diff options
Diffstat (limited to 'src/mongo/db/repl/topology_coordinator.h')
| -rw-r--r-- | src/mongo/db/repl/topology_coordinator.h | 850 |
1 files changed, 425 insertions, 425 deletions
diff --git a/src/mongo/db/repl/topology_coordinator.h b/src/mongo/db/repl/topology_coordinator.h index 3af054b3010..0dbc81baac5 100644 --- a/src/mongo/db/repl/topology_coordinator.h +++ b/src/mongo/db/repl/topology_coordinator.h @@ -40,444 +40,444 @@ namespace mongo { - class Timestamp; +class Timestamp; namespace repl { - class HeartbeatResponseAction; - class OpTime; - class ReplSetHeartbeatArgs; - class ReplicaSetConfig; - class TagSubgroup; - class LastVote; - struct MemberState; +class HeartbeatResponseAction; +class OpTime; +class ReplSetHeartbeatArgs; +class ReplicaSetConfig; +class TagSubgroup; +class LastVote; +struct MemberState; + +/** + * Replication Topology Coordinator interface. + * + * This object is responsible for managing the topology of the cluster. + * Tasks include consensus and leader election, chaining, and configuration management. + * Methods of this class should be non-blocking. + */ +class TopologyCoordinator { + MONGO_DISALLOW_COPYING(TopologyCoordinator); + +public: + class Role; + + virtual ~TopologyCoordinator(); + + //////////////////////////////////////////////////////////// + // + // State inspection methods. + // + //////////////////////////////////////////////////////////// + + /** + * Gets the role of this member in the replication protocol. + */ + virtual Role getRole() const = 0; + + /** + * Gets the MemberState of this member in the replica set. + */ + virtual MemberState getMemberState() const = 0; + + /** + * Returns the address of the current sync source, or an empty HostAndPort if there is no + * current sync source. + */ + virtual HostAndPort getSyncSourceAddress() const = 0; + + /** + * Retrieves a vector of HostAndPorts containing all nodes that are neither DOWN nor + * ourself. + */ + virtual std::vector<HostAndPort> getMaybeUpHostAndPorts() const = 0; /** - * Replication Topology Coordinator interface. + * Gets the earliest time the current node will stand for election. + */ + virtual Date_t getStepDownTime() const = 0; + + /** + * Gets the current value of the maintenance mode counter. + */ + virtual int getMaintenanceCount() const = 0; + + /** + * Gets the latest term this member is aware of. If this member is the primary, + * it's the current term of the replica set. + */ + virtual long long getTerm() const = 0; + + /** + * Sets the latest term this member is aware of to the higher of its current value and + * the value passed in as "term". + * Returns true if the local term value is changed. + */ + virtual bool updateTerm(long long term) = 0; + + //////////////////////////////////////////////////////////// + // + // Basic state manipulation methods. + // + //////////////////////////////////////////////////////////// + + /** + * Sets the index into the config used when we next choose a sync source + */ + virtual void setForceSyncSourceIndex(int index) = 0; + + /** + * Chooses and sets a new sync source, based on our current knowledge of the world. + */ + virtual HostAndPort chooseNewSyncSource(Date_t now, const OpTime& lastOpApplied) = 0; + + /** + * Suppresses selecting "host" as sync source until "until". + */ + virtual void blacklistSyncSource(const HostAndPort& host, Date_t until) = 0; + + /** + * Removes a single entry "host" from the list of potential sync sources which we + * have blacklisted, if it is supposed to be unblacklisted by "now". + */ + virtual void unblacklistSyncSource(const HostAndPort& host, Date_t now) = 0; + + /** + * Clears the list of potential sync sources we have blacklisted. + */ + virtual void clearSyncSourceBlacklist() = 0; + + /** + * Determines if a new sync source should be chosen, if a better candidate sync source is + * available. If the current sync source's last optime is more than _maxSyncSourceLagSecs + * behind any syncable source, this function returns true. + * + * "now" is used to skip over currently blacklisted sync sources. + */ + virtual bool shouldChangeSyncSource(const HostAndPort& currentSource, Date_t now) const = 0; + + /** + * Checks whether we are a single node set and we are not in a stepdown period. If so, + * puts us into candidate mode, otherwise does nothing. This is used to ensure that + * nodes in a single node replset become primary again when their stepdown