path: root/src/mongo/db/commands/create_indexes.cpp

/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    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.
 *
 *    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.
 *
 *    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>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    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)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kIndex

#include "mongo/platform/basic.h"

#include <string>
#include <vector>

#include "mongo/base/string_data.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/catalog/index_key_validate.h"
#include "mongo/db/catalog/multi_index_block.h"
#include "mongo/db/command_generic_argument.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/enable_coordinator_for_create_indexes_command_gen.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/index_builds_coordinator.h"
#include "mongo/db/op_observer.h"
#include "mongo/db/ops/insert.h"
#include "mongo/db/repl/replication_coordinator.h"
#include "mongo/db/s/collection_metadata.h"
#include "mongo/db/s/collection_sharding_state.h"
#include "mongo/db/s/database_sharding_state.h"
#include "mongo/db/server_options.h"
#include "mongo/db/views/view_catalog.h"
#include "mongo/s/shard_key_pattern.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
#include "mongo/util/uuid.h"

namespace mongo {

namespace {

constexpr auto kIndexesFieldName = "indexes"_sd;
constexpr auto kCommandName = "createIndexes"_sd;
constexpr auto kTwoPhaseCommandName = "twoPhaseCreateIndexes"_sd;
constexpr auto kCreateCollectionAutomaticallyFieldName = "createdCollectionAutomatically"_sd;
constexpr auto kNumIndexesBeforeFieldName = "numIndexesBefore"_sd;
constexpr auto kNumIndexesAfterFieldName = "numIndexesAfter"_sd;
constexpr auto kNoteFieldName = "note"_sd;

/**
 * Parses the index specifications from 'cmdObj', validates them, and returns equivalent index
 * specifications that have any missing attributes filled in. If any index specification is
 * malformed, then an error status is returned.
 */
StatusWith<std::vector<BSONObj>> parseAndValidateIndexSpecs(
    OperationContext* opCtx,
    const NamespaceString& ns,
    const BSONObj& cmdObj,
    const ServerGlobalParams::FeatureCompatibility& featureCompatibility) {
    bool hasIndexesField = false;

    std::vector<BSONObj> indexSpecs;
    for (auto&& cmdElem : cmdObj) {
        auto cmdElemFieldName = cmdElem.fieldNameStringData();

        if (kIndexesFieldName == cmdElemFieldName) {
            if (cmdElem.type() != BSONType::Array) {
                return {ErrorCodes::TypeMismatch,
                        str::stream() << "The field '" << kIndexesFieldName
                                      << "' must be an array, but got "
                                      << typeName(cmdElem.type())};
            }

            for (auto&& indexesElem : cmdElem.Obj()) {
                if (indexesElem.type() != BSONType::Object) {
                    return {ErrorCodes::TypeMismatch,
                            str::stream() << "The elements of the '" << kIndexesFieldName
                                          << "' array must be objects, but got "
                                          << typeName(indexesElem.type())};
                }

                auto indexSpecStatus = index_key_validate::validateIndexSpec(
                    opCtx, indexesElem.Obj(), ns, featureCompatibility);
                if (!indexSpecStatus.isOK()) {
                    return indexSpecStatus.getStatus();
                }
                auto indexSpec = indexSpecStatus.getValue();

                if (IndexDescriptor::isIdIndexPattern(
                        indexSpec[IndexDescriptor::kKeyPatternFieldName].Obj())) {
                    auto status = index_key_validate::validateIdIndexSpec(indexSpec);
                    if (!status.isOK()) {
                        return status;
                    }
                } else if (indexSpec[IndexDescriptor::kIndexNameFieldName].String() == "_id_"_sd) {
                    return {ErrorCodes::BadValue,
                            str::stream() << "The index name '_id_' is reserved for the _id index, "
                                             "which must have key pattern {_id: 1}, found "
                                          << indexSpec[IndexDescriptor::kKeyPatternFieldName]};
                } else if (indexSpec[IndexDescriptor::kIndexNameFieldName].String() == "*"_sd) {
                    // An index named '*' cannot be dropped on its own, because a dropIndex oplog
                    // entry with a '*' as an index name means "drop all indexes in this
                    // collection".  We disallow creation of such indexes to avoid this conflict.
                    return {ErrorCodes::BadValue, "The index name '*' is not valid."};
                }

