Raft

State machine type class

class RSMP sm v | sm -> v where

Interface to handle commands in the underlying state machine. Functional dependency permitting only a single state machine command to be defined to update the state machine.

Associated Types

data RSMPError sm v

type RSMPCtx sm v = ctx | ctx -> sm v

Methods

applyCmdRSMP :: RSMPCtx sm v -> sm -> v -> Either (RSMPError sm v) sm

class (Monad m, RSMP sm v) => RSM sm v m | m sm -> v where

Methods

validateCmd :: v -> m (Either (RSMPError sm v) ())

askRSMPCtx :: m (RSMPCtx sm v)

Networking type classes

class RaftSendRPC m v where

Interface for nodes to send messages to one another. E.g. Control.Concurrent.Chan, Network.Socket, etc.

Methods

sendRPC :: NodeId -> RPCMessage v -> m ()

Instances

(MonadIO m, MonadConc m, Serialize v, Show v) => RaftSendRPC (RaftSocketT v m) v

Defined in Examples.Raft.Socket.Node

Methods

sendRPC :: NodeId -> RPCMessage v -> RaftSocketT v m ()

class Show (RaftRecvRPCError m v) => RaftRecvRPC m v where

Interface for nodes to receive messages from one another

Associated Types

type RaftRecvRPCError m v

Methods

receiveRPC :: m (Either (RaftRecvRPCError m v) (RPCMessage v))

Instances

(MonadIO m, MonadConc m, Show v) => RaftRecvRPC (RaftSocketT v m) v

Defined in Examples.Raft.Socket.Node

Associated Types

type RaftRecvRPCError (RaftSocketT v m) v :: Type

Methods

receiveRPC :: RaftSocketT v m (Either (RaftRecvRPCError (RaftSocketT v m) v) (RPCMessage v))

class RaftSendClient m sm where

Interface for Raft nodes to send messages to clients

Methods

sendClient :: ClientId -> ClientResponse sm -> m ()

Instances

(MonadIO m, MonadConc m, Serialize sm) => RaftSendClient (RaftSocketT v m) sm

Defined in Examples.Raft.Socket.Node

Methods

sendClient :: ClientId -> ClientResponse sm -> RaftSocketT v m ()

class Show (RaftRecvClientError m v) => RaftRecvClient m v where

Interface for Raft nodes to receive messages from clients

Associated Types

type RaftRecvClientError m v

Methods

receiveClient :: m (Either (RaftRecvClientError m v) (ClientRequest v))

Instances

(MonadIO m, MonadConc m, Serialize v) => RaftRecvClient (RaftSocketT v m) v

Defined in Examples.Raft.Socket.Node

Associated Types

type RaftRecvClientError (RaftSocketT v m) v :: Type

Methods

receiveClient :: RaftSocketT v m (Either (RaftRecvClientError (RaftSocketT v m) v) (ClientRequest v))

class Monad m => RaftPersist m where

Provides an interface to read and write the persistent state to disk.

Associated Types

type RaftPersistError m

Methods

readPersistentState :: Exception (RaftPersistError m) => m (Either (RaftPersistError m) PersistentState)

writePersistentState :: Exception (RaftPersistError m) => PersistentState -> m (Either (RaftPersistError m) ())

Instances

(MonadIO m, MonadConc m) => RaftPersist (RaftFileStoreT m)

Defined in Examples.Raft.FileStore

Associated Types

type RaftPersistError (RaftFileStoreT m) :: Type

Methods

readPersistentState :: RaftFileStoreT m (Either (RaftPersistError (RaftFileStoreT m)) PersistentState)

writePersistentState :: PersistentState -> RaftFileStoreT m (Either (RaftPersistError (RaftFileStoreT m)) ())

type EventChan m v = TChan (STM m) (Event v)

data RaftEnv v m

The raft server environment composed of the concurrent variables used in the effectful raft layer.

Constructors

RaftEnv

Fields

• eventChan :: EventChan m v
• resetElectionTimer :: m ()
• resetHeartbeatTimer :: m ()
• raftNodeConfig :: NodeConfig
• raftNodeLogDest :: LogDest

runRaftNode

Arguments

:: (Show v, Show sm, Show (Action sm v), MonadIO m, MonadConc m, MonadFail m, RSM sm v m, Show (RSMPError sm v), RaftSendRPC m v, RaftRecvRPC m v, RaftSendClient m sm, RaftRecvClient m v, RaftLog m v, RaftLogExceptions m, RaftPersist m, Exception (RaftPersistError m))

=> NodeConfig

Node configuration

-> LogDest

Logs destination

-> Int

Timer seed

-> sm

Initial state machine state

-> m ()

Run timers, RPC and client request handlers and start event loop. It should run forever

runRaftT :: MonadConc m => RaftNodeState -> RaftEnv v m -> RaftT v m () -> m ()

handleEventLoop :: forall sm v m. (Show v, Show sm, Show (Action sm v), MonadIO m, MonadConc m, MonadFail m, RSM sm v m, Show (RSMPError sm v), RaftPersist m, RaftSendRPC m v, RaftSendClient m sm, RaftLog m v, RaftLogExceptions m, RaftPersist m, Exception (RaftPersistError m)) => sm -> RaftT v m ()