period ends. + */ + virtual bool becomeCandidateIfStepdownPeriodOverAndSingleNodeSet(Date_t now) = 0; + + /** + * Sets the earliest time the current node will stand for election to "newTime". + * + * Until this time, while the node may report itself as electable, it will not stand + * for election. + */ + virtual void setElectionSleepUntil(Date_t newTime) = 0; + + /** + * Sets the reported mode of this node to one of RS_SECONDARY, RS_STARTUP2, RS_ROLLBACK or + * RS_RECOVERING, when getRole() == Role::follower. This is the interface by which the + * applier changes the reported member state of the current node, and enables or suppresses + * electability of the current node. All modes but RS_SECONDARY indicate an unelectable + * follower state (one that cannot transition to candidate). + */ + virtual void setFollowerMode(MemberState::MS newMode) = 0; + + /** + * Adjusts the maintenance mode count by "inc". + * + * It is an error to call this method if getRole() does not return Role::follower. + * It is an error to allow the maintenance count to go negative. + */ + virtual void adjustMaintenanceCountBy(int inc) = 0; + + //////////////////////////////////////////////////////////// + // + // Methods that prepare responses to command requests. + // + //////////////////////////////////////////////////////////// + + // produces a reply to a replSetSyncFrom command + virtual void prepareSyncFromResponse(const ReplicationExecutor::CallbackArgs& data, + const HostAndPort& target, + const OpTime& lastOpApplied, + BSONObjBuilder* response, + Status* result) = 0; + + // produce a reply to a replSetFresh command + virtual void prepareFreshResponse(const ReplicationCoordinator::ReplSetFreshArgs& args, + Date_t now, + const OpTime& lastOpApplied, + BSONObjBuilder* response, + Status* result) = 0; + + // produce a reply to a received electCmd + virtual void prepareElectResponse(const ReplicationCoordinator::ReplSetElectArgs& args, + Date_t now, + const OpTime& lastOpApplied, + BSONObjBuilder* response, + Status* result) = 0; + + // produce a reply to a heartbeat + virtual Status prepareHeartbeatResponse(Date_t now, + const ReplSetHeartbeatArgs& args, + const std::string& ourSetName, + const OpTime& lastOpApplied, + ReplSetHeartbeatResponse* response) = 0; + + // produce a reply to a V1 heartbeat + virtual Status prepareHeartbeatResponseV1(Date_t now, + const ReplSetHeartbeatArgsV1& args, + const std::string& ourSetName, + const OpTime& lastOpApplied, + ReplSetHeartbeatResponse* response) = 0; + + // produce a reply to a status request + virtual void prepareStatusResponse(const ReplicationExecutor::CallbackArgs& data, + Date_t now, + unsigned uptime, + const OpTime& lastOpApplied, + BSONObjBuilder* response, + Status* result) = 0; + + // produce a reply to an ismaster request. It is only valid to call this if we are a + // replset. + virtual void fillIsMasterForReplSet(IsMasterResponse* response) = 0; + + // produce a reply to a freeze request + virtual void prepareFreezeResponse(Date_t now, int secs, BSONObjBuilder* response) = 0; + + //////////////////////////////////////////////////////////// + // + // Methods for sending and receiving heartbeats, + // reconfiguring and handling the results of standing for + // election. + // + //////////////////////////////////////////////////////////// + + /** + * Updates the topology coordinator's notion of the replica set configuration. * - * This object is responsible for managing the topology of the cluster. - * Tasks include consensus and leader election, chaining, and configuration management. - * Methods of this class should be non-blocking. - */ - class TopologyCoordinator { - MONGO_DISALLOW_COPYING(TopologyCoordinator); - public: - class Role; - - virtual ~TopologyCoordinator(); - - //////////////////////////////////////////////////////////// - // - // State inspection methods. - // - //////////////////////////////////////////////////////////// - - /** - * Gets the role of this member in the replication protocol. - */ - virtual Role getRole() const = 0; - - /** - * Gets the MemberState of this member in the replica set. - */ - virtual MemberState getMemberState() const = 0; - - /** - * Returns the address of the current sync source, or an empty HostAndPort if there is no - * current sync source. - */ - virtual HostAndPort getSyncSourceAddress() const = 0; - - /** - * Retrieves a vector of HostAndPorts containing all nodes that