                indexSpecs.push_back(std::move(indexSpec));
            }

            hasIndexesField = true;
        } else if (kCommandName == cmdElemFieldName || kTwoPhaseCommandName == cmdElemFieldName ||
                   isGenericArgument(cmdElemFieldName)) {
            continue;
        } else {
            return {ErrorCodes::BadValue,
                    str::stream() << "Invalid field specified for " << kCommandName << " command: "
                                  << cmdElemFieldName};
        }
    }

    if (!hasIndexesField) {
        return {ErrorCodes::FailedToParse,
                str::stream() << "The '" << kIndexesFieldName
                              << "' field is a required argument of the "
                              << kCommandName
                              << " command"};
    }

    if (indexSpecs.empty()) {
        return {ErrorCodes::BadValue, "Must specify at least one index to create"};
    }

    return indexSpecs;
}

/**
 * Returns a vector of index specs with the filled in collection default options and removes any
 * indexes that already exist on the collection. If the returned vector is empty after returning, no
 * new indexes need to be built. Throws on error.
 */
std::vector<BSONObj> resolveDefaultsAndRemoveExistingIndexes(OperationContext* opCtx,
                                                             const Collection* collection,
                                                             std::vector<BSONObj> validatedSpecs) {
    auto swDefaults = collection->addCollationDefaultsToIndexSpecsForCreate(opCtx, validatedSpecs);
    uassertStatusOK(swDefaults.getStatus());

    auto indexCatalog = collection->getIndexCatalog();
    return indexCatalog->removeExistingIndexes(opCtx, swDefaults.getValue(), /*throwOnError=*/true);
}

void checkUniqueIndexConstraints(OperationContext* opCtx,
                                 const NamespaceString& nss,
                                 const BSONObj& newIdxKey) {
    invariant(opCtx->lockState()->isCollectionLockedForMode(nss.ns(), MODE_X));

    const auto metadata = CollectionShardingState::get(opCtx, nss)->getCurrentMetadata();
    if (!metadata->isSharded())
        return;

    const ShardKeyPattern shardKeyPattern(metadata->getKeyPattern());
    uassert(ErrorCodes::CannotCreateIndex,
            str::stream() << "cannot create unique index over " << newIdxKey
                          << " with shard key pattern "
                          << shardKeyPattern.toBSON(),
            shardKeyPattern.isUniqueIndexCompatible(newIdxKey));
}

bool runCreateIndexes(OperationContext* opCtx,
                      const std::string& dbname,
                      const BSONObj& cmdObj,
                      std::string& errmsg,
                      BSONObjBuilder& result,
                      bool runTwoPhaseBuild) {
    const NamespaceString ns(CommandHelpers::parseNsCollectionRequired(dbname, cmdObj));
    uassertStatusOK(userAllowedWriteNS(ns));

    // Disallow users from creating new indexes on config.transactions since the sessions code
    // was optimized to not update indexes
    uassert(ErrorCodes::IllegalOperation,
            str::stream() << "not allowed to create index on " << ns.ns(),
            ns != NamespaceString::kSessionTransactionsTableNamespace);

    auto specs = uassertStatusOK(
        parseAndValidateIndexSpecs(opCtx, ns, cmdObj, serverGlobalParams.featureCompatibility));

