path: root/src/mongo/db/exec/timeseries_modify.cpp

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#include "mongo/db/exec/timeseries_modify.h"

#include "mongo/db/catalog/document_validation.h"
#include "mongo/db/query/plan_executor_impl.h"
#include "mongo/db/timeseries/timeseries_write_util.h"
#include "mongo/db/update/update_util.h"

#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kWrite

namespace mongo {

const char* TimeseriesModifyStage::kStageType = "TS_MODIFY";

TimeseriesModifyStage::TimeseriesModifyStage(ExpressionContext* expCtx,
                                             TimeseriesModifyParams&& params,
                                             WorkingSet* ws,
                                             std::unique_ptr<PlanStage> child,
                                             const ScopedCollectionAcquisition& coll,
                                             BucketUnpacker bucketUnpacker,
                                             std::unique_ptr<MatchExpression> residualPredicate)
    : RequiresWritableCollectionStage(kStageType, expCtx, coll),
      _params(std::move(params)),
      _ws(ws),
      _bucketUnpacker{std::move(bucketUnpacker)},
      _residualPredicate(std::move(residualPredicate)),
      _preWriteFilter(opCtx(), coll.nss()) {
    tassert(7308200,
            "Multi deletes must have a residual predicate",
            _isSingletonWrite() || _residualPredicate || _params.isUpdate);
    tassert(7308300,
            "Can return the deleted measurement only if deleting one",
            !_params.returnDeleted || _isSingletonWrite());
    _children.emplace_back(std::move(child));

    // These three properties are only used for the queryPlanner explain and will not change while
    // executing this stage.
    _specificStats.opType = [&] {
        if (_params.isUpdate) {
            return _isMultiWrite() ? "updateMany" : "updateOne";
        }
        return _isMultiWrite() ? "deleteMany" : "deleteOne";
    }();
    _specificStats.bucketFilter = _params.canonicalQuery->getQueryObj();
    if (_residualPredicate) {
        _specificStats.residualFilter = _residualPredicate->serialize();
    }

    tassert(7314202,
            "Updates must specify an update driver",
            _params.updateDriver || !_params.isUpdate);
    _specificStats.isModUpdate =
        _params.isUpdate && _params.updateDriver->type() == UpdateDriver::UpdateType::kOperator;
}

bool TimeseriesModifyStage::isEOF() {
    if (_isSingletonWrite() && _specificStats.nMeasurementsModified > 0) {
        // If we have a measurement to return, we should not return EOF so that we can get a chance
        // to get called again and return the measurement.
        return !_deletedMeasurementToReturn;
    }
    return child()->isEOF() && _retryBucketId == WorkingSet::INVALID_ID;
}

std::unique_ptr<PlanStageStats> TimeseriesModifyStage::getStats() {
    _commonStats.isEOF = isEOF();
    auto ret = std::make_unique<PlanStageStats>(_commonStats, stageType());
    ret->specific = std::make_unique<TimeseriesModifyStats>(_specificStats);
    for (const auto& child : _children) {
        ret->children.emplace_back(child->getStats());
    }
    return ret;
}


std::pair<std::vector<BSONObj>, std::vector<write_ops::InsertCommandRequest>>
TimeseriesModifyStage::_buildInsertOps(const std::vector<BSONObj>& matchedMeasurements,
                                       std::vector<BSONObj>& unchangedMeasurements) {
    // Determine which documents to update based on which ones are actually being changed.
    std::vector<BSONObj> modifiedMeasurements;

    const bool isUserInitiatedWrite = opCtx()->writesAreReplicated() &&
        !(_params.isFromOplogApplication ||
          _params.updateDriver->type() == UpdateDriver::UpdateType::kDelta || _params.fromMigrate);

    for (auto&& measurement : matchedMeasurements) {
        // Timeseries updates are never in place, because we execute them as a delete of the old
        // measurement plus an insert of the modified one.
        mutablebson::Document doc(measurement, mutablebson::Document::kInPlaceDisabled);

        // Note that timeseries measurment _ids are allowed to be changed, so we don't have any
        // immutable fields.
        FieldRefSet immutablePaths;
        const bool isInsert = false;
        bool docWasModified = false;

        if (!_params.updateDriver->needMatchDetails()) {
            uassertStatusOK(_params.updateDriver->update(opCtx(),
                                                         "",
                                                         &doc,
                                                         isUserInitiatedWrite,
                                                         immutablePaths,
                                                         isInsert,
                                                         nullptr,
                                                         &docWasModified));
        } else {
            // If there was a matched field, obtain it.
            MatchDetails matchDetails;
            matchDetails.requestElemMatchKey();

