path: root/src/mongo/db/repl/replset_commands.cpp

/**
*    Copyright (C) 2008 10gen Inc.
*
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*
*    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
*    GNU Affero General Public License for more details.
*
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
*    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 GNU Affero General 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::kCommand

#define MONGO_PCH_WHITELISTED
#include "mongo/platform/basic.h"
#include "mongo/pch.h"
#undef MONGO_PCH_WHITELISTED

#include "mongo/db/repl/replset_commands.h"

#include "mongo/base/init.h"
#include "mongo/base/status.h"
#include "mongo/bson/util/bson_extract.h"
#include "mongo/db/auth/action_set.h"
#include "mongo/db/auth/action_type.h"
#include "mongo/db/auth/authorization_manager.h"
#include "mongo/db/commands.h"
#include "mongo/db/dbhelpers.h"
#include "mongo/db/global_environment_experiment.h"
#include "mongo/db/repl/handshake_args.h"
#include "mongo/db/repl/oplog.h"
#include "mongo/db/repl/repl_set_heartbeat_args.h"
#include "mongo/db/repl/repl_set_heartbeat_response.h"
#include "mongo/db/repl/repl_set_seed_list.h"
#include "mongo/db/repl/replication_coordinator_global.h"
#include "mongo/db/repl/replication_coordinator_external_state_impl.h"
#include "mongo/db/repl/scoped_conn.h"
#include "mongo/db/repl/update_position_args.h"
#include "mongo/db/storage/storage_engine.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"

namespace mongo {
namespace repl {

    unsigned replSetForceInitialSyncFailure = 0;

    // Testing only, enabled via command-line.
    class CmdReplSetTest : public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "Just for regression tests.\n";
        }
        // No auth needed because it only works when enabled via command line.
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {}
        CmdReplSetTest() : ReplSetCommand("replSetTest") { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            log() << "replSet replSetTest command received: " << cmdObj.toString();

            if( cmdObj.hasElement("forceInitialSyncFailure") ) {
                replSetForceInitialSyncFailure = (unsigned) cmdObj["forceInitialSyncFailure"].Number();
                return true;
            }

            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            return false;
        }
    };
    MONGO_INITIALIZER(RegisterReplSetTestCmd)(InitializerContext* context) {
        if (Command::testCommandsEnabled) {
            // Leaked intentionally: a Command registers itself when constructed.
            new CmdReplSetTest();
        }
        return Status::OK();
    }

    /** get rollback id.  used to check if a rollback happened during some interval of time.
        as consumed, the rollback id is not in any particular order, it simply changes on each rollback.
        @see incRBID()
    */
    class CmdReplSetGetRBID : public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "internal";
        }
        CmdReplSetGetRBID() : ReplSetCommand("replSetGetRBID") {}
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::internal);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            status = getGlobalReplicationCoordinator()->processReplSetGetRBID(&result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetRBID;

    /** helper to get rollback id from another server. */
    int getRBID(DBClientConnection *c) {
        bo info;
        c->simpleCommand("admin", &info, "replSetGetRBID");
        return info["rbid"].numberInt();
    }

    class CmdReplSetGetStatus : public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "Report status of a replica set from the POV of this server\n";
            help << "{ replSetGetStatus : 1 }";
            help << "\nhttp://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetGetStatus);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetGetStatus() : ReplSetCommand("replSetGetStatus", true) { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            if ( cmdObj["forShell"].trueValue() )
                lastError.disableForCommand();