    // Do not use AutoGetOrCreateDb because we may relock the database in mode X.
    Lock::DBLock dbLock(opCtx, ns.db(), MODE_IX);
    if (!repl::ReplicationCoordinator::get(opCtx)->canAcceptWritesFor(opCtx, ns)) {
        uasserted(ErrorCodes::NotMaster,
                  str::stream() << "Not primary while creating indexes in " << ns.ns());
    }

    const auto indexesAlreadyExist = [&result](int numIndexes) {
        result.append("numIndexesBefore", numIndexes);
        result.append("numIndexesAfter", numIndexes);
        result.append("note", "all indexes already exist");
        return true;
    };

    // Before potentially taking an exclusive database lock, check if all indexes already exist
    // while holding an intent lock. Only continue if new indexes need to be built and the
    // database should be re-locked in exclusive mode.
    {
        AutoGetCollection autoColl(opCtx, ns, MODE_IX);
        if (auto collection = autoColl.getCollection()) {
            auto specsCopy = resolveDefaultsAndRemoveExistingIndexes(opCtx, collection, specs);
            if (specsCopy.size() == 0) {
                return indexesAlreadyExist(collection->getIndexCatalog()->numIndexesTotal(opCtx));
            }
        }
    }

    // Relocking temporarily releases the Database lock while holding a Global IX lock. This
    // prevents the replication state from changing, but requires abandoning the current
    // snapshot in case indexes change during the period of time where no database lock is held.
    opCtx->recoveryUnit()->abandonSnapshot();
    dbLock.relockWithMode(MODE_X);

    // Allow the strong lock acquisition above to be interrupted, but from this point forward do
    // not allow locks or re-locks to be interrupted.
    UninterruptibleLockGuard noInterrupt(opCtx->lockState());

    auto databaseHolder = DatabaseHolder::get(opCtx);
    auto db = databaseHolder->getDb(opCtx, ns.db());
    if (!db) {
        db = databaseHolder->openDb(opCtx, ns.db());
    }

    {
        auto& dss = DatabaseShardingState::get(db);
        auto dssLock = DatabaseShardingState::DSSLock::lock(opCtx, &dss);
        dss.checkDbVersion(opCtx, dssLock);
    }

    Collection* collection = db->getCollection(opCtx, ns);
    if (collection) {
        result.appendBool("createdCollectionAutomatically", false);
    } else {
        if (db->getViewCatalog()->lookup(opCtx, ns.ns())) {
            errmsg = "Cannot create indexes on a view";
            uasserted(ErrorCodes::CommandNotSupportedOnView, errmsg);
        }

        uassertStatusOK(userAllowedCreateNS(ns.db(), ns.coll()));

        writeConflictRetry(opCtx, kCommandName, ns.ns(), [&] {
            WriteUnitOfWork wunit(opCtx);
            collection = db->createCollection(opCtx, ns.ns(), CollectionOptions());
            invariant(collection);
            wunit.commit();
        });
        result.appendBool("createdCollectionAutomatically", true);
    }

    // Use AutoStatsTracker to update Top.
    boost::optional<AutoStatsTracker> statsTracker;
    const boost::optional<int> dbProfilingLevel = boost::none;
    statsTracker.emplace(opCtx,
                         ns,
                         Top::LockType::WriteLocked,
                         AutoStatsTracker::LogMode::kUpdateTopAndCurop,
                         dbProfilingLevel);


    MultiIndexBlock indexer(opCtx, collection);

    const size_t origSpecsSize = specs.size();
    specs = resolveDefaultsAndRemoveExistingIndexes(opCtx, collection, std::move(specs));

    const int numIndexesBefore = collection->getIndexCatalog()->numIndexesTotal(opCtx);
    if (specs.size() == 0) {
        return indexesAlreadyExist(numIndexesBefore);
    }

    result.append("numIndexesBefore", numIndexesBefore);

    if (specs.size() != origSpecsSize) {
        result.append("note", "index already exists");
    }

    for (size_t i = 0; i < specs.size(); i++) {
        const BSONObj& spec = specs[i];
        if (spec["unique"].trueValue()) {
            checkUniqueIndexConstraints(opCtx, ns, spec["key"].Obj());
        }
    }

    std::vector<BSONObj> indexInfoObjs =
        writeConflictRetry(opCtx, kCommandName, ns.ns(), [&indexer, &specs] {
            return uassertStatusOK(indexer.init(specs));
        });

