mirror of https://gitee.com/bigwinds/arangodb
87 lines
3.3 KiB
C++
87 lines
3.3 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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////////////////////////////////////////////////////////////////////////////////
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#include "SubqueryStartExecutor.h"
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#include "Aql/ExecutionState.h"
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#include "Aql/OutputAqlItemRow.h"
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#include "Aql/SingleRowFetcher.h"
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#include "Aql/Stats.h"
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using namespace arangodb;
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using namespace arangodb::aql;
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SubqueryStartExecutor::SubqueryStartExecutor(Fetcher& fetcher, Infos& infos)
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: _fetcher(fetcher),
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_state(ExecutionState::HASMORE),
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_input(CreateInvalidInputRowHint{}) {}
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SubqueryStartExecutor::~SubqueryStartExecutor() = default;
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std::pair<ExecutionState, NoStats> SubqueryStartExecutor::produceRows(OutputAqlItemRow& output) {
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while (!output.isFull()) {
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TRI_ASSERT(!output.produced());
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if (_state == ExecutionState::DONE && !_input.isInitialized()) {
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// We need to handle shadowRows now. It is the job of this node to
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// increase the shadow row depth
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ShadowAqlItemRow shadowRow{CreateInvalidShadowRowHint{}};
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std::tie(_state, shadowRow) = _fetcher.fetchShadowRow();
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if (!shadowRow.isInitialized()) {
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TRI_ASSERT(_state == ExecutionState::WAITING || _state == ExecutionState::DONE);
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// We are either fully DONE, or WAITING
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return {_state, NoStats{}};
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}
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output.increaseShadowRowDepth(shadowRow);
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} else {
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// This loop alternates between data row and shadow row
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if (_input.isInitialized()) {
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output.createShadowRow(_input);
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_input = InputAqlItemRow(CreateInvalidInputRowHint{});
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} else {
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// We need to round the number of rows, otherwise this might be called with atMost == 0
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std::tie(_state, _input) = _fetcher.fetchRow((output.numRowsLeft() + 1) / 2);
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if (!_input.isInitialized()) {
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TRI_ASSERT(_state == ExecutionState::WAITING || _state == ExecutionState::DONE);
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return {_state, NoStats{}};
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}
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TRI_ASSERT(!output.isFull());
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output.copyRow(_input);
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}
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}
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output.advanceRow();
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}
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if (_input.isInitialized()) {
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// We at least need to insert the Shadow row!
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return {ExecutionState::HASMORE, NoStats{}};
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}
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// Take state from dependency.
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return {_state, NoStats{}};
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}
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std::pair<ExecutionState, size_t> SubqueryStartExecutor::expectedNumberOfRows(size_t atMost) const {
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ExecutionState state{ExecutionState::HASMORE};
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size_t expected = 0;
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std::tie(state, expected) = _fetcher.preFetchNumberOfRows(atMost);
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// We will write one shadow row per input data row.
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// We might write less on all shadow rows in input, right now we do not figure this out yes.
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return {state, expected * 2};
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}
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