Client data types

data ClientRequest v

Representation of a client request coupled with the client id

Constructors

ClientRequest ClientId (ClientReq v)

Instances

Show v => Show (ClientRequest v)

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientRequest v -> ShowS

show :: ClientRequest v -> String

showList :: [ClientRequest v] -> ShowS

Generic (ClientRequest v)

Defined in Raft.Client

Associated Types

type Rep (ClientRequest v) :: Type -> Type

Methods

from :: ClientRequest v -> Rep (ClientRequest v) x

to :: Rep (ClientRequest v) x -> ClientRequest v

Serialize v => Serialize (ClientRequest v)

Defined in Raft.Client

Methods

put :: Putter (ClientRequest v)

get :: Get (ClientRequest v)

type Rep (ClientRequest v)

Defined in Raft.Client

type Rep (ClientRequest v) = D1 (MetaData "ClientRequest" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "ClientRequest" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 ClientId) :*: S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (ClientReq v))))

data ClientReq v

Representation of a client request

Constructors

ClientReadReq

Request the latest state of the state machine

ClientWriteReq v

Write a command

Instances

Show v => Show (ClientReq v)

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientReq v -> ShowS

show :: ClientReq v -> String

showList :: [ClientReq v] -> ShowS

Generic (ClientReq v)

Defined in Raft.Client

Associated Types

type Rep (ClientReq v) :: Type -> Type

Methods

from :: ClientReq v -> Rep (ClientReq v) x

to :: Rep (ClientReq v) x -> ClientReq v

Serialize v => Serialize (ClientReq v)

Defined in Raft.Client

Methods

put :: Putter (ClientReq v)

get :: Get (ClientReq v)

type Rep (ClientReq v)

Defined in Raft.Client

type Rep (ClientReq v) = D1 (MetaData "ClientReq" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "ClientReadReq" PrefixI False) (U1 :: Type -> Type) :+: C1 (MetaCons "ClientWriteReq" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 v)))

data ClientResponse s

Representation of a client response

Constructors

ClientReadResponse (ClientReadResp s)

Respond with the latest state of the state machine.

ClientWriteResponse ClientWriteResp

Respond with the index of the entry appended to the log

ClientRedirectResponse ClientRedirResp

Respond with the node id of the current leader

Instances

Show s => Show (ClientResponse s)

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientResponse s -> ShowS

show :: ClientResponse s -> String

showList :: [ClientResponse s] -> ShowS

Generic (ClientResponse s)

Defined in Raft.Client

Associated Types

type Rep (ClientResponse s) :: Type -> Type

Methods

from :: ClientResponse s -> Rep (ClientResponse s) x

to :: Rep (ClientResponse s) x -> ClientResponse s

Serialize s => Serialize (ClientResponse s)

Defined in Raft.Client

Methods

put :: Putter (ClientResponse s)

get :: Get (ClientResponse s)

type Rep (ClientResponse s)

Defined in Raft.Client

type Rep (ClientResponse s) = D1 (MetaData "ClientResponse" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "ClientReadResponse" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (ClientReadResp s))) :+: (C1 (MetaCons "ClientWriteResponse" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 ClientWriteResp)) :+: C1 (MetaCons "ClientRedirectResponse" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 ClientRedirResp))))

newtype ClientReadResp s

Representation of a read response to a client The s stands for the "current" state of the state machine

Constructors

ClientReadResp s

Instances

Show s => Show (ClientReadResp s)

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientReadResp s -> ShowS

show :: ClientReadResp s -> String

showList :: [ClientReadResp s] -> ShowS

Generic (ClientReadResp s)

Defined in Raft.Client

Associated Types

type Rep (ClientReadResp s) :: Type -> Type

Methods

from :: ClientReadResp s -> Rep (ClientReadResp s) x

to :: Rep (ClientReadResp s) x -> ClientReadResp s

Serialize s => Serialize (ClientReadResp s)

Defined in Raft.Client

Methods

put :: Putter (ClientReadResp s)

get :: Get (ClientReadResp s)

type Rep (ClientReadResp s)

Defined in Raft.Client

type Rep (ClientReadResp s) = D1 (MetaData "ClientReadResp" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" True) (C1 (MetaCons "ClientReadResp" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 s)))

data ClientWriteResp

Representation of a write response to a client

Constructors

ClientWriteResp Index

Index of the entry appended to the log due to the previous client request

Instances

Show ClientWriteResp

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientWriteResp -> ShowS

show :: ClientWriteResp -> String

showList :: [ClientWriteResp] -> ShowS

Generic ClientWriteResp

Defined in Raft.Client

Associated Types

type Rep ClientWriteResp :: Type -> Type

Methods

from :: ClientWriteResp -> Rep ClientWriteResp x

to :: Rep ClientWriteResp x -> ClientWriteResp

Serialize ClientWriteResp

Defined in Raft.Client

Methods

put :: Putter ClientWriteResp

get :: Get ClientWriteResp

type Rep ClientWriteResp

Defined in Raft.Client

type Rep ClientWriteResp = D1 (MetaData "ClientWriteResp" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "ClientWriteResp" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Index)))

