示例#1
0
文件: fetch.cpp 项目: 328500920/mongo
    PlanStage::StageState FetchStage::fetchCompleted(WorkingSetID* out) {
        WorkingSetMember* member = _ws->get(_idBeingPagedIn);

        // The DiskLoc we're waiting to page in was invalidated (forced fetch).  Test for
        // matching and maybe pass it up.
        if (member->state == WorkingSetMember::OWNED_OBJ) {
            WorkingSetID memberID = _idBeingPagedIn;
            _idBeingPagedIn = WorkingSet::INVALID_ID;
            return returnIfMatches(member, memberID, out);
        }

        // Assume that the caller has fetched appropriately.
        // TODO: Do we want to double-check the runner?  Not sure how reliable likelyInMemory is
        // on all platforms.
        verify(member->hasLoc());
        verify(!member->hasObj());

        // Make the (unowned) object.
        Record* record = member->loc.rec();
        const char* data = record->dataNoThrowing();
        member->obj = BSONObj(data);

        // Don't need index data anymore as we have an obj.
        member->keyData.clear();
        member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
        verify(!member->obj.isOwned());

        // Return the obj if it passes our filter.
        WorkingSetID memberID = _idBeingPagedIn;
        _idBeingPagedIn = WorkingSet::INVALID_ID;
        return returnIfMatches(member, memberID, out);
    }
示例#2
0
    bool MultiPlanRunner::workAllPlans(BSONObj* objOut) {
        bool planHitEOF = false;

        for (size_t i = 0; i < _candidates.size(); ++i) {
            CandidatePlan& candidate = _candidates[i];
            if (candidate.failed) { continue; }

            // Yield, if we can yield ourselves.
            if (NULL != _yieldPolicy.get() && _yieldPolicy->shouldYield()) {
                saveState();
                _yieldPolicy->yield();
                if (_failure || _killed) { return false; }
                restoreState();
            }

            WorkingSetID id = WorkingSet::INVALID_ID;
            PlanStage::StageState state = candidate.root->work(&id);

            if (PlanStage::ADVANCED == state) {
                // Save result for later.
                candidate.results.push_back(id);
            }
            else if (PlanStage::NEED_TIME == state) {
                // Fall through to yield check at end of large conditional.
            }
            else if (PlanStage::NEED_FETCH == state) {
                // id has a loc and refers to an obj we need to fetch.
                WorkingSetMember* member = candidate.ws->get(id);

                // This must be true for somebody to request a fetch and can only change when an
                // invalidation happens, which is when we give up a lock.  Don't give up the
                // lock between receiving the NEED_FETCH and actually fetching(?).
                verify(member->hasLoc());

                // Actually bring record into memory.
                Record* record = member->loc.rec();

                // If we're allowed to, go to disk outside of the lock.
                if (NULL != _yieldPolicy.get()) {
                    saveState();
                    _yieldPolicy->yield(record);
                    if (_failure || _killed) { return false; }
                    restoreState();
                }
                else {
                    // We're set to manually yield.  We go to disk in the lock.
                    record->touch();
                }

                // Record should be in memory now.  Log if it's not.
                if (!Record::likelyInPhysicalMemory(record->dataNoThrowing())) {
                    OCCASIONALLY {
                        warning() << "Record wasn't in memory immediately after fetch: "
                            << member->loc.toString() << endl;
                    }
                }

                // Note that we're not freeing id.  Fetch semantics say that we shouldn't.
            }
示例#3
0
文件: fetch.cpp 项目: hipsterbd/mongo
    PlanStage::StageState FetchStage::work(WorkingSetID* out) {
        ++_commonStats.works;

        if (isEOF()) { return PlanStage::IS_EOF; }

        // If we asked our parent for a page-in last time work(...) was called, finish the fetch.
        if (WorkingSet::INVALID_ID != _idBeingPagedIn) {
            cout << "fetch completed, id being paged on " << _idBeingPagedIn << endl;
            return fetchCompleted(out);
        }

        // If we're here, we're not waiting for a DiskLoc to be fetched.  Get another to-be-fetched
        // result from our child.
        WorkingSetID id;
        StageState status = _child->work(&id);

        if (PlanStage::ADVANCED == status) {
            WorkingSetMember* member = _ws->get(id);

            // If there's an obj there, there is no fetching to perform.
            if (member->hasObj()) {
                ++_specificStats.alreadyHasObj;
                return returnIfMatches(member, id, out);
            }