are neither DOWN nor - * ourself. - */ - virtual std::vector<HostAndPort> getMaybeUpHostAndPorts() const = 0; - - /** - * Gets the earliest time the current node will stand for election. - */ - virtual Date_t getStepDownTime() const = 0; - - /** - * Gets the current value of the maintenance mode counter. - */ - virtual int getMaintenanceCount() const = 0; - - /** - * Gets the latest term this member is aware of. If this member is the primary, - * it's the current term of the replica set. - */ - virtual long long getTerm() const = 0; - - /** - * Sets the latest term this member is aware of to the higher of its current value and - * the value passed in as "term". - * Returns true if the local term value is changed. - */ - virtual bool updateTerm(long long term) = 0; - - //////////////////////////////////////////////////////////// - // - // Basic state manipulation methods. - // - //////////////////////////////////////////////////////////// - - /** - * Sets the index into the config used when we next choose a sync source - */ - virtual void setForceSyncSourceIndex(int index) = 0; - - /** - * Chooses and sets a new sync source, based on our current knowledge of the world. - */ - virtual HostAndPort chooseNewSyncSource(Date_t now, const OpTime& lastOpApplied) = 0; - - /** - * Suppresses selecting "host" as sync source until "until". - */ - virtual void blacklistSyncSource(const HostAndPort& host, Date_t until) = 0; - - /** - * Removes a single entry "host" from the list of potential sync sources which we - * have blacklisted, if it is supposed to be unblacklisted by "now". - */ - virtual void unblacklistSyncSource(const HostAndPort& host, Date_t now) = 0; - - /** - * Clears the list of potential sync sources we have blacklisted. - */ - virtual void clearSyncSourceBlacklist() = 0; - - /** - * Determines if a new sync source should be chosen, if a better candidate sync source is - * available. If the current sync source's last optime is more than _maxSyncSourceLagSecs - * behind any syncable source, this function returns true. - * - * "now" is used to skip over currently blacklisted sync sources. - */ - virtual bool shouldChangeSyncSource(const HostAndPort& currentSource, Date_t now) const = 0; - - /** - * Checks whether we are a single node set and we are not in a stepdown period. If so, - * puts us into candidate mode, otherwise does nothing. This is used to ensure that - * nodes in a single node replset become primary again when their stepdown period ends. - */ - virtual bool becomeCandidateIfStepdownPeriodOverAndSingleNodeSet(Date_t now) = 0; - - /** - * Sets the earliest time the current node will stand for election to "newTime". - * - * Until this time, while the node may report itself as electable, it will not stand - * for election. - */ - virtual void setElectionSleepUntil(Date_t newTime) = 0; - - /** - * Sets the reported mode of this node to one of RS_SECONDARY, RS_STARTUP2, RS_ROLLBACK or - * RS_RECOVERING, when getRole() == Role::follower. This is the interface by which the - * applier changes the reported member state of the current node, and enables or suppresses - * electability of the current node. All modes but RS_SECONDARY indicate an unelectable - * follower state (one that cannot transition to candidate). - */ - virtual void setFollowerMode(MemberState::MS newMode) = 0; - - /** - * Adjusts the maintenance mode count by "inc". - * - * It is an error to call this method if getRole() does not return Role::follower. - * It is an error to allow the maintenance count to go negative. - */ - virtual void adjustMaintenanceCountBy(int inc) = 0; - - //////////////////////////////////////////////////////////// - // - // Methods that prepare responses to command requests. - // - //////////////////////////////////////////////////////////// - - // produces a reply to a replSetSyncFrom command - virtual void prepareSyncFromResponse(const ReplicationExecutor::CallbackArgs& data, - const HostAndPort& target, - const OpTime& lastOpApplied, - BSONObjBuilder* response, - Status* result) = 0; - - // produce a reply to a replSetFresh command - virtual void prepareFreshResponse(const ReplicationCoordinator::ReplSetFreshArgs& args, - Date_t now, - const OpTime& lastOpApplied, - BSONObjBuilder* response, - Status* result) = 0; - - // produce a reply to a received electCmd - virtual void prepareElectResponse(const ReplicationCoordinator::ReplSetElectArgs& args, - Date_t