C++ ShardType类代码示例

        /**
         * Stores sample shard and ping information at the current version.
         */
        void storeShardsAndPings(int numShards, int numPings) {
            DBDirectClient client(&_txn);

            for (int i = 0; i < numShards; i++) {
                ShardType shard;
                shard.setName(OID::gen().toString());
                shard.setHost((string) (str::stream() << "$dummyShard:" << (i + 1) << "0000"));

                client.insert(ShardType::ConfigNS, shard.toBSON());
            }

            for (int i = 0; i < numPings; i++) {

                MongosType ping;
                ping.setName((string) (str::stream() << "$dummyMongos:" << (i + 1) << "0000"));
                ping.setPing(jsTime());
                ping.setMongoVersion(versionString);
                ping.setConfigVersion(CURRENT_CONFIG_VERSION);

                if (i % 2 == 0) {
                    ping.setPing(ping.getPing() - Minutes(10));
                }

                client.insert(MongosType::ConfigNS, ping.toBSON());
            }
        }

    void ShardRegistry::reload() {
        vector<ShardType> shards;
        Status status = _catalogManager->getAllShards(&shards);
        massert(13632, "couldn't get updated shard list from config server", status.isOK());

        int numShards = shards.size();

        LOG(1) << "found " << numShards << " shards listed on config server(s)";

        boost::lock_guard<boost::mutex> lk(_mutex);

        _lookup.clear();
        _rsLookup.clear();

        ShardType configServerShard;
        configServerShard.setName("config");
        configServerShard.setHost(_catalogManager->connectionString().toString());

        _addShard_inlock(configServerShard);

        for (const ShardType& shardType : shards) {
            uassertStatusOK(shardType.validate());

            // Skip the config host even if there is one left over from legacy installations. The
            // config host is installed manually from the catalog manager data.
            if (shardType.getName() == "config") {
                continue;
            }

            _addShard_inlock(shardType);
        }
    }

void ShardRegistry::_addShard_inlock(const ShardType& shardType) {
    // This validation should ideally go inside the ShardType::validate call. However, doing
    // it there would prevent us from loading previously faulty shard hosts, which might have
    // been stored (i.e., the entire getAllShards call would fail).
    auto shardHostStatus = ConnectionString::parse(shardType.getHost());
    if (!shardHostStatus.isOK()) {
        warning() << "Unable to parse shard host " << shardHostStatus.getStatus().toString();
    }

    const ConnectionString& shardHost(shardHostStatus.getValue());

    shared_ptr<Shard> shard;

    if (shardHost.type() == ConnectionString::SYNC) {
        // Sync cluster connections (legacy config server) do not go through the normal targeting
        // mechanism and must only be reachable through CatalogManagerLegacy or legacy-style queries
        // and inserts. Do not create targeter for these connections. This code should go away after
        // 3.2 is released.
        shard = std::make_shared<Shard>(shardType.getName(), shardHost, nullptr);
    } else {
        // Non-SYNC shards use targeter factory.
        shard = std::make_shared<Shard>(
            shardType.getName(), shardHost, _targeterFactory->create(shardHost));
    }

    _updateLookupMapsForShard_inlock(std::move(shard), shardHost);
}

TEST_F(EnableShardingTest, succeedsWhenTheDatabaseIsAlreadySharded) {
    ShardType shard;
    shard.setName("shard0");
    shard.setHost("shard0:12");

    ASSERT_OK(setupShards(vector<ShardType>{shard}));

    setupDatabase("db5", shard.getName(), true);

    auto status =
        ShardingCatalogManager::get(operationContext())->enableSharding(operationContext(), "db5");
    ASSERT_OK(status);
}