            // We have to re-apply the filter to get the matched element.
            tassert(7662500,
                    "measurement must pass filter",
                    _residualPredicate->matchesBSON(measurement, &matchDetails));

            uassertStatusOK(_params.updateDriver->update(
                opCtx(),
                matchDetails.hasElemMatchKey() ? matchDetails.elemMatchKey() : "",
                &doc,
                isUserInitiatedWrite,
                immutablePaths,
                isInsert,
                nullptr,
                &docWasModified));
        }

        if (docWasModified) {
            modifiedMeasurements.emplace_back(doc.getObject());
        } else {
            // The document wasn't modified, write it back to the original bucket unchanged.
            unchangedMeasurements.emplace_back(std::move(measurement));
        }
    }

    auto insertOps = timeseries::makeInsertsToNewBuckets(modifiedMeasurements,
                                                         collection()->ns(),
                                                         *collection()->getTimeseriesOptions(),
                                                         collection()->getDefaultCollator());
    return std::make_pair<std::vector<BSONObj>, std::vector<write_ops::InsertCommandRequest>>(
        std::move(modifiedMeasurements), std::move(insertOps));
}

template <typename F>
std::pair<bool, PlanStage::StageState> TimeseriesModifyStage::_writeToTimeseriesBuckets(
    ScopeGuard<F>& bucketFreer,
    WorkingSetID bucketWsmId,
    std::vector<BSONObj>&& unchangedMeasurements,
    const std::vector<BSONObj>& matchedMeasurements,
    bool bucketFromMigrate) {
    // No measurements needed to be updated or deleted from the bucket document.
    if (matchedMeasurements.empty()) {
        return {false, PlanStage::NEED_TIME};
    }
    _specificStats.nMeasurementsMatched += matchedMeasurements.size();

    auto updateResult = _params.isUpdate
        ? _buildInsertOps(matchedMeasurements, unchangedMeasurements)
        : std::pair<std::vector<BSONObj>, std::vector<write_ops::InsertCommandRequest>>{};

    // If this is a delete, we will be deleting all matched measurements. If this is an update, we
    // may not need to modify all measurements, since some may be no-op updates.
    const auto& modifiedMeasurements = _params.isUpdate ? updateResult.first : matchedMeasurements;

    // After applying the updates, no measurements needed to be updated in the bucket document.
    if (modifiedMeasurements.empty()) {
        return {false, PlanStage::NEED_TIME};
    }

    // We don't actually write anything if we are in explain mode but we still need to update the
    // stats and let the caller think as if the write succeeded if there's any deleted measurement.
    if (_params.isExplain) {
        _specificStats.nMeasurementsModified += modifiedMeasurements.size();
        return {true, PlanStage::NEED_TIME};
    }

    handlePlanStageYield(
        expCtx(),
        "TimeseriesModifyStage saveState",
        collection()->ns().ns(),
        [&] {
            child()->saveState();
            return PlanStage::NEED_TIME /* unused */;
        },
        [&] {
            // yieldHandler
            std::terminate();
        });

    auto recordId = _ws->get(bucketWsmId)->recordId;

    OID bucketId = record_id_helpers::toBSONAs(recordId, "_id")["_id"].OID();
    auto modificationOp =
        timeseries::makeModificationOp(bucketId, collection(), unchangedMeasurements);
    try {
        const auto modificationRet = handlePlanStageYield(
            expCtx(),
            "TimeseriesModifyStage modifyBucket",
            collection()->ns().ns(),
            [&] {
                timeseries::performAtomicWrites(opCtx(),
                                                collection(),
                                                recordId,
                                                modificationOp,
                                                updateResult.second,
                                                bucketFromMigrate,
                                                _params.stmtId);
                return PlanStage::NEED_TIME;
            },
            [&] {
                // yieldHandler
                // We need to retry the bucket, so we should not free the current bucket.
                bucketFreer.dismiss();
                _retryBucket(bucketWsmId);
            });
        if (modificationRet != PlanStage::NEED_TIME) {
            return {false, PlanStage::NEED_YIELD};
        }
    } catch (const ExceptionFor<ErrorCodes::StaleConfig>& ex) {
        if (ShardVersion::isPlacementVersionIgnored(ex->getVersionReceived()) &&
            ex->getCriticalSectionSignal()) {
            // If the placement version is IGNORED and we encountered a critical section, then
            // yield, wait for the critical section to finish and then we'll resume the write
            // from the point we had left. We do this to prevent large multi-writes from
            // repeatedly failing due to StaleConfig and exhausting the mongos retry attempts.
            planExecutorShardingCriticalSectionFuture(opCtx()) = ex->getCriticalSectionSignal();
            // We need to retry the bucket, so we should not free the current bucket.
            bucketFreer.dismiss();
            _retryBucket(bucketWsmId);
            return {false, PlanStage::NEED_YIELD};
        }
        throw;
    }
    _specificStats.nMeasurementsModified += modifiedMeasurements.size();