data ClientRedirResp

Representation of a redirect response to a client

Constructors

ClientRedirResp CurrentLeader

Instances

Show ClientRedirResp

Defined in Raft.Client

Methods

showsPrec :: Int -> ClientRedirResp -> ShowS

show :: ClientRedirResp -> String

showList :: [ClientRedirResp] -> ShowS

Generic ClientRedirResp

Defined in Raft.Client

Associated Types

type Rep ClientRedirResp :: Type -> Type

Methods

from :: ClientRedirResp -> Rep ClientRedirResp x

to :: Rep ClientRedirResp x -> ClientRedirResp

Serialize ClientRedirResp

Defined in Raft.Client

Methods

put :: Putter ClientRedirResp

get :: Get ClientRedirResp

type Rep ClientRedirResp

Defined in Raft.Client

type Rep ClientRedirResp = D1 (MetaData "ClientRedirResp" "Raft.Client" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "ClientRedirResp" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 CurrentLeader)))

Configuration

data NodeConfig

Configuration of a node in the cluster

Constructors

NodeConfig

Fields

• configNodeId :: NodeId

  Node id of the running node

• configNodeIds :: NodeIds

  Set of all other node ids in the cluster

• configElectionTimeout :: (Natural, Natural)

  Range of times an election timeout can take

• configHeartbeatTimeout :: Natural

  Heartbeat timeout timer

Instances

Show NodeConfig

Defined in Raft.Config

Methods

showsPrec :: Int -> NodeConfig -> ShowS

show :: NodeConfig -> String

showList :: [NodeConfig] -> ShowS

Events

data Event v

Representation of events a raft node can send and receive

Constructors

MessageEvent (MessageEvent v)

TimeoutEvent Timeout

Instances

Show v => Show (Event v)

Defined in Raft.Event

Methods

showsPrec :: Int -> Event v -> ShowS

show :: Event v -> String

showList :: [Event v] -> ShowS

data Timeout

Representation of timeouts

Constructors

ElectionTimeout

Timeout after which a follower will become candidate

HeartbeatTimeout

Timeout after which a leader will send AppendEntries RPC to all peers

Instances

Show Timeout

Defined in Raft.Event

Methods

showsPrec :: Int -> Timeout -> ShowS

show :: Timeout -> String

showList :: [Timeout] -> ShowS

data MessageEvent v

Representation of message events to a node

Constructors

RPCMessageEvent (RPCMessage v)

Incoming event from a peer

ClientRequestEvent (ClientRequest v)

Incoming event from a client

Instances

Show v => Show (MessageEvent v)

Defined in Raft.Event

Methods

showsPrec :: Int -> MessageEvent v -> ShowS

show :: MessageEvent v -> String

showList :: [MessageEvent v] -> ShowS

Generic (MessageEvent v)

Defined in Raft.Event

Associated Types

type Rep (MessageEvent v) :: Type -> Type

Methods

from :: MessageEvent v -> Rep (MessageEvent v) x

to :: Rep (MessageEvent v) x -> MessageEvent v

Serialize v => Serialize (MessageEvent v)

Defined in Raft.Event

Methods

put :: Putter (MessageEvent v)

get :: Get (MessageEvent v)

type Rep (MessageEvent v)

Defined in Raft.Event

type Rep (MessageEvent v) = D1 (MetaData "MessageEvent" "Raft.Event" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "RPCMessageEvent" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (RPCMessage v))) :+: C1 (MetaCons "ClientRequestEvent" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (ClientRequest v))))

Log

data Entry v

Representation of an entry in the replicated log

Constructors

Entry

Fields

• entryIndex :: Index

  Index of entry in the log

• entryTerm :: Term

  Term when entry was received by leader

• entryValue :: EntryValue v

  Command to update state machine

• entryIssuer :: EntryIssuer

  Id of the client that issued the command

Instances

Show v => Show (Entry v)

Defined in Raft.Log

Methods

showsPrec :: Int -> Entry v -> ShowS

show :: Entry v -> String

showList :: [Entry v] -> ShowS

Generic (Entry v)

Defined in Raft.Log

Associated Types

type Rep (Entry v) :: Type -> Type

Methods

from :: Entry v -> Rep (Entry v) x

to :: Rep (Entry v) x -> Entry v

Serialize v => Serialize (Entry v)

Defined in Raft.Log

Methods

put :: Putter (Entry v)

get :: Get (Entry v)

type Rep (Entry v)

Defined in Raft.Log

type Rep (Entry v) = D1 (MetaData "Entry" "Raft.Log" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "Entry" PrefixI True) ((S1 (MetaSel (Just "entryIndex") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Index) :*: S1 (MetaSel (Just "entryTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term)) :*: (S1 (MetaSel (Just "entryValue") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (EntryValue v)) :*: S1 (MetaSel (Just "entryIssuer") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 EntryIssuer))))

type Entries v = Seq (Entry v)

class Monad m => RaftWriteLog m v where

Provides an interface for nodes to write log entries to storage.

