Safe Haskell	Safe-Inferred
Language	Haskell2010

Hydra.Network.Heartbeat

Description

An implementation of an application-level failure detector. This module exposes a Component withHeartbeat than can be used to wrap another NetworkComponent and piggy-back on it to send and propagate Heartbeat messages and detect other parties' liveness.

It is inspired by the Increasing timeout algorithms from the book Introduction to Reliable and Secure Distributed Programming by Cachin et al. which is an Eventually Perfect Failure Detector suitable for partially synchronous network settings. It has the following behaviour:

It broadcasts a Ping to other parties through the underlying Network implementation if the last message has been sent more than 3s ago
When receiving messages from other parties, it records reception time and notifies underlying node with a Connected message
If new messages are received from alive parties before 3s timeout expires no new Connected message is sent * If main thread detects that a formerly alive party has not been seen for more than 3s, it is marked as suspected and a Disconnected message is sent to the node.

Synopsis

data HeartbeatState = HeartbeatState {
- alive :: Map NodeId Time
- suspected :: Set NodeId
- lastSent :: Maybe Time
}
initialHeartbeatState :: HeartbeatState
data Heartbeat msg
- = Data NodeId msg
- | Ping NodeId
heartbeatDelay :: DiffTime
livenessDelay :: DiffTime
type ConnectionMessages m = Connectivity -> m ()
withHeartbeat :: (MonadAsync m, MonadDelay m) => NodeId -> ConnectionMessages m -> NetworkComponent m (Heartbeat msg) a -> NetworkComponent m msg a
updateStateFromIncomingMessages :: (MonadSTM m, MonadMonotonicTime m) => TVar m HeartbeatState -> ConnectionMessages m -> NetworkCallback msg m -> NetworkCallback (Heartbeat msg) m
updateStateFromOutgoingMessages :: (MonadSTM m, MonadMonotonicTime m) => NodeId -> TVar m HeartbeatState -> Network m (Heartbeat msg) -> Network m msg
updateLastSent :: MonadSTM m => TVar m HeartbeatState -> Time -> m ()
checkHeartbeatState :: (MonadDelay m, MonadSTM m) => NodeId -> TVar m HeartbeatState -> Network m (Heartbeat msg) -> m ()
shouldSendHeartbeat :: Time -> HeartbeatState -> Bool
checkRemoteParties :: (MonadDelay m, MonadSTM m) => TVar m HeartbeatState -> ConnectionMessages m -> m ()
updateSuspected :: MonadSTM m => TVar m HeartbeatState -> Time -> m (Set NodeId)
checkTimeout :: (DiffTime -> DiffTime) -> Time -> Time -> Bool

Documentation

data HeartbeatState Source #

Constructors

HeartbeatState
Fields alive :: Map NodeId Time The map of known `Connected` parties with the last time they've been "seen". This is updated when we see a message from another node suspected :: Set NodeId The set of known parties which might be `Disconnected` This is updated after some time no message has been received from a node. lastSent :: Maybe Time The timestamp of the last sent message.

Instances

Instances details

Eq HeartbeatState Source #
Instance details Defined in Hydra.Network.Heartbeat Methods (==) :: HeartbeatState -> HeartbeatState -> Bool Source # (/=) :: HeartbeatState -> HeartbeatState -> Bool Source #

initialHeartbeatState :: HeartbeatState Source #

data Heartbeat msg Source #

Constructors

Data NodeId msg
Ping NodeId

Instances

Instances details

FromJSON msg => FromJSON (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods parseJSON :: Value -> Parser (Heartbeat msg) parseJSONList :: Value -> Parser [Heartbeat msg]
ToJSON msg => ToJSON (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods toJSON :: Heartbeat msg -> Value toEncoding :: Heartbeat msg -> Encoding toJSONList :: [Heartbeat msg] -> Value toEncodingList :: [Heartbeat msg] -> Encoding
Generic (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Associated Types type Rep (Heartbeat msg) :: Type -> Type Source # Methods from :: Heartbeat msg -> Rep (Heartbeat msg) x Source # to :: Rep (Heartbeat msg) x -> Heartbeat msg Source #
Show msg => Show (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods showsPrec :: Int -> Heartbeat msg -> ShowS Source # show :: Heartbeat msg -> String Source # showList :: [Heartbeat msg] -> ShowS Source #
FromCBOR msg => FromCBOR (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods fromCBOR :: Decoder s (Heartbeat msg) label :: Proxy (Heartbeat msg) -> Text
ToCBOR msg => ToCBOR (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods toCBOR :: Heartbeat msg -> Encoding encodedSizeExpr :: (forall t. ToCBOR t => Proxy t -> Size) -> Proxy (Heartbeat msg) -> Size encodedListSizeExpr :: (forall t. ToCBOR t => Proxy t -> Size) -> Proxy [Heartbeat msg] -> Size
ToCBOR msg => SignableRepresentation (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods getSignableRepresentation :: Heartbeat msg -> ByteString
Eq msg => Eq (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat Methods (==) :: Heartbeat msg -> Heartbeat msg -> Bool Source # (/=) :: Heartbeat msg -> Heartbeat msg -> Bool Source #
type Rep (Heartbeat msg) Source #
Instance details Defined in Hydra.Network.Heartbeat type Rep (Heartbeat msg) = D1 ('MetaData "Heartbeat" "Hydra.Network.Heartbeat" "hydra-node-0.13.0-HKlbaPrFKjs2dhEMwn7ono" 'False) (C1 ('MetaCons "Data" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 NodeId) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 msg)) :+: C1 ('MetaCons "Ping" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 NodeId)))

heartbeatDelay :: DiffTime Source #

Delay between each heartbeat check.

livenessDelay :: DiffTime Source #

Maximal delay between expected and sent heartbeats.

type ConnectionMessages m = Connectivity -> m () Source #

withHeartbeat :: (MonadAsync m, MonadDelay m) => NodeId -> ConnectionMessages m -> NetworkComponent m (Heartbeat msg) a -> NetworkComponent m msg a Source #

Wrap a NetworkComponent and handle sending/receiving of heartbeats.

updateStateFromIncomingMessages :: (MonadSTM m, MonadMonotonicTime m) => TVar m HeartbeatState -> ConnectionMessages m -> NetworkCallback msg m -> NetworkCallback (Heartbeat msg) m Source #

updateStateFromOutgoingMessages :: (MonadSTM m, MonadMonotonicTime m) => NodeId -> TVar m HeartbeatState -> Network m (Heartbeat msg) -> Network m msg Source #

updateLastSent :: MonadSTM m => TVar m HeartbeatState -> Time -> m () Source #

checkHeartbeatState :: (MonadDelay m, MonadSTM m) => NodeId -> TVar m HeartbeatState -> Network m (Heartbeat msg) -> m () Source #

shouldSendHeartbeat :: Time -> HeartbeatState -> Bool Source #

checkRemoteParties :: (MonadDelay m, MonadSTM m) => TVar m HeartbeatState -> ConnectionMessages m -> m () Source #

updateSuspected :: MonadSTM m => TVar m HeartbeatState -> Time -> m (Set NodeId) Source #

checkTimeout :: (DiffTime -> DiffTime) -> Time -> Time -> Bool Source #