path: root/src/mongo/db/global_index.cpp

/**
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 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
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 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
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 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
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 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
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 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
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 */

#include "mongo/db/global_index.h"

#include "mongo/bson/bsonobj.h"
#include "mongo/db/catalog/clustered_collection_util.h"
#include "mongo/db/catalog/collection_write_path.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/catalog_raii.h"
#include "mongo/db/concurrency/exception_util.h"
#include "mongo/db/exec/delete_stage.h"
#include "mongo/db/index_builds_coordinator.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/op_observer/op_observer.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/query/internal_plans.h"
#include "mongo/db/shard_role.h"
#include "mongo/db/storage/key_string.h"
#include "mongo/db/transaction/retryable_writes_stats.h"
#include "mongo/db/transaction/transaction_participant.h"
#include "mongo/logv2/log.h"

#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kIndex

namespace mongo::global_index {

namespace {  // Anonymous namespace for private functions.

// Build an index entry to insert.
BSONObj buildIndexEntry(const BSONObj& key, const BSONObj& docKey) {
    // Generate the KeyString representation of the index key.
    // Current limitations:
    // - Only supports ascending order.
    // - We assume unique: true, and there's no support for other index options.
    // - No support for multikey indexes.

    KeyString::Builder ks(KeyString::Version::V1);
    ks.resetToKey(BSONObj::stripFieldNames(key), KeyString::ALL_ASCENDING);
    const auto& indexTB = ks.getTypeBits();

    // Build the index entry, consisting of:
    // - '_id': the document key, if provided (for inserts).
    // - 'ik': the KeyString representation of the index key.
    // - 'tb': the index key's TypeBits. Only present if non-zero.

    BSONObjBuilder indexEntryBuilder;
    indexEntryBuilder.append(kContainerIndexDocKeyFieldName, docKey);
    indexEntryBuilder.append(
        kContainerIndexKeyFieldName,
        BSONBinData(ks.getBuffer(), ks.getSize(), BinDataType::BinDataGeneral));
    if (!indexTB.isAllZeros()) {
        indexEntryBuilder.append(
            kContainerIndexKeyTypeBitsFieldName,
            BSONBinData(indexTB.getBuffer(), indexTB.getSize(), BinDataType::BinDataGeneral));
    }
    return indexEntryBuilder.obj();
}

RecordIdBound docKeyToRecordIdBound(const BSONObj& docKey) {
    // Build RecordIdBound corresponding to docKey.
    KeyString::Builder keyBuilder(KeyString::Version::kLatestVersion);
    keyBuilder.appendObject(docKey);
    return RecordIdBound(RecordId(keyBuilder.getBuffer(), keyBuilder.getSize()));
}

bool checkRetryableDDLStatementExecuted(OperationContext* opCtx) {
    // StmtId will always be 0, as the ddl commands only replicate a
    // createGlobalIndex/dropGlobalIndex oplog entry.
    constexpr StmtId stmtId = 0;
    if (opCtx->isRetryableWrite()) {
        const auto txnParticipant = TransactionParticipant::get(opCtx);
        if (txnParticipant.checkStatementExecuted(opCtx, stmtId)) {
            RetryableWritesStats::get(opCtx)->incrementRetriedCommandsCount();
            RetryableWritesStats::get(opCtx)->incrementRetriedStatementsCount();
            return true;
        }
    }
    return false;
}
}  // namespace


void createContainer(OperationContext* opCtx, const UUID& indexUUID) {
    if (checkRetryableDDLStatementExecuted(opCtx)) {
        LOGV2_DEBUG(6789203,
                    1,
                    "_shardsvrCreateGlobalIndex retried statement already executed",
                    "indexUUID"_attr = indexUUID);
        return;
    }

    const auto nss = NamespaceString::makeGlobalIndexNSS(indexUUID);
    LOGV2(6789200, "Create global index container", "indexUUID"_attr = indexUUID);

