mirror of https://gitee.com/bigwinds/arangodb
126 lines
4.2 KiB
C++
126 lines
4.2 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 Tobias Gödderz
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////////////////////////////////////////////////////////////////////////////////
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#include "UnsortedGatherExecutor.h"
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#include "Aql/IdExecutor.h" // for IdExecutorInfos
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#include "Aql/MultiDependencySingleRowFetcher.h"
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#include "Aql/OutputAqlItemRow.h"
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#include "Aql/Stats.h"
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#include "Basics/debugging.h"
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using namespace arangodb;
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using namespace arangodb::aql;
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UnsortedGatherExecutor::UnsortedGatherExecutor(Fetcher& fetcher, Infos& infos)
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: _fetcher(fetcher) {}
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UnsortedGatherExecutor::~UnsortedGatherExecutor() = default;
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auto UnsortedGatherExecutor::produceRows(OutputAqlItemRow& output)
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-> std::pair<ExecutionState, Stats> {
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while (!output.isFull() && !done()) {
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// Note that fetchNextRow may return DONE (because the current dependency is
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// DONE), and also return an unitialized row in that case, but we are not
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// DONE completely - that's what `done()` is for.
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auto [state, inputRow] = fetchNextRow(output.numRowsLeft());
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if (state == ExecutionState::WAITING) {
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return {state, {}};
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}
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// HASMORE => inputRow.isInitialized()
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TRI_ASSERT(state == ExecutionState::DONE || inputRow.isInitialized());
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if (inputRow.isInitialized()) {
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output.copyRow(inputRow);
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TRI_ASSERT(output.produced());
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output.advanceRow();
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}
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}
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auto state = done() ? ExecutionState::DONE : ExecutionState::HASMORE;
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return {state, {}};
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}
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auto UnsortedGatherExecutor::fetcher() const noexcept -> const Fetcher& {
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return _fetcher;
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}
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auto UnsortedGatherExecutor::fetcher() noexcept -> Fetcher& { return _fetcher; }
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auto UnsortedGatherExecutor::numDependencies() const
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noexcept(noexcept(_fetcher.numberDependencies())) -> size_t {
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return _fetcher.numberDependencies();
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}
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auto UnsortedGatherExecutor::fetchNextRow(size_t atMost)
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-> std::pair<ExecutionState, InputAqlItemRow> {
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auto res = fetcher().fetchRowForDependency(currentDependency(), atMost);
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if (res.first == ExecutionState::DONE) {
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advanceDependency();
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}
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return res;
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}
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auto UnsortedGatherExecutor::skipNextRows(size_t atMost)
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-> std::pair<ExecutionState, size_t> {
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auto res = fetcher().skipRowsForDependency(currentDependency(), atMost);
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if (res.first == ExecutionState::DONE) {
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advanceDependency();
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}
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return res;
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}
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auto UnsortedGatherExecutor::done() const noexcept -> bool {
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return _currentDependency >= numDependencies();
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}
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auto UnsortedGatherExecutor::currentDependency() const noexcept -> size_t {
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return _currentDependency;
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}
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auto UnsortedGatherExecutor::advanceDependency() noexcept -> void {
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TRI_ASSERT(_currentDependency < numDependencies());
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++_currentDependency;
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}
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auto UnsortedGatherExecutor::skipRows(size_t const atMost)
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-> std::tuple<ExecutionState, UnsortedGatherExecutor::Stats, size_t> {
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auto const rowsLeftToSkip = [&atMost, &skipped = this->_skipped]() {
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TRI_ASSERT(atMost >= skipped);
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return atMost - skipped;
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};
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while (rowsLeftToSkip() > 0 && !done()) {
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// Note that skipNextRow may return DONE (because the current dependency is
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// DONE), and also return an unitialized row in that case, but we are not
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// DONE completely - that's what `done()` is for.
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auto [state, skipped] = skipNextRows(rowsLeftToSkip());
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_skipped += skipped;
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if (state == ExecutionState::WAITING) {
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return {state, {}, 0};
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}
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}
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auto state = done() ? ExecutionState::DONE : ExecutionState::HASMORE;
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auto skipped = size_t{0};
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std::swap(skipped, _skipped);
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return {state, {}, skipped};
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}
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