mirror of https://gitee.com/bigwinds/arangodb
112 lines
3.7 KiB
C++
112 lines
3.7 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2019 ArangoDB GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Michael Hackstein
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/// @author Markus Pfeiffer
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_AQL_SUBQUERY_END_EXECUTOR_H
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#define ARANGOD_AQL_SUBQUERY_END_EXECUTOR_H
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#include "Aql/ExecutionState.h"
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#include "Aql/ExecutorInfos.h"
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#include "Aql/InputAqlItemRow.h"
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#include "Aql/SingleRowFetcher.h"
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#include "Aql/Stats.h"
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#include <velocypack/Builder.h>
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#include <velocypack/velocypack-aliases.h>
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namespace arangodb {
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namespace aql {
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class NoStats;
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class OutputAqlItemRow;
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template <BlockPassthrough>
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class SingleRowFetcher;
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class SubqueryEndExecutorInfos : public ExecutorInfos {
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public:
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SubqueryEndExecutorInfos(std::shared_ptr<std::unordered_set<RegisterId>> readableInputRegisters,
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std::shared_ptr<std::unordered_set<RegisterId>> writeableOutputRegisters,
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RegisterId nrInputRegisters, RegisterId nrOutputRegisters,
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std::unordered_set<RegisterId> const& registersToClear,
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std::unordered_set<RegisterId> registersToKeep,
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velocypack::Options const* options, RegisterId inReg,
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RegisterId outReg);
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SubqueryEndExecutorInfos() = delete;
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SubqueryEndExecutorInfos(SubqueryEndExecutorInfos&&) noexcept = default;
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SubqueryEndExecutorInfos(SubqueryEndExecutorInfos const&) = delete;
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~SubqueryEndExecutorInfos();
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[[nodiscard]] velocypack::Options const* vpackOptions() const noexcept;
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[[nodiscard]] RegisterId getOutputRegister() const noexcept;
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[[nodiscard]] bool usesInputRegister() const noexcept;
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[[nodiscard]] RegisterId getInputRegister() const noexcept;
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private:
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velocypack::Options const* _vpackOptions;
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RegisterId const _outReg;
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RegisterId const _inReg;
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};
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class SubqueryEndExecutor {
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public:
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struct Properties {
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static constexpr bool preservesOrder = true;
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static constexpr BlockPassthrough allowsBlockPassthrough = BlockPassthrough::Disable;
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static constexpr bool inputSizeRestrictsOutputSize = true;
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};
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using Fetcher = SingleRowFetcher<Properties::allowsBlockPassthrough>;
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using Infos = SubqueryEndExecutorInfos;
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using Stats = NoStats;
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SubqueryEndExecutor(Fetcher& fetcher, SubqueryEndExecutorInfos& infos);
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~SubqueryEndExecutor();
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std::pair<ExecutionState, Stats> produceRows(OutputAqlItemRow& output);
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std::pair<ExecutionState, size_t> expectedNumberOfRows(size_t atMost) const;
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private:
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enum State : int {
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ACCUMULATE,
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RELEVANT_SHADOW_ROW_PENDING,
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FORWARD_IRRELEVANT_SHADOW_ROWS
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};
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void resetAccumulator();
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private:
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Fetcher& _fetcher;
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SubqueryEndExecutorInfos& _infos;
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// Accumulator for rows between shadow rows.
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// We need to allocate the buffer ourselves because we need to keep
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// control of it to hand over to an AqlValue
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std::unique_ptr<arangodb::velocypack::Buffer<uint8_t>> _buffer;
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std::unique_ptr<VPackBuilder> _accumulator;
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State _state;
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};
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} // namespace aql
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} // namespace arangodb
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#endif
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