Files
scylladb/atomic_cell_hash.hh
Botond Dénes ba7a9d2ac3 imr: switch back to open-coded description of structures
Commit aab6b0ee27 introduced the
controversial new IMR format, which relied on a very template-heavy
infrastructure to generate serialization and deserialization code via
template meta-programming. The promise was that this new format, beyond
solving the problems the previous open-coded representation had (working
on linearized buffers), will speed up migrating other components to this
IMR format, as the IMR infrastructure reduces code bloat, makes the code
more readable via declarative type descriptions as well as safer.
However, the results were almost the opposite. The template
meta-programming used by the IMR infrastructure proved very hard to
understand. Developers don't want to read or modify it. Maintainers
don't want to see it being used anywhere else. In short, nobody wants to
touch it.

This commit does a conceptual revert of
aab6b0ee27. A verbatim revert is not
possible because related code evolved a lot since the merge. Also, going
back to the previous code would mean we regress as we'd revert the move
to fragmented buffers. So this revert is only conceptual, it changes the
underlying infrastructure back to the previous open-coded one, but keeps
the fragmented buffers, as well as the interface of the related
components (to the extent possible).

Fixes: #5578
2021-02-16 23:43:07 +01:00

96 lines
3.0 KiB
C++

/*
* Copyright (C) 2015 ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
// Not part of atomic_cell.hh to avoid cyclic dependency between types.hh and atomic_cell.hh
#include "types.hh"
#include "types/collection.hh"
#include "atomic_cell.hh"
#include "atomic_cell_or_collection.hh"
#include "hashing.hh"
#include "counters.hh"
template<>
struct appending_hash<collection_mutation_view> {
template<typename Hasher>
void operator()(Hasher& h, collection_mutation_view cell, const column_definition& cdef) const {
cell.with_deserialized(*cdef.type, [&] (collection_mutation_view_description m_view) {
::feed_hash(h, m_view.tomb);
for (auto&& key_and_value : m_view.cells) {
::feed_hash(h, key_and_value.first);
::feed_hash(h, key_and_value.second, cdef);
}
});
}
};
template<>
struct appending_hash<atomic_cell_view> {
template<typename Hasher>
void operator()(Hasher& h, atomic_cell_view cell, const column_definition& cdef) const {
feed_hash(h, cell.is_live());
feed_hash(h, cell.timestamp());
if (cell.is_live()) {
if (cdef.is_counter()) {
::feed_hash(h, counter_cell_view(cell));
return;
}
if (cell.is_live_and_has_ttl()) {
feed_hash(h, cell.expiry());
feed_hash(h, cell.ttl());
}
feed_hash(h, cell.value());
} else {
feed_hash(h, cell.deletion_time());
}
}
};
template<>
struct appending_hash<atomic_cell> {
template<typename Hasher>
void operator()(Hasher& h, const atomic_cell& cell, const column_definition& cdef) const {
feed_hash(h, static_cast<atomic_cell_view>(cell), cdef);
}
};
template<>
struct appending_hash<collection_mutation> {
template<typename Hasher>
void operator()(Hasher& h, const collection_mutation& cm, const column_definition& cdef) const {
feed_hash(h, static_cast<collection_mutation_view>(cm), cdef);
}
};
template<>
struct appending_hash<atomic_cell_or_collection> {
template<typename Hasher>
void operator()(Hasher& h, const atomic_cell_or_collection& c, const column_definition& cdef) const {
if (cdef.is_atomic()) {
feed_hash(h, c.as_atomic_cell(cdef), cdef);
} else {
feed_hash(h, c.as_collection_mutation(), cdef);
}
}
};