Associated Types

type RaftWriteLogError m

Methods

writeLogEntries :: Exception (RaftWriteLogError m) => Entries v -> m (Either (RaftWriteLogError m) ())

Write the given log entries to storage

Instances

(MonadIO m, MonadConc m, Serialize v) => RaftWriteLog (RaftFileStoreT m) v

Defined in Examples.Raft.FileStore

Associated Types

type RaftWriteLogError (RaftFileStoreT m) :: Type

Methods

writeLogEntries :: Entries v -> RaftFileStoreT m (Either (RaftWriteLogError (RaftFileStoreT m)) ())

data DeleteSuccess v

Constructors

DeleteSuccess

class Monad m => RaftDeleteLog m v where

Provides an interface for nodes to delete log entries from storage.

Associated Types

type RaftDeleteLogError m

Methods

deleteLogEntriesFrom :: Exception (RaftDeleteLogError m) => Index -> m (Either (RaftDeleteLogError m) (DeleteSuccess v))

Delete log entries from a given index; e.g. 'deleteLogEntriesFrom 7' should delete every log entry with an index >= 7.

Instances

(MonadIO m, MonadConc m, Serialize v) => RaftDeleteLog (RaftFileStoreT m) v

Defined in Examples.Raft.FileStore

Associated Types

type RaftDeleteLogError (RaftFileStoreT m) :: Type

Methods

deleteLogEntriesFrom :: Index -> RaftFileStoreT m (Either (RaftDeleteLogError (RaftFileStoreT m)) (DeleteSuccess v))

class Monad m => RaftReadLog m v where

Provides an interface for nodes to read log entries from storage.

Minimal complete definition

readLogEntry, readLastLogEntry

Associated Types

type RaftReadLogError m

Methods

readLogEntry :: Exception (RaftReadLogError m) => Index -> m (Either (RaftReadLogError m) (Maybe (Entry v)))

Read the log at a given index

readLogEntriesFrom :: Exception (RaftReadLogError m) => Index -> m (Either (RaftReadLogError m) (Entries v))

Read log entries from a specific index onwards, including the specific index

readLastLogEntry :: Exception (RaftReadLogError m) => m (Either (RaftReadLogError m) (Maybe (Entry v)))

Read the last log entry in the log

readLogEntriesFrom :: Exception (RaftReadLogError m) => Index -> m (Either (RaftReadLogError m) (Entries v))

Read log entries from a specific index onwards, including the specific index

Instances

(MonadIO m, MonadConc m, Serialize v) => RaftReadLog (RaftFileStoreT m) v

Defined in Examples.Raft.FileStore

Associated Types

type RaftReadLogError (RaftFileStoreT m) :: Type

Methods

readLogEntry :: Index -> RaftFileStoreT m (Either (RaftReadLogError (RaftFileStoreT m)) (Maybe (Entry v)))

readLogEntriesFrom :: Index -> RaftFileStoreT m (Either (RaftReadLogError (RaftFileStoreT m)) (Entries v))

readLastLogEntry :: RaftFileStoreT m (Either (RaftReadLogError (RaftFileStoreT m)) (Maybe (Entry v)))

type RaftLog m v = (RaftReadLog m v, RaftWriteLog m v, RaftDeleteLog m v)

data RaftLogError m

Representation of possible errors that come from reading, writing or deleting logs from the persistent storage

Constructors

RaftLogReadError (RaftReadLogError m)

RaftLogWriteError (RaftWriteLogError m)

RaftLogDeleteError (RaftDeleteLogError m)

type RaftLogExceptions m = (Exception (RaftReadLogError m), Exception (RaftWriteLogError m), Exception (RaftDeleteLogError m))

Logging

data LogDest

Representation of the logs' destination

Constructors

LogFile FilePath

LogStdout

NoLogs

data Severity

Representation of the severity of the logs

Constructors

Info

Debug

Critical

Instances

Show Severity

Defined in Raft.Logging

Methods

showsPrec :: Int -> Severity -> ShowS

show :: Severity -> String

showList :: [Severity] -> ShowS

Raft node states

data Mode

Constructors

Follower

Candidate

Leader

Instances

Show Mode

Defined in Raft.NodeState

Methods

showsPrec :: Int -> Mode -> ShowS

show :: Mode -> String

showList :: [Mode] -> ShowS

data RaftNodeState where

Existential type hiding the internal node state

Constructors

RaftNodeState

Fields

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

Instances

Show RaftNodeState

Defined in Raft.NodeState

Methods

showsPrec :: Int -> RaftNodeState -> ShowS

show :: RaftNodeState -> String

showList :: [RaftNodeState] -> ShowS

data NodeState (a :: Mode) where

The volatile state of a Raft Node

Constructors

NodeFollowerState :: FollowerState -> NodeState Follower

NodeCandidateState :: CandidateState -> NodeState Candidate

NodeLeaderState :: LeaderState -> NodeState Leader

Instances

Show (NodeState v)

Defined in Raft.NodeState

Methods

showsPrec :: Int -> NodeState v -> ShowS

show :: NodeState v -> String

showList :: [NodeState v] -> ShowS

data CurrentLeader

Representation of the current leader in the cluster. The system is considered to be unavailable if there is no leader

