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https://github.com/scylladb/scylladb.git
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ba7a9d2ac3
Commitaab6b0ee27introduced 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 ofaab6b0ee27. 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
75 lines
3.2 KiB
C++
75 lines
3.2 KiB
C++
/*
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* Copyright (C) 2015 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "atomic_cell.hh"
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#include "collection_mutation.hh"
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#include "schema.hh"
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#include "hashing.hh"
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// A variant type that can hold either an atomic_cell, or a serialized collection.
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// Which type is stored is determined by the schema.
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// Has an "empty" state.
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// Objects moved-from are left in an empty state.
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class atomic_cell_or_collection final {
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managed_bytes _data;
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private:
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atomic_cell_or_collection(managed_bytes&& data) : _data(std::move(data)) {}
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public:
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atomic_cell_or_collection() = default;
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atomic_cell_or_collection(atomic_cell_or_collection&&) = default;
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atomic_cell_or_collection(const atomic_cell_or_collection&) = delete;
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atomic_cell_or_collection& operator=(atomic_cell_or_collection&&) = default;
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atomic_cell_or_collection& operator=(const atomic_cell_or_collection&) = delete;
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atomic_cell_or_collection(atomic_cell ac) : _data(std::move(ac._data)) {}
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atomic_cell_or_collection(const abstract_type& at, atomic_cell_view acv);
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static atomic_cell_or_collection from_atomic_cell(atomic_cell data) { return { std::move(data._data) }; }
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atomic_cell_view as_atomic_cell(const column_definition& cdef) const { return atomic_cell_view::from_bytes(*cdef.type, _data); }
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atomic_cell_mutable_view as_mutable_atomic_cell(const column_definition& cdef) { return atomic_cell_mutable_view::from_bytes(*cdef.type, _data); }
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atomic_cell_or_collection(collection_mutation cm) : _data(std::move(cm._data)) { }
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atomic_cell_or_collection copy(const abstract_type&) const;
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explicit operator bool() const {
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return !_data.empty();
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}
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static constexpr bool can_use_mutable_view() {
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return true;
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}
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static atomic_cell_or_collection from_collection_mutation(collection_mutation data) { return std::move(data._data); }
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collection_mutation_view as_collection_mutation() const;
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bytes_view serialize() const;
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bool equals(const abstract_type& type, const atomic_cell_or_collection& other) const;
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size_t external_memory_usage(const abstract_type&) const;
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class printer {
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const column_definition& _cdef;
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const atomic_cell_or_collection& _cell;
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public:
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printer(const column_definition& cdef, const atomic_cell_or_collection& cell)
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: _cdef(cdef), _cell(cell) { }
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printer(const printer&) = delete;
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printer(printer&&) = delete;
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friend std::ostream& operator<<(std::ostream&, const printer&);
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};
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friend std::ostream& operator<<(std::ostream&, const printer&);
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};
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