diff options
Diffstat (limited to 'src/mongo/db/exec/and_hash.h')
| -rw-r--r-- | src/mongo/db/exec/and_hash.h | 150 |
1 files changed, 75 insertions, 75 deletions
diff --git a/src/mongo/db/exec/and_hash.h b/src/mongo/db/exec/and_hash.h index 16e7ec3759f..efe625619db 100644 --- a/src/mongo/db/exec/and_hash.h +++ b/src/mongo/db/exec/and_hash.h @@ -38,106 +38,106 @@ namespace mongo { +/** + * Reads from N children, each of which must have a valid RecordId. Uses a hash table to + * intersect the outputs of the N children, and outputs the intersection. + * + * Preconditions: Valid RecordId. More than one child. + * + * Any RecordId that we keep a reference to that is invalidated before we are able to return it + * is fetched and added to the WorkingSet as "flagged for further review." Because this stage + * operates with RecordIds, we are unable to evaluate the AND for the invalidated RecordId, and it + * must be fully matched later. + */ +class AndHashStage : public PlanStage { +public: + AndHashStage(WorkingSet* ws, const Collection* collection); + /** - * Reads from N children, each of which must have a valid RecordId. Uses a hash table to - * intersect the outputs of the N children, and outputs the intersection. - * - * Preconditions: Valid RecordId. More than one child. - * - * Any RecordId that we keep a reference to that is invalidated before we are able to return it - * is fetched and added to the WorkingSet as "flagged for further review." Because this stage - * operates with RecordIds, we are unable to evaluate the AND for the invalidated RecordId, and it - * must be fully matched later. + * For testing only. Allows tests to set memory usage threshold. */ - class AndHashStage : public PlanStage { - public: - AndHashStage(WorkingSet* ws, const Collection* collection); - - /** - * For testing only. Allows tests to set memory usage threshold. - */ - AndHashStage(WorkingSet* ws, - const Collection* collection, - size_t maxMemUsage); + AndHashStage(WorkingSet* ws, const Collection* collection, size_t maxMemUsage); - virtual ~AndHashStage(); + virtual ~AndHashStage(); - void addChild(PlanStage* child); + void addChild(PlanStage* child); - /** - * Returns memory usage. - * For testing only. - */ - size_t getMemUsage() const; + /** + * Returns memory usage. + * For testing only. + */ + size_t getMemUsage() const; - virtual StageState work(WorkingSetID* out); - virtual bool isEOF(); + virtual StageState work(WorkingSetID* out); + virtual bool isEOF(); - virtual void saveState(); - virtual void restoreState(OperationContext* opCtx); - virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type); + virtual void saveState(); + virtual void restoreState(OperationContext* opCtx); + virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type); - virtual std::vector<PlanStage*> getChildren() const; + virtual std::vector<PlanStage*> getChildren() const; - virtual StageType stageType() const { return STAGE_AND_HASH; } + virtual StageType stageType() const { + return STAGE_AND_HASH; + } - virtual PlanStageStats* getStats(); + virtual PlanStageStats* getStats(); - virtual const CommonStats* getCommonStats() const; + virtual const CommonStats* getCommonStats() const; - virtual const SpecificStats* getSpecificStats() const; + virtual const SpecificStats* getSpecificStats() const; - static const char* kStageType; + static const char* kStageType; - private: - static const size_t kLookAheadWorks; +private: + static const size_t kLookAheadWorks; - StageState readFirstChild(WorkingSetID* out); - StageState hashOtherChildren(WorkingSetID* out); - StageState workChild(size_t childNo, WorkingSetID* out); + StageState readFirstChild(WorkingSetID* out); + StageState hashOtherChildren(WorkingSetID* out); + StageState workChild(size_t childNo, WorkingSetID* out); - // Not owned by us. - const Collection* _collection; + // Not owned by us. + const Collection* _collection; - // Not owned by us. - WorkingSet* _ws; + // Not owned by us. + WorkingSet* _ws; - // The stages we read from. Owned by us. - std::vector<PlanStage*> _children; + // The stages we read from. Owned by us. + std::vector<PlanStage*> _children; - // We want to see if any of our children are EOF immediately. This requires working them a - // few times to see if they hit EOF or if they produce a result. If they produce a result, - // we place that result here. - std::vector<WorkingSetID> _lookAheadResults; + // We want to see if any of our children are EOF immediately. This requires working them a + // few times to see if they hit EOF or if they produce a result. If they produce a result, + // we place that result here. + std::vector<WorkingSetID> _lookAheadResults; - // _dataMap is filled out by the first child and probed by subsequent children. This is the - // hash table that we create by intersecting _children and probe with the last child. - typedef unordered_map<RecordId, WorkingSetID, RecordId::Hasher> DataMap; - DataMap _dataMap; + // _dataMap is filled out by the first child and probed by subsequent children. This is the + // hash table that we create by intersecting _children and probe with the last child. + typedef unordered_map<RecordId, WorkingSetID, RecordId::Hasher> DataMap; + DataMap _dataMap; - // Keeps track of what elements from _dataMap subsequent children have seen. - // Only used while _hashingChildren. - typedef unordered_set<RecordId, RecordId::Hasher> SeenMap; - SeenMap _seenMap; + // Keeps track of what elements from _dataMap subsequent children have seen. + // Only used while _hashingChildren. + typedef unordered_set<RecordId, RecordId::Hasher> SeenMap; + SeenMap _seenMap; - // True if we're still intersecting _children[0..._children.size()-1]. - bool _hashingChildren; + // True if we're still intersecting _children[0..._children.size()-1]. + bool _hashingChildren; - // Which child are we currently working on? - size_t _currentChild; + // Which child are we currently working on? + size_t _currentChild; - // Stats - CommonStats _commonStats; - AndHashStats _specificStats; + // Stats + CommonStats _commonStats; + AndHashStats _specificStats; - // The usage in bytes of all buffered data that we're holding. - // Memory usage is calculated from keys held in _dataMap only. - // For simplicity, results in _lookAheadResults do not count towards the limit. - size_t _memUsage; + // The usage in bytes of all buffered data that we're holding. + // Memory usage is calculated from keys held in _dataMap only. + // For simplicity, results in _lookAheadResults do not count towards the limit. + size_t _memUsage; - // Upper limit for buffered data memory usage. - // Defaults to 32 MB (See kMaxBytes in and_hash.cpp). - size_t _maxMemUsage; - }; + // Upper limit for buffered data memory usage. + // Defaults to 32 MB (See kMaxBytes in and_hash.cpp). + size_t _maxMemUsage; +}; } // namespace mongo |