Constructors

CurrentLeader LeaderId

NoLeader

Instances

Eq CurrentLeader

Defined in Raft.NodeState

Methods

(==) :: CurrentLeader -> CurrentLeader -> Bool

(/=) :: CurrentLeader -> CurrentLeader -> Bool

Show CurrentLeader

Defined in Raft.NodeState

Methods

showsPrec :: Int -> CurrentLeader -> ShowS

show :: CurrentLeader -> String

showList :: [CurrentLeader] -> ShowS

Generic CurrentLeader

Defined in Raft.NodeState

Associated Types

type Rep CurrentLeader :: Type -> Type

Methods

from :: CurrentLeader -> Rep CurrentLeader x

to :: Rep CurrentLeader x -> CurrentLeader

Serialize CurrentLeader

Defined in Raft.NodeState

Methods

put :: Putter CurrentLeader

get :: Get CurrentLeader

type Rep CurrentLeader

Defined in Raft.NodeState

type Rep CurrentLeader = D1 (MetaData "CurrentLeader" "Raft.NodeState" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "CurrentLeader" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 LeaderId)) :+: C1 (MetaCons "NoLeader" PrefixI False) (U1 :: Type -> Type))

data FollowerState

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

• fsLastLogEntryData :: (Index, Term)

  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

Instances

Show FollowerState

Defined in Raft.NodeState

Methods

showsPrec :: Int -> FollowerState -> ShowS

show :: FollowerState -> String

showList :: [FollowerState] -> ShowS

data CandidateState

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

• csLastLogEntryData :: (Index, Term)

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

Instances

Show CandidateState

Defined in Raft.NodeState

Methods

showsPrec :: Int -> CandidateState -> ShowS

show :: CandidateState -> String

showList :: [CandidateState] -> ShowS

data LeaderState

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

• lsLastLogEntryData :: (Index, Term, Maybe EntryIssuer)

  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.

Instances

Show LeaderState

Defined in Raft.NodeState

Methods

showsPrec :: Int -> LeaderState -> ShowS

show :: LeaderState -> String

showList :: [LeaderState] -> ShowS

initRaftNodeState :: RaftNodeState

A node in Raft begins as a follower

isFollower :: NodeState s -> Bool

Check if node is in a follower state

isCandidate :: NodeState s -> Bool

Check if node is in a candidate state

isLeader :: NodeState s -> Bool

Check if node is in a leader state

setLastLogEntryData :: NodeState ns -> Entries v -> NodeState ns

Update the last log entry in the node's log

getLastLogEntryData :: NodeState ns -> (Index, Term)

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

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

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

Persistent state

data PersistentState

Persistent state that all Raft nodes maintain, regardless of node state.

Constructors

PersistentState

Fields

• currentTerm :: Term

  Last term server has seen

• votedFor :: Maybe NodeId

  Candidate id that received vote in current term

Instances

Show PersistentState

Defined in Raft.Persistent

Methods

showsPrec :: Int -> PersistentState -> ShowS

show :: PersistentState -> String

showList :: [PersistentState] -> ShowS

Generic PersistentState

Defined in Raft.Persistent

Associated Types

type Rep PersistentState :: Type -> Type

Methods

from :: PersistentState -> Rep PersistentState x

to :: Rep PersistentState x -> PersistentState

Serialize PersistentState

Defined in Raft.Persistent

Methods

put :: Putter PersistentState

get :: Get PersistentState

MonadState PersistentState (TransitionM sm v)

Defined in Raft.Monad

Methods

get :: TransitionM sm v PersistentState

put :: PersistentState -> TransitionM sm v ()

state :: (PersistentState -> (a, PersistentState)) -> TransitionM sm v a

RaftLogger (RWS (TransitionEnv sm) [Action sm v] PersistentState)

Defined in Raft.Monad

Methods

loggerNodeId :: RWS (TransitionEnv sm) [Action sm v] PersistentState NodeId

loggerNodeState :: RWS (TransitionEnv sm) [Action sm v] PersistentState RaftNodeState

type Rep PersistentState

Defined in Raft.Persistent

type Rep PersistentState = D1 (MetaData "PersistentState" "Raft.Persistent" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "PersistentState" PrefixI True) (S1 (MetaSel (Just "currentTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: S1 (MetaSel (Just "votedFor") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Maybe NodeId))))

initPersistentState :: PersistentState

A node initiates its persistent state with term 0 and with its vote blank

Basic types

type NodeId = ByteString

Unique identifier of a Raft node

type NodeIds = Set NodeId

newtype ClientId

Unique identifier of a client

Constructors

ClientId NodeId

Instances

Eq ClientId

Defined in Raft.Types

Methods

(==) :: ClientId -> ClientId -> Bool

(/=) :: ClientId -> ClientId -> Bool

Ord ClientId

Defined in Raft.Types

Methods

compare :: ClientId -> ClientId -> Ordering

(<) :: ClientId -> ClientId -> Bool

(<=) :: ClientId -> ClientId -> Bool

(>) :: ClientId -> ClientId -> Bool

(>=) :: ClientId -> ClientId -> Bool

max :: ClientId -> ClientId -> ClientId

min :: ClientId -> ClientId -> ClientId

Show ClientId

Defined in Raft.Types

Methods

showsPrec :: Int -> ClientId -> ShowS

show :: ClientId -> String

showList :: [ClientId] -> ShowS

Generic ClientId

Defined in Raft.Types

Associated Types

type Rep ClientId :: Type -> Type

Methods

from :: ClientId -> Rep ClientId x

to :: Rep ClientId x -> ClientId

Serialize ClientId

Defined in Raft.Types

Methods

put :: Putter ClientId

get :: Get ClientId

type Rep ClientId

Defined in Raft.Types

type Rep ClientId = D1 (MetaData "ClientId" "Raft.Types" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" True) (C1 (MetaCons "ClientId" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 NodeId)))