now, - const OpTime& lastOpApplied, - BSONObjBuilder* response, - Status* result) = 0; - - // produce a reply to a heartbeat - virtual Status prepareHeartbeatResponse(Date_t now, - const ReplSetHeartbeatArgs& args, - const std::string& ourSetName, - const OpTime& lastOpApplied, - ReplSetHeartbeatResponse* response) = 0; - - // produce a reply to a V1 heartbeat - virtual Status prepareHeartbeatResponseV1(Date_t now, - const ReplSetHeartbeatArgsV1& args, - const std::string& ourSetName, - const OpTime& lastOpApplied, - ReplSetHeartbeatResponse* response) = 0; - - // produce a reply to a status request - virtual void prepareStatusResponse(const ReplicationExecutor::CallbackArgs& data, - Date_t now, - unsigned uptime, - const OpTime& lastOpApplied, - BSONObjBuilder* response, - Status* result) = 0; - - // produce a reply to an ismaster request. It is only valid to call this if we are a - // replset. - virtual void fillIsMasterForReplSet(IsMasterResponse* response) = 0; - - // produce a reply to a freeze request - virtual void prepareFreezeResponse(Date_t now, int secs, BSONObjBuilder* response) = 0; - - //////////////////////////////////////////////////////////// - // - // Methods for sending and receiving heartbeats, - // reconfiguring and handling the results of standing for - // election. - // - //////////////////////////////////////////////////////////// - - /** - * Updates the topology coordinator's notion of the replica set configuration. - * - * "newConfig" is the new configuration, and "selfIndex" is the index of this - * node's configuration information in "newConfig", or "selfIndex" is -1 to - * indicate that this node is not a member of "newConfig". - * - * newConfig.isInitialized() should be true, though implementations may accept - * configurations where this is not true, for testing purposes. - */ - virtual void updateConfig(const ReplicaSetConfig& newConfig, - int selfIndex, - Date_t now, - const OpTime& lastOpApplied) = 0; - - /** - * Prepares a heartbeat request appropriate for sending to "target", assuming the - * current time is "now". "ourSetName" is used as the name for our replica set if - * the topology coordinator does not have a valid configuration installed. - * - * The returned pair contains proper arguments for a replSetHeartbeat command, and - * an amount of time to wait for the response. - * - * This call should be paired (with intervening network communication) with a call to - * processHeartbeatResponse for the same "target". - */ - virtual std::pair<ReplSetHeartbeatArgs, Milliseconds> prepareHeartbeatRequest( - Date_t now, - const std::string& ourSetName, - const HostAndPort& target) = 0; - virtual std::pair<ReplSetHeartbeatArgsV1, Milliseconds> prepareHeartbeatRequestV1( - Date_t now, - const std::string& ourSetName, - const HostAndPort& target) = 0; - - /** - * Processes a heartbeat response from "target" that arrived around "now", having - * spent "networkRoundTripTime" millis on the network. - * - * Updates internal topology coordinator state, and returns instructions about what action - * to take next. - * - * If the next action indicates StartElection, the topology coordinator has transitioned to - * the "candidate" role, and will remain there until processWinElection or - * processLoseElection are called. - * - * If the next action indicates "StepDownSelf", the topology coordinator has transitioned - * to the "follower" role from "leader", and the caller should take any necessary actions - * to become a follower. - * - * If the next action indicates "StepDownRemotePrimary", the caller should take steps to - * cause the specified remote host to step down from primary to secondary. - * - * If the next action indicates "Reconfig", the caller should verify the configuration in - * hbResponse is acceptable, perform any other reconfiguration actions it must, and call - * updateConfig with the new configuration and the appropriate value for "selfIndex". It - * must also wrap up any outstanding elections (by calling processLoseElection or - * processWinElection) before calling updateConfig. - * - * This call should be paired (with intervening network communication) with a call to - * prepareHeartbeatRequest for the same "target". - */ - virtual HeartbeatResponseAction processHeartbeatResponse( - Date_t now, - Milliseconds networkRoundTripTime, - const HostAndPort& target, - const StatusWith<ReplSetHeartbeatResponse>& hbResponse, - const