    // Create the container.
    return writeConflictRetry(opCtx, "createGlobalIndexContainer", nss, [&]() {
        const auto indexKeySpec =
            BSON("v" << 2 << "name" << kContainerIndexKeyFieldName.toString() + "_1"
                     << "key" << BSON(kContainerIndexKeyFieldName << 1) << "unique" << true);

        WriteUnitOfWork wuow(opCtx);

        // createIndexesOnEmptyCollection requires the MODE_X collection lock.
        AutoGetCollection autoColl(opCtx, nss, MODE_X);
        if (!autoColl) {
            {
                repl::UnreplicatedWritesBlock unreplicatedWrites(opCtx);

                auto db = autoColl.ensureDbExists(opCtx);

                CollectionOptions collOptions;
                collOptions.clusteredIndex = clustered_util::makeDefaultClusteredIdIndex();
                collOptions.uuid = indexUUID;
                db->createCollection(opCtx, nss, collOptions);

                CollectionWriter writer(opCtx, nss);
                IndexBuildsCoordinator::get(opCtx)->createIndexesOnEmptyCollection(
                    opCtx, writer, {indexKeySpec}, false);
            }
            auto opObserver = opCtx->getServiceContext()->getOpObserver();
            opObserver->onCreateGlobalIndex(opCtx, nss, indexUUID);

            wuow.commit();
        } else {
            // Container already exists, this can happen when attempting to create a global index
            // that already exists. Sanity check its storage format.
            tassert(6789204,
                    str::stream() << "Collection with UUID " << indexUUID
                                  << " already exists but it's not clustered.",
                    autoColl->getCollectionOptions().clusteredIndex);
            tassert(6789205,
                    str::stream() << "Collection with UUID " << indexUUID
                                  << " already exists but it's missing a unique index on "
                                  << kContainerIndexKeyFieldName << ".",
                    autoColl->getIndexCatalog()->findIndexByKeyPatternAndOptions(
                        opCtx,
                        BSON(kContainerIndexKeyFieldName << 1),
                        indexKeySpec,
                        IndexCatalog::InclusionPolicy::kReady));
            tassert(6789206,
                    str::stream() << "Collection with namespace " << nss.toStringForErrorMsg()
                                  << " already exists but it has inconsistent UUID "
                                  << autoColl->uuid().toString() << ".",
                    autoColl->uuid() == indexUUID);
            LOGV2(6789201, "Global index container already exists", "indexUUID"_attr = indexUUID);
        }
        return;
    });
}

void dropContainer(OperationContext* opCtx, const UUID& indexUUID) {
    if (checkRetryableDDLStatementExecuted(opCtx)) {
        LOGV2_DEBUG(6789303,
                    1,
                    "_shardsvrDropGlobalIndex retried statement already executed",
                    "indexUUID"_attr = indexUUID);
        return;
    }

    const auto nss = NamespaceString::makeGlobalIndexNSS(indexUUID);
    LOGV2(6789300, "Drop global index container", "indexUUID"_attr = indexUUID);

    // Drop the container.
    return writeConflictRetry(opCtx, "dropGlobalIndexContainer", nss, [&]() {
        AutoGetCollection autoColl(opCtx, nss, MODE_X);
        if (!autoColl) {
            // Idempotent command, return OK if the collection is non-existing.
            return;
        }

        const auto numKeys = autoColl->numRecords(opCtx);

        WriteUnitOfWork wuow(opCtx);
        {
            repl::UnreplicatedWritesBlock unreplicatedWrites(opCtx);
            uassertStatusOK(autoColl.getDb()->dropCollection(opCtx, nss));
        }

        auto opObserver = opCtx->getServiceContext()->getOpObserver();
        opObserver->onDropGlobalIndex(opCtx, nss, indexUUID, numKeys);

        wuow.commit();
        return;
    });
}

void insertKey(OperationContext* opCtx,
               const CollectionPtr& container,
               const BSONObj& key,
               const BSONObj& docKey) {
    const auto indexEntry = buildIndexEntry(key, docKey);
    invariant(!opCtx->writesAreReplicated());

    uassertStatusOK(collection_internal::insertDocument(
        opCtx, container, InsertStatement(indexEntry), nullptr));
}

void insertKey(OperationContext* opCtx,
               const UUID& indexUUID,
               const BSONObj& key,
               const BSONObj& docKey) {
    const auto ns = NamespaceString::makeGlobalIndexNSS(indexUUID);
    const auto indexEntry = buildIndexEntry(key, docKey);

