fee0b7fa48
This patch makes the row limit enforced by the storage_proxy layer. It adds a row limit to the query_result_merger, useful when merging results for concurrent queries. More importantly, it provides guarantees that upper layers may be relying on implicitly (e.g., the paging code). Signed-off-by: Duarte Nunes <duarte@scylladb.com>
59 lines
1.8 KiB
C++
59 lines
1.8 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 "core/distributed.hh"
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#include "query-result.hh"
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namespace query {
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// Merges non-overlapping results into one
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// Implements @Reducer concept from distributed.hh
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class result_merger {
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std::vector<foreign_ptr<lw_shared_ptr<query::result>>> _partial;
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const uint32_t _max_rows;
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const uint32_t _max_partitions;
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public:
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explicit result_merger(uint32_t max_rows, uint32_t max_partitions)
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: _max_rows(max_rows)
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, _max_partitions(max_partitions)
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{ }
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void reserve(size_t size) {
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_partial.reserve(size);
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}
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void operator()(foreign_ptr<lw_shared_ptr<query::result>> r) {
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if (!_partial.empty() && _partial.back()->is_short_read()) {
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return;
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}
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_partial.emplace_back(std::move(r));
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}
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// FIXME: Eventually we should return a composite_query_result here
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// which holds the vector of query results and which can be quickly turned
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// into packet fragments by the transport layer without copying the data.
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foreign_ptr<lw_shared_ptr<query::result>> get();
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};
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}
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