C++ ConnectionString::toString方法代码示例

void ShardRegistryData::_addShard_inlock(const std::shared_ptr<Shard>& shard) {
    const ShardId shardId = shard->getId();
    const ConnectionString connString = shard->originalConnString();

    auto currentShard = _findByShardId_inlock(shardId);
    if (currentShard) {
        auto oldConnString = currentShard->originalConnString();

        if (oldConnString.toString() != connString.toString()) {
            log() << "Updating ShardRegistry connection string for shard " << currentShard->getId()
                  << " from: " << oldConnString.toString() << " to: " << connString.toString();
        }

        for (const auto& host : oldConnString.getServers()) {
            _lookup.erase(host.toString());
            _hostLookup.erase(host);
        }
        _lookup.erase(oldConnString.toString());
    }

    _lookup[shard->getId()] = shard;

    if (connString.type() == ConnectionString::SET) {
        _rsLookup[connString.getSetName()] = shard;
    } else if (connString.type() == ConnectionString::CUSTOM) {
        // CUSTOM connection strings (ie "$dummy:10000) become DBDirectClient connections which
        // always return "localhost" as their response to getServerAddress().  This is just for
        // making dbtest work.
        _lookup[ShardId("localhost")] = shard;
        _hostLookup[HostAndPort("localhost")] = shard;
    }

    // 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 and all nodes are sharding aware by default.
    _lookup[connString.toString()] = shard;

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

shared_ptr<ReplicaSetMonitor> ReplicaSetMonitorManager::getOrCreateMonitor(
    const ConnectionString& connStr) {
    invariant(connStr.type() == ConnectionString::SET);

    stdx::lock_guard<stdx::mutex> lk(_mutex);
    _setupTaskExecutorInLock(connStr.toString());
    auto setName = connStr.getSetName();
    auto monitor = _monitors[setName].lock();
    if (monitor) {
        uassertNotMixingSSL(monitor->getOriginalUri().getSSLMode(), transport::kGlobalSSLMode);
        return monitor;
    }

    log() << "Starting new replica set monitor for " << connStr.toString();

    auto newMonitor = std::make_shared<ReplicaSetMonitor>(MongoURI(connStr));
    _monitors[setName] = newMonitor;
    newMonitor->init();
    return newMonitor;
}

    /**
     * Upgrades v4 to v5.
     */
    bool doUpgradeV4ToV5(const ConnectionString& configLoc,
                         const VersionType& lastVersionInfo,
                         string* errMsg)
    {
        string dummy;
        if (!errMsg) errMsg = &dummy;

        verify(lastVersionInfo.getCurrentVersion() == UpgradeHistory_MandatoryEpochVersion);
        Status result = preUpgradeCheck(configLoc, lastVersionInfo, minMongoProcessVersion);

        if (!result.isOK()) {
            if (result.code() == ErrorCodes::ManualInterventionRequired) {
                *errMsg = cannotCleanupMessage;
            }
            else {
                *errMsg = result.toString();
            }

            return false;
        }

        // This is not needed because we are not actually going to make any modifications
        // on the other collections in the config server for this particular upgrade.
        // startConfigUpgrade(configLoc.toString(),
        //                    lastVersionInfo.getCurrentVersion(),
        //                    OID::gen());

        // If we actually need to modify something in the config servers these need to follow
        // after calling startConfigUpgrade(...):
        //
        // 1. Acquire necessary locks.
        // 2. Make a backup of the collections we are about to modify.
        // 3. Perform the upgrade process on the backup collection.
        // 4. Verify that no changes were made to the collections since the backup was performed.
        // 5. Call enterConfigUpgradeCriticalSection(configLoc.toString(),
        //    lastVersionInfo.getCurrentVersion()).
        // 6. Rename the backup collection to the name of the original collection with
        //    dropTarget set to true.

