Files
scylladb/schema/caching_options.cc
Kefu Chai f5b05cf981 treewide: use defaulted operator!=() and operator==()
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
2023-04-27 10:24:46 +03:00

80 lines
2.0 KiB
C++

/*
* Copyright (C) 2021-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#include "caching_options.hh"
#include <boost/lexical_cast.hpp>
#include <map>
#include "exceptions/exceptions.hh"
#include "utils/rjson.hh"
caching_options::caching_options(sstring k, sstring r, bool enabled)
: _key_cache(k), _row_cache(r), _enabled(enabled) {
if ((k != "ALL") && (k != "NONE")) {
throw exceptions::configuration_exception("Invalid key value: " + k);
}
if ((r == "ALL") || (r == "NONE")) {
return;
} else {
try {
boost::lexical_cast<unsigned long>(r);
} catch (boost::bad_lexical_cast& e) {
throw exceptions::configuration_exception("Invalid key value: " + r);
}
}
}
caching_options::caching_options()
: _key_cache(default_key), _row_cache(default_row) {
}
std::map<sstring, sstring>
caching_options::to_map() const {
std::map<sstring, sstring> res = {{ "keys", _key_cache },
{ "rows_per_partition", _row_cache }};
if (!_enabled) {
res.insert({"enabled", "false"});
}
return res;
}
sstring
caching_options::to_sstring() const {
return rjson::print(rjson::from_string_map(to_map()));
}
caching_options
caching_options::get_disabled_caching_options() {
return caching_options("NONE", "NONE", false);
}
caching_options
caching_options::from_map(const std::map<sstring, sstring>& map) {
sstring k = default_key;
sstring r = default_row;
bool e = true;
for (auto& p : map) {
if (p.first == "keys") {
k = p.second;
} else if (p.first == "rows_per_partition") {
r = p.second;
} else if (p.first == "enabled") {
e = p.second == "true";
} else {
throw exceptions::configuration_exception(format("Invalid caching option: {}", p.first));
}
}
return caching_options(k, r, e);
}
caching_options
caching_options::from_sstring(const sstring& str) {
return from_map(rjson::parse_to_map<std::map<sstring, sstring>>(str));
}