newtype LeaderId

Unique identifier of a leader

Constructors

LeaderId

Fields

• unLeaderId :: NodeId

Instances

Eq LeaderId

Defined in Raft.Types

Methods

(==) :: LeaderId -> LeaderId -> Bool

(/=) :: LeaderId -> LeaderId -> Bool

Show LeaderId

Defined in Raft.Types

Methods

showsPrec :: Int -> LeaderId -> ShowS

show :: LeaderId -> String

showList :: [LeaderId] -> ShowS

Generic LeaderId

Defined in Raft.Types

Associated Types

type Rep LeaderId :: Type -> Type

Methods

from :: LeaderId -> Rep LeaderId x

to :: Rep LeaderId x -> LeaderId

Serialize LeaderId

Defined in Raft.Types

Methods

put :: Putter LeaderId

get :: Get LeaderId

type Rep LeaderId

Defined in Raft.Types

type Rep LeaderId = D1 (MetaData "LeaderId" "Raft.Types" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" True) (C1 (MetaCons "LeaderId" PrefixI True) (S1 (MetaSel (Just "unLeaderId") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 NodeId)))

newtype Term

Representation of monotonic election terms

Constructors

Term Natural

Instances

Enum Term

Defined in Raft.Types

Methods

succ :: Term -> Term

pred :: Term -> Term

toEnum :: Int -> Term

fromEnum :: Term -> Int

enumFrom :: Term -> [Term]

enumFromThen :: Term -> Term -> [Term]

enumFromTo :: Term -> Term -> [Term]

enumFromThenTo :: Term -> Term -> Term -> [Term]

Eq Term

Defined in Raft.Types

Methods

(==) :: Term -> Term -> Bool

(/=) :: Term -> Term -> Bool

Ord Term

Defined in Raft.Types

Methods

compare :: Term -> Term -> Ordering

(<) :: Term -> Term -> Bool

(<=) :: Term -> Term -> Bool

(>) :: Term -> Term -> Bool

(>=) :: Term -> Term -> Bool

max :: Term -> Term -> Term

min :: Term -> Term -> Term

Show Term

Defined in Raft.Types

Methods

showsPrec :: Int -> Term -> ShowS

show :: Term -> String

showList :: [Term] -> ShowS

Generic Term

Defined in Raft.Types

Associated Types

type Rep Term :: Type -> Type

Methods

from :: Term -> Rep Term x

to :: Rep Term x -> Term

Serialize Term

Defined in Raft.Types

Methods

put :: Putter Term

get :: Get Term

type Rep Term

Defined in Raft.Types

type Rep Term = D1 (MetaData "Term" "Raft.Types" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" True) (C1 (MetaCons "Term" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Natural)))

newtype Index

Representation of monotonic indices

Constructors

Index Natural

Instances

Enum Index

Defined in Raft.Types

Methods

succ :: Index -> Index

pred :: Index -> Index

toEnum :: Int -> Index

fromEnum :: Index -> Int

enumFrom :: Index -> [Index]

enumFromThen :: Index -> Index -> [Index]

enumFromTo :: Index -> Index -> [Index]

enumFromThenTo :: Index -> Index -> Index -> [Index]

Eq Index

Defined in Raft.Types

Methods

(==) :: Index -> Index -> Bool

(/=) :: Index -> Index -> Bool

Integral Index

Defined in Raft.Types

Methods

quot :: Index -> Index -> Index

rem :: Index -> Index -> Index

div :: Index -> Index -> Index

mod :: Index -> Index -> Index

quotRem :: Index -> Index -> (Index, Index)

divMod :: Index -> Index -> (Index, Index)

toInteger :: Index -> Integer

Num Index

Defined in Raft.Types

Methods

(+) :: Index -> Index -> Index

(-) :: Index -> Index -> Index

(*) :: Index -> Index -> Index

negate :: Index -> Index

abs :: Index -> Index

signum :: Index -> Index

fromInteger :: Integer -> Index

Ord Index

Defined in Raft.Types

Methods

compare :: Index -> Index -> Ordering

(<) :: Index -> Index -> Bool

(<=) :: Index -> Index -> Bool

(>) :: Index -> Index -> Bool

(>=) :: Index -> Index -> Bool

max :: Index -> Index -> Index

min :: Index -> Index -> Index

Real Index

Defined in Raft.Types

Methods

toRational :: Index -> Rational

Show Index

Defined in Raft.Types

Methods

showsPrec :: Int -> Index -> ShowS

show :: Index -> String

showList :: [Index] -> ShowS

Generic Index

Defined in Raft.Types

Associated Types

type Rep Index :: Type -> Type

Methods

from :: Index -> Rep Index x

to :: Rep Index x -> Index

Serialize Index

Defined in Raft.Types

Methods

put :: Putter Index

get :: Get Index

type Rep Index

Defined in Raft.Types

type Rep Index = D1 (MetaData "Index" "Raft.Types" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" True) (C1 (MetaCons "Index" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Natural)))

term0 :: Term

Initial term. Terms start at 0

index0 :: Index

Initial index. Indeces start at 0

RPC

data RPC v

Constructors

AppendEntriesRPC (AppendEntries v)