        /**
         * Stores a legacy { version : X } config server entry
         */
        void storeLegacyConfigVersion(int version) {

            if (version == 0) return;

            if (version == 1) {
                ShardType shard;
                shard.setName("test");
                shard.setHost("$dummy:10000");
                client().insert(ShardType::ConfigNS, shard.toBSON());
                return;
            }

            client().insert(VersionType::ConfigNS, BSON("_id" << 1 << "version" << version));
        }

void ShardRegistry::_addShard_inlock(const ShardType& shardType) {
    // This validation should ideally go inside the ShardType::validate call. However, doing
    // it there would prevent us from loading previously faulty shard hosts, which might have
    // been stored (i.e., the entire getAllShards call would fail).
    auto shardHostStatus = ConnectionString::parse(shardType.getHost());
    if (!shardHostStatus.isOK()) {
        warning() << "Unable to parse shard host " << shardHostStatus.getStatus().toString();
    }

    const ConnectionString& shardHost(shardHostStatus.getValue());

    shared_ptr<Shard> shard;

    if (shardHost.type() == ConnectionString::SYNC) {
        // Sync cluster connections (legacy config server) do not go through the normal targeting
        // mechanism and must only be reachable through CatalogManagerLegacy or legacy-style queries
        // and inserts. Do not create targeter for these connections. This code should go away after
        // 3.2 is released.
        shard = std::make_shared<Shard>(shardType.getName(), shardHost, nullptr);
    } else {
        // Non-SYNC shards use targeter factory.
        shard = std::make_shared<Shard>(
            shardType.getName(), shardHost, std::move(_targeterFactory->create(shardHost)));
    }

    _lookup[shardType.getName()] = shard;

    if (shardHost.type() == ConnectionString::SET) {
        _rsLookup[shardHost.getSetName()] = shard;
    }

    // Config servers never go through the set shard version mechanism, so there is no need to have
    // them in the reverse-lookup map.
    if (shard->isConfig()) {
        return;
    }

    // TODO: The only reason to have the shard host names in the lookup table is for the
    // setShardVersion call, which resolves the shard id from the shard address. This is
    // error-prone and will go away eventually when we switch all communications to go through
    // the remote command runner.
    _lookup[shardType.getHost()] = shard;

    for (const HostAndPort& hostAndPort : shardHost.getServers()) {
        _lookup[hostAndPort.toString()] = shard;
    }
}

    void ShardRegistry::_addShard_inlock(const ShardType& shardType) {
        // This validation should ideally go inside the ShardType::validate call. However, doing
        // it there would prevent us from loading previously faulty shard hosts, which might have
        // been stored (i.e., the entire getAllShards call would fail).
        auto shardHostStatus = ConnectionString::parse(shardType.getHost());
        if (!shardHostStatus.isOK()) {
            warning() << "Unable to parse shard host "
                        << shardHostStatus.getStatus().toString();
        }

        const ConnectionString& shardHost(shardHostStatus.getValue());

        shared_ptr<Shard> shard = boost::make_shared<Shard>(shardType.getName(),
                                                            shardHost,
                                                            shardType.getMaxSize(),
                                                            shardType.getDraining());
        _lookup[shardType.getName()] = shard;
        _lookup[shardType.getHost()] = shard;

        if (shardHost.type() == ConnectionString::SET) {
            if (shardHost.getSetName().size()) {
                _rsLookup[shardHost.getSetName()] = shard;
            }

            vector<HostAndPort> servers = shardHost.getServers();
            for (unsigned i = 0; i < servers.size(); i++) {
                _lookup[servers[i].toString()] = shard;
            }
        }
    }

void ShardingTestFixture::expectSetShardVersion(const HostAndPort& expectedHost,
                                                const ShardType& expectedShard,
                                                const NamespaceString& expectedNs,
                                                const ChunkVersion& expectedChunkVersion) {
    onCommand([&](const RemoteCommandRequest& request) {
        ASSERT_EQ(expectedHost, request.target);
        ASSERT_EQUALS(rpc::makeEmptyMetadata(), request.metadata);

        SetShardVersionRequest ssv =
            assertGet(SetShardVersionRequest::parseFromBSON(request.cmdObj));

        ASSERT(!ssv.isInit());
        ASSERT(ssv.isAuthoritative());
        ASSERT_EQ(grid.shardRegistry()->getConfigServerConnectionString().toString(),
                  ssv.getConfigServer().toString());
        ASSERT_EQ(expectedShard.getHost(), ssv.getShardConnectionString().toString());
        ASSERT_EQ(expectedNs.toString(), ssv.getNS().ns());
        ASSERT_EQ(expectedChunkVersion.toString(), ssv.getNSVersion().toString());

        return BSON("ok" << true);
    });
}

    Status checkClusterMongoVersions(const ConnectionString& configLoc,
                                     const string& minMongoVersion)
    {
        scoped_ptr<ScopedDbConnection> connPtr;