    // If we're a background index, replace exclusive db lock with an intent lock, so that
    // other readers and writers can proceed during this phase.
    if (indexer.isBackgroundBuilding()) {
        opCtx->recoveryUnit()->abandonSnapshot();
        dbLock.relockWithMode(MODE_IX);
    }

    auto relockOnErrorGuard = makeGuard([&] {
        // Must have exclusive DB lock before we clean up the index build via the
        // destructor of 'indexer'.
        if (indexer.isBackgroundBuilding()) {
            try {
                // This function cannot throw today, but we will preemptively prepare for
                // that day, to avoid data corruption due to lack of index cleanup.
                opCtx->recoveryUnit()->abandonSnapshot();
                dbLock.relockWithMode(MODE_X);
            } catch (...) {
                std::terminate();
            }
        }
    });

    // Collection scan and insert into index, followed by a drain of writes received in the
    // background.
    {
        Lock::CollectionLock colLock(opCtx->lockState(), ns.ns(), MODE_IX);
        uassertStatusOK(indexer.insertAllDocumentsInCollection());
    }

    if (MONGO_FAIL_POINT(hangAfterIndexBuildDumpsInsertsFromBulk)) {
        log() << "Hanging after dumping inserts from bulk builder";
        MONGO_FAIL_POINT_PAUSE_WHILE_SET(hangAfterIndexBuildDumpsInsertsFromBulk);
    }

    // Perform the first drain while holding an intent lock.
    {
        opCtx->recoveryUnit()->abandonSnapshot();
        Lock::CollectionLock colLock(opCtx->lockState(), ns.ns(), MODE_IS);

        // Read at a point in time so that the drain, which will timestamp writes at lastApplied,
        // can never commit writes earlier than its read timestamp.
        uassertStatusOK(indexer.drainBackgroundWrites(RecoveryUnit::ReadSource::kNoOverlap));
    }

    if (MONGO_FAIL_POINT(hangAfterIndexBuildFirstDrain)) {
        log() << "Hanging after index build first drain";
        MONGO_FAIL_POINT_PAUSE_WHILE_SET(hangAfterIndexBuildFirstDrain);
    }

    // Perform the second drain while stopping writes on the collection.
    {
        opCtx->recoveryUnit()->abandonSnapshot();
        Lock::CollectionLock colLock(opCtx->lockState(), ns.ns(), MODE_S);

        uassertStatusOK(indexer.drainBackgroundWrites());
    }

    if (MONGO_FAIL_POINT(hangAfterIndexBuildSecondDrain)) {
        log() << "Hanging after index build second drain";
        MONGO_FAIL_POINT_PAUSE_WHILE_SET(hangAfterIndexBuildSecondDrain);
    }

    relockOnErrorGuard.dismiss();

    // Need to return db lock back to exclusive, to complete the index build.
    if (indexer.isBackgroundBuilding()) {
        opCtx->recoveryUnit()->abandonSnapshot();
        dbLock.relockWithMode(MODE_X);

        auto db = databaseHolder->getDb(opCtx, ns.db());
        if (db) {
            auto& dss = DatabaseShardingState::get(db);
            auto dssLock = DatabaseShardingState::DSSLock::lock(opCtx, &dss);
            dss.checkDbVersion(opCtx, dssLock);
        }

        invariant(db);
        invariant(db->getCollection(opCtx, ns));
    }

    // Perform the third and final drain after releasing a shared lock and reacquiring an
    // exclusive lock on the database.
    uassertStatusOK(indexer.drainBackgroundWrites());

