text: /**
   *    Copyright (C) 2014 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #pragma once
  
  #include <atomic>
  
  #include "mongo/platform/atomic_proxy.h"
  
  namespace mongo {
  
  //
  // multi-plan ranking
  //
  
  // Max number of times we call work() on plans before comparing them,
  // for small collections.
  extern std::atomic<int> internalQueryPlanEvaluationWorks;
  
  // For large collections, the number times we work() candidate plans is
  // taken as this fraction of the collection size.
  extern AtomicDouble internalQueryPlanEvaluationCollFraction;
  
  // Stop working plans once a plan returns this many results.
  extern std::atomic<int> internalQueryPlanEvaluationMaxResults;
  
  // Do we give a big ranking bonus to intersection plans?
  extern std::atomic<bool> internalQueryForceIntersectionPlans;
  
  // Do we have ixisect on at all?
  extern std::atomic<bool> internalQueryPlannerEnableIndexIntersection;
  
  // Do we use hash-based intersection for rooted $and queries?
  extern std::atomic<bool> internalQueryPlannerEnableHashIntersection;
  
  //
  // plan cache
  //
  
  // How many entries in the cache?
  extern std::atomic<int> internalQueryCacheSize;
  
  // How many feedback entries do we collect before possibly evicting from the cache based on bad
  // performance?
  extern std::atomic<int> internalQueryCacheFeedbacksStored;
  
  // How many times more works must we perform in order to justify plan cache eviction
  // and replanning?
  extern AtomicDouble internalQueryCacheEvictionRatio;
  
  //
  // Planning and enumeration.
  //
  
  // How many indexed solutions will QueryPlanner::plan output?
  extern std::atomic<int> internalQueryPlannerMaxIndexedSolutions;
  
  // How many solutions will the enumerator consider at each OR?
  extern std::atomic<int> internalQueryEnumerationMaxOrSolutions;
  
  // How many intersections will the enumerator consider at each AND?
  extern std::atomic<int> internalQueryEnumerationMaxIntersectPerAnd;
  
  // Do we want to plan each child of the OR independently?
  extern std::atomic<bool> internalQueryPlanOrChildrenIndependently;
  
  // How many index scans are we willing to produce in order to obtain a sort order
  // during explodeForSort?
  extern std::atomic<int> internalQueryMaxScansToExplode;
  
  //
  // Query execution.
  //
  
  extern std::atomic<int> internalQueryExecMaxBlockingSortBytes;
  
  // Yield after this many "should yield?" checks.
  extern std::atomic<int> internalQueryExecYieldIterations;
  
  // Yield if it's been at least this many milliseconds since we last yielded.
  extern std::atomic<int> internalQueryExecYieldPeriodMS;
  
  }  // namespace mongo
  