        //
        // Find mongos pings in config server
        //

        try {
            connPtr.reset(new ScopedDbConnection(configLoc, 30));
            ScopedDbConnection& conn = *connPtr;
            scoped_ptr<DBClientCursor> cursor(_safeCursor(conn->query(MongosType::ConfigNS,
                                                                      Query())));

            while (cursor->more()) {

                BSONObj pingDoc = cursor->next();

                MongosType ping;
                string errMsg;
                // NOTE: We don't care if the ping is invalid, legacy stuff will be
                if (!ping.parseBSON(pingDoc, &errMsg)) {
                    warning() << "could not parse ping document: " << pingDoc << causedBy(errMsg)
                              << endl;
                    continue;
                }

                string mongoVersion = "2.0";
                // Hack to determine older mongos versions from ping format
                if (ping.isWaitingSet()) mongoVersion = "2.2";
                if (ping.isMongoVersionSet() && ping.getMongoVersion() != "") {
                    mongoVersion = ping.getMongoVersion();
                }

                Date_t lastPing = ping.getPing();

                long long quietIntervalMillis = 0;
                Date_t currentJsTime = jsTime();
                if (currentJsTime >= lastPing) {
                    quietIntervalMillis = static_cast<long long>(currentJsTime - lastPing);
                }
                long long quietIntervalMins = quietIntervalMillis / (60 * 1000);

                // We assume that anything that hasn't pinged in 5 minutes is probably down
                if (quietIntervalMins >= 5) {
                    log() << "stale mongos detected " << quietIntervalMins << " minutes ago,"
                          << " network location is " << pingDoc["_id"].String()
                          << ", not checking version" << endl;
            	}
                else {
                    if (versionCmp(mongoVersion, minMongoVersion) < 0) {
                        return Status(ErrorCodes::RemoteValidationError,
                                      stream() << "version " << mongoVersion << " of mongos at "
                                               << ping.getName()
                                               << " is not compatible with the config update, "
                                               << "you must wait 5 minutes "
                                               << "after shutting down a pre-" << minMongoVersion
                                               << " mongos");
                    }
                }
            }
        }
        catch (const DBException& e) {
            return e.toStatus("could not read mongos pings collection");
        }

        //
        // Load shards from config server
        //

        vector<ConnectionString> shardLocs;

        try {
            ScopedDbConnection& conn = *connPtr;
            scoped_ptr<DBClientCursor> cursor(_safeCursor(conn->query(ShardType::ConfigNS,
                                                                      Query())));

            while (cursor->more()) {

                BSONObj shardDoc = cursor->next();

                ShardType shard;
                string errMsg;
                if (!shard.parseBSON(shardDoc, &errMsg) || !shard.isValid(&errMsg)) {
                    connPtr->done();
                    return Status(ErrorCodes::UnsupportedFormat,
                                  stream() << "invalid shard " << shardDoc
                                           << " read from the config server" << causedBy(errMsg));
                }

                ConnectionString shardLoc = ConnectionString::parse(shard.getHost(), errMsg);
                if (shardLoc.type() == ConnectionString::INVALID) {
                    connPtr->done();
                    return Status(ErrorCodes::UnsupportedFormat,
                                  stream() << "invalid shard host " << shard.getHost()
                                           << " read from the config server" << causedBy(errMsg));
                }

                shardLocs.push_back(shardLoc);
//.........这里部分代码省略.........

void ShardRegistry::_addConfigShard_inlock() {
    ShardType configServerShard;
    configServerShard.setName("config");
    configServerShard.setHost(_catalogManager->connectionString().toString());
    _addShard_inlock(configServerShard);
}