    // This is required before completion.
    uassertStatusOK(indexer.checkConstraints());

    writeConflictRetry(opCtx, kCommandName, ns.ns(), [&] {
        WriteUnitOfWork wunit(opCtx);

        uassertStatusOK(indexer.commit([opCtx, &ns, collection](const BSONObj& spec) {
            opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
                opCtx, ns, *(collection->uuid()), spec, false);
        }));

        wunit.commit();
    });

    result.append("numIndexesAfter", collection->getIndexCatalog()->numIndexesTotal(opCtx));

    return true;
}

bool runCreateIndexesWithCoordinator(OperationContext* opCtx,
                                     const std::string& dbname,
                                     const BSONObj& cmdObj,
                                     std::string& errmsg,
                                     BSONObjBuilder& result,
                                     bool runTwoPhaseBuild) {
    const NamespaceString ns(CommandHelpers::parseNsCollectionRequired(dbname, cmdObj));
    uassertStatusOK(userAllowedWriteNS(ns));

    // Disallow users from creating new indexes on config.transactions since the sessions code
    // was optimized to not update indexes
    uassert(ErrorCodes::IllegalOperation,
            str::stream() << "not allowed to create index on " << ns.ns(),
            ns != NamespaceString::kSessionTransactionsTableNamespace);

    auto specs = uassertStatusOK(
        parseAndValidateIndexSpecs(opCtx, ns, cmdObj, serverGlobalParams.featureCompatibility));

    // Preliminary checks before handing control over to IndexBuildsCoordinator:
    // 1) We are in a replication mode that allows for index creation.
    // 2) Check sharding state.
    // 3) Create the collection to hold the index(es) if necessary.
    OptionalCollectionUUID collectionUUID;
    {
        // Do not use AutoGetOrCreateDb because we may relock the database in mode X.
        Lock::DBLock dbLock(opCtx, ns.db(), MODE_IX);
        if (!repl::ReplicationCoordinator::get(opCtx)->canAcceptWritesFor(opCtx, ns)) {
            uasserted(ErrorCodes::NotMaster,
                      str::stream() << "Not primary while creating indexes in " << ns.ns());
        }

        // Before potentially taking an exclusive database lock, check if all indexes already exist
        // while holding an intent lock. Only continue if new indexes need to be built and the
        // database should be re-locked in exclusive mode.
        AutoGetCollection autoColl(opCtx, ns, MODE_IX);
        auto db = autoColl.getDb();
        auto collection = autoColl.getCollection();
        if (collection) {
            invariant(db, str::stream() << "Database missing for index build: " << ns);
            auto& dss = DatabaseShardingState::get(db);
            auto dssLock = DatabaseShardingState::DSSLock::lock(opCtx, &dss);
            dss.checkDbVersion(opCtx, dssLock);
            collectionUUID = collection->uuid();
            result.appendBool(kCreateCollectionAutomaticallyFieldName, false);
            auto specsCopy = resolveDefaultsAndRemoveExistingIndexes(opCtx, collection, specs);
            // Return from command invocation early if we  are not adding any new indexes.
            if (specsCopy.size() == 0) {
                auto numIndexes = collection->getIndexCatalog()->numIndexesTotal(opCtx);
                result.append(kNumIndexesBeforeFieldName, numIndexes);
                result.append(kNumIndexesAfterFieldName, numIndexes);
                result.append(kNoteFieldName, "all indexes already exist");
                return true;
            }
        } else {
            // Relocking temporarily releases the Database lock while holding a Global IX lock. This
            // prevents the replication state from changing, but requires abandoning the current
            // snapshot in case indexes change during the period of time where no database lock is
            // held.
            opCtx->recoveryUnit()->abandonSnapshot();
            dbLock.relockWithMode(MODE_X);

            // Allow the strong lock acquisition above to be interrupted, but from this point
            // forward do not allow locks or re-locks to be interrupted.
            UninterruptibleLockGuard noInterrupt(opCtx->lockState());

            auto databaseHolder = DatabaseHolder::get(opCtx);
            db = databaseHolder->getDb(opCtx, ns.db());
            if (!db) {
                db = databaseHolder->openDb(opCtx, ns.db());
            }
            auto& dss = DatabaseShardingState::get(db);
            auto dssLock = DatabaseShardingState::DSSLock::lock(opCtx, &dss);
            dss.checkDbVersion(opCtx, dssLock);

