diff options
Diffstat (limited to 'src/mongo/db/exec/fetch.h')
| -rw-r--r-- | src/mongo/db/exec/fetch.h | 134 |
1 files changed, 67 insertions, 67 deletions
diff --git a/src/mongo/db/exec/fetch.h b/src/mongo/db/exec/fetch.h index 3d0962a3508..1ba3ba427e2 100644 --- a/src/mongo/db/exec/fetch.h +++ b/src/mongo/db/exec/fetch.h @@ -37,82 +37,82 @@ namespace mongo { - /** - * This stage turns a RecordId into a BSONObj. - * - * In WorkingSetMember terms, it transitions from LOC_AND_IDX to LOC_AND_OBJ by reading - * the record at the provided loc. Returns verbatim any data that already has an object. - * - * Preconditions: Valid RecordId. - */ - class FetchStage : public PlanStage { - public: - FetchStage(OperationContext* txn, - WorkingSet* ws, - PlanStage* child, - const MatchExpression* filter, - const Collection* collection); - - virtual ~FetchStage(); - - virtual bool isEOF(); - virtual StageState work(WorkingSetID* out); - - 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 StageType stageType() const { return STAGE_FETCH; } - - PlanStageStats* getStats(); - - virtual const CommonStats* getCommonStats(); +/** + * This stage turns a RecordId into a BSONObj. + * + * In WorkingSetMember terms, it transitions from LOC_AND_IDX to LOC_AND_OBJ by reading + * the record at the provided loc. Returns verbatim any data that already has an object. + * + * Preconditions: Valid RecordId. + */ +class FetchStage : public PlanStage { +public: + FetchStage(OperationContext* txn, + WorkingSet* ws, + PlanStage* child, + const MatchExpression* filter, + const Collection* collection); - virtual const SpecificStats* getSpecificStats(); + virtual ~FetchStage(); - static const char* kStageType; + virtual bool isEOF(); + virtual StageState work(WorkingSetID* out); - private: + virtual void saveState(); + virtual void restoreState(OperationContext* opCtx); + virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type); - /** - * If the member (with id memberID) passes our filter, set *out to memberID and return that - * ADVANCED. Otherwise, free memberID and return NEED_TIME. - */ - StageState returnIfMatches(WorkingSetMember* member, WorkingSetID memberID, - WorkingSetID* out); + virtual std::vector<PlanStage*> getChildren() const; - OperationContext* _txn; + virtual StageType stageType() const { + return STAGE_FETCH; + } - // Collection which is used by this stage. Used to resolve record ids retrieved by child - // stages. The lifetime of the collection must supersede that of the stage. - const Collection* _collection; + PlanStageStats* getStats(); - // _ws is not owned by us. - WorkingSet* _ws; - boost::scoped_ptr<PlanStage> _child; + virtual const CommonStats* getCommonStats(); - // The filter is not owned by us. - const MatchExpression* _filter; + virtual const SpecificStats* getSpecificStats(); - // If we want to return a RecordId and it points to something that's not in memory, - // we return a "please page this in" result. We add a RecordFetcher given back to us by the - // storage engine to the WSM. The RecordFetcher is used by the PlanExecutor when it handles - // the fetch request. - // - // Some stages which request fetches don't need to use '_idBeingPagedIn' (e.g., - // CollectionScan) because they are implemented with an underlying iterator which keeps - // track of the next WSM to be returned. A FetchStage has no such iterator, but rather - // streams its results from the child. Therefore, when it requests a yield via NEED_FETCH, - // the current WSM must be saved so that the fetched result can be returned on the next - // call to work(). This also requires special invalidation handling not found in stages like - // CollectionScan for when '_idBeingPagedIn' is invalidated before it can be returned. - WorkingSetID _idBeingPagedIn; + static const char* kStageType; - // Stats - CommonStats _commonStats; - FetchStats _specificStats; - }; +private: + /** + * If the member (with id memberID) passes our filter, set *out to memberID and return that + * ADVANCED. Otherwise, free memberID and return NEED_TIME. + */ + StageState returnIfMatches(WorkingSetMember* member, WorkingSetID memberID, WorkingSetID* out); + + OperationContext* _txn; + + // Collection which is used by this stage. Used to resolve record ids retrieved by child + // stages. The lifetime of the collection must supersede that of the stage. + const Collection* _collection; + + // _ws is not owned by us. + WorkingSet* _ws; + boost::scoped_ptr<PlanStage> _child; + + // The filter is not owned by us. + const MatchExpression* _filter; + + // If we want to return a RecordId and it points to something that's not in memory, + // we return a "please page this in" result. We add a RecordFetcher given back to us by the + // storage engine to the WSM. The RecordFetcher is used by the PlanExecutor when it handles + // the fetch request. + // + // Some stages which request fetches don't need to use '_idBeingPagedIn' (e.g., + // CollectionScan) because they are implemented with an underlying iterator which keeps + // track of the next WSM to be returned. A FetchStage has no such iterator, but rather + // streams its results from the child. Therefore, when it requests a yield via NEED_FETCH, + // the current WSM must be saved so that the fetched result can be returned on the next + // call to work(). This also requires special invalidation handling not found in stages like + // CollectionScan for when '_idBeingPagedIn' is invalidated before it can be returned. + WorkingSetID _idBeingPagedIn; + + // Stats + CommonStats _commonStats; + FetchStats _specificStats; +}; } // namespace mongo |