StatusWith<ShardType> ShardingCatalogManager::_validateHostAsShard(
    OperationContext* opCtx,
    std::shared_ptr<RemoteCommandTargeter> targeter,
    const std::string* shardProposedName,
    const ConnectionString& connectionString) {
    auto swCommandResponse = _runCommandForAddShard(
        opCtx, targeter.get(), NamespaceString::kAdminDb, BSON("isMaster" << 1));
    if (swCommandResponse.getStatus() == ErrorCodes::IncompatibleServerVersion) {
        return swCommandResponse.getStatus().withReason(
            str::stream() << "Cannot add " << connectionString.toString()
                          << " as a shard because its binary version is not compatible with "
                             "the cluster's featureCompatibilityVersion.");
    } else if (!swCommandResponse.isOK()) {
        return swCommandResponse.getStatus();
    }

    // Check for a command response error
    auto resIsMasterStatus = std::move(swCommandResponse.getValue().commandStatus);
    if (!resIsMasterStatus.isOK()) {
        return resIsMasterStatus.withContext(str::stream()
                                             << "Error running isMaster against "
                                             << targeter->connectionString().toString());
    }

    auto resIsMaster = std::move(swCommandResponse.getValue().response);

    // Fail if the node being added is a mongos.
    const std::string msg = resIsMaster.getStringField("msg");
    if (msg == "isdbgrid") {
        return {ErrorCodes::IllegalOperation, "cannot add a mongos as a shard"};
    }

    // Extract the maxWireVersion so we can verify that the node being added has a binary version
    // greater than or equal to the cluster's featureCompatibilityVersion. We expect an incompatible
    // binary node to be unable to communicate, returning an IncompatibleServerVersion error,
    // because of our internal wire version protocol. So we can safely invariant here that the node
    // is compatible.
    long long maxWireVersion;
    Status status = bsonExtractIntegerField(resIsMaster, "maxWireVersion", &maxWireVersion);
    if (!status.isOK()) {
        return status.withContext(str::stream() << "isMaster returned invalid 'maxWireVersion' "
                                                << "field when attempting to add "
                                                << connectionString.toString()
                                                << " as a shard");
    }
    if (serverGlobalParams.featureCompatibility.getVersion() >
        ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo40) {
        // If the cluster's FCV is 4.2, or upgrading to / downgrading from, the node being added
        // must be a v4.2 binary.
        invariant(maxWireVersion == WireVersion::LATEST_WIRE_VERSION);
    } else {
        // If the cluster's FCV is 4.0, the node being added must be a v4.0 or v4.2 binary.
        invariant(serverGlobalParams.featureCompatibility.getVersion() ==
                  ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo40);
        invariant(maxWireVersion >= WireVersion::LATEST_WIRE_VERSION - 1);
    }

    // Check whether there is a master. If there isn't, the replica set may not have been
    // initiated. If the connection is a standalone, it will return true for isMaster.
    bool isMaster;
    status = bsonExtractBooleanField(resIsMaster, "ismaster", &isMaster);
    if (!status.isOK()) {
        return status.withContext(str::stream() << "isMaster returned invalid 'ismaster' "
                                                << "field when attempting to add "
                                                << connectionString.toString()
                                                << " as a shard");
    }
    if (!isMaster) {
        return {ErrorCodes::NotMaster,
                str::stream()
                    << connectionString.toString()
                    << " does not have a master. If this is a replica set, ensure that it has a"
                    << " healthy primary and that the set has been properly initiated."};
    }

    const std::string providedSetName = connectionString.getSetName();
    const std::string foundSetName = resIsMaster["setName"].str();

    // Make sure the specified replica set name (if any) matches the actual shard's replica set
    if (providedSetName.empty() && !foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "host is part of set " << foundSetName << "; "
                              << "use replica set url format "
                              << "<setname>/<server1>,<server2>, ..."};
    }

    if (!providedSetName.empty() && foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "host did not return a set name; "
                              << "is the replica set still initializing? "
                              << resIsMaster};
    }

    // Make sure the set name specified in the connection string matches the one where its hosts
    // belong into
    if (!providedSetName.empty() && (providedSetName != foundSetName)) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "the provided connection string (" << connectionString.toString()
                              << ") does not match the actual set name "
                              << foundSetName};
//.........这里部分代码省略.........

void ShardRegistry::_addConfigShard_inlock() {
    ShardType configServerShard;
    configServerShard.setName("config");
    configServerShard.setHost(_configServerCS.toString());
    _addShard_inlock(configServerShard);
}

