Raft.NodeState

Documentation

data Transition (init :: Mode) (res :: Mode) where

All valid state transitions of a Raft node

Constructors

StartElection :: Transition Follower Candidate

HigherTermFoundFollower :: Transition Follower Follower

RestartElection :: Transition Candidate Candidate

DiscoverLeader :: Transition Candidate Follower

HigherTermFoundCandidate :: Transition Candidate Follower

BecomeLeader :: Transition Candidate Leader

HandleClientReq :: Transition Leader Leader

SendHeartbeat :: Transition Leader Leader

DiscoverNewLeader :: Transition Leader Follower

HigherTermFoundLeader :: Transition Leader Follower

Noop :: Transition init init

Instances

Show (Transition init res)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> Transition init res -> ShowS

show :: Transition init res -> String

showList :: [Transition init res] -> ShowS

data ResultState init v where

Existential type hiding the result type of a transition

Constructors

ResultState :: Show v => Transition init res -> NodeState res v -> ResultState init v

Instances

Show v => Show (ResultState init v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> ResultState init v -> ShowS

show :: ResultState init v -> String

showList :: [ResultState init v] -> ShowS

followerResultState :: Show v => Transition init Follower -> FollowerState v -> ResultState init v

candidateResultState :: Show v => Transition init Candidate -> CandidateState v -> ResultState init v

leaderResultState :: Show v => Transition init Leader -> LeaderState v -> ResultState init v

data RaftNodeState v where

Existential type hiding the internal node state

Constructors

RaftNodeState

Fields

• :: { unRaftNodeState :: NodeState s v
•    } -> RaftNodeState v

Instances

Show v => Show (RaftNodeState v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> RaftNodeState v -> ShowS

show :: RaftNodeState v -> String

showList :: [RaftNodeState v] -> ShowS

Monad m => MonadState (RaftNodeState v) (RaftT v m)

Defined in Raft.Monad

Methods

get :: RaftT v m (RaftNodeState v)

put :: RaftNodeState v -> RaftT v m ()

state :: (RaftNodeState v -> (a, RaftNodeState v)) -> RaftT v m a

nodeMode :: RaftNodeState v -> Mode

initRaftNodeState :: RaftNodeState v

A node in Raft begins as a follower

data NodeState (a :: Mode) v where

The volatile state of a Raft Node

Constructors

NodeFollowerState :: FollowerState v -> NodeState Follower v

NodeCandidateState :: CandidateState v -> NodeState Candidate v

NodeLeaderState :: LeaderState v -> NodeState Leader v

Instances

Show v => Show (NodeState s v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> NodeState s v -> ShowS

show :: NodeState s v -> String

showList :: [NodeState s v] -> ShowS

data FollowerState v

Constructors

FollowerState

Fields

• fsCurrentLeader :: CurrentLeader

  Id of the current leader

• fsCommitIndex :: Index

  Index of highest log entry known to be committed

• fsLastApplied :: Index

  Index of highest log entry applied to state machine

• fsLastLogEntry :: LastLogEntry v

  Index and term of the last log entry in the node's log

• fsTermAtAEPrevIndex :: Maybe Term

  The term of the log entry specified in and AppendEntriesRPC

• fsClientReqCache :: ClientWriteReqCache

  The client write request cache, growing linearly with the number of clients

Instances

Show v => Show (FollowerState v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> FollowerState v -> ShowS

show :: FollowerState v -> String

showList :: [FollowerState v] -> ShowS

data CandidateState v

Constructors

CandidateState

Fields

• csCommitIndex :: Index

  Index of highest log entry known to be committed

• csLastApplied :: Index

  Index of highest log entry applied to state machine

• csVotes :: NodeIds

  Votes from other nodes in the raft network

• csLastLogEntry :: LastLogEntry v

  Index and term of the last log entry in the node's log

• csClientReqCache :: ClientWriteReqCache

  The client write request cache, growing linearly with the number of clients

Instances

Show v => Show (CandidateState v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> CandidateState v -> ShowS

show :: CandidateState v -> String

showList :: [CandidateState v] -> ShowS

data ClientReadReqData

Constructors

ClientReadReqData

Fields

• crrdClientId :: ClientId
• crrdReadReq :: ClientReadReq

Instances

Show ClientReadReqData

Defined in Raft.NodeState

Methods

showsPrec :: Int -> ClientReadReqData -> ShowS

show :: ClientReadReqData -> String

showList :: [ClientReadReqData] -> ShowS

type ClientReadReqs = Map Int (ClientReadReqData, Int)

The type mapping the number of the read request serviced to the id of the client that issued it and the number of success responses from followers confirming the leadership of the current leader

type ClientWriteReqCache = Map ClientId (SerialNum, Maybe Index)

The type mapping client ids to the serial number of their latest write requests and the index of the entry if it has been replicated.

data LeaderState v

Constructors

LeaderState

Fields

• lsCommitIndex :: Index

  Index of highest log entry known to be committed

• lsLastApplied :: Index

  Index of highest log entry applied to state machine

• lsNextIndex :: Map NodeId Index

  For each server, index of the next log entry to send to that server

• lsMatchIndex :: Map NodeId Index

  For each server, index of highest log entry known to be replicated on server

• lsLastLogEntry :: LastLogEntry v

  Index, term, and client id of the last log entry in the node's log. The only time `Maybe ClientId` will be Nothing is at the initial term.

• lsReadReqsHandled :: Int

  Number of read requests handled this term

• lsReadRequest :: ClientReadReqs

  The number of successful responses received regarding a specific read request heartbeat.

• lsClientReqCache :: ClientWriteReqCache

  The cache of client write requests received by the leader

Instances

Show v => Show (LeaderState v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> LeaderState v -> ShowS

show :: LeaderState v -> String

showList :: [LeaderState v] -> ShowS

setLastLogEntry :: NodeState s v -> Entries v -> NodeState s v

Update the last log entry in the node's log

getLastLogEntry :: NodeState ns v -> LastLogEntry v

Get the last applied index and the commit index of the last log entry in the node's log

getLastLogEntryIndex :: NodeState ns v -> Index

getCommitIndex :: NodeState ns v -> Index

getLastAppliedAndCommitIndex :: NodeState ns v -> (Index, Index)

Get the index of highest log entry applied to state machine and the index of highest log entry known to be committed

isFollower :: NodeState s v -> Bool

Check if node is in a follower state

isCandidate :: NodeState s v -> Bool

Check if node is in a candidate state

isLeader :: NodeState s v -> Bool

Check if node is in a leader state