OpTime& myLastOpApplied) = 0; - - /** - * If getRole() == Role::candidate and this node has not voted too recently, updates the - * lastVote tracker and returns true. Otherwise, returns false. - */ - virtual bool voteForMyself(Date_t now) = 0; - - /** - * Increase the term. - */ - virtual void incrementTerm() = 0; - - /** - * Set lastVote to be for ourself in this term. - */ - virtual void voteForMyselfV1() = 0; - - /** - * Performs state updates associated with winning an election. - * - * It is an error to call this if the topology coordinator is not in candidate mode. - * - * Exactly one of either processWinElection or processLoseElection must be called if - * processHeartbeatResponse returns StartElection, to exit candidate mode. - */ - virtual void processWinElection(OID electionId, Timestamp electionOpTime) = 0; - - /** - * Performs state updates associated with losing an election. - * - * It is an error to call this if the topology coordinator is not in candidate mode. - * - * Exactly one of either processWinElection or processLoseElection must be called if - * processHeartbeatResponse returns StartElection, to exit candidate mode. - */ - virtual void processLoseElection() = 0; - - /** - * Tries to transition the coordinator from the leader role to the follower role. - * - * Fails if "force" is not set and no follower is known to be up. It is illegal - * to call this method if the node is not leader. - * - * Returns whether or not the step down succeeded. - */ - virtual bool stepDown(Date_t until, bool force, const OpTime& lastOpApplied) = 0; - - /** - * Sometimes a request to step down comes in (like via a heartbeat), but we don't have the - * global exclusive lock so we can't actually stepdown at that moment. When that happens - * we record that a stepdown request is pending and schedule work to stepdown in the global - * lock. This method is called after holding the global lock to perform the actual - * stepdown, but only if the node hasn't already stepped down another way since the work was - * scheduled. Returns true if it actually steps down, and false otherwise. - */ - virtual bool stepDownIfPending() = 0; - - /** - * Considers whether or not this node should stand for election, and returns true - * if the node has transitioned to candidate role as a result of the call. - */ - virtual bool checkShouldStandForElection(Date_t now, const OpTime& lastOpApplied) = 0; - - /** - * Set the outgoing heartbeat message from self - */ - virtual void setMyHeartbeatMessage(const Date_t now, const std::string& s) = 0; - - /** - * Prepares a BSONObj describing the current term, primary, and lastOp information. - */ - virtual void prepareCursorResponseInfo(BSONObjBuilder* objBuilder, - const OpTime& lastCommittedOpTime) const = 0; - - /** - * Writes into 'output' all the information needed to generate a summary of the current - * replication state for use by the web interface. - */ - virtual void summarizeAsHtml(ReplSetHtmlSummary* output) = 0; - - /** - * Prepares a ReplSetRequestVotesResponse. - */ - virtual void processReplSetRequestVotes(const ReplSetRequestVotesArgs& args, - ReplSetRequestVotesResponse* response, - const OpTime& lastAppliedOpTime) = 0; - - /** - * Determines whether or not the newly elected primary is valid from our perspective. - * If it is, sets the _currentPrimaryIndex and term to the received values. - * If it is not, return ErrorCode::BadValue and the current term from our perspective. - * Populate responseTerm with the current term from our perspective. - */ - virtual Status processReplSetDeclareElectionWinner( - const ReplSetDeclareElectionWinnerArgs& args, - long long* responseTerm) = 0; - - /** - * Loads an initial LastVote document, which was read from local storage. - * - * Called only during replication startup. All other updates are done internally. - */ - virtual void loadLastVote(const LastVote& lastVote) = 0; - - /** - * Returns the most recent term this node is aware of. - */ - virtual long long getTerm() = 0; - - /** - * Readies the TopologyCoordinator for stepdown. - */ - virtual void prepareForStepDown() = 0; - - protected: - TopologyCoordinator() {} - }; - - /** - * Type that denotes the role of a node in the replication protocol. + * "newConfig" is the new configuration, and "selfIndex" is the index of this + * node's configuration information in "newConfig", or "selfIndex" is -1 to + * indicate that this