C++ QuerySolutionNode类代码示例

void SortKeyGenerator::getBoundsForSort(OperationContext* txn,
                                        const BSONObj& queryObj,
                                        const BSONObj& sortObj) {
    QueryPlannerParams params;
    params.options = QueryPlannerParams::NO_TABLE_SCAN;

    // We're creating a "virtual index" with key pattern equal to the sort order.
    IndexEntry sortOrder(sortObj,
                         IndexNames::BTREE,
                         true,
                         MultikeyPaths{},
                         false,
                         false,
                         "doesnt_matter",
                         NULL,
                         BSONObj());
    params.indices.push_back(sortOrder);

    auto statusWithQueryForSort = CanonicalQuery::canonicalize(
        txn, NamespaceString("fake.ns"), queryObj, ExtensionsCallbackNoop());
    verify(statusWithQueryForSort.isOK());
    std::unique_ptr<CanonicalQuery> queryForSort = std::move(statusWithQueryForSort.getValue());

    std::vector<QuerySolution*> solns;
    LOG(5) << "Sort key generation: Planning to obtain bounds for sort.";
    QueryPlanner::plan(*queryForSort, params, &solns);

    // TODO: are there ever > 1 solns?  If so, do we look for a specific soln?
    if (1 == solns.size()) {
        IndexScanNode* ixScan = NULL;
        QuerySolutionNode* rootNode = solns[0]->root.get();

        if (rootNode->getType() == STAGE_FETCH) {
            FetchNode* fetchNode = static_cast<FetchNode*>(rootNode);
            if (fetchNode->children[0]->getType() != STAGE_IXSCAN) {
                delete solns[0];
                // No bounds.
                return;
            }
            ixScan = static_cast<IndexScanNode*>(fetchNode->children[0]);
        } else if (rootNode->getType() == STAGE_IXSCAN) {
            ixScan = static_cast<IndexScanNode*>(rootNode);
        }

        if (ixScan) {
            _bounds.fields.swap(ixScan->bounds.fields);
            _hasBounds = true;
        }
    }

    for (size_t i = 0; i < solns.size(); ++i) {
        delete solns[i];
    }
}

    /**
     * If possible, turn the provided QuerySolution into a QuerySolution that uses a DistinctNode
     * to provide results for the distinct command.
     *
     * If the provided solution could be mutated successfully, returns true, otherwise returns
     * false.
     */
    bool turnIxscanIntoDistinctIxscan(QuerySolution* soln, const string& field) {
        QuerySolutionNode* root = soln->root.get();

        // We're looking for a project on top of an ixscan.
        if (STAGE_PROJECTION == root->getType() && (STAGE_IXSCAN == root->children[0]->getType())) {
            IndexScanNode* isn = static_cast<IndexScanNode*>(root->children[0]);

            // An additional filter must be applied to the data in the key, so we can't just skip
            // all the keys with a given value; we must examine every one to find the one that (may)
            // pass the filter.
            if (NULL != isn->filter.get()) {
                return false;
            }

            // We only set this when we have special query modifiers (.max() or .min()) or other
            // special cases.  Don't want to handle the interactions between those and distinct.
            // Don't think this will ever really be true but if it somehow is, just ignore this
            // soln.
            if (isn->bounds.isSimpleRange) {
                return false;
            }

            // Make a new DistinctNode.  We swap this for the ixscan in the provided solution.
            DistinctNode* dn = new DistinctNode();
            dn->indexKeyPattern = isn->indexKeyPattern;
            dn->direction = isn->direction;
            dn->bounds = isn->bounds;

            // Figure out which field we're skipping to the next value of.  TODO: We currently only
            // try to distinct-hack when there is an index prefixed by the field we're distinct-ing
            // over.  Consider removing this code if we stick with that policy.
            dn->fieldNo = 0;
            BSONObjIterator it(isn->indexKeyPattern);
            while (it.more()) {
                if (field == it.next().fieldName()) {
                    break;
                }
                dn->fieldNo++;
            }

            // Delete the old index scan, set the child of project to the fast distinct scan.
            delete root->children[0];
            root->children[0] = dn;
            return true;
        }

        return false;
    }

    void SortStageKeyGenerator::getBoundsForSort(const BSONObj& queryObj, const BSONObj& sortObj) {
        QueryPlannerParams params;
        params.options = QueryPlannerParams::NO_TABLE_SCAN;

        // We're creating a "virtual index" with key pattern equal to the sort order.
        IndexEntry sortOrder(sortObj, IndexNames::BTREE, true, false, false, "doesnt_matter",
                             BSONObj());
        params.indices.push_back(sortOrder);