        // We're only after the version bump in commitConfigUpgrade here since we never
        // get into the critical section.
        Status commitStatus = commitConfigUpgrade(configLoc.toString(),
                                                  lastVersionInfo.getCurrentVersion(),
                                                  MIN_COMPATIBLE_CONFIG_VERSION,
                                                  CURRENT_CONFIG_VERSION);

        if (!commitStatus.isOK()) {
            *errMsg = commitStatus.toString();
            return false;
        }

        return true;
    }

shared_ptr<ReplicaSetMonitor> ReplicaSetMonitorManager::getOrCreateMonitor(
    const ConnectionString& connStr) {
    invariant(connStr.type() == ConnectionString::SET);

    stdx::lock_guard<stdx::mutex> lk(_mutex);
    _setupTaskExecutorInLock(connStr.toString());
    auto setName = connStr.getSetName();
    auto monitor = _monitors[setName].lock();
    if (monitor) {
        return monitor;
    }

    const std::set<HostAndPort> servers(connStr.getServers().begin(), connStr.getServers().end());

    log() << "Starting new replica set monitor for " << connStr.toString();

    auto newMonitor = std::make_shared<ReplicaSetMonitor>(setName, servers);
    _monitors[setName] = newMonitor;
    newMonitor->init();
    return newMonitor;
}

    void LegacyDistLockPinger::acknowledgeStopPing(const ConnectionString& addr,
                                                   const string& processId) {
        {
            boost::lock_guard<boost::mutex> lk(_mutex);

            string pingId = pingThreadId(addr, processId);

            _kill.erase(pingId);
            _seen.erase(pingId);
        }

        try {
            ScopedDbConnection conn(addr.toString(), 30.0);
            conn->remove(LockpingsType::ConfigNS, BSON(LockpingsType::process(processId)));
        }
        catch (const DBException& ex) {
            warning() << "Error encountered while stopping ping on " << processId
                      << causedBy(ex);
        }
    }

void StartChunkCloneRequest::appendAsCommand(
    BSONObjBuilder* builder,
    const NamespaceString& nss,
    const MigrationSessionId& shardVersion,
    const ConnectionString& configServerConnectionString,
    const std::string& fromShardId,
    const std::string& toShardId,
    const BSONObj& chunkMinKey,
    const BSONObj& chunkMaxKey,
    const BSONObj& shardKeyPattern,
    const MigrationSecondaryThrottleOptions& secondaryThrottle) {
    invariant(builder->asTempObj().isEmpty());
    invariant(nss.isValid());

    builder->append(kRecvChunkStart, nss.ns());
    builder->append(kConfigServerConnectionString, configServerConnectionString.toString());
    builder->append(kFromShardId, fromShardId);
    builder->append(kToShardId, toShardId);
    builder->append(kChunkMinKey, chunkMinKey);
    builder->append(kChunkMaxKey, chunkMaxKey);
    builder->append(kShardKeyPattern, shardKeyPattern);
    secondaryThrottle.append(builder);
}

    // In order to be accepted as a new shard, that mongod must not have
    // any database name that exists already in any other shards.
    // If that test passes, the new shard's databases are going to be entered as
    // non-sharded db's whose primary is the newly added shard.
    StatusWith<vector<string>> getDBNames(const ConnectionString& shardConnectionString,
                                          ScopedDbConnection& conn) {
        vector<string> dbNames;

        BSONObj resListDB;
        if (!conn->runCommand("admin", BSON("listDatabases" << 1), resListDB)) {
            return Status(ErrorCodes::OperationFailed,
                          str::stream() << "failed listing "
                                        << shardConnectionString.toString()
                                        << "'s databases:" << resListDB);
        }

        BSONObjIterator i(resListDB["databases"].Obj());
        while (i.more()) {
            BSONObj dbEntry = i.next().Obj();
            const string& dbName = dbEntry["name"].String();
            if (!(dbName == "local" || dbName == "admin" || dbName == "config")) {
                dbNames.push_back(dbName);
            }
        }

        return dbNames;
    }

void ShardRegistry::_updateLookupMapsForShard_inlock(shared_ptr<Shard> shard,
                                                     const ConnectionString& newConnString) {
    auto oldConnString = shard->getConnString();
    for (const auto& host : oldConnString.getServers()) {
        _lookup.erase(host.toString());
    }