            // We would not reach this point if we were able to check existing indexes on the
            // collection.
            invariant(!collection);
            if (db->getViewCatalog()->lookup(opCtx, ns.ns())) {
                errmsg = str::stream() << "Cannot create indexes on a view: " << ns.ns();
                uasserted(ErrorCodes::CommandNotSupportedOnView, errmsg);
            }

            uassertStatusOK(userAllowedCreateNS(ns.db(), ns.coll()));

            collectionUUID = UUID::gen();
            CollectionOptions options;
            options.uuid = collectionUUID;
            writeConflictRetry(opCtx, kCommandName, ns.ns(), [&] {
                WriteUnitOfWork wunit(opCtx);
                collection = db->createCollection(opCtx, ns.ns(), options);
                invariant(collection,
                          str::stream() << "Failed to create collection " << ns.ns()
                                        << " during index creation: "
                                        << redact(cmdObj));
                wunit.commit();
            });
            result.appendBool(kCreateCollectionAutomaticallyFieldName, true);
        }
    }

    // Use AutoStatsTracker to update Top.
    boost::optional<AutoStatsTracker> statsTracker;
    const boost::optional<int> dbProfilingLevel = boost::none;
    statsTracker.emplace(opCtx,
                         ns,
                         Top::LockType::WriteLocked,
                         AutoStatsTracker::LogMode::kUpdateTopAndCurop,
                         dbProfilingLevel);

    auto indexBuildsCoord = IndexBuildsCoordinator::get(opCtx);
    auto buildUUID = UUID::gen();
    log() << "Registering index build: " << buildUUID;
    ReplIndexBuildState::IndexCatalogStats stats;
    try {
        auto buildIndexFuture = uassertStatusOK(
            indexBuildsCoord->startIndexBuild(opCtx, *collectionUUID, specs, buildUUID));

        auto deadline = opCtx->getDeadline();
        // Date_t::max() means no deadline.
        if (deadline == Date_t::max()) {
            log() << "Waiting for index build to complete: " << buildUUID;
        } else {
            log() << "Waiting for index build to complete: " << buildUUID
                  << " (deadline: " << deadline << ")";
        }

        // Throws on error.
        try {
            stats = buildIndexFuture.get(opCtx);
        } catch (const ExceptionForCat<ErrorCategory::Interruption>& interruptionEx) {
            // It is unclear whether the interruption originated from the current opCtx instance
            // for the createIndexes command or that the IndexBuildsCoordinator task was interrupted
            // independently of this command invocation. We'll defensively abort the index build
            // with the assumption that if the index build was already in the midst of tearing down,
            // this be a no-op.
            log() << "Index build interrupted: " << buildUUID << ": aborting index build.";
            auto abortIndexFuture = indexBuildsCoord->abortIndexBuildByBuildUUID(
                buildUUID,
                str::stream() << "Index build interrupted: " << buildUUID << ": "
                              << interruptionEx.toString());
            log() << "Index build aborted: " << buildUUID << ": "
                  << abortIndexFuture.getNoThrow(opCtx);
            throw;
        }

        log() << "Index build completed: " << buildUUID;
    } catch (DBException& ex) {
        // If the collection is dropped after the initial checks in this function (before the
        // AutoStatsTracker is created), the IndexBuildsCoordinator (either startIndexBuild() or
        // the the task running the index build) may return NamespaceNotFound. This is not
        // considered an error and the command should return success.
        if (ErrorCodes::NamespaceNotFound == ex.code()) {
            log() << "Index build failed: " << buildUUID << ": collection dropped: " << ns;
            return true;
        }