    // Insert the index entry.
    writeConflictRetry(opCtx, "insertGlobalIndexKey", ns, [&] {
        WriteUnitOfWork wuow(opCtx);
        AutoGetCollection autoColl(opCtx, ns, MODE_IX);
        auto& container = autoColl.getCollection();

        uassert(6789402,
                str::stream() << "Global index container with UUID " << indexUUID
                              << " does not exist.",
                container);

        {
            repl::UnreplicatedWritesBlock unreplicatedWrites(opCtx);
            insertKey(opCtx, container, key, docKey);
        }

        opCtx->getServiceContext()->getOpObserver()->onInsertGlobalIndexKey(
            opCtx, ns, indexUUID, key, docKey);

        wuow.commit();
    });
}

void deleteKey(OperationContext* opCtx,
               const ScopedCollectionAcquisition& container,
               const BSONObj& key,
               const BSONObj& docKey) {
    const auto indexEntry = buildIndexEntry(key, docKey);
    invariant(!opCtx->writesAreReplicated());

    // Params for single delete (isMulti=false).
    auto deleteStageParams = std::make_unique<DeleteStageParams>();
    deleteStageParams->returnDeleted = true;

    auto docKeyRecordId = docKeyToRecordIdBound(docKey);

    // Global index container is a clustered collection, where the _id is the docKey, which
    // is why we delete using a collection scan.
    auto planExecutor = InternalPlanner::deleteWithCollectionScan(
        opCtx,
        container,
        std::move(deleteStageParams),
        PlanYieldPolicy::YieldPolicy::NO_YIELD,
        InternalPlanner::FORWARD,
        docKeyRecordId,
        docKeyRecordId,
        CollectionScanParams::ScanBoundInclusion::kIncludeBothStartAndEndRecords);

    // For now _id is unique, so we assume only one entry can be returned.
    BSONObj deletedObj;
    auto execState = planExecutor->getNext(&deletedObj, nullptr);

    // Return error if no document has been found or if the associated "key" does not match the key
    // provided as parameter.
    uassert(ErrorCodes::KeyNotFound,
            str::stream() << "Global index container with UUID " << container.uuid()
                          << " does not contain specified entry. key:" << key
                          << ", docKey:" << docKey,
            execState == PlanExecutor::ExecState::ADVANCED &&
                deletedObj.woCompare(buildIndexEntry(key, docKey)) == 0);

    fassert(6924202, planExecutor->isEOF());
}

void deleteKey(OperationContext* opCtx,
               const UUID& indexUUID,
               const BSONObj& key,
               const BSONObj& docKey) {
    const auto ns = NamespaceString::makeGlobalIndexNSS(indexUUID);

    // Find and delete the index entry.
    writeConflictRetry(opCtx, "deleteGlobalIndexKey", ns, [&] {
        WriteUnitOfWork wuow(opCtx);

        const auto coll = acquireCollection(
            opCtx,
            CollectionAcquisitionRequest::fromOpCtx(opCtx, ns, AcquisitionPrerequisites::kWrite),
            MODE_IX);
        uassert(6924201,
                str::stream() << "Global index container with UUID " << indexUUID
                              << " does not exist.",
                coll.exists());

        {
            repl::UnreplicatedWritesBlock unreplicatedWrites(opCtx);
            deleteKey(opCtx, coll, key, docKey);
        }

        opCtx->getServiceContext()->getOpObserver()->onDeleteGlobalIndexKey(
            opCtx, ns, indexUUID, key, docKey);

        wuow.commit();
    });
}

}  // namespace mongo::global_index