation_write_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:536:79)>, utils::internal::result_catcher<exceptions::mutation_write_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:541:79)>, utils::internal::result_catcher<exceptions::already_exists_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:546:71)>, utils::internal::result_catcher<exceptions::prepared_query_not_found_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:551:81)>, utils::internal::result_catcher<exceptions::function_execution_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:556:75)>, utils::internal::result_catcher<exceptions::rate_limit_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:561:67)>, utils::internal::result_catcher<exceptions::cassandra_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:566:66)>, utils::internal::result_catcher<std::exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:578:49)>, utils::internal::result_catcher_dots<(lambda at /home/kefu/dev/scylladb/transport/server.cc:591:38)>>::invoke_in_try_catch<(lambda at /home/kefu/dev/scylladb/utils/result_try.hh:194:16)>' requested here
326 | return try_catch_chain_impl<R, Converter, CatchHandlers...>::template invoke_in_try_catch<>(
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:518:54: note: in instantiation of function template specialization 'utils::internal::try_catch_chain_impl<boost::outcome_v2::basic_result<seastar::foreign_ptr<std::unique_ptr<cql_transport::response>>, utils::exception_container<exceptions::mutation_write_timeout_exception, exceptions::read_timeout_exception, exceptions::read_failure_exception, exceptions::rate_limit_exception>, utils::exception_container_throw_policy>, utils::internal::noop_converter, utils::internal::result_catcher<exceptions::unavailable_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:521:68)>, utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>, utils::internal::result_catcher<exceptions::read_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:531:69)>, utils::internal::result_catcher<exceptions::mutation_write_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:536:79)>, utils::internal::result_catcher<exceptions::mutation_write_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:541:79)>, utils::internal::result_catcher<exceptions::already_exists_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:546:71)>, utils::internal::result_catcher<exceptions::prepared_query_not_found_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:551:81)>, utils::internal::result_catcher<exceptions::function_execution_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:556:75)>, utils::internal::result_catcher<exceptions::rate_limit_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:561:67)>, utils::internal::result_catcher<exceptions::cassandra_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:566:66)>, utils::internal::result_catcher<std::exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:578:49)>, utils::internal::result_catcher_dots<(lambda at /home/kefu/dev/scylladb/transport/server.cc:591:38)>>::invoke_in_try_catch<(lambda at /home/kefu/dev/scylladb/utils/result_try.hh:518:76)>' requested here
518 | result_type res = try_catch_chain_type::template invoke_in_try_catch<>([&fun] (bool&) { return fun(); }, handlers...);
| ^
/home/kefu/dev/scylladb/transport/server.cc:484:83: note: in instantiation of function template specialization 'utils::result_try<(lambda at /home/kefu/dev/scylladb/transport/server.cc:484:94), utils::internal::result_catcher<exceptions::unavailable_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:521:68)>, utils::internal::result_catcher<exceptions::read_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:526:69)>, utils::internal::result_catcher<exceptions::read_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:531:69)>, utils::internal::result_catcher<exceptions::mutation_write_timeout_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:536:79)>, utils::internal::result_catcher<exceptions::mutation_write_failure_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:541:79)>, utils::internal::result_catcher<exceptions::already_exists_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:546:71)>, utils::internal::result_catcher<exceptions::prepared_query_not_found_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:551:81)>, utils::internal::result_catcher<exceptions::function_execution_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:556:75)>, utils::internal::result_catcher<exceptions::rate_limit_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:561:67)>, utils::internal::result_catcher<exceptions::cassandra_exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:566:66)>, utils::internal::result_catcher<std::exception, (lambda at /home/kefu/dev/scylladb/transport/server.cc:578:49)>, utils::internal::result_catcher_dots<(lambda at /home/kefu/dev/scylladb/transport/server.cc:591:38)>>' requested here
484 | return utils::result_into_future<result_with_foreign_response_ptr>(utils::result_try([&] () -> result_with_foreign_response_ptr {
| ^
/home/kefu/dev/scylladb/utils/result_try.hh:33:5: note: candidate function template not viable: expects an rvalue for 1st argument
33 | invoke(F&& f, Args&&... args) {
| ^ ~~~~~
```
so to prepare for the change to pass template parameter explicitly,
let's pass `f` as a `const` reference, instead of as a rvalue refernece.
also, this parameter type matches with our usage case -- we always
pass a member variable `_cb` to `invoke`, and we don't expect that
`invoke()` would move it away.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
quote from Avi's comment
> It's supposed to be illegal to call handle(...) without this->,
> because handle() is a dependent name (but many compilers don't
> insist, gcc is stricter here). So two error messages competed,
> and "unused this capture" won.
without this change, Clang complains that `this` is not used with
`-Wunused-lambda-capture`.
in this change, `this` is used. in this change, `this` is explicitly
referenced to silence Clang's warning.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
The `result_try` and `result_futurize_try` are supposed to handle both
failed results and exceptions in a way similar to a try..catch block.
In order to catch exceptions, the metaprogramming machinery invokes the
fallible code inside a stack of try..catch blocks, each one of them
handling one exception. This is done instead of creating a single
try..catch block, as to my knowledge it is not possible to create
a try..catch block with the number of "catch" clauses depending on a
variadic template parameter pack.
Unfortunately, a "try" with multiple "catches" is not functionally
equivalent to a "try block stack". Consider the following code:
try {
try {
return execute_try_block();
} catch (const derived_exception&) {
// 1
}
} catch (const base_exception&) {
// 2
}
If `execute_try_block` throws `derived_exception` and the (1) catch
handler rethrows this exception, it will also be handled in (2), which
is not the same behavior as if the try..catch stack was "flat".
This causes wrong behavior in `result_try` and `result_futurize_try`.
The following snippet has the same, wrong behavior as the previous one:
return utils::result_try([&] {
return execute_try_block();
}, utils::result_catch<derived_exception>([&] (const auto&& ex) {
// 1
}), utils::result_catch<base_exception>([&] (const auto&& ex) {
// 2
});
This commit fixes the problem by adding a boolean flag which is set just
before a catch handler is executed. If another catch handler is
accidentally matched due to exception rethrow, the catch handler is
skipped and exception is automatically rethrown.
Tests: unit(dev, debug)
Fixes: #10211Closes#10216
Adds two methods to result_try's exception handles:
- as_inner: returns a {l,r}-value reference either to the exception
container, or the exception_ptr. This allows to use them in operations
which work on both types, e.g. logging.
- clone_inner: returns a copy of the underlying exception container or
exception ptr.
Currently, the catch handlers in result_futurize_try are required to
return a future, although they are always being called with
seastar::futurize_invoke, so if their result is not future it could be
converted to one anyway. This commit relaxes the ConvertsWithTo
constraint in order to allow this conversion.
Adds result_try and result_futurize_try - functions which allow to
convert existing try..catch blocks into a version which handles C++
exceptions, failed results with exception containers and, depending on
the function variant, exceptional futures.