    // As restoreState may restore (recreate) cursors, cursors are tied to the transaction in which
    // they are created, and a WriteUnitOfWork is a transaction, make sure to restore the state
    // outside of the WriteUnitOfWork.
    auto status = handlePlanStageYield(
        expCtx(),
        "TimeseriesModifyStage restoreState",
        collection()->ns().ns(),
        [&] {
            child()->restoreState(&collection());
            return PlanStage::NEED_TIME;
        },
        // yieldHandler
        // Note we don't need to retry anything in this case since the write already was committed.
        // However, we still need to return the affected measurement (if it was requested). We don't
        // need to rely on the storage engine to return the affected document since we already have
        // it in memory.
        [&] { /* noop */ });

    return {true, status};
}

template <typename F>
std::pair<boost::optional<PlanStage::StageState>, bool>
TimeseriesModifyStage::_checkIfWritingToOrphanedBucket(ScopeGuard<F>& bucketFreer,
                                                       WorkingSetID id) {
    // If we are in explain mode, we do not need to check if the bucket is orphaned since we're not
    // writing to bucket. If we are migrating a bucket, we also do not need to check if the bucket
    // is not writable and just return it.
    if (_params.isExplain || _params.fromMigrate) {
        return {boost::none, _params.fromMigrate};
    }
    return _preWriteFilter.checkIfNotWritable(_ws->get(id)->doc.value(),
                                              "timeseries "_sd + _specificStats.opType,
                                              collection()->ns(),
                                              [&](const ExceptionFor<ErrorCodes::StaleConfig>& ex) {
                                                  planExecutorShardingCriticalSectionFuture(
                                                      opCtx()) = ex->getCriticalSectionSignal();
                                                  // Retry the write if we're in the sharding
                                                  // critical section.
                                                  bucketFreer.dismiss();
                                                  _retryBucket(id);
                                              });
}

PlanStage::StageState TimeseriesModifyStage::_getNextBucket(WorkingSetID& id) {
    if (_retryBucketId == WorkingSet::INVALID_ID) {
        auto status = child()->work(&id);
        if (status != PlanStage::ADVANCED) {
            return status;
        }
    } else {
        id = _retryBucketId;
        _retryBucketId = WorkingSet::INVALID_ID;
    }

    // We may not have an up-to-date bucket for this RecordId. Fetch it and ensure that it still
    // exists and matches our bucket-level predicate if it is not believed to be up-to-date.
    bool docStillMatches;

    const auto status = handlePlanStageYield(
        expCtx(),
        "TimeseriesModifyStage:: ensureStillMatches",
        collection()->ns().ns(),
        [&] {
            docStillMatches = write_stage_common::ensureStillMatches(
                collection(), opCtx(), _ws, id, _params.canonicalQuery);
            return PlanStage::NEED_TIME;
        },
        [&] {
            // yieldHandler
            // There was a problem trying to detect if the document still exists, so retry.
            _retryBucket(id);
        });
    if (status != PlanStage::NEED_TIME) {
        return status;
    }
    return docStillMatches ? PlanStage::ADVANCED : PlanStage::NEED_TIME;
}

void TimeseriesModifyStage::_retryBucket(WorkingSetID bucketId) {
    tassert(7309302,
            "Cannot be in the middle of unpacking a bucket if retrying",
            !_bucketUnpacker.hasNext());
    tassert(7309303,
            "Cannot retry two buckets at the same time",
            _retryBucketId == WorkingSet::INVALID_ID);

    _retryBucketId = bucketId;
}

void TimeseriesModifyStage::_prepareToReturnDeletedMeasurement(WorkingSetID& out,
                                                               BSONObj measurement) {
    out = _ws->allocate();
    auto member = _ws->get(out);
    // The measurement does not have record id.
    member->recordId = RecordId{};
    member->doc.value() = Document{std::move(measurement)};
    _ws->transitionToOwnedObj(out);
}