    _lookup[shard->getId()] = shard;

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

    // 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 and all nodes are sharding aware by default.
    _lookup[newConnString.toString()] = shard;

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

 void Shard::setAddress( const ConnectionString& cs) {
     verify( _name.size() );
     _addr = cs.toString();
     _cs = cs;
     staticShardInfo.set( _name , *this , true , false );
 }

void BatchWriteExec::executeBatch(const BatchedCommandRequest& clientRequest,
                                  BatchedCommandResponse* clientResponse) {
    LOG(4) << "starting execution of write batch of size "
           << static_cast<int>(clientRequest.sizeWriteOps()) << " for " << clientRequest.getNS()
           << endl;

    BatchWriteOp batchOp;
    batchOp.initClientRequest(&clientRequest);

    // Current batch status
    bool refreshedTargeter = false;
    int rounds = 0;
    int numCompletedOps = 0;
    int numRoundsWithoutProgress = 0;

    while (!batchOp.isFinished()) {
        //
        // Get child batches to send using the targeter
        //
        // Targeting errors can be caused by remote metadata changing (the collection could have
        // been dropped and recreated, for example with a new shard key).  If a remote metadata
        // change occurs *before* a client sends us a batch, we need to make sure that we don't
        // error out just because we're staler than the client - otherwise mongos will be have
        // unpredictable behavior.
        //
        // (If a metadata change happens *during* or *after* a client sends us a batch, however,
        // we make no guarantees about delivery.)
        //
        // For this reason, we don't record targeting errors until we've refreshed our targeting
        // metadata at least once *after* receiving the client batch - at that point, we know:
        //
        // 1) our new metadata is the same as the metadata when the client sent a batch, and so
        //    targeting errors are real.
        // OR
        // 2) our new metadata is a newer version than when the client sent a batch, and so
        //    the metadata must have changed after the client batch was sent.  We don't need to
        //    deliver in this case, since for all the client knows we may have gotten the batch
        //    exactly when the metadata changed.
        //

        OwnedPointerVector<TargetedWriteBatch> childBatchesOwned;
        vector<TargetedWriteBatch*>& childBatches = childBatchesOwned.mutableVector();

        // If we've already had a targeting error, we've refreshed the metadata once and can
        // record target errors definitively.
        bool recordTargetErrors = refreshedTargeter;
        Status targetStatus = batchOp.targetBatch(*_targeter, recordTargetErrors, &childBatches);
        if (!targetStatus.isOK()) {
            // Don't do anything until a targeter refresh
            _targeter->noteCouldNotTarget();
            refreshedTargeter = true;
            ++_stats->numTargetErrors;
            dassert(childBatches.size() == 0u);
        }

        //
        // Send all child batches
        //

        size_t numSent = 0;
        size_t numToSend = childBatches.size();
        bool remoteMetadataChanging = false;
        while (numSent != numToSend) {
            // Collect batches out on the network, mapped by endpoint
            OwnedHostBatchMap ownedPendingBatches;
            OwnedHostBatchMap::MapType& pendingBatches = ownedPendingBatches.mutableMap();

            //
            // Send side
            //

            // Get as many batches as we can at once
            for (vector<TargetedWriteBatch*>::iterator it = childBatches.begin();
                 it != childBatches.end();
                 ++it) {
                //
                // Collect the info needed to dispatch our targeted batch
                //

                TargetedWriteBatch* nextBatch = *it;
                // If the batch is NULL, we sent it previously, so skip
                if (nextBatch == NULL)
                    continue;

                // Figure out what host we need to dispatch our targeted batch
                ConnectionString shardHost;
                Status resolveStatus =
                    _resolver->chooseWriteHost(nextBatch->getEndpoint().shardName, &shardHost);
                if (!resolveStatus.isOK()) {
                    ++_stats->numResolveErrors;

                    // Record a resolve failure
                    // TODO: It may be necessary to refresh the cache if stale, or maybe just
                    // cancel and retarget the batch
                    WriteErrorDetail error;
                    buildErrorFrom(resolveStatus, &error);

                    LOG(4) << "unable to send write batch to " << shardHost.toString()
                           << causedBy(resolveStatus.toString()) << endl;

//.........这里部分代码省略.........

