mirror of https://gitee.com/bigwinds/arangodb
81 lines
2.5 KiB
C++
81 lines
2.5 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS 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 Jan Steemann
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_AQL_COST_ESTIMATE_H
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#define ARANGOD_AQL_COST_ESTIMATE_H 1
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#include "Basics/Common.h"
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namespace arangodb {
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namespace aql {
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/// @brief a simple object containing a cost estimate for ExecutionNodes
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struct CostEstimate {
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/// @brief create the cost estimate from values
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CostEstimate(double estimatedCost, size_t estimatedNrItems)
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: estimatedCost(estimatedCost), estimatedNrItems(estimatedNrItems) {}
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/// @brief initialize a still-invalid cost estimate
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CostEstimate() : CostEstimate(-1.0, 0) {}
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bool operator==(CostEstimate const& other) const {
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return estimatedCost == other.estimatedCost && estimatedNrItems == other.estimatedNrItems;
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}
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/// @brief return an empty but valid cost estimate
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static CostEstimate empty() { return CostEstimate(0.0, 0); }
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/// @brief invalidate the cost estimate
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void invalidate() {
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// a value of < 0 will mean that the cost estimation was not performed yet
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estimatedCost = -1.0;
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estimatedNrItems = 0;
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TRI_ASSERT(!isValid());
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}
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/// @brief invalidate to a valid but empty estimate
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void initialize() {
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estimatedCost = 0.0;
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estimatedNrItems = 0;
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TRI_ASSERT(isValid());
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}
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/// @brief whether or not the estimate is valid
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inline bool isValid() const {
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// a value of < 0 will mean that the cost estimation was not performed yet
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return estimatedCost >= 0.0;
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}
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/// @brief estimated cost produced by the node
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double estimatedCost;
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/// @brief cost
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/// @brief estimated number of items returned by the node
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size_t estimatedNrItems;
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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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