            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            status = getGlobalReplicationCoordinator()->processReplSetGetStatus(&result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetGetStatus;

    class CmdReplSetGetConfig : public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "Returns the current replica set configuration";
            help << "{ replSetGetConfig : 1 }";
            help << "\nhttp://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetGetConfig);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetGetConfig() : ReplSetCommand("replSetGetConfig", true) { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj,
                         int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            getGlobalReplicationCoordinator()->processReplSetGetConfig(&result);
            return true;
        }
    } cmdReplSetGetConfig;

namespace {
    HostAndPort someHostAndPortForMe() {
        const char* ips = serverGlobalParams.bind_ip.c_str();
        while (*ips) {
            std::string ip;
            const char* comma = strchr(ips, ',');
            if (comma) {
                ip = std::string(ips, comma - ips);
                ips = comma + 1;
            }
            else {
                ip = std::string(ips);
                ips = "";
            }
            HostAndPort h = HostAndPort(ip, serverGlobalParams.port);
            if (!h.isLocalHost()) {
                return h;
            }
        }

        std::string h = getHostName();
        verify(!h.empty());
        verify(h != "localhost");
        return HostAndPort(h, serverGlobalParams.port);
    }
} // namespace

    class CmdReplSetInitiate : public ReplSetCommand {
    public:
        virtual bool isWriteCommandForConfigServer() const { return false; }
        CmdReplSetInitiate() : ReplSetCommand("replSetInitiate") { }
        virtual void help(stringstream& h) const {
            h << "Initiate/christen a replica set.";
            h << "\nhttp://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetConfigure);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        virtual bool run(OperationContext* txn,
                         const string& ,
                         BSONObj& cmdObj,
                         int, string& errmsg,
                         BSONObjBuilder& result,
                         bool fromRepl) {

            BSONObj configObj;
            if( cmdObj["replSetInitiate"].type() == Object ) {
                configObj = cmdObj["replSetInitiate"].Obj();
            }

            if (configObj.isEmpty()) {
                result.append("info2", "no configuration explicitly specified -- making one");
                log() << "replSet info initiate : no configuration specified.  "
                    "Using a default configuration for the set";

                ReplicationCoordinatorExternalStateImpl externalState;
                std::string name;
                std::vector<HostAndPort> seeds;
                std::set<HostAndPort> seedSet;
                parseReplSetSeedList(
                        &externalState,
                        getGlobalReplicationCoordinator()->getSettings().replSet,
                        name,
                        seeds,
                        seedSet); // may throw...

                BSONObjBuilder b;
                b.append("_id", name);
                b.append("version", 1);
                BSONObjBuilder members;
                HostAndPort me = someHostAndPortForMe();
                members.append("0", BSON( "_id" << 0 << "host" << me.toString() ));
                result.append("me", me.toString());
                for( unsigned i = 0; i < seeds.size(); i++ ) {
                    members.append(BSONObjBuilder::numStr(i+1),
                                   BSON( "_id" << i+1 << "host" << seeds[i].toString()));
                }
                b.appendArray("members", members.obj());
                configObj = b.obj();
                log() << "replSet created this configuration for initiation : " <<
                        configObj.toString();
            }

            if (configObj.getField("version").eoo()) {
                // Missing version field defaults to version 1.
                BSONObjBuilder builder;
                builder.appendElements(configObj);
                builder.append("version", 1);
                configObj = builder.obj();
            }

            Status status = getGlobalReplicationCoordinator()->processReplSetInitiate(txn,
                                                                                      configObj,
                                                                                      &result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetInitiate;

    class CmdReplSetReconfig : public ReplSetCommand {
        RWLock mutex; /* we don't need rw but we wanted try capability. :-( */
    public:
        virtual void help( stringstream &help ) const {
            help << "Adjust configuration of a replica set\n";
            help << "{ replSetReconfig : config_object }";
            help << "\nhttp://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetConfigure);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetReconfig() : ReplSetCommand("replSetReconfig"), mutex("rsreconfig") { }
        virtual bool run(OperationContext* txn, const string& a, BSONObj& b, int e, string& errmsg, BSONObjBuilder& c, bool d) {
            try {
                rwlock_try_write lk(mutex);
                return _run(txn, a,b,e,errmsg,c,d);
            }
            catch(rwlock_try_write::exception&) { }
            errmsg = "a replSetReconfig is already in progress";
            return false;
        }
    private:
        bool _run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK()) {
                return appendCommandStatus(result, status);
            }

            if( cmdObj["replSetReconfig"].type() != Object ) {
                errmsg = "no configuration specified";
                return false;
            }

