path: root/src/mongo/db/s/config/configsvr_reshard_collection_cmd.cpp

/**
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 *    it under the terms of the Server Side Public License, version 1,
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 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *    code of portions of this program with the OpenSSL library under certain
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#include "mongo/platform/basic.h"

#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/feature_compatibility_version.h"
#include "mongo/db/query/collation/collator_factory_interface.h"
#include "mongo/db/repl/primary_only_service.h"
#include "mongo/db/repl/repl_client_info.h"
#include "mongo/db/s/resharding/coordinator_document_gen.h"
#include "mongo/db/s/resharding/resharding_coordinator_service.h"
#include "mongo/db/s/resharding/resharding_server_parameters_gen.h"
#include "mongo/db/s/resharding/resharding_util.h"
#include "mongo/db/s/sharding_data_transform_metrics.h"
#include "mongo/db/vector_clock.h"
#include "mongo/logv2/log.h"
#include "mongo/s/catalog/type_tags.h"
#include "mongo/s/grid.h"
#include "mongo/s/request_types/reshard_collection_gen.h"
#include "mongo/s/resharding/resharding_feature_flag_gen.h"

#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand


namespace mongo {

MONGO_FAIL_POINT_DEFINE(reshardCollectionJoinedExistingOperation);

namespace {

// Returns a resharding instance if one exists for the same collection and shard key already.
boost::optional<std::shared_ptr<ReshardingCoordinatorService::ReshardingCoordinator>>
getExistingInstanceToJoin(OperationContext* opCtx,
                          const NamespaceString& nss,
                          const BSONObj& newShardKey) {
    auto instances =
        getReshardingStateMachines<ReshardingCoordinatorService,
                                   ReshardingCoordinatorService::ReshardingCoordinator>(opCtx, nss);
    for (const auto& instance : instances) {
        if (SimpleBSONObjComparator::kInstance.evaluate(
                instance->getMetadata().getReshardingKey().toBSON() == newShardKey)) {
            return instance;
        }
    }
    return boost::none;
}

class ConfigsvrReshardCollectionCommand final
    : public TypedCommand<ConfigsvrReshardCollectionCommand> {
public:
    using Request = ConfigsvrReshardCollection;

    class Invocation final : public InvocationBase {
    public:
        using InvocationBase::InvocationBase;

        void typedRun(OperationContext* opCtx) {
            uassert(ErrorCodes::IllegalOperation,
                    "_configsvrReshardCollection can only be run on config servers",
                    serverGlobalParams.clusterRole == ClusterRole::ConfigServer);
            CommandHelpers::uassertCommandRunWithMajority(Request::kCommandName,
                                                          opCtx->getWriteConcern());
            repl::ReadConcernArgs::get(opCtx) =
                repl::ReadConcernArgs(repl::ReadConcernLevel::kLocalReadConcern);

            const NamespaceString& nss = ns();

            const auto catalogClient = Grid::get(opCtx)->catalogClient();
            try {
                const auto collEntry = catalogClient->getCollection(opCtx, nss);
                uassert(ErrorCodes::NotImplemented,
                        "reshardCollection command of a sharded time-series collection is not "
                        "supported",
                        !collEntry.getTimeseriesFields());
            } catch (const ExceptionFor<ErrorCodes::NamespaceNotFound>&) {
                // collection doesn't exist or not sharded, skip check for time-series collection.
            }

            uassert(ErrorCodes::BadValue,
                    "The unique field must be false",
                    !request().getUnique().get_value_or(false));

            if (request().getCollation()) {
                auto& collation = request().getCollation().get();
                auto collator =
                    uassertStatusOK(CollatorFactoryInterface::get(opCtx->getServiceContext())
                                        ->makeFromBSON(collation));
                uassert(ErrorCodes::BadValue,
                        str::stream()
                            << "The collation for reshardCollection must be {locale: 'simple'}, "
                            << "but found: " << collation,
                        !collator);
            }

            const auto& authoritativeTags =
                uassertStatusOK(catalogClient->getTagsForCollection(opCtx, nss));
            if (!authoritativeTags.empty()) {
                uassert(ErrorCodes::BadValue,
                        "Must specify value for zones field",
                        request().getZones());
            }

            if (const auto& presetChunks = request().get_presetReshardedChunks()) {
                uassert(ErrorCodes::BadValue,
                        "Test commands must be enabled when a value is provided for field: "
                        "_presetReshardedChunks",
                        getTestCommandsEnabled());

                uassert(ErrorCodes::BadValue,
                        "Must specify only one of _presetReshardedChunks or numInitialChunks",
                        !(bool(request().getNumInitialChunks())));

                validateReshardedChunks(
                    *presetChunks, opCtx, ShardKeyPattern(request().getKey()).getKeyPattern());
            }

