Files
scylladb/schema_mutations.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

161 lines
6.7 KiB
C++

/*
* Copyright 2015-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#include "schema_mutations.hh"
#include "mutation/canonical_mutation.hh"
#include "db/schema_tables.hh"
#include "utils/hashers.hh"
#include "utils/UUID_gen.hh"
schema_mutations::schema_mutations(canonical_mutation columnfamilies,
canonical_mutation columns,
bool is_view,
std::optional<canonical_mutation> indices,
std::optional<canonical_mutation> dropped_columns,
std::optional<canonical_mutation> scylla_tables,
std::optional<canonical_mutation> view_virtual_columns,
std::optional<canonical_mutation> computed_columns)
: _columnfamilies(columnfamilies.to_mutation(is_view ? db::schema_tables::views() : db::schema_tables::tables()))
, _columns(columns.to_mutation(db::schema_tables::columns()))
, _view_virtual_columns(view_virtual_columns ? mutation_opt{view_virtual_columns.value().to_mutation(db::schema_tables::view_virtual_columns())} : std::nullopt)
, _computed_columns(computed_columns ? mutation_opt{computed_columns.value().to_mutation(db::schema_tables::computed_columns())} : std::nullopt)
, _indices(indices ? mutation_opt{indices.value().to_mutation(db::schema_tables::indexes())} : std::nullopt)
, _dropped_columns(dropped_columns ? mutation_opt{dropped_columns.value().to_mutation(db::schema_tables::dropped_columns())} : std::nullopt)
, _scylla_tables(scylla_tables ? mutation_opt{scylla_tables.value().to_mutation(db::schema_tables::scylla_tables())} : std::nullopt)
{}
void schema_mutations::copy_to(std::vector<mutation>& dst) const {
dst.push_back(_columnfamilies);
dst.push_back(_columns);
if (_view_virtual_columns) {
dst.push_back(*_view_virtual_columns);
}
if (_computed_columns) {
dst.push_back(*_computed_columns);
}
if (_indices) {
dst.push_back(*_indices);
}
if (_dropped_columns) {
dst.push_back(*_dropped_columns);
}
if (_scylla_tables) {
dst.push_back(*_scylla_tables);
}
}
table_schema_version schema_mutations::digest() const {
if (_scylla_tables) {
auto rs = query::result_set(*_scylla_tables);
if (!rs.empty()) {
auto&& row = rs.row(0);
auto val = row.get<utils::UUID>("version");
if (val) {
return table_schema_version(*val);
}
}
}
md5_hasher h;
db::schema_features sf = db::schema_features::full();
// Disable this feature so that the digest remains compactible with Scylla
// versions prior to this feature.
// This digest affects the table schema version calculation and it's important
// that all nodes arrive at the same table schema version to avoid needless schema version
// pulls. Table schema versions are calculated on boot when we don't yet
// know all the cluster features, so we could get different table versions after reboot
// in an already upgraded cluster.
sf.remove<db::schema_feature::DIGEST_INSENSITIVE_TO_EXPIRY>();
db::schema_tables::feed_hash_for_schema_digest(h, _columnfamilies, sf);
db::schema_tables::feed_hash_for_schema_digest(h, _columns, sf);
if (_view_virtual_columns && !_view_virtual_columns->partition().empty()) {
db::schema_tables::feed_hash_for_schema_digest(h, *_view_virtual_columns, sf);
}
if (_computed_columns && !_computed_columns->partition().empty()) {
db::schema_tables::feed_hash_for_schema_digest(h, *_computed_columns, sf);
}
if (_indices && !_indices->partition().empty()) {
db::schema_tables::feed_hash_for_schema_digest(h, *_indices, sf);
}
if (_dropped_columns && !_dropped_columns->partition().empty()) {
db::schema_tables::feed_hash_for_schema_digest(h, *_dropped_columns, sf);
}
if (_scylla_tables) {
db::schema_tables::feed_hash_for_schema_digest(h, *_scylla_tables, sf);
}
return table_schema_version(utils::UUID_gen::get_name_UUID(h.finalize()));
}
std::optional<sstring> schema_mutations::partitioner() const {
if (_scylla_tables) {
auto rs = query::result_set(*_scylla_tables);
if (!rs.empty()) {
return rs.row(0).get<sstring>("partitioner");
}
}
return { };
}
static mutation_opt compact(const mutation_opt& m) {
if (!m) {
return m;
}
return db::schema_tables::compact_for_schema_digest(*m);
}
static mutation_opt compact(const mutation& m) {
return db::schema_tables::compact_for_schema_digest(m);
}
bool schema_mutations::operator==(const schema_mutations& other) const {
return compact(_columnfamilies) == compact(other._columnfamilies)
&& compact(_columns) == compact(other._columns)
&& compact(_view_virtual_columns) == compact(other._view_virtual_columns)
&& compact(_computed_columns) == compact(other._computed_columns)
&& compact(_indices) == compact(other._indices)
&& compact(_dropped_columns) == compact(other._dropped_columns)
&& compact(_scylla_tables) == compact(other._scylla_tables)
;
}
bool schema_mutations::live() const {
return _columnfamilies.live_row_count() > 0 || _columns.live_row_count() > 0 ||
(_view_virtual_columns && _view_virtual_columns->live_row_count() > 0) ||
(_computed_columns && _computed_columns->live_row_count() > 0);
}
bool schema_mutations::is_view() const {
return _columnfamilies.schema() == db::schema_tables::views();
}
std::ostream& operator<<(std::ostream& out, const schema_mutations& sm) {
out << "schema_mutations{\n";
out << " tables=" << sm.columnfamilies_mutation() << ",\n";
out << " scylla_tables=" << sm.scylla_tables() << ",\n";
out << " columns=" << sm.columns_mutation() << ",\n";
out << " dropped_columns=" << sm.dropped_columns_mutation() << ",\n";
out << " indices=" << sm.indices_mutation() << ",\n";
out << " computed_columns=" << sm.computed_columns_mutation() << ",\n";
out << " view_virtual_columns=" << sm.view_virtual_columns_mutation() << "\n";
out << "}";
return out;
}
schema_mutations& schema_mutations::operator+=(schema_mutations&& sm) {
_columnfamilies += std::move(sm._columnfamilies);
_columns += std::move(sm._columns);
apply(_computed_columns, std::move(sm._computed_columns));
apply(_view_virtual_columns, std::move(sm._view_virtual_columns));
apply(_indices, std::move(sm._indices));
apply(_dropped_columns, std::move(sm._dropped_columns));
apply(_scylla_tables, std::move(sm._scylla_tables));
return *this;
}