            // We need a valid loc to fetch from and this is the only state that has one.
            verify(WorkingSetMember::LOC_AND_IDX == member->state);
            verify(member->hasLoc());

            Record* record = member->loc.rec();
            const char* data = record->dataNoThrowing();

            if (!recordInMemory(data)) {
                // member->loc points to a record that's NOT in memory.  Pass a fetch request up.
                verify(WorkingSet::INVALID_ID == _idBeingPagedIn);
                _idBeingPagedIn = id;
                *out = id;
                ++_commonStats.needFetch;
                return PlanStage::NEED_FETCH;
            }
            else {
                // Don't need index data anymore as we have an obj.
                member->keyData.clear();
                member->obj = BSONObj(data);
                member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
                return returnIfMatches(member, id, out);
            }
        }
        else {
            if (PlanStage::NEED_FETCH == status) {
                *out = id;
                ++_commonStats.needFetch;
            }
            else if (PlanStage::NEED_TIME == status) {
                ++_commonStats.needTime;
            }
            return status;
        }
    }
示例#4
0
    bool MultiPlanRunner::workAllPlans() {
        for (size_t i = 0; i < _candidates.size(); ++i) {
            CandidatePlan& candidate = _candidates[i];

            WorkingSetID id;
            PlanStage::StageState state = candidate.root->work(&id);
            if (PlanStage::ADVANCED == state) {
                // Save result for later.
                candidate.results.push(id);
            }
            else if (PlanStage::NEED_TIME == state) {
                // Nothing to do here.
            }
            else if (PlanStage::NEED_FETCH == state) {
                // XXX: We can yield to do this.  We have to deal with synchronization issues with
                // regards to the working set and invalidation.  What if another thread invalidates
                // the thing we're fetching?  The loc could vanish between hasLoc() and the actual
                // fetch...

                // id has a loc and refers to an obj we need to fetch.
                WorkingSetMember* member = candidate.ws->get(id);

                // This must be true for somebody to request a fetch and can only change when an
                // invalidation happens, which is when we give up a lock.  Don't give up the
                // lock between receiving the NEED_FETCH and actually fetching(?).
                verify(member->hasLoc());

                // Actually bring record into memory.
                Record* record = member->loc.rec();
                record->touch();

                // Record should be in memory now.  Log if it's not.
                if (!Record::likelyInPhysicalMemory(record->dataNoThrowing())) {
                    OCCASIONALLY {
                        warning() << "Record wasn't in memory immediately after fetch: "
                            << member->loc.toString() << endl;
                    }
                }

                // Note that we're not freeing id.  Fetch semantics say that we shouldn't.
            }
示例#5
0
    Runner::RunnerState IDHackRunner::getNext(BSONObj* objOut, DiskLoc* dlOut) {
        if (_killed) { return Runner::RUNNER_DEAD; }
        if (_done) { return Runner::RUNNER_EOF; }

        // Use the index catalog to get the id index.
        IndexCatalog* catalog = _collection->getIndexCatalog();

        // Find the index we use.
        const IndexDescriptor* idDesc = catalog->findIdIndex();
        if (NULL == idDesc) {
            _done = true;
            return Runner::RUNNER_EOF;
        }

        BtreeBasedAccessMethod* accessMethod = catalog->getBtreeBasedIndex( idDesc );

        BSONObj key = _query->getQueryObj()["_id"].wrap();

        // Look up the key by going directly to the Btree.
        DiskLoc loc = accessMethod->findSingle( key );

        _done = true;

        // Key not found.
        if (loc.isNull()) {
            return Runner::RUNNER_EOF;
        }

        // Set out parameters and note that we're done w/lookup.
        if (NULL != objOut) {
            Record* record = loc.rec();

            // If the record isn't in memory...
            if (!Record::likelyInPhysicalMemory(record->dataNoThrowing())) {
                // And we're allowed to yield ourselves...
                if (Runner::YIELD_AUTO == _policy) {
                    // Note what we're yielding to fetch so that we don't crash if the loc is
                    // deleted during a yield.
                    _locFetching = loc;
                    // Yield.  TODO: Do we want to bother yielding if micros < 0?
                    int micros = ClientCursor::suggestYieldMicros();
                    ClientCursor::staticYield(micros, "", record);
                    // This can happen when we're yielded for various reasons (e.g. db/idx dropped).
                    if (_killed) {
                        return Runner::RUNNER_DEAD;
                    }
                }
            }