            // Returns boost::none if there isn't any work to be done by the resharding operation.
            auto instance = ([&]() -> boost::optional<std::shared_ptr<
                                       ReshardingCoordinatorService::ReshardingCoordinator>> {
                FixedFCVRegion fixedFcv(opCtx);

                uassert(ErrorCodes::CommandNotSupported,
                        "reshardCollection command not enabled",
                        resharding::gFeatureFlagResharding.isEnabled(
                            serverGlobalParams.featureCompatibility));

                if (auto existingInstance =
                        getExistingInstanceToJoin(opCtx, nss, request().getKey())) {
                    // Join the existing resharding operation to prevent generating a new resharding
                    // instance if the same command is issued consecutively due to client disconnect
                    // etc.
                    opCtx->setAlwaysInterruptAtStepDownOrUp_UNSAFE();
                    reshardCollectionJoinedExistingOperation.pauseWhileSet(opCtx);
                    existingInstance.get()->getCoordinatorDocWrittenFuture().get(opCtx);
                    return existingInstance;
                }

                // (Generic FCV reference): To run this command and ensure the consistency of the
                // metadata we need to make sure we are on a stable state.
                uassert(ErrorCodes::CommandNotSupported,
                        "Resharding is not supported for this version, please update the FCV to "
                        "latest.",
                        !serverGlobalParams.featureCompatibility.isUpgradingOrDowngrading());

                const auto cm = uassertStatusOK(
                    Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfoWithRefresh(
                        opCtx, nss));

                const auto currentShardKey = cm.getShardKeyPattern().getKeyPattern();
                if (SimpleBSONObjComparator::kInstance.evaluate(currentShardKey.toBSON() ==
                                                                request().getKey())) {
                    // There isn't any work to be done by the resharding operation since the
                    // existing shard key matches the desired new shard key.
                    return boost::none;
                }

                auto tempReshardingNss = constructTemporaryReshardingNss(nss.db(), cm.getUUID());


                if (auto zones = request().getZones()) {
                    checkForOverlappingZones(*zones);
                }

                auto coordinatorDoc =
                    ReshardingCoordinatorDocument(std::move(CoordinatorStateEnum::kUnused),
                                                  {},   // donorShards
                                                  {});  // recipientShards

                // Generate the resharding metadata for the ReshardingCoordinatorDocument.
                auto reshardingUUID = UUID::gen();
                auto existingUUID = cm.getUUID();
                auto commonMetadata = CommonReshardingMetadata(std::move(reshardingUUID),
                                                               ns(),
                                                               std::move(existingUUID),
                                                               std::move(tempReshardingNss),
                                                               request().getKey());
                commonMetadata.setStartTime(
                    opCtx->getServiceContext()->getFastClockSource()->now());

                coordinatorDoc.setCommonReshardingMetadata(std::move(commonMetadata));
                coordinatorDoc.setZones(request().getZones());
                coordinatorDoc.setPresetReshardedChunks(request().get_presetReshardedChunks());
                coordinatorDoc.setNumInitialChunks(request().getNumInitialChunks());

                opCtx->setAlwaysInterruptAtStepDownOrUp_UNSAFE();
                auto registry = repl::PrimaryOnlyServiceRegistry::get(opCtx->getServiceContext());
                auto service =
                    registry->lookupServiceByName(ReshardingCoordinatorService::kServiceName);
                auto instance = ReshardingCoordinatorService::ReshardingCoordinator::getOrCreate(
                    opCtx, service, coordinatorDoc.toBSON());

                instance->getCoordinatorDocWrittenFuture().get(opCtx);
                return instance;
            })();

            if (instance) {
                // There is work to be done in order to have the collection's shard key match the
                // requested shard key. Wait until the work is complete.
                instance.get()->getCompletionFuture().get(opCtx);
            }
            repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
        }

    private:
        NamespaceString ns() const override {
            return request().getCommandParameter();
        }

        bool supportsWriteConcern() const override {
            return true;
        }

        void doCheckAuthorization(OperationContext* opCtx) const override {
            uassert(ErrorCodes::Unauthorized,
                    "Unauthorized",
                    AuthorizationSession::get(opCtx->getClient())
                        ->isAuthorizedForActionsOnResource(ResourcePattern::forClusterResource(),
                                                           ActionType::internal));
        }
    };

    bool skipApiVersionCheck() const override {
        // Internal command (server to server).
        return true;
    }

    std::string help() const override {
        return "Internal command, which is exported by the sharding config server. Do not call "
               "directly. Reshards a collection on a new shard key.";
    }

    bool adminOnly() const override {
        return true;
    }

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

}  // namespace
}  // namespace mongo