StatusWith<ShardType> ShardingCatalogManagerImpl::_validateHostAsShard(
    OperationContext* txn,
    std::shared_ptr<RemoteCommandTargeter> targeter,
    const std::string* shardProposedName,
    const ConnectionString& connectionString) {
    // Check whether any host in the connection is already part of the cluster.
    Grid::get(txn)->shardRegistry()->reload(txn);
    for (const auto& hostAndPort : connectionString.getServers()) {
        std::shared_ptr<Shard> shard;
        shard = Grid::get(txn)->shardRegistry()->getShardNoReload(hostAndPort.toString());
        if (shard) {
            return {ErrorCodes::OperationFailed,
                    str::stream() << "'" << hostAndPort.toString() << "' "
                    << "is already a member of the existing shard '"
                    << shard->getConnString().toString()
                    << "' ("
                    << shard->getId()
                    << ")."};
        }
    }

    // Check for mongos and older version mongod connections, and whether the hosts
    // can be found for the user specified replset.
    auto swCommandResponse =
        _runCommandForAddShard(txn, targeter.get(), "admin", BSON("isMaster" << 1));
    if (!swCommandResponse.isOK()) {
        if (swCommandResponse.getStatus() == ErrorCodes::RPCProtocolNegotiationFailed) {
            // Mongos to mongos commands are no longer supported in the wire protocol
            // (because mongos does not support OP_COMMAND), similarly for a new mongos
            // and an old mongod. So the call will fail in such cases.
            // TODO: If/When mongos ever supports opCommands, this logic will break because
            // cmdStatus will be OK.
            return {ErrorCodes::RPCProtocolNegotiationFailed,
                    str::stream() << targeter->connectionString().toString()
                    << " does not recognize the RPC protocol being used. This is"
                    << " likely because it contains a node that is a mongos or an old"
                    << " version of mongod."};
        } else {
            return swCommandResponse.getStatus();
        }
    }

    // Check for a command response error
    auto resIsMasterStatus = std::move(swCommandResponse.getValue().commandStatus);
    if (!resIsMasterStatus.isOK()) {
        return {resIsMasterStatus.code(),
                str::stream() << "Error running isMaster against "
                << targeter->connectionString().toString()
                << ": "
                << causedBy(resIsMasterStatus)};
    }

    auto resIsMaster = std::move(swCommandResponse.getValue().response);

    // Check whether there is a master. If there isn't, the replica set may not have been
    // initiated. If the connection is a standalone, it will return true for isMaster.
    bool isMaster;
    Status status = bsonExtractBooleanField(resIsMaster, "ismaster", &isMaster);
    if (!status.isOK()) {
        return Status(status.code(),
                      str::stream() << "isMaster returned invalid 'ismaster' "
                      << "field when attempting to add "
                      << connectionString.toString()
                      << " as a shard: "
                      << status.reason());
    }
    if (!isMaster) {
        return {ErrorCodes::NotMaster,
                str::stream()
                << connectionString.toString()
                << " does not have a master. If this is a replica set, ensure that it has a"
                << " healthy primary and that the set has been properly initiated."};
    }

    const string providedSetName = connectionString.getSetName();
    const string foundSetName = resIsMaster["setName"].str();

    // Make sure the specified replica set name (if any) matches the actual shard's replica set
    if (providedSetName.empty() && !foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "host is part of set " << foundSetName << "; "
                << "use replica set url format "
                << "<setname>/<server1>,<server2>, ..."};
    }

    if (!providedSetName.empty() && foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "host did not return a set name; "
                << "is the replica set still initializing? "
                << resIsMaster};
    }

    // Make sure the set name specified in the connection string matches the one where its hosts
    // belong into
    if (!providedSetName.empty() && (providedSetName != foundSetName)) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "the provided connection string (" << connectionString.toString()
                << ") does not match the actual set name "
                << foundSetName};
    }
//.........这里部分代码省略.........