            ReplicationCoordinator::ReplSetReconfigArgs parsedArgs;
            parsedArgs.newConfigObj =  cmdObj["replSetReconfig"].Obj();
            parsedArgs.force = cmdObj.hasField("force") && cmdObj["force"].trueValue();
            status = getGlobalReplicationCoordinator()->processReplSetReconfig(txn,
                                                                               parsedArgs,
                                                                               &result);
            if (status.isOK() && !parsedArgs.force) {
                logOpInitiate(txn, BSON("msg" << "Reconfig set" << 
                                        "version" << parsedArgs.newConfigObj["version"]));
            }
            return appendCommandStatus(result, status);
        }
    } cmdReplSetReconfig;

    class CmdReplSetFreeze : public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "{ replSetFreeze : <seconds> }";
            help << "'freeze' state of member to the extent we can do that.  What this really means is that\n";
            help << "this node will not attempt to become primary until the time period specified expires.\n";
            help << "You can call again with {replSetFreeze:0} to unfreeze sooner.\n";
            help << "A process restart unfreezes the member also.\n";
            help << "\nhttp://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetStateChange);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetFreeze() : ReplSetCommand("replSetFreeze") { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            int secs = (int) cmdObj.firstElement().numberInt();
            return appendCommandStatus(
                    result,
                    getGlobalReplicationCoordinator()->processReplSetFreeze(secs, &result));
        }
    } cmdReplSetFreeze;

    class CmdReplSetStepDown: public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "{ replSetStepDown : <seconds> }\n";
            help << "Step down as primary.  Will not try to reelect self for the specified time period (1 minute if no numeric secs value specified).\n";
            help << "(If another member with same priority takes over in the meantime, it will stay primary.)\n";
            help << "http://dochub.mongodb.org/core/replicasetcommands";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetStateChange);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetStepDown() : ReplSetCommand("replSetStepDown") { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            const bool force = cmdObj["force"].trueValue();

            long long stepDownForSecs = cmdObj.firstElement().numberLong();
            if (stepDownForSecs == 0) {
                stepDownForSecs = 60;
            }
            else if (stepDownForSecs < 0) {
                status = Status(ErrorCodes::BadValue,
                                "stepdown period must be a positive integer");
                return appendCommandStatus(result, status);
            }

            long long secondaryCatchUpPeriodSecs;
            status = bsonExtractIntegerField(cmdObj,
                                             "secondaryCatchUpPeriodSecs",
                                             &secondaryCatchUpPeriodSecs);
            if (status.code() == ErrorCodes::NoSuchKey) {
                // if field is absent, default values
                if (force) {
                    secondaryCatchUpPeriodSecs = 0;
                }
                else {
                    secondaryCatchUpPeriodSecs = 10;
                }
            }
            else if (!status.isOK()) {
                return appendCommandStatus(result, status);
            }

            if (secondaryCatchUpPeriodSecs < 0) {
                status = Status(ErrorCodes::BadValue,
                                "secondaryCatchUpPeriodSecs period must be a positive or absent");
                return appendCommandStatus(result, status);
            }

            if (stepDownForSecs < secondaryCatchUpPeriodSecs) {
                status = Status(ErrorCodes::BadValue,
                                "stepdown period must be longer than secondaryCatchUpPeriodSecs");
                return appendCommandStatus(result, status);
            }

            status = getGlobalReplicationCoordinator()->stepDown(
                    txn,
                    force,
                    ReplicationCoordinator::Milliseconds(secondaryCatchUpPeriodSecs * 1000),
                    ReplicationCoordinator::Milliseconds(stepDownForSecs * 1000));
            return appendCommandStatus(result, status);
        }
    } cmdReplSetStepDown;

    class CmdReplSetMaintenance: public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "{ replSetMaintenance : bool }\n";
            help << "Enable or disable maintenance mode.";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetStateChange);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetMaintenance() : ReplSetCommand("replSetMaintenance") { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            return appendCommandStatus(
                    result,
                    getGlobalReplicationCoordinator()->setMaintenanceMode(
                            cmdObj["replSetMaintenance"].trueValue()));
        }
    } cmdReplSetMaintenance;