StatusWith<std::string> ShardingCatalogManager::addShard(
    OperationContext* opCtx,
    const std::string* shardProposedName,
    const ConnectionString& shardConnectionString,
    const long long maxSize) {
    if (shardConnectionString.type() == ConnectionString::INVALID) {
        return {ErrorCodes::BadValue, "Invalid connection string"};
    }

    if (shardProposedName && shardProposedName->empty()) {
        return {ErrorCodes::BadValue, "shard name cannot be empty"};
    }

    // Only one addShard operation can be in progress at a time.
    Lock::ExclusiveLock lk(opCtx->lockState(), _kShardMembershipLock);

    // Check if this shard has already been added (can happen in the case of a retry after a network
    // error, for example) and thus this addShard request should be considered a no-op.
    auto existingShard =
        _checkIfShardExists(opCtx, shardConnectionString, shardProposedName, maxSize);
    if (!existingShard.isOK()) {
        return existingShard.getStatus();
    }
    if (existingShard.getValue()) {
        // These hosts already belong to an existing shard, so report success and terminate the
        // addShard request.  Make sure to set the last optime for the client to the system last
        // optime so that we'll still wait for replication so that this state is visible in the
        // committed snapshot.
        repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
        return existingShard.getValue()->getName();
    }

    // Force a reload of the ShardRegistry to ensure that, in case this addShard is to re-add a
    // replica set that has recently been removed, we have detached the ReplicaSetMonitor for the
    // set with that setName from the ReplicaSetMonitorManager and will create a new
    // ReplicaSetMonitor when targeting the set below.
    // Note: This is necessary because as of 3.4, removeShard is performed by mongos (unlike
    // addShard), so the ShardRegistry is not synchronously reloaded on the config server when a
    // shard is removed.
    if (!Grid::get(opCtx)->shardRegistry()->reload(opCtx)) {
        // If the first reload joined an existing one, call reload again to ensure the reload is
        // fresh.
        Grid::get(opCtx)->shardRegistry()->reload(opCtx);
    }

    // TODO: Don't create a detached Shard object, create a detached RemoteCommandTargeter instead.
    const std::shared_ptr<Shard> shard{
        Grid::get(opCtx)->shardRegistry()->createConnection(shardConnectionString)};
    invariant(shard);
    auto targeter = shard->getTargeter();

    auto stopMonitoringGuard = MakeGuard([&] {
        if (shardConnectionString.type() == ConnectionString::SET) {
            // This is a workaround for the case were we could have some bad shard being
            // requested to be added and we put that bad connection string on the global replica set
            // monitor registry. It needs to be cleaned up so that when a correct replica set is
            // added, it will be recreated.
            ReplicaSetMonitor::remove(shardConnectionString.getSetName());
        }
    });

    // Validate the specified connection string may serve as shard at all
    auto shardStatus =
        _validateHostAsShard(opCtx, targeter, shardProposedName, shardConnectionString);
    if (!shardStatus.isOK()) {
        return shardStatus.getStatus();
    }
    ShardType& shardType = shardStatus.getValue();

    // Check that none of the existing shard candidate's dbs exist already
    auto dbNamesStatus = _getDBNamesListFromShard(opCtx, targeter);
    if (!dbNamesStatus.isOK()) {
        return dbNamesStatus.getStatus();
    }

    for (const auto& dbName : dbNamesStatus.getValue()) {
        auto dbt = Grid::get(opCtx)->catalogClient()->getDatabase(
            opCtx, dbName, repl::ReadConcernLevel::kLocalReadConcern);
        if (dbt.isOK()) {
            const auto& dbDoc = dbt.getValue().value;
            return Status(ErrorCodes::OperationFailed,
                          str::stream() << "can't add shard "
                                        << "'"
                                        << shardConnectionString.toString()
                                        << "'"
                                        << " because a local database '"
                                        << dbName
                                        << "' exists in another "
                                        << dbDoc.getPrimary());
        } else if (dbt != ErrorCodes::NamespaceNotFound) {
            return dbt.getStatus();
        }
    }