        CanonicalQuery* rawQueryForSort;
        verify(CanonicalQuery::canonicalize(
                "fake_ns", queryObj, &rawQueryForSort, WhereCallbackNoop()).isOK());
        auto_ptr<CanonicalQuery> queryForSort(rawQueryForSort);

        vector<QuerySolution*> solns;
        QLOG() << "Sort stage: Planning to obtain bounds for sort." << endl;
        QueryPlanner::plan(*queryForSort, params, &solns);

        // TODO: are there ever > 1 solns?  If so, do we look for a specific soln?
        if (1 == solns.size()) {
            IndexScanNode* ixScan = NULL;
            QuerySolutionNode* rootNode = solns[0]->root.get();

            if (rootNode->getType() == STAGE_FETCH) {
                FetchNode* fetchNode = static_cast<FetchNode*>(rootNode);
                if (fetchNode->children[0]->getType() != STAGE_IXSCAN) {
                    delete solns[0];
                    // No bounds.
                    return;
                }
                ixScan = static_cast<IndexScanNode*>(fetchNode->children[0]);
            }
            else if (rootNode->getType() == STAGE_IXSCAN) {
                ixScan = static_cast<IndexScanNode*>(rootNode);
            }

            if (ixScan) {
                _bounds.fields.swap(ixScan->bounds.fields);
                _hasBounds = true;
            }
        }

        for (size_t i = 0; i < solns.size(); ++i) {
            delete solns[i];
        }
    }

    //static
    bool StageBuilder::build(const QuerySolution& solution, PlanStage** rootOut,
                             WorkingSet** wsOut) {
        QuerySolutionNode* root = solution.root.get();
        if (NULL == root) { return false; }

        if (STAGE_COLLSCAN == root->getType()) {
            const CollectionScanNode* csn = static_cast<const CollectionScanNode*>(root);
            CollectionScanParams params;
            params.ns = csn->name;
            params.tailable = csn->tailable;
            params.direction = (csn->direction == 1) ? CollectionScanParams::FORWARD
                                                     : CollectionScanParams::BACKWARD;
            *wsOut = new WorkingSet();
            *rootOut = new CollectionScan(params, *wsOut, csn->filter);
            return true;
        }
        else {
            return false;
        }
    }

//.........这里部分代码省略.........
                _child.reset(new MultiPlanStage(_txn, _collection,
                                                branchResult->canonicalQuery.get()));
                MultiPlanStage* multiPlanStage = static_cast<MultiPlanStage*>(_child.get());

                // Dump all the solutions into the MPS.
                for (size_t ix = 0; ix < branchResult->solutions.size(); ++ix) {
                    PlanStage* nextPlanRoot;
                    invariant(StageBuilder::build(_txn,
                                                  _collection,
                                                  *branchResult->solutions[ix],
                                                  _ws,
                                                  &nextPlanRoot));

                    // Takes ownership of solution with index 'ix' and 'nextPlanRoot'.
                    multiPlanStage->addPlan(branchResult->solutions.releaseAt(ix),
                                            nextPlanRoot,
                                            _ws);
                }

                Status planSelectStat = multiPlanStage->pickBestPlan(yieldPolicy);
                if (!planSelectStat.isOK()) {
                    return planSelectStat;
                }

                if (!multiPlanStage->bestPlanChosen()) {
                    mongoutils::str::stream ss;
                    ss << "Failed to pick best plan for subchild "
                       << branchResult->canonicalQuery->toString();
                    return Status(ErrorCodes::BadValue, ss);
                }

                QuerySolution* bestSoln = multiPlanStage->bestSolution();

                // Check that we have good cache data. For example, we don't cache things
                // for 2d indices.
                if (NULL == bestSoln->cacheData.get()) {
                    mongoutils::str::stream ss;
                    ss << "No cache data for subchild " << orChild->toString();
                    return Status(ErrorCodes::BadValue, ss);
                }

                if (SolutionCacheData::USE_INDEX_TAGS_SOLN != bestSoln->cacheData->solnType) {
                    mongoutils::str::stream ss;
                    ss << "No indexed cache data for subchild "
                       << orChild->toString();
                    return Status(ErrorCodes::BadValue, ss);
                }

                // Add the index assignments to our original query.
                Status tagStatus = QueryPlanner::tagAccordingToCache(
                    orChild, bestSoln->cacheData->tree.get(), _indexMap);

                if (!tagStatus.isOK()) {
                    mongoutils::str::stream ss;
                    ss << "Failed to extract indices from subchild "
                       << orChild->toString();
                    return Status(ErrorCodes::BadValue, ss);
                }

                cacheData->children.push_back(bestSoln->cacheData->tree->clone());
            }
        }