StatusWith<ShardType> ShardingCatalogManagerImpl::_validateHostAsShard(
    OperationContext* opCtx,
    std::shared_ptr<RemoteCommandTargeter> targeter,
    const std::string* shardProposedName,
    const ConnectionString& connectionString) {

    // Check if the node being added is a mongos or a version of mongod too old to speak the current
    // communication protocol.
    auto swCommandResponse =
        _runCommandForAddShard(opCtx, targeter.get(), "admin", BSON("isMaster" << 1));
    if (!swCommandResponse.isOK()) {
        if (swCommandResponse.getStatus() == ErrorCodes::RPCProtocolNegotiationFailed) {
            // Mongos to mongos commands are no longer supported in the wire protocol
            // (because mongos does not support OP_COMMAND), similarly for a new mongos
            // and an old mongod. So the call will fail in such cases.
            // TODO: If/When mongos ever supports opCommands, this logic will break because
            // cmdStatus will be OK.
            return {ErrorCodes::RPCProtocolNegotiationFailed,
                    str::stream() << targeter->connectionString().toString()
                                  << " does not recognize the RPC protocol being used. This is"
                                  << " likely because it contains a node that is a mongos or an old"
                                  << " version of mongod."};
        } else {
            return swCommandResponse.getStatus();
        }
    }

    // Check for a command response error
    auto resIsMasterStatus = std::move(swCommandResponse.getValue().commandStatus);
    if (!resIsMasterStatus.isOK()) {
        return {resIsMasterStatus.code(),
                str::stream() << "Error running isMaster against "
                              << targeter->connectionString().toString()
                              << ": "
                              << causedBy(resIsMasterStatus)};
    }

    auto resIsMaster = std::move(swCommandResponse.getValue().response);

    // Check that the node being added is a new enough version.
    // If we're running this code, that means the mongos that the addShard request originated from
    // must be at least version 3.4 (since 3.2 mongoses don't know about the _configsvrAddShard
    // command).  Since it is illegal to have v3.4 mongoses with v3.2 shards, we should reject
    // adding any shards that are not v3.4.  We can determine this by checking that the
    // maxWireVersion reported in isMaster is at least COMMANDS_ACCEPT_WRITE_CONCERN.
    // TODO(SERVER-25623): This approach won't work to prevent v3.6 mongoses from adding v3.4
    // shards, so we'll have to rethink this during the 3.5 development cycle.

    long long maxWireVersion;
    Status status = bsonExtractIntegerField(resIsMaster, "maxWireVersion", &maxWireVersion);
    if (!status.isOK()) {
        return Status(status.code(),
                      str::stream() << "isMaster returned invalid 'maxWireVersion' "
                                    << "field when attempting to add "
                                    << connectionString.toString()
                                    << " as a shard: "
                                    << status.reason());
    }
    if (maxWireVersion < WireVersion::COMMANDS_ACCEPT_WRITE_CONCERN) {
        return Status(ErrorCodes::IncompatibleServerVersion,
                      str::stream() << "Cannot add " << connectionString.toString()
                                    << " as a shard because we detected a mongod with server "
                                       "version older than 3.4.0.  It is invalid to add v3.2 and "
                                       "older shards through a v3.4 mongos.");
    }


    // Check whether there is a master. If there isn't, the replica set may not have been
    // initiated. If the connection is a standalone, it will return true for isMaster.
    bool isMaster;
    status = bsonExtractBooleanField(resIsMaster, "ismaster", &isMaster);
    if (!status.isOK()) {
        return Status(status.code(),
                      str::stream() << "isMaster returned invalid 'ismaster' "
                                    << "field when attempting to add "
                                    << connectionString.toString()
                                    << " as a shard: "
                                    << status.reason());
    }
    if (!isMaster) {
        return {ErrorCodes::NotMaster,
                str::stream()
                    << connectionString.toString()
                    << " does not have a master. If this is a replica set, ensure that it has a"
                    << " healthy primary and that the set has been properly initiated."};
    }

    const std::string providedSetName = connectionString.getSetName();
    const std::string foundSetName = resIsMaster["setName"].str();

    // Make sure the specified replica set name (if any) matches the actual shard's replica set
    if (providedSetName.empty() && !foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
                str::stream() << "host is part of set " << foundSetName << "; "
                              << "use replica set url format "
                              << "<setname>/<server1>,<server2>, ..."};
    }

    if (!providedSetName.empty() && foundSetName.empty()) {
        return {ErrorCodes::OperationFailed,
//.........这里部分代码省略.........