AppendEntriesResponseRPC AppendEntriesResponse

RequestVoteRPC RequestVote

RequestVoteResponseRPC RequestVoteResponse

Instances

Show v => Show (RPC v)

Defined in Raft.RPC

Methods

showsPrec :: Int -> RPC v -> ShowS

show :: RPC v -> String

showList :: [RPC v] -> ShowS

Generic (RPC v)

Defined in Raft.RPC

Associated Types

type Rep (RPC v) :: Type -> Type

Methods

from :: RPC v -> Rep (RPC v) x

to :: Rep (RPC v) x -> RPC v

Serialize v => Serialize (RPC v)

Defined in Raft.RPC

Methods

put :: Putter (RPC v)

get :: Get (RPC v)

type Rep (RPC v)

Defined in Raft.RPC

type Rep (RPC v) = D1 (MetaData "RPC" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) ((C1 (MetaCons "AppendEntriesRPC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (AppendEntries v))) :+: C1 (MetaCons "AppendEntriesResponseRPC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 AppendEntriesResponse))) :+: (C1 (MetaCons "RequestVoteRPC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 RequestVote)) :+: C1 (MetaCons "RequestVoteResponseRPC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 RequestVoteResponse))))

class RPCType a v where

Methods

toRPC :: a -> RPC v

Instances

RPCType RequestVoteResponse v

Defined in Raft.RPC

Methods

toRPC :: RequestVoteResponse -> RPC v

RPCType RequestVote v

Defined in Raft.RPC

Methods

toRPC :: RequestVote -> RPC v

RPCType AppendEntriesResponse v

Defined in Raft.RPC

Methods

toRPC :: AppendEntriesResponse -> RPC v

RPCType (AppendEntries v) v

Defined in Raft.RPC

Methods

toRPC :: AppendEntries v -> RPC v

data RPCMessage v

Representation of a message sent between nodes

Constructors

RPCMessage

Fields

• sender :: NodeId
• rpc :: RPC v

Instances

Show v => Show (RPCMessage v)

Defined in Raft.RPC

Methods

showsPrec :: Int -> RPCMessage v -> ShowS

show :: RPCMessage v -> String

showList :: [RPCMessage v] -> ShowS

Generic (RPCMessage v)

Defined in Raft.RPC

Associated Types

type Rep (RPCMessage v) :: Type -> Type

Methods

from :: RPCMessage v -> Rep (RPCMessage v) x

to :: Rep (RPCMessage v) x -> RPCMessage v

Serialize v => Serialize (RPCMessage v)

Defined in Raft.RPC

Methods

put :: Putter (RPCMessage v)

get :: Get (RPCMessage v)

type Rep (RPCMessage v)

Defined in Raft.RPC

type Rep (RPCMessage v) = D1 (MetaData "RPCMessage" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "RPCMessage" PrefixI True) (S1 (MetaSel (Just "sender") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 NodeId) :*: S1 (MetaSel (Just "rpc") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (RPC v))))

data AppendEntries v

Representation of a message sent from a leader to its peers

Constructors

AppendEntries

Fields

• aeTerm :: Term

  Leader's term

• aeLeaderId :: LeaderId

  Leader's identifier so that followers can redirect clients

• aePrevLogIndex :: Index

  Index of log entry immediately preceding new ones

• aePrevLogTerm :: Term

  Term of aePrevLogIndex entry

• aeEntries :: Entries v

  Log entries to store (empty for heartbeat)

• aeLeaderCommit :: Index

  Leader's commit index

• aeReadRequest :: Maybe Int

  which read request the message corresponds to

Instances

Show v => Show (AppendEntries v)

Defined in Raft.RPC

Methods

showsPrec :: Int -> AppendEntries v -> ShowS

show :: AppendEntries v -> String

showList :: [AppendEntries v] -> ShowS

Generic (AppendEntries v)

Defined in Raft.RPC

Associated Types

type Rep (AppendEntries v) :: Type -> Type

Methods

from :: AppendEntries v -> Rep (AppendEntries v) x

to :: Rep (AppendEntries v) x -> AppendEntries v

Serialize v => Serialize (AppendEntries v)

Defined in Raft.RPC

Methods

put :: Putter (AppendEntries v)

get :: Get (AppendEntries v)

RPCType (AppendEntries v) v

Defined in Raft.RPC

Methods

toRPC :: AppendEntries v -> RPC v

type Rep (AppendEntries v)