node is not a member of "newConfig". * - * The role is distinct from MemberState, in that it only deals with the - * roles a node plays in the basic protocol -- leader, follower and candidate. - * The mapping between MemberState and Role is complex -- several MemberStates - * map to the follower role, and MemberState::RS_SECONDARY maps to either - * follower or candidate roles, e.g. + * newConfig.isInitialized() should be true, though implementations may accept + * configurations where this is not true, for testing purposes. */ - class TopologyCoordinator::Role { - public: - /** - * Constant indicating leader role. - */ - static const Role leader; + virtual void updateConfig(const ReplicaSetConfig& newConfig, + int selfIndex, + Date_t now, + const OpTime& lastOpApplied) = 0; - /** - * Constant indicating follower role. - */ - static const Role follower; + /** + * Prepares a heartbeat request appropriate for sending to "target", assuming the + * current time is "now". "ourSetName" is used as the name for our replica set if + * the topology coordinator does not have a valid configuration installed. + * + * The returned pair contains proper arguments for a replSetHeartbeat command, and + * an amount of time to wait for the response. + * + * This call should be paired (with intervening network communication) with a call to + * processHeartbeatResponse for the same "target". + */ + virtual std::pair<ReplSetHeartbeatArgs, Milliseconds> prepareHeartbeatRequest( + Date_t now, const std::string& ourSetName, const HostAndPort& target) = 0; + virtual std::pair<ReplSetHeartbeatArgsV1, Milliseconds> prepareHeartbeatRequestV1( + Date_t now, const std::string& ourSetName, const HostAndPort& target) = 0; - /** - * Constant indicating candidate role - */ - static const Role candidate; + /** + * Processes a heartbeat response from "target" that arrived around "now", having + * spent "networkRoundTripTime" millis on the network. + * + * Updates internal topology coordinator state, and returns instructions about what action + * to take next. + * + * If the next action indicates StartElection, the topology coordinator has transitioned to + * the "candidate" role, and will remain there until processWinElection or + * processLoseElection are called. + * + * If the next action indicates "StepDownSelf", the topology coordinator has transitioned + * to the "follower" role from "leader", and the caller should take any necessary actions + * to become a follower. + * + * If the next action indicates "StepDownRemotePrimary", the caller should take steps to + * cause the specified remote host to step down from primary to secondary. + * + * If the next action indicates "Reconfig", the caller should verify the configuration in + * hbResponse is acceptable, perform any other reconfiguration actions it must, and call + * updateConfig with the new configuration and the appropriate value for "selfIndex". It + * must also wrap up any outstanding elections (by calling processLoseElection or + * processWinElection) before calling updateConfig. + * + * This call should be paired (with intervening network communication) with a call to + * prepareHeartbeatRequest for the same "target". + */ + virtual HeartbeatResponseAction processHeartbeatResponse( + Date_t now, + Milliseconds networkRoundTripTime, + const HostAndPort& target, + const StatusWith<ReplSetHeartbeatResponse>& hbResponse, + const OpTime& myLastOpApplied) = 0; + + /** + * If getRole() == Role::candidate and this node has not voted too recently, updates the + * lastVote tracker and returns true. Otherwise, returns false. + */ + virtual bool voteForMyself(Date_t now) = 0; + + /** + * Increase the term. + */ + virtual void incrementTerm() = 0; + + /** + * Set lastVote to be for ourself in this term. + */ + virtual void voteForMyselfV1() = 0; + + /** + * Performs state updates associated with winning an election. + * + * It is an error to call this if the topology coordinator is not in candidate mode. + * + * Exactly one of either processWinElection or processLoseElection must be called if + * processHeartbeatResponse returns StartElection, to exit candidate mode. + */ + virtual void processWinElection(OID electionId, Timestamp electionOpTime) = 0; + + /** + * Performs state updates associated with losing an election. + * + * It is an error to call this if the topology coordinator is not in candidate mode. + * + * Exactly one of either