    class CmdReplSetSyncFrom: public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "{ replSetSyncFrom : \"host:port\" }\n";
            help << "Change who this member is syncing from.";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::replSetStateChange);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetSyncFrom() : ReplSetCommand("replSetSyncFrom") { }
        virtual bool run(OperationContext* txn, const string&, 
                         BSONObj& cmdObj, 
                         int, 
                         string& errmsg, 
                         BSONObjBuilder& result, 
                         bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            HostAndPort targetHostAndPort;
            status = targetHostAndPort.initialize(cmdObj["replSetSyncFrom"].valuestrsafe());
            if (!status.isOK())
                return appendCommandStatus(result, status);

            return appendCommandStatus(
                    result,
                    getGlobalReplicationCoordinator()->processReplSetSyncFrom(targetHostAndPort,
                                                                              &result));
        }
    } cmdReplSetSyncFrom;

    class CmdReplSetUpdatePosition: public ReplSetCommand {
    public:
        virtual void help( stringstream &help ) const {
            help << "internal";
        }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::internal);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        CmdReplSetUpdatePosition() : ReplSetCommand("replSetUpdatePosition") { }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg,
                         BSONObjBuilder& result, bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            if (cmdObj.hasField("handshake")) {
                // we have received a handshake, not an update message
                // handshakes are done here to ensure the receiving end supports the update command

                HandshakeArgs handshake;
                status = handshake.initialize(cmdObj["handshake"].embeddedObject());
                if (!status.isOK())
                    return appendCommandStatus(result, status);

                if (!handshake.hasMemberId()) {
                    return appendCommandStatus(
                            result,
                            Status(ErrorCodes::NoSuchKey,
                                   "replSetUpdatePosition handshake was missing 'member' field"));
                }

                return appendCommandStatus(
                        result,
                        getGlobalReplicationCoordinator()->processHandshake(txn, handshake));
            }

            UpdatePositionArgs args;
            status = args.initialize(cmdObj);
            if (!status.isOK())
                return appendCommandStatus(result, status);
            
            return appendCommandStatus(
                    result,
                    getGlobalReplicationCoordinator()->processReplSetUpdatePosition(args));
                    
        }
    } cmdReplSetUpdatePosition;

namespace {
    /**
     * Returns true if there is no data on this server. Useful when starting replication.
     * The "local" database does NOT count except for "rs.oplog" collection.
     * Used to set the hasData field on replset heartbeat command response.
     */
    bool replHasDatabases(OperationContext* txn) {
        vector<string> names;
        StorageEngine* storageEngine = getGlobalEnvironment()->getGlobalStorageEngine();
        storageEngine->listDatabases(&names);

        if( names.size() >= 2 ) return true;
        if( names.size() == 1 ) {
            if( names[0] != "local" )
                return true;

            // we have a local database.  return true if oplog isn't empty
            BSONObj o;
            if (Helpers::getSingleton(txn, repl::rsoplog, o)) {
                return true;
            }
        }
        return false;
    }

} // namespace

    MONGO_FP_DECLARE(rsDelayHeartbeatResponse);

    /* { replSetHeartbeat : <setname> } */
    class CmdReplSetHeartbeat : public ReplSetCommand {
    public:
        void help(stringstream& h) const { h << "internal"; }
        CmdReplSetHeartbeat() : ReplSetCommand("replSetHeartbeat") { }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::internal);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {

            MONGO_FAIL_POINT_BLOCK(rsDelayHeartbeatResponse, delay) {
                const BSONObj& data = delay.getData();
                sleepsecs(data["delay"].numberInt());
            }

