eb2e88e925
Since linearization_context is thread_local every time it is accessed the compiler needs to emit code that checks if it was already constructed and does so if it wasn't. Moreover, upon leaving the context from the outermost scope the map needs to be cleared. All these operations impose some performance overhead and aren't really necessary if no buffers were linearised (the expected case). This patch rearranges the code so that lineatization_context is trivially constructible and the map is cleared only if it was modified.
53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
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/*
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* Copyright 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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#include "managed_bytes.hh"
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thread_local managed_bytes::linearization_context managed_bytes::_linearization_context;
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thread_local std::unordered_map<const blob_storage*, std::unique_ptr<bytes_view::value_type[]>> managed_bytes::_lc_state;
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void
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managed_bytes::linearization_context::forget(const blob_storage* p) noexcept {
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_lc_state.erase(p);
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}
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const bytes_view::value_type*
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managed_bytes::do_linearize() const {
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auto& lc = _linearization_context;
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assert(lc._nesting);
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lc._state_ptr = &_lc_state;
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auto b = _u.ptr;
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auto i = _lc_state.find(b);
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if (i == _lc_state.end()) {
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auto data = std::unique_ptr<bytes_view::value_type[]>(new bytes_view::value_type[b->size]);
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auto e = data.get();
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while (b) {
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e = std::copy_n(b->data, b->frag_size, e);
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b = b->next;
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}
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i = _lc_state.emplace(_u.ptr, std::move(data)).first;
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}
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return i->second.get();
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}
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