    // Check that the shard candidate does not have a local config.system.sessions collection
    auto res = _dropSessionsCollection(opCtx, targeter);

    if (!res.isOK()) {
        return res.withContext(
            "can't add shard with a local copy of config.system.sessions, please drop this "
//.........这里部分代码省略.........

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 Balancer::run() {

        // this is the body of a BackgroundJob so if we throw here we're basically ending the balancer thread prematurely
        while ( ! inShutdown() ) {

            if ( ! _init() ) {
                log() << "will retry to initialize balancer in one minute" << endl;
                sleepsecs( 60 );
                continue;
            }

            break;
        }

        int sleepTime = 10;

        // getConnectioString and dist lock constructor does not throw, which is what we expect on while
        // on the balancer thread
        ConnectionString config = configServer.getConnectionString();
        DistributedLock balanceLock( config , "balancer" );

        while ( ! inShutdown() ) {

            try {

                ScopedDbConnection conn(config.toString(), 30);

                // ping has to be first so we keep things in the config server in sync
                _ping();

                // use fresh shard state
                Shard::reloadShardInfo();

                // refresh chunk size (even though another balancer might be active)
                Chunk::refreshChunkSize();

                SettingsType balancerConfig;
                string errMsg;

                if (!grid.getBalancerSettings(&balancerConfig, &errMsg)) {
                    warning() << errMsg;
                    return ;
                }

                // now make sure we should even be running
                if ((balancerConfig.isKeySet() && // balancer config doc exists
                        !grid.shouldBalance(balancerConfig)) ||
                        MONGO_FAIL_POINT(skipBalanceRound)) {

                    LOG(1) << "skipping balancing round because balancing is disabled" << endl;

                    // Ping again so scripts can determine if we're active without waiting
                    _ping( true );

                    conn.done();

                    sleepsecs( sleepTime );
                    continue;
                }

                uassert( 13258 , "oids broken after resetting!" , _checkOIDs() );

                {
                    dist_lock_try lk( &balanceLock , "doing balance round" );
                    if ( ! lk.got() ) {
                        LOG(1) << "skipping balancing round because another balancer is active" << endl;

                        // Ping again so scripts can determine if we're active without waiting
                        _ping( true );

                        conn.done();
                        
                        sleepsecs( sleepTime ); // no need to wake up soon
                        continue;
                    }

                    if ( !isConfigServerConsistent() ) {
                        conn.done();
                        warning() << "Skipping balancing round because data inconsistency"
                                  << " was detected amongst the config servers." << endl;
                        sleepsecs( sleepTime );
                        continue;
                    }

                    const bool waitForDelete = (balancerConfig.isWaitForDeleteSet() ?
                            balancerConfig.getWaitForDelete() : false);

                    scoped_ptr<WriteConcernOptions> writeConcern;
                    if (balancerConfig.isKeySet()) { // if balancer doc exists.
                        StatusWith<WriteConcernOptions*> extractStatus =
                                balancerConfig.extractWriteConcern();
                        if (extractStatus.isOK()) {
                            writeConcern.reset(extractStatus.getValue());
                        }
                        else {
                            warning() << extractStatus.toString();
                        }
                    }

                    LOG(1) << "*** start balancing round. "
//.........这里部分代码省略.........