PlanStage::StageState TimeseriesModifyStage::doWork(WorkingSetID* out) {
    if (isEOF()) {
        return PlanStage::IS_EOF;
    }

    if (_deletedMeasurementToReturn) {
        // If we fall into this case, then we were asked to return the deleted measurement but we
        // were not able to do so in the previous call to doWork() because we needed to yield. Now
        // that we are back, we can return the deleted measurement.
        _prepareToReturnDeletedMeasurement(*out, *_deletedMeasurementToReturn);
        _deletedMeasurementToReturn.reset();
        return PlanStage::ADVANCED;
    }

    tassert(7495500,
            "Expected bucketUnpacker's current bucket to be exhausted",
            !_bucketUnpacker.hasNext());

    auto id = WorkingSet::INVALID_ID;
    auto status = _getNextBucket(id);
    if (status != PlanStage::ADVANCED) {
        if (status == PlanStage::NEED_YIELD) {
            *out = id;
        }
        return status;
    }

    // We want to free this member when we return because we either have an owned copy of the bucket
    // for normal write and write to orphan cases, or we skip the bucket.
    ScopeGuard bucketFreer([&] { _ws->free(id); });

    auto member = _ws->get(id);
    tassert(7459100, "Expected a RecordId from the child stage", member->hasRecordId());

    // Determine if we are writing to an orphaned bucket - such writes should be excluded from
    // user-visible change stream events. This will be achieved later by setting 'fromMigrate' flag
    // when calling performAtomicWrites().
    auto [immediateReturnStageState, bucketFromMigrate] =
        _checkIfWritingToOrphanedBucket(bucketFreer, id);
    if (immediateReturnStageState) {
        return *immediateReturnStageState;
    }
    tassert(7309304,
            "Expected no bucket to retry after getting a new bucket",
            _retryBucketId == WorkingSet::INVALID_ID);

    // Unpack the bucket and determine which measurements match the residual predicate.
    auto ownedBucket = member->doc.value().toBson().getOwned();
    _bucketUnpacker.reset(std::move(ownedBucket));
    // Closed buckets should have been filtered out by the bucket predicate.
    tassert(7554700, "Expected bucket to not be closed", !_bucketUnpacker.isClosedBucket());
    ++_specificStats.nBucketsUnpacked;

    std::vector<BSONObj> unchangedMeasurements;
    std::vector<BSONObj> modifiedMeasurements;

    while (_bucketUnpacker.hasNext()) {
        auto measurement = _bucketUnpacker.getNext().toBson();
        // We should stop deleting measurements once we hit the limit of one in the not multi case.
        bool shouldContinueModifying = _isMultiWrite() || modifiedMeasurements.empty();
        if (shouldContinueModifying &&
            (!_residualPredicate || _residualPredicate->matchesBSON(measurement))) {
            modifiedMeasurements.push_back(measurement);
        } else {
            unchangedMeasurements.push_back(measurement);
        }
    }

    auto isWriteSuccessful = false;
    std::tie(isWriteSuccessful, status) = _writeToTimeseriesBuckets(
        bucketFreer, id, std::move(unchangedMeasurements), modifiedMeasurements, bucketFromMigrate);
    if (status != PlanStage::NEED_TIME) {
        *out = WorkingSet::INVALID_ID;
        if (_params.returnDeleted && isWriteSuccessful) {
            // If asked to return the deleted measurement and the write was successful but we need
            // to yield, we need to save the deleted measurement to return it later. See isEOF() for
            // more info.
            tassert(7308301,
                    "Can return only one deleted measurement",
                    modifiedMeasurements.size() == 1);
            _deletedMeasurementToReturn = std::move(modifiedMeasurements[0]);
        }
    } else if (_params.returnDeleted && isWriteSuccessful) {
        // If the write was successful and if asked to return the deleted measurement, we return it
        // immediately.
        _prepareToReturnDeletedMeasurement(*out, modifiedMeasurements[0]);
        status = PlanStage::ADVANCED;
    }
    return status;
}

void TimeseriesModifyStage::doRestoreStateRequiresCollection() {
    const NamespaceString& ns = collection()->ns();
    uassert(ErrorCodes::PrimarySteppedDown,
            "Demoted from primary while removing from {}"_format(ns.toStringForErrorMsg()),
            !opCtx()->writesAreReplicated() ||
                repl::ReplicationCoordinator::get(opCtx())->canAcceptWritesFor(opCtx(), ns));

    _preWriteFilter.restoreState();
}
}  // namespace mongo