            Status status = Status(ErrorCodes::InternalError, "status not set in heartbeat code");
            /* we don't call ReplSetCommand::check() here because heartbeat
               checks many things that are pre-initialization. */
            if (!getGlobalReplicationCoordinator()->getSettings().usingReplSets()) {
                status = Status(ErrorCodes::NoReplicationEnabled, "not running with --replSet");
                return appendCommandStatus(result, status);
            }

            /* we want to keep heartbeat connections open when relinquishing primary.
               tag them here. */
            {
                AbstractMessagingPort *mp = txn->getClient()->port();
                if( mp )
                    mp->tag |= ScopedConn::keepOpen;
            }

            ReplSetHeartbeatArgs args;
            status = args.initialize(cmdObj);
            if (!status.isOK()) {
                return appendCommandStatus(result, status);
            }

            // ugh.
            if (args.getCheckEmpty()) {
                result.append("hasData", replHasDatabases(txn));
            }

            ReplSetHeartbeatResponse response;
            status = getGlobalReplicationCoordinator()->processHeartbeat(args, &response);
            if (status.isOK())
                response.addToBSON(&result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetHeartbeat;

    /** the first cmd called by a node seeking election and it's a basic sanity
        test: do any of the nodes it can reach know that it can't be the primary?
        */
    class CmdReplSetFresh : public ReplSetCommand {
    public:
        void help(stringstream& h) const { h << "internal"; }
        CmdReplSetFresh() : ReplSetCommand("replSetFresh") { }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::internal);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }

        virtual bool run(OperationContext* txn,
                         const string&,
                         BSONObj& cmdObj,
                         int,
                         string& errmsg,
                         BSONObjBuilder& result,
                         bool fromRepl) {
            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            ReplicationCoordinator::ReplSetFreshArgs parsedArgs;
            parsedArgs.id = cmdObj["id"].Int();
            parsedArgs.setName = cmdObj["set"].checkAndGetStringData();
            parsedArgs.who = HostAndPort(cmdObj["who"].String());
            BSONElement cfgverElement = cmdObj["cfgver"];
            uassert(28525,
                    str::stream() << "Expected cfgver argument to replSetFresh command to have "
                    "numeric type, but found " << typeName(cfgverElement.type()),
                    cfgverElement.isNumber());
            parsedArgs.cfgver = cfgverElement.safeNumberLong();
            parsedArgs.opTime = OpTime(cmdObj["opTime"].Date());

            status = getGlobalReplicationCoordinator()->processReplSetFresh(parsedArgs, &result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetFresh;

    class CmdReplSetElect : public ReplSetCommand {
    public:
        void help(stringstream& h) const { h << "internal"; }
        CmdReplSetElect() : ReplSetCommand("replSetElect") { }
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            ActionSet actions;
            actions.addAction(ActionType::internal);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }
    private:
        virtual bool run(OperationContext* txn,
                         const string&,
                         BSONObj& cmdObj,
                         int,
                         string& errmsg,
                         BSONObjBuilder& result,
                         bool fromRepl) {
            DEV log() << "replSet received elect msg " << cmdObj.toString();
            else LOG(2) << "replSet received elect msg " << cmdObj.toString();

            Status status = getGlobalReplicationCoordinator()->checkReplEnabledForCommand(&result);
            if (!status.isOK())
                return appendCommandStatus(result, status);

            ReplicationCoordinator::ReplSetElectArgs parsedArgs;
            parsedArgs.set = cmdObj["set"].checkAndGetStringData();
            parsedArgs.whoid = cmdObj["whoid"].Int();
            BSONElement cfgverElement = cmdObj["cfgver"];
            uassert(28526,
                    str::stream() << "Expected cfgver argument to replSetElect command to have "
                    "numeric type, but found " << typeName(cfgverElement.type()),
                    cfgverElement.isNumber());
            parsedArgs.cfgver = cfgverElement.safeNumberLong();
            parsedArgs.round = cmdObj["round"].OID();

            status = getGlobalReplicationCoordinator()->processReplSetElect(parsedArgs, &result);
            return appendCommandStatus(result, status);
        }
    } cmdReplSetElect;

} // namespace repl
} // namespace mongo