mirror of https://gitee.com/bigwinds/arangodb
53 lines
1.7 KiB
C++
53 lines
1.7 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_CLUSTER_ENGINE_CLUSTER_SELECTIVITY_ESTIMATES_H
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#define ARANGOD_CLUSTER_ENGINE_CLUSTER_SELECTIVITY_ESTIMATES_H 1
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#include "Basics/Common.h"
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#include "Basics/ReadWriteLock.h"
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namespace arangodb {
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class LogicalCollection;
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///@brief basic cache for selectivity estimates in the cluster
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class ClusterSelectivityEstimates {
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public:
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explicit ClusterSelectivityEstimates(LogicalCollection& collection);
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void flush();
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std::unordered_map<std::string, double> get(bool allowUpdate) const;
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void set(std::unordered_map<std::string, double>&& estimates);
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private:
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LogicalCollection& _collection;
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mutable basics::ReadWriteLock _lock;
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mutable std::unordered_map<std::string, double> _estimates;
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mutable double _expireStamp;
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static constexpr double defaultTtl = 60.0;
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};
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}
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#endif
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