Defined in Raft.RPC

type Rep (AppendEntries v) = D1 (MetaData "AppendEntries" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "AppendEntries" PrefixI True) ((S1 (MetaSel (Just "aeTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: (S1 (MetaSel (Just "aeLeaderId") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 LeaderId) :*: S1 (MetaSel (Just "aePrevLogIndex") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Index))) :*: ((S1 (MetaSel (Just "aePrevLogTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: S1 (MetaSel (Just "aeEntries") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Entries v))) :*: (S1 (MetaSel (Just "aeLeaderCommit") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Index) :*: S1 (MetaSel (Just "aeReadRequest") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Maybe Int))))))

data AppendEntriesResponse

Representation of the response from a follower to an AppendEntries message

Constructors

AppendEntriesResponse

Fields

• aerTerm :: Term

  current term for leader to update itself

• aerSuccess :: Bool

  true if follower contained entry matching aePrevLogIndex and aePrevLogTerm

• aerReadRequest :: Maybe Int

  which read request the response corresponds to

Instances

Show AppendEntriesResponse

Defined in Raft.RPC

Methods

showsPrec :: Int -> AppendEntriesResponse -> ShowS

show :: AppendEntriesResponse -> String

showList :: [AppendEntriesResponse] -> ShowS

Generic AppendEntriesResponse

Defined in Raft.RPC

Associated Types

type Rep AppendEntriesResponse :: Type -> Type

Methods

from :: AppendEntriesResponse -> Rep AppendEntriesResponse x

to :: Rep AppendEntriesResponse x -> AppendEntriesResponse

Serialize AppendEntriesResponse

Defined in Raft.RPC

Methods

put :: Putter AppendEntriesResponse

get :: Get AppendEntriesResponse

RPCType AppendEntriesResponse v

Defined in Raft.RPC

Methods

toRPC :: AppendEntriesResponse -> RPC v

type Rep AppendEntriesResponse

Defined in Raft.RPC

type Rep AppendEntriesResponse = D1 (MetaData "AppendEntriesResponse" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "AppendEntriesResponse" PrefixI True) (S1 (MetaSel (Just "aerTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: (S1 (MetaSel (Just "aerSuccess") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Bool) :*: S1 (MetaSel (Just "aerReadRequest") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Maybe Int)))))

data RequestVote

Representation of the message sent by candidates to their peers to request their vote

Constructors

RequestVote

Fields

• rvTerm :: Term

  candidates term

• rvCandidateId :: NodeId

  candidate requesting vote

• rvLastLogIndex :: Index

  index of candidate's last log entry

• rvLastLogTerm :: Term

  term of candidate's last log entry

Instances

Show RequestVote

Defined in Raft.RPC

Methods

showsPrec :: Int -> RequestVote -> ShowS

show :: RequestVote -> String

showList :: [RequestVote] -> ShowS

Generic RequestVote

Defined in Raft.RPC

Associated Types

type Rep RequestVote :: Type -> Type

Methods

from :: RequestVote -> Rep RequestVote x

to :: Rep RequestVote x -> RequestVote

Serialize RequestVote

Defined in Raft.RPC

Methods

put :: Putter RequestVote

get :: Get RequestVote

RPCType RequestVote v

Defined in Raft.RPC

Methods

toRPC :: RequestVote -> RPC v

type Rep RequestVote

Defined in Raft.RPC

type Rep RequestVote = D1 (MetaData "RequestVote" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "RequestVote" PrefixI True) ((S1 (MetaSel (Just "rvTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: S1 (MetaSel (Just "rvCandidateId") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 NodeId)) :*: (S1 (MetaSel (Just "rvLastLogIndex") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Index) :*: S1 (MetaSel (Just "rvLastLogTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term))))

data RequestVoteResponse

Representation of a response to a RequestVote message

Constructors

RequestVoteResponse

Fields

• rvrTerm :: Term

  current term for candidate to update itself

• rvrVoteGranted :: Bool

  true means candidate recieved vote

Instances

Show RequestVoteResponse

Defined in Raft.RPC

Methods

showsPrec :: Int -> RequestVoteResponse -> ShowS

show :: RequestVoteResponse -> String

showList :: [RequestVoteResponse] -> ShowS

Generic RequestVoteResponse

Defined in Raft.RPC

Associated Types

type Rep RequestVoteResponse :: Type -> Type

Methods

from :: RequestVoteResponse -> Rep RequestVoteResponse x

to :: Rep RequestVoteResponse x -> RequestVoteResponse

Serialize RequestVoteResponse

Defined in Raft.RPC

Methods

put :: Putter RequestVoteResponse

get :: Get RequestVoteResponse

RPCType RequestVoteResponse v

Defined in Raft.RPC

Methods

toRPC :: RequestVoteResponse -> RPC v

type Rep RequestVoteResponse

Defined in Raft.RPC

type Rep RequestVoteResponse = D1 (MetaData "RequestVoteResponse" "Raft.RPC" "libraft-0.1.1.0-8nwazCMBvi7EUIW9UIbZhF" False) (C1 (MetaCons "RequestVoteResponse" PrefixI True) (S1 (MetaSel (Just "rvrTerm") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Term) :*: S1 (MetaSel (Just "rvrVoteGranted") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Bool)))

data AppendEntriesData v

The data used to construct an AppendEntries value, snapshotted from the node state at the time the AppendEntries val should be created.

Constructors

AppendEntriesData

Fields

• aedTerm :: Term
• aedLeaderCommit :: Index
• aedEntriesSpec :: EntriesSpec v

Instances

Show v => Show (AppendEntriesData v)

Defined in Raft.RPC

Methods

showsPrec :: Int -> AppendEntriesData v -> ShowS

show :: AppendEntriesData v -> String

showList :: [AppendEntriesData v] -> ShowS