        // Must do this before using the planner functionality.
        sortUsingTags(orExpr.get());

        // Use the cached index assignments to build solnRoot.  Takes ownership of 'orExpr'.
        QuerySolutionNode* solnRoot = QueryPlannerAccess::buildIndexedDataAccess(
            *_query, orExpr.release(), false, _plannerParams.indices, _plannerParams);

        if (NULL == solnRoot) {
            mongoutils::str::stream ss;
            ss << "Failed to build indexed data path for subplanned query\n";
            return Status(ErrorCodes::BadValue, ss);
        }

        QLOG() << "Subplanner: fully tagged tree is " << solnRoot->toString();

        // Takes ownership of 'solnRoot'
        _compositeSolution.reset(QueryPlannerAnalysis::analyzeDataAccess(*_query,
                                                                         _plannerParams,
                                                                         solnRoot));

        if (NULL == _compositeSolution.get()) {
            mongoutils::str::stream ss;
            ss << "Failed to analyze subplanned query";
            return Status(ErrorCodes::BadValue, ss);
        }

        QLOG() << "Subplanner: Composite solution is " << _compositeSolution->toString() << endl;

        // Use the index tags from planning each branch to construct the composite solution,
        // and set that solution as our child stage.
        _ws->clear();
        PlanStage* root;
        invariant(StageBuilder::build(_txn, _collection, *_compositeSolution.get(), _ws, &root));
        _child.reset(root);

        return Status::OK();
    }

//.........这里部分代码省略.........

                multiPlanStage->pickBestPlan();
                if (! multiPlanStage->bestPlanChosen()) {
                    QLOG() << "Subplanner: Failed to pick best plan for subchild "
                           << orChildCQ->toString();
                    return false;
                }

                Runner* mpr = new SingleSolutionRunner(_collection,
                                                       orChildCQ.release(),
                                                       multiPlanStage->bestSolution(),
                                                       multiPlanStage,
                                                       sharedWorkingSet);

                _underlyingRunner.reset(mpr);

                if (_killed) {
                    QLOG() << "Subplanner: Killed while picking best plan for subchild "
                           << orChild->toString();
                    return false;
                }

                QuerySolution* bestSoln = multiPlanStage->bestSolution();

                if (SolutionCacheData::USE_INDEX_TAGS_SOLN != bestSoln->cacheData->solnType) {
                    QLOG() << "Subplanner: No indexed cache data for subchild "
                           << orChild->toString();
                    return false;
                }

                // Add the index assignments to our original query.
                Status tagStatus = QueryPlanner::tagAccordingToCache(
                    orChild, bestSoln->cacheData->tree.get(), _indexMap);

                if (!tagStatus.isOK()) {
                    QLOG() << "Subplanner: Failed to extract indices from subchild "
                           << orChild->toString();
                    return false;
                }

                cacheData->children.push_back(bestSoln->cacheData->tree->clone());
            }
        }

        // Must do this before using the planner functionality.
        sortUsingTags(theOr.get());

        // Use the cached index assignments to build solnRoot.  Takes ownership of 'theOr'
        QuerySolutionNode* solnRoot = QueryPlannerAccess::buildIndexedDataAccess(
            *_query, theOr.release(), false, _plannerParams.indices);

        if (NULL == solnRoot) {
            QLOG() << "Subplanner: Failed to build indexed data path for subplanned query\n";
            return false;
        }

        QLOG() << "Subplanner: fully tagged tree is " << solnRoot->toString();

        // Takes ownership of 'solnRoot'
        QuerySolution* soln = QueryPlannerAnalysis::analyzeDataAccess(*_query,
                                                                      _plannerParams,
                                                                      solnRoot);

        if (NULL == soln) {
            QLOG() << "Subplanner: Failed to analyze subplanned query";
            return false;
        }

        // We want our franken-solution to be cached.
        SolutionCacheData* scd = new SolutionCacheData();
        scd->tree.reset(cacheData.release());
        soln->cacheData.reset(scd);

        QLOG() << "Subplanner: Composite solution is " << soln->toString() << endl;

        // We use one of these even if there is one plan.  We do this so that the entry is cached
        // with stats obtained in the same fashion as a competitive ranking would have obtained
        // them.
        MultiPlanStage* multiPlanStage = new MultiPlanStage(_collection, _query.get());
        WorkingSet* ws = new WorkingSet();
        PlanStage* root;
        verify(StageBuilder::build(_txn, _collection, *soln, ws, &root));
        multiPlanStage->addPlan(soln, root, ws); // Takes ownership first two arguments.