            // Either the data was in memory or we paged it in.
            *objOut = loc.obj();

            // If we're sharded make sure the key belongs to us.  We need the object to do this.
            if (shardingState.needCollectionMetadata(_query->ns())) {
                CollectionMetadataPtr m = shardingState.getCollectionMetadata(_query->ns());
                if (m) {
                    KeyPattern kp(m->getKeyPattern());
                    if (!m->keyBelongsToMe( kp.extractSingleKey(*objOut))) {
                        // We have something with a matching _id but it doesn't belong to me.
                        return Runner::RUNNER_EOF;
                    }
                }
            }

            // If there is a projection...
            if (NULL != _query->getProj()) {
                // Create something to execute it.
                auto_ptr<ProjectionExec> projExec(new ProjectionExec(_query->getParsed().getProj(),
                                                                     _query->root()));
                projExec->transform(*objOut, objOut);
            }
        }

        // Return the DiskLoc if the caller wants it.
        if (NULL != dlOut) {
            *dlOut = loc;
        }

        return Runner::RUNNER_ADVANCED;
    }
示例#6
0
    Runner::RunnerState IDHackRunner::getNext(BSONObj* objOut, DiskLoc* dlOut) {
        if (_killed) { return Runner::RUNNER_DEAD; }
        if (_done) { return Runner::RUNNER_EOF; }

        // Use the index catalog to get the id index.
        const IndexCatalog* catalog = _collection->getIndexCatalog();

        // Find the index we use.
        IndexDescriptor* idDesc = catalog->findIdIndex();
        if (NULL == idDesc) {
            _done = true;
            return Runner::RUNNER_EOF;
        }

        // This may not be valid always.  See SERVER-12397.
        const BtreeBasedAccessMethod* accessMethod =
            static_cast<const BtreeBasedAccessMethod*>(catalog->getIndex(idDesc));

        // Look up the key by going directly to the Btree.
        DiskLoc loc = accessMethod->findSingle( _key );

        _done = true;

        // Key not found.
        if (loc.isNull()) {
            return Runner::RUNNER_EOF;
        }

        _nscanned++;

        // Set out parameters and note that we're done w/lookup.
        if (NULL == objOut) {
            // No object requested - nothing to do.
        }
        else if (hasIDProjection(_query.get())) {
            // Covered query on _id field only.
            // Set object to search key.
            // Search key is retrieved from the canonical query at
            // construction and always contains the _id field name.
            // It is possible to construct the ID hack runner with just the collection
            // and the key object (which could be {"": my_obj_id}) but _query would be null
            // in that case and the query would never be seen as covered.
            *objOut = _key.getOwned();
        }
        else {
            invariant(!hasIDProjection(_query.get()));

            // Fetch object from storage.
            Record* record = loc.rec();

            _nscannedObjects++;

            // If the record isn't in memory...
            if (!Record::likelyInPhysicalMemory(record->dataNoThrowing())) {
                // And we're allowed to yield ourselves...
                if (Runner::YIELD_AUTO == _policy) {
                    // Note what we're yielding to fetch so that we don't crash if the loc is
                    // deleted during a yield.
                    _locFetching = loc;
                    // Yield.  TODO: Do we want to bother yielding if micros < 0?
                    int micros = ClientCursor::suggestYieldMicros();
                    ClientCursor::staticYield(micros, "", record);
                    // This can happen when we're yielded for various reasons (e.g. db/idx dropped).
                    if (_killed) {
                        return Runner::RUNNER_DEAD;
                    }
                }
            }

            // Either the data was in memory or we paged it in.
            *objOut = loc.obj();

            // If we're sharded make sure the key belongs to us.  We need the object to do this.
            if (shardingState.needCollectionMetadata(_collection->ns().ns())) {
                CollectionMetadataPtr m = shardingState.getCollectionMetadata(_collection->ns().ns());
                if (m) {
                    KeyPattern kp(m->getKeyPattern());
                    if (!m->keyBelongsToMe( kp.extractSingleKey(*objOut))) {
                        // We have something with a matching _id but it doesn't belong to me.
                        return Runner::RUNNER_EOF;
                    }
                }
            }
        }

        // Return the DiskLoc if the caller wants it.
        if (NULL != dlOut) {
            *dlOut = loc;
        }

        return Runner::RUNNER_ADVANCED;
    }