StatusWith<string> ShardingCatalogManagerImpl::addShard(
    OperationContext* txn,
    const std::string* shardProposedName,
    const ConnectionString& shardConnectionString,
    const long long maxSize) {
    if (shardConnectionString.type() == ConnectionString::INVALID) {
        return {ErrorCodes::BadValue, "Invalid connection string"};
    }

    if (shardProposedName && shardProposedName->empty()) {
        return {ErrorCodes::BadValue, "shard name cannot be empty"};
    }

    // TODO: Don't create a detached Shard object, create a detached RemoteCommandTargeter instead.
    const std::shared_ptr<Shard> shard{
        Grid::get(txn)->shardRegistry()->createConnection(shardConnectionString)};
    invariant(shard);
    auto targeter = shard->getTargeter();

    // Validate the specified connection string may serve as shard at all
    auto shardStatus =
        _validateHostAsShard(txn, targeter, shardProposedName, shardConnectionString);
    if (!shardStatus.isOK()) {
        // TODO: This is a workaround for the case were we could have some bad shard being
        // requested to be added and we put that bad connection string on the global replica set
        // monitor registry. It needs to be cleaned up so that when a correct replica set is added,
        // it will be recreated.
        ReplicaSetMonitor::remove(shardConnectionString.getSetName());
        return shardStatus.getStatus();
    }

    ShardType& shardType = shardStatus.getValue();

    auto dbNamesStatus = _getDBNamesListFromShard(txn, targeter);
    if (!dbNamesStatus.isOK()) {
        return dbNamesStatus.getStatus();
    }

    // Check that none of the existing shard candidate's dbs exist already
    for (const string& dbName : dbNamesStatus.getValue()) {
        auto dbt = _catalogClient->getDatabase(txn, dbName);
        if (dbt.isOK()) {
            const auto& dbDoc = dbt.getValue().value;
            return Status(ErrorCodes::OperationFailed,
                          str::stream() << "can't add shard "
                          << "'"
                          << shardConnectionString.toString()
                          << "'"
                          << " because a local database '"
                          << dbName
                          << "' exists in another "
                          << dbDoc.getPrimary());
        } else if (dbt != ErrorCodes::NamespaceNotFound) {
            return dbt.getStatus();
        }
    }

    // If a name for a shard wasn't provided, generate one
    if (shardType.getName().empty()) {
        StatusWith<string> result = _generateNewShardName(txn);
        if (!result.isOK()) {
            return result.getStatus();
        }
        shardType.setName(result.getValue());
    }

    if (maxSize > 0) {
        shardType.setMaxSizeMB(maxSize);
    }

    ShardIdentityType shardIdentity;
    shardIdentity.setConfigsvrConnString(
        Grid::get(txn)->shardRegistry()->getConfigServerConnectionString());
    shardIdentity.setShardName(shardType.getName());
    shardIdentity.setClusterId(Grid::get(txn)->shardRegistry()->getClusterId());
    auto validateStatus = shardIdentity.validate();
    if (!validateStatus.isOK()) {
        return validateStatus;
    }

    log() << "going to insert shardIdentity document into shard: " << shardIdentity.toString();

    auto updateRequest = shardIdentity.createUpsertForAddShard();
    BatchedCommandRequest commandRequest(updateRequest.release());
    commandRequest.setNS(NamespaceString::kConfigCollectionNamespace);
    commandRequest.setWriteConcern(kMajorityWriteConcern.toBSON());

    auto swCommandResponse =
        _runCommandForAddShard(txn, targeter.get(), "admin", commandRequest.toBSON());

    if (!swCommandResponse.isOK()) {
        return swCommandResponse.getStatus();
    }

    auto commandResponse = std::move(swCommandResponse.getValue());

    BatchedCommandResponse batchResponse;
    auto batchResponseStatus =
        Shard::CommandResponse::processBatchWriteResponse(commandResponse, &batchResponse);
    if (!batchResponseStatus.isOK()) {
//.........这里部分代码省略.........

ScopedDbConnection::ScopedDbConnection(const ConnectionString& host, double socketTimeout)
    : _host(host.toString()),
      _conn(globalConnPool.get(host, socketTimeout)),
      _socketTimeout(socketTimeout) {
    _setSocketTimeout();
}