        multiPlanStage->pickBestPlan();
        if (! multiPlanStage->bestPlanChosen()) {
            QLOG() << "Subplanner: Failed to pick best plan for subchild "
                   << _query->toString();
            return false;
        }

        Runner* mpr = new SingleSolutionRunner(_collection,
                                               _query.release(),
                                               multiPlanStage->bestSolution(),
                                               multiPlanStage,
                                               ws);
        _underlyingRunner.reset(mpr);

        return true;
    }

//.........这里部分代码省略.........
            ON_BLOCK_EXIT([&] {
                invariant(_children.size() == 1);  // Make sure nothing else was added to _children.
                _children.pop_back();
            });
            MultiPlanStage* multiPlanStage = static_cast<MultiPlanStage*>(child().get());

            // Dump all the solutions into the MPS.
            for (size_t ix = 0; ix < branchResult->solutions.size(); ++ix) {
                PlanStage* nextPlanRoot;
                invariant(StageBuilder::build(getOpCtx(),
                                              _collection,
                                              *branchResult->canonicalQuery,
                                              *branchResult->solutions[ix],
                                              _ws,
                                              &nextPlanRoot));

                // Takes ownership of solution with index 'ix' and 'nextPlanRoot'.
                multiPlanStage->addPlan(branchResult->solutions.releaseAt(ix), nextPlanRoot, _ws);
            }

            Status planSelectStat = multiPlanStage->pickBestPlan(yieldPolicy);
            if (!planSelectStat.isOK()) {
                return planSelectStat;
            }

            if (!multiPlanStage->bestPlanChosen()) {
                mongoutils::str::stream ss;
                ss << "Failed to pick best plan for subchild "
                   << branchResult->canonicalQuery->toString();
                return Status(ErrorCodes::BadValue, ss);
            }

            QuerySolution* bestSoln = multiPlanStage->bestSolution();

            // Check that we have good cache data. For example, we don't cache things
            // for 2d indices.
            if (NULL == bestSoln->cacheData.get()) {
                mongoutils::str::stream ss;
                ss << "No cache data for subchild " << orChild->toString();
                return Status(ErrorCodes::BadValue, ss);
            }

            if (SolutionCacheData::USE_INDEX_TAGS_SOLN != bestSoln->cacheData->solnType) {
                mongoutils::str::stream ss;
                ss << "No indexed cache data for subchild " << orChild->toString();
                return Status(ErrorCodes::BadValue, ss);
            }

            // Add the index assignments to our original query.
            Status tagStatus = QueryPlanner::tagAccordingToCache(
                orChild, bestSoln->cacheData->tree.get(), _indexMap);

            if (!tagStatus.isOK()) {
                mongoutils::str::stream ss;
                ss << "Failed to extract indices from subchild " << orChild->toString();
                return Status(ErrorCodes::BadValue, ss);
            }

            cacheData->children.push_back(bestSoln->cacheData->tree->clone());
        }
    }

    // Must do this before using the planner functionality.
    sortUsingTags(_orExpression.get());

    // Use the cached index assignments to build solnRoot. Takes ownership of '_orExpression'.
    QuerySolutionNode* solnRoot = QueryPlannerAccess::buildIndexedDataAccess(
        *_query, _orExpression.release(), false, _plannerParams.indices, _plannerParams);

    if (NULL == solnRoot) {
        mongoutils::str::stream ss;
        ss << "Failed to build indexed data path for subplanned query\n";
        return Status(ErrorCodes::BadValue, ss);
    }

    LOG(5) << "Subplanner: fully tagged tree is " << solnRoot->toString();

    // Takes ownership of 'solnRoot'
    _compositeSolution.reset(
        QueryPlannerAnalysis::analyzeDataAccess(*_query, _plannerParams, solnRoot));

    if (NULL == _compositeSolution.get()) {
        mongoutils::str::stream ss;
        ss << "Failed to analyze subplanned query";
        return Status(ErrorCodes::BadValue, ss);
    }

    LOG(5) << "Subplanner: Composite solution is " << _compositeSolution->toString();

    // Use the index tags from planning each branch to construct the composite solution,
    // and set that solution as our child stage.
    _ws->clear();
    PlanStage* root;
    invariant(StageBuilder::build(
        getOpCtx(), _collection, *_query, *_compositeSolution.get(), _ws, &root));
    invariant(_children.empty());
    _children.emplace_back(root);

    return Status::OK();
}