        // All other errors should be forwarded to the caller with index build information included.
        log() << "Index build failed: " << buildUUID << ": " << ex.toStatus();
        ex.addContext(str::stream() << "Index build failed: " << buildUUID << ": Collection " << ns
                                    << " ( "
                                    << *collectionUUID
                                    << " )");
        throw;
    }


    result.append(kNumIndexesBeforeFieldName, stats.numIndexesBefore);
    result.append(kNumIndexesAfterFieldName, stats.numIndexesAfter);
    if (stats.numIndexesAfter == stats.numIndexesBefore) {
        result.append(kNoteFieldName, "all indexes already exist");
    } else if (stats.numIndexesAfter < stats.numIndexesBefore + int(specs.size())) {
        result.append(kNoteFieldName, "index already exists");
    }

    return true;
}

/**
 * { createIndexes : "bar", indexes : [ { ns : "test.bar", key : { x : 1 }, name: "x_1" } ] }
 */
class CmdCreateIndex : public ErrmsgCommandDeprecated {
public:
    CmdCreateIndex() : ErrmsgCommandDeprecated(kCommandName) {}

    bool supportsWriteConcern(const BSONObj& cmd) const override {
        return true;
    }

    AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
        return AllowedOnSecondary::kNever;
    }

    Status checkAuthForCommand(Client* client,
                               const std::string& dbname,
                               const BSONObj& cmdObj) const override {
        ActionSet actions;
        actions.addAction(ActionType::createIndex);
        Privilege p(parseResourcePattern(dbname, cmdObj), actions);
        if (AuthorizationSession::get(client)->isAuthorizedForPrivilege(p))
            return Status::OK();
        return Status(ErrorCodes::Unauthorized, "Unauthorized");
    }

    bool errmsgRun(OperationContext* opCtx,
                   const std::string& dbname,
                   const BSONObj& cmdObj,
                   std::string& errmsg,
                   BSONObjBuilder& result) override {
        if (enableIndexBuildsCoordinatorForCreateIndexesCommand) {
            return runCreateIndexesWithCoordinator(
                opCtx, dbname, cmdObj, errmsg, result, false /*two phase build*/);
        }
        return runCreateIndexes(opCtx, dbname, cmdObj, errmsg, result, false /*two phase build*/);
    }

} cmdCreateIndex;

/**
 * A temporary duplicate of the createIndexes command that runs two phase index builds for gradual
 * testing purposes. Otherwise, all of the necessary replication changes for the Simultaneous Index
 * Builds project would have to be turned on all at once because so much testing already exists that
 * would break with incremental changes.
 *
 * {twoPhaseCreateIndexes : "bar", indexes : [ { ns : "test.bar", key : { x : 1 }, name: "x_1" } ]}
 */
class CmdTwoPhaseCreateIndex : public ErrmsgCommandDeprecated {
public:
    CmdTwoPhaseCreateIndex() : ErrmsgCommandDeprecated(kTwoPhaseCommandName) {}

    bool supportsWriteConcern(const BSONObj& cmd) const override {
        return true;
    }

    AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
        return AllowedOnSecondary::kNever;
    }

    Status checkAuthForCommand(Client* client,
                               const std::string& dbname,
                               const BSONObj& cmdObj) const override {
        ActionSet actions;
        actions.addAction(ActionType::createIndex);
        Privilege p(parseResourcePattern(dbname, cmdObj), actions);
        if (AuthorizationSession::get(client)->isAuthorizedForPrivilege(p))
            return Status::OK();
        return Status(ErrorCodes::Unauthorized, "Unauthorized");
    }

    bool errmsgRun(OperationContext* opCtx,
                   const std::string& dbname,
                   const BSONObj& cmdObj,
                   std::string& errmsg,
                   BSONObjBuilder& result) override {
        return runCreateIndexesWithCoordinator(
            opCtx, dbname, cmdObj, errmsg, result, true /*two phase build*/);
    }

} cmdTwoPhaseCreateIndex;

}  // namespace
}  // namespace mongo