processWinElection or processLoseElection must be called if + * processHeartbeatResponse returns StartElection, to exit candidate mode. + */ + virtual void processLoseElection() = 0; + + /** + * Tries to transition the coordinator from the leader role to the follower role. + * + * Fails if "force" is not set and no follower is known to be up. It is illegal + * to call this method if the node is not leader. + * + * Returns whether or not the step down succeeded. + */ + virtual bool stepDown(Date_t until, bool force, const OpTime& lastOpApplied) = 0; + + /** + * Sometimes a request to step down comes in (like via a heartbeat), but we don't have the + * global exclusive lock so we can't actually stepdown at that moment. When that happens + * we record that a stepdown request is pending and schedule work to stepdown in the global + * lock. This method is called after holding the global lock to perform the actual + * stepdown, but only if the node hasn't already stepped down another way since the work was + * scheduled. Returns true if it actually steps down, and false otherwise. + */ + virtual bool stepDownIfPending() = 0; + + /** + * Considers whether or not this node should stand for election, and returns true + * if the node has transitioned to candidate role as a result of the call. + */ + virtual bool checkShouldStandForElection(Date_t now, const OpTime& lastOpApplied) = 0; + + /** + * Set the outgoing heartbeat message from self + */ + virtual void setMyHeartbeatMessage(const Date_t now, const std::string& s) = 0; + + /** + * Prepares a BSONObj describing the current term, primary, and lastOp information. + */ + virtual void prepareCursorResponseInfo(BSONObjBuilder* objBuilder, + const OpTime& lastCommittedOpTime) const = 0; + + /** + * Writes into 'output' all the information needed to generate a summary of the current + * replication state for use by the web interface. + */ + virtual void summarizeAsHtml(ReplSetHtmlSummary* output) = 0; + + /** + * Prepares a ReplSetRequestVotesResponse. + */ + virtual void processReplSetRequestVotes(const ReplSetRequestVotesArgs& args, + ReplSetRequestVotesResponse* response, + const OpTime& lastAppliedOpTime) = 0; + + /** + * Determines whether or not the newly elected primary is valid from our perspective. + * If it is, sets the _currentPrimaryIndex and term to the received values. + * If it is not, return ErrorCode::BadValue and the current term from our perspective. + * Populate responseTerm with the current term from our perspective. + */ + virtual Status processReplSetDeclareElectionWinner(const ReplSetDeclareElectionWinnerArgs& args, + long long* responseTerm) = 0; + + /** + * Loads an initial LastVote document, which was read from local storage. + * + * Called only during replication startup. All other updates are done internally. + */ + virtual void loadLastVote(const LastVote& lastVote) = 0; + + /** + * Returns the most recent term this node is aware of. + */ + virtual long long getTerm() = 0; + + /** + * Readies the TopologyCoordinator for stepdown. + */ + virtual void prepareForStepDown() = 0; + +protected: + TopologyCoordinator() {} +}; + +/** + * Type that denotes the role of a node in the replication protocol. + * + * The role is distinct from MemberState, in that it only deals with the + * roles a node plays in the basic protocol -- leader, follower and candidate. + * The mapping between MemberState and Role is complex -- several MemberStates + * map to the follower role, and MemberState::RS_SECONDARY maps to either + * follower or candidate roles, e.g. + */ +class TopologyCoordinator::Role { +public: + /** + * Constant indicating leader role. + */ + static const Role leader; + + /** + * Constant indicating follower role. + */ + static const Role follower; + + /** + * Constant indicating candidate role + */ + static const Role candidate; - Role() {} + Role() {} - bool operator==(Role other) const { return _value == other._value; } - bool operator!=(Role other) const { return _value != other._value; } + bool operator==(Role other) const { + return _value == other._value; + } + bool operator!=(Role other) const { + return _value != other._value; + } - std::string toString() const; + std::string toString() const; - private: - explicit Role(int value); +private: + explicit Role(int value); - int _value; - }; + int _value; +}; -} // namespace repl -} // namespace mongo +} // namespace repl +} // namespace mongo |