57de2c26b3
Deserialisation function returns a structure containing both the value and its length in the input buffer. In the vast majority of the cases the caller will already know the length and having this structure will make it harder for the compiler to emit good code, especially if the function is not inlined. In practice I've seen the structure causing register pressure problems that lead to spilling variables to memory.
59 lines
1.6 KiB
C++
59 lines
1.6 KiB
C++
/*
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* Copyright 2017 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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//
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// For reference, see https://developers.google.com/protocol-buffers/docs/encoding#varints
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//
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#pragma once
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#include "bytes.hh"
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#include <cstdint>
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using vint_size_type = bytes::size_type;
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static constexpr size_t max_vint_length = 9;
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struct unsigned_vint final {
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using value_type = uint64_t;
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static vint_size_type serialized_size(value_type) noexcept;
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static vint_size_type serialize(value_type, bytes::iterator out);
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static value_type deserialize(bytes_view v);
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static vint_size_type serialized_size_from_first_byte(bytes::value_type first_byte);
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};
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struct signed_vint final {
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using value_type = int64_t;
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static vint_size_type serialized_size(value_type) noexcept;
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static vint_size_type serialize(value_type, bytes::iterator out);
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static value_type deserialize(bytes_view v);
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static vint_size_type serialized_size_from_